presentation layer in information technology

Engineering Mathematics
Discrete Mathematics
Operating System
Computer Networks
Digital Logic and Design
C Programming
Data Structures
Theory of Computation
Compiler Design
Computer Org and Architecture

Presentation Layer in OSI model

Prerequisite : OSI Model

Introduction : Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model. This layer is also known as Translation layer, as this layer serves as a data translator for the network. The data which this layer receives from the Application Layer is extracted and manipulated here as per the required format to transmit over the network. The main responsibility of this layer is to provide or define the data format and encryption. The presentation layer is also called as Syntax layer since it is responsible for maintaining the proper syntax of the data which it either receives or transmits to other layer(s).

Functions of Presentation Layer :

The presentation layer, being the 6th layer in the OSI model, performs several types of functions, which are described below-

Presentation layer format and encrypts data to be sent across the network.
This layer takes care that the data is sent in such a way that the receiver will understand the information (data) and will be able to use the data efficiently and effectively.
This layer manages the abstract data structures and allows high-level data structures (example- banking records), which are to be defined or exchanged.
This layer carries out the encryption at the transmitter and decryption at the receiver.
This layer carries out data compression to reduce the bandwidth of the data to be transmitted (the primary goal of data compression is to reduce the number of bits which is to be transmitted).
This layer is responsible for interoperability (ability of computers to exchange and make use of information) between encoding methods as different computers use different encoding methods.
This layer basically deals with the presentation part of the data.
Presentation layer, carries out the data compression (number of bits reduction while transmission), which in return improves the data throughput.
This layer also deals with the issues of string representation.
The presentation layer is also responsible for integrating all the formats into a standardized format for efficient and effective communication.
This layer encodes the message from the user-dependent format to the common format and vice-versa for communication between dissimilar systems.
This layer deals with the syntax and semantics of the messages.
This layer also ensures that the messages which are to be presented to the upper as well as the lower layer should be standardized as well as in an accurate format too.
Presentation layer is also responsible for translation, formatting, and delivery of information for processing or display.
This layer also performs serialization (process of translating a data structure or an object into a format that can be stored or transmitted easily).

Features of Presentation Layer in the OSI model: Presentation layer, being the 6th layer in the OSI model, plays a vital role while communication is taking place between two devices in a network.

List of features which are provided by the presentation layer are:

Presentation layer could apply certain sophisticated compression techniques, so fewer bytes of data are required to represent the information when it is sent over the network.
If two or more devices are communicating over an encrypted connection, then this presentation layer is responsible for adding encryption on the sender’s end as well as the decoding the encryption on the receiver’s end so that it can represent the application layer with unencrypted, readable data.
This layer formats and encrypts data to be sent over a network, providing freedom from compatibility problems.
This presentation layer also negotiates the Transfer Syntax.
This presentation layer is also responsible for compressing data it receives from the application layer before delivering it to the session layer (which is the 5th layer in the OSI model) and thus improves the speed as well as the efficiency of communication by minimizing the amount of the data to be transferred.

Working of Presentation Layer in the OSI model : Presentation layer in the OSI model, as a translator, converts the data sent by the application layer of the transmitting node into an acceptable and compatible data format based on the applicable network protocol and architecture. Upon arrival at the receiving computer, the presentation layer translates data into an acceptable format usable by the application layer. Basically, in other words, this layer takes care of any issues occurring when transmitted data must be viewed in a format different from the original format. Being the functional part of the OSI mode, the presentation layer performs a multitude (large number of) data conversion algorithms and character translation functions. Mainly, this layer is responsible for managing two network characteristics: protocol (set of rules) and architecture.

Presentation Layer Protocols : Presentation layer being the 6th layer, but the most important layer in the OSI model performs several types of functionalities, which makes sure that data which is being transferred or received should be accurate or clear to all the devices which are there in a closed network. Presentation Layer, for performing translations or other specified functions, needs to use certain protocols which are defined below –

Apple Filing Protocol (AFP): Apple Filing Protocol is the proprietary network protocol (communications protocol) that offers services to macOS or the classic macOS. This is basically the network file control protocol specifically designed for Mac-based platforms.
Lightweight Presentation Protocol (LPP): Lightweight Presentation Protocol is that protocol which is used to provide ISO presentation services on the top of TCP/IP based protocol stacks.
NetWare Core Protocol (NCP): NetWare Core Protocol is the network protocol which is used to access file, print, directory, clock synchronization, messaging, remote command execution and other network service functions.
Network Data Representation (NDR): Network Data Representation is basically the implementation of the presentation layer in the OSI model, which provides or defines various primitive data types, constructed data types and also several types of data representations.
External Data Representation (XDR): External Data Representation (XDR) is the standard for the description and encoding of data. It is useful for transferring data between computer architectures and has been used to communicate data between very diverse machines. Converting from local representation to XDR is called encoding, whereas converting XDR into local representation is called decoding.
Secure Socket Layer (SSL): The Secure Socket Layer protocol provides security to the data that is being transferred between the web browser and the server. SSL encrypts the link between a web server and a browser, which ensures that all data passed between them remains private and free from attacks.

Please Login to comment...

Improve your Coding Skills with Practice

What kind of Experience do you want to share?

Layer 6 Presentation Layer

De/Encryption, Encoding, String representation

The presentation layer (data presentation layer, data provision level) sets the system-dependent representation of the data (for example, ASCII, EBCDIC) into an independent form, enabling the syntactically correct data exchange between different systems. Also, functions such as data compression and encryption are guaranteed that data to be sent by the application layer of a system that can be read by the application layer of another system to the layer 6. The presentation layer. If necessary, the presentation layer acts as a translator between different data formats, by making an understandable for both systems data format, the ASN.1 (Abstract Syntax Notation One) used.

OSI Layer 6 - Presentation Layer

The presentation layer is responsible for the delivery and formatting of information to the application layer for further processing or display. It relieves the application layer of concern regarding syntactical differences in data representation within the end-user systems. An example of a presentation service would be the conversion of an EBCDIC-coded text computer file to an ASCII-coded file. The presentation layer is the lowest layer at which application programmers consider data structure and presentation, instead of simply sending data in the form of datagrams or packets between hosts. This layer deals with issues of string representation - whether they use the Pascal method (an integer length field followed by the specified amount of bytes) or the C/C++ method (null-terminated strings, e.g. "thisisastring\0"). The idea is that the application layer should be able to point at the data to be moved, and the presentation layer will deal with the rest. Serialization of complex data structures into flat byte-strings (using mechanisms such as TLV or XML) can be thought of as the key functionality of the presentation layer. Encryption is typically done at this level too, although it can be done on the application, session, transport, or network layers, each having its own advantages and disadvantages. Decryption is also handled at the presentation layer. For example, when logging on to bank account sites the presentation layer will decrypt the data as it is received.[1] Another example is representing structure, which is normally standardized at this level, often by using XML. As well as simple pieces of data, like strings, more complicated things are standardized in this layer. Two common examples are 'objects' in object-oriented programming, and the exact way that streaming video is transmitted. In many widely used applications and protocols, no distinction is made between the presentation and application layers. For example, HyperText Transfer Protocol (HTTP), generally regarded as an application-layer protocol, has presentation-layer aspects such as the ability to identify character encoding for proper conversion, which is then done in the application layer. Within the service layering semantics of the OSI network architecture, the presentation layer responds to service requests from the application layer and issues service requests to the session layer. In the OSI model: the presentation layer ensures the information that the application layer of one system sends out is readable by the application layer of another system. For example, a PC program communicates with another computer, one using extended binary coded decimal interchange code (EBCDIC) and the other using ASCII to represent the same characters. If necessary, the presentation layer might be able to translate between multiple data formats by using a common format. Wikipedia

Data conversion
Character code translation
Compression
Encryption and Decryption

The Presentation OSI Layer is usually composed of 2 sublayers that are:

CASE common application service element

ACSE	Association Control Service Element
ROSE	Remote Operation Service Element
CCR	Commitment Concurrency and Recovery
RTSE	Reliable Transfer Service Element

SASE specific application service element

FTAM	File Transfer, Access and Manager
VT	Virtual Terminal
MOTIS	Message Oriented Text Interchange Standard
CMIP	Common Management Information Protocol
JTM	Job Transfer and Manipulation
MMS	Manufacturing Messaging Service
RDA	Remote Database Access
DTP	Distributed Transaction Processing

Layer 7 Application Layer

Layer 6 presentation layer, layer 5 session layer, layer 4 transport layer, layer 3 network layer, layer 2 data link layer, layer 1 physical layer.

The OSI Model – The 7 Layers of Networking Explained in Plain English

By Chloe Tucker

This article explains the Open Systems Interconnection (OSI) model and the 7 layers of networking, in plain English.

The OSI model is a conceptual framework that is used to describe how a network functions. In plain English, the OSI model helped standardize the way computer systems send information to each other.

Learning networking is a bit like learning a language - there are lots of standards and then some exceptions. Therefore, it’s important to really understand that the OSI model is not a set of rules. It is a tool for understanding how networks function.

Once you learn the OSI model, you will be able to further understand and appreciate this glorious entity we call the Internet, as well as be able to troubleshoot networking issues with greater fluency and ease.

All hail the Internet!

Prerequisites

You don’t need any prior programming or networking experience to understand this article. However, you will need:

Basic familiarity with common networking terms (explained below)
A curiosity about how things work :)

Learning Objectives

Over the course of this article, you will learn:

What the OSI model is
The purpose of each of the 7 layers
The problems that can happen at each of the 7 layers
The difference between TCP/IP model and the OSI model

Common Networking Terms

Here are some common networking terms that you should be familiar with to get the most out of this article. I’ll use these terms when I talk about OSI layers next.

A node is a physical electronic device hooked up to a network, for example a computer, printer, router, and so on. If set up properly, a node is capable of sending and/or receiving information over a network.

Nodes may be set up adjacent to one other, wherein Node A can connect directly to Node B, or there may be an intermediate node, like a switch or a router, set up between Node A and Node B.

Typically, routers connect networks to the Internet and switches operate within a network to facilitate intra-network communication. Learn more about hub vs. switch vs. router.

Here's an example:

For the nitpicky among us (yep, I see you), host is another term that you will encounter in networking. I will define a host as a type of node that requires an IP address. All hosts are nodes, but not all nodes are hosts. Please Tweet angrily at me if you disagree.

Links connect nodes on a network. Links can be wired, like Ethernet, or cable-free, like WiFi.

Links to can either be point-to-point, where Node A is connected to Node B, or multipoint, where Node A is connected to Node B and Node C.

When we’re talking about information being transmitted, this may also be described as a one-to-one vs. a one-to-many relationship.

A protocol is a mutually agreed upon set of rules that allows two nodes on a network to exchange data.

“A protocol defines the rules governing the syntax (what can be communicated), semantics (how it can be communicated), and synchronization (when and at what speed it can be communicated) of the communications procedure. Protocols can be implemented on hardware, software, or a combination of both. Protocols can be created by anyone, but the most widely adopted protocols are based on standards.” - The Illustrated Network.

Both wired and cable-free links can have protocols.

While anyone can create a protocol, the most widely adopted protocols are often based on standards published by Internet organizations such as the Internet Engineering Task Force (IETF).

A network is a general term for a group of computers, printers, or any other device that wants to share data.

Network types include LAN, HAN, CAN, MAN, WAN, BAN, or VPN. Think I’m just randomly rhyming things with the word can ? I can ’t say I am - these are all real network types. Learn more here .

Topology describes how nodes and links fit together in a network configuration, often depicted in a diagram. Here are some common network topology types:

What is Network Topology? Best Guides to Types & Diagrams - DNSstuff

A network consists of nodes, links between nodes, and protocols that govern data transmission between nodes.

At whatever scale and complexity networks get to, you will understand what’s happening in all computer networks by learning the OSI model and 7 layers of networking.

What is the OSI Model?

The OSI model consists of 7 layers of networking.

First, what’s a layer?

No, a layer - not a lair . Here there are no dragons.

A layer is a way of categorizing and grouping functionality and behavior on and of a network.

In the OSI model, layers are organized from the most tangible and most physical, to less tangible and less physical but closer to the end user.

Each layer abstracts lower level functionality away until by the time you get to the highest layer. All the details and inner workings of all the other layers are hidden from the end user.

How to remember all the names of the layers? Easy.

Please | Physical Layer
Do | Data Link Layer
Not | Network Layer
Tell (the) | Transport Layer
Secret | Session Layer
Password (to) | Presentation Layer
Anyone | Application Layer

Keep in mind that while certain technologies, like protocols, may logically “belong to” one layer more than another, not all technologies fit neatly into a single layer in the OSI model. For example, Ethernet, 802.11 (Wifi) and the Address Resolution Protocol (ARP) procedure operate on >1 layer.

The OSI is a model and a tool, not a set of rules.

OSI Layer 1

Layer 1 is the physical layer . There’s a lot of technology in Layer 1 - everything from physical network devices, cabling, to how the cables hook up to the devices. Plus if we don’t need cables, what the signal type and transmission methods are (for example, wireless broadband).

Instead of listing every type of technology in Layer 1, I’ve created broader categories for these technologies. I encourage readers to learn more about each of these categories:

Nodes (devices) and networking hardware components. Devices include hubs, repeaters, routers, computers, printers, and so on. Hardware components that live inside of these devices include antennas, amplifiers, Network Interface Cards (NICs), and more.
Device interface mechanics. How and where does a cable connect to a device (cable connector and device socket)? What is the size and shape of the connector, and how many pins does it have? What dictates when a pin is active or inactive?
Functional and procedural logic. What is the function of each pin in the connector - send or receive? What procedural logic dictates the sequence of events so a node can start to communicate with another node on Layer 2?
Cabling protocols and specifications. Ethernet (CAT), USB, Digital Subscriber Line (DSL) , and more. Specifications include maximum cable length, modulation techniques, radio specifications, line coding, and bits synchronization (more on that below).
Cable types. Options include shielded or unshielded twisted pair, untwisted pair, coaxial and so on. Learn more about cable types here .
Signal type. Baseband is a single bit stream at a time, like a railway track - one-way only. Broadband consists of multiple bit streams at the same time, like a bi-directional highway.
Signal transmission method (may be wired or cable-free). Options include electrical (Ethernet), light (optical networks, fiber optics), radio waves (802.11 WiFi, a/b/g/n/ac/ax variants or Bluetooth). If cable-free, then also consider frequency: 2.5 GHz vs. 5 GHz. If it’s cabled, consider voltage. If cabled and Ethernet, also consider networking standards like 100BASE-T and related standards.

The data unit on Layer 1 is the bit.

A bit the smallest unit of transmittable digital information. Bits are binary, so either a 0 or a 1. Bytes, consisting of 8 bits, are used to represent single characters, like a letter, numeral, or symbol.

Bits are sent to and from hardware devices in accordance with the supported data rate (transmission rate, in number of bits per second or millisecond) and are synchronized so the number of bits sent and received per unit of time remains consistent (this is called bit synchronization). The way bits are transmitted depends on the signal transmission method.

Nodes can send, receive, or send and receive bits. If they can only do one, then the node uses a simplex mode. If they can do both, then the node uses a duplex mode. If a node can send and receive at the same time, it’s full-duplex – if not, it’s just half-duplex.

The original Ethernet was half-duplex. Full-duplex Ethernet is an option now, given the right equipment.

How to Troubleshoot OSI Layer 1 Problems

Here are some Layer 1 problems to watch out for:

Defunct cables, for example damaged wires or broken connectors
Broken hardware network devices, for example damaged circuits
Stuff being unplugged (...we’ve all been there)

If there are issues in Layer 1, anything beyond Layer 1 will not function properly.

Layer 1 contains the infrastructure that makes communication on networks possible.

It defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating physical links between network devices. - Source

Fun fact: deep-sea communications cables transmit data around the world. This map will blow your mind: https://www.submarinecablemap.com/

And because you made it this far, here’s a koala:

OSI Layer 2

Layer 2 is the data link layer . Layer 2 defines how data is formatted for transmission, how much data can flow between nodes, for how long, and what to do when errors are detected in this flow.

In more official tech terms:

Line discipline. Who should talk for how long? How long should nodes be able to transit information for?
Flow control. How much data should be transmitted?
Error control - detection and correction . All data transmission methods have potential for errors, from electrical spikes to dirty connectors. Once Layer 2 technologies tell network administrators about an issue on Layer 2 or Layer 1, the system administrator can correct for those errors on subsequent layers. Layer 2 is mostly concerned with error detection, not error correction. ( Source )

There are two distinct sublayers within Layer 2:

Media Access Control (MAC): the MAC sublayer handles the assignment of a hardware identification number, called a MAC address, that uniquely identifies each device on a network. No two devices should have the same MAC address. The MAC address is assigned at the point of manufacturing. It is automatically recognized by most networks. MAC addresses live on Network Interface Cards (NICs). Switches keep track of all MAC addresses on a network. Learn more about MAC addresses on PC Mag and in this article . Learn more about network switches here .
Logical Link Control (LLC): the LLC sublayer handles framing addressing and flow control. The speed depends on the link between nodes, for example Ethernet or Wifi.

The data unit on Layer 2 is a frame .

Each frame contains a frame header, body, and a frame trailer:

Header: typically includes MAC addresses for the source and destination nodes.
Body: consists of the bits being transmitted.
Trailer: includes error detection information. When errors are detected, and depending on the implementation or configuration of a network or protocol, frames may be discarded or the error may be reported up to higher layers for further error correction. Examples of error detection mechanisms: Cyclic Redundancy Check (CRC) and Frame Check Sequence (FCS). Learn more about error detection techniques here .

Example of frames, the network layer, and the physical layer

Typically there is a maximum frame size limit, called an Maximum Transmission Unit, MTU. Jumbo frames exceed the standard MTU, learn more about jumbo frames here .

How to Troubleshoot OSI Layer 2 Problems

Here are some Layer 2 problems to watch out for:

All the problems that can occur on Layer 1
Unsuccessful connections (sessions) between two nodes
Sessions that are successfully established but intermittently fail
Frame collisions

The Data Link Layer allows nodes to communicate with each other within a local area network. The foundations of line discipline, flow control, and error control are established in this layer.

OSI Layer 3

Layer 3 is the network layer . This is where we send information between and across networks through the use of routers. Instead of just node-to-node communication, we can now do network-to-network communication.

Routers are the workhorse of Layer 3 - we couldn’t have Layer 3 without them. They move data packets across multiple networks.

Not only do they connect to Internet Service Providers (ISPs) to provide access to the Internet, they also keep track of what’s on its network (remember that switches keep track of all MAC addresses on a network), what other networks it’s connected to, and the different paths for routing data packets across these networks.

Routers store all of this addressing and routing information in routing tables.

Here’s a simple example of a routing table:

A routing table showing the destination, subnet mask, and interface

The data unit on Layer 3 is the data packet . Typically, each data packet contains a frame plus an IP address information wrapper. In other words, frames are encapsulated by Layer 3 addressing information.

The data being transmitted in a packet is also sometimes called the payload . While each packet has everything it needs to get to its destination, whether or not it makes it there is another story.

Layer 3 transmissions are connectionless, or best effort - they don't do anything but send the traffic where it’s supposed to go. More on data transport protocols on Layer 4.

Once a node is connected to the Internet, it is assigned an Internet Protocol (IP) address, which looks either like 172.16. 254.1 (IPv4 address convention) or like 2001:0db8:85a3:0000:0000:8a2e:0370:7334 (IPv6 address convention). Routers use IP addresses in their routing tables.

IP addresses are associated with the physical node’s MAC address via the Address Resolution Protocol (ARP), which resolves MAC addresses with the node’s corresponding IP address.

ARP is conventionally considered part of Layer 2, but since IP addresses don’t exist until Layer 3, it’s also part of Layer 3.

How to Troubleshoot OSI Layer 3 Problems

Here are some Layer 3 problems to watch out for:

All the problems that can crop up on previous layers :)
Faulty or non-functional router or other node
IP address is incorrectly configured

Many answers to Layer 3 questions will require the use of command-line tools like ping , trace , show ip route , or show ip protocols . Learn more about troubleshooting on layer 1-3 here .

The Network Layer allows nodes to connect to the Internet and send information across different networks.

OSI Layer 4

Layer 4 is the transport layer . This where we dive into the nitty gritty specifics of the connection between two nodes and how information is transmitted between them. It builds on the functions of Layer 2 - line discipline, flow control, and error control.

This layer is also responsible for data packet segmentation, or how data packets are broken up and sent over the network.

Unlike the previous layer, Layer 4 also has an understanding of the whole message, not just the contents of each individual data packet. With this understanding, Layer 4 is able to manage network congestion by not sending all the packets at once.

The data units of Layer 4 go by a few names. For TCP, the data unit is a packet. For UDP, a packet is referred to as a datagram. I’ll just use the term data packet here for the sake of simplicity.

Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are two of the most well-known protocols in Layer 4.

TCP, a connection-oriented protocol, prioritizes data quality over speed.

TCP explicitly establishes a connection with the destination node and requires a handshake between the source and destination nodes when data is transmitted. The handshake confirms that data was received. If the destination node does not receive all of the data, TCP will ask for a retry.

TCP also ensures that packets are delivered or reassembled in the correct order. Learn more about TCP here .

UDP, a connectionless protocol, prioritizes speed over data quality. UDP does not require a handshake, which is why it’s called connectionless.

Because UDP doesn’t have to wait for this acknowledgement, it can send data at a faster rate, but not all of the data may be successfully transmitted and we’d never know.

If information is split up into multiple datagrams, unless those datagrams contain a sequence number, UDP does not ensure that packets are reassembled in the correct order. Learn more about UDP here .

TCP and UDP both send data to specific ports on a network device, which has an IP address. The combination of the IP address and the port number is called a socket.

Learn more about sockets here .

Learn more about the differences and similarities between these two protocols here .

How to Troubleshoot OSI Layer 4 Problems

Here are some Layer 4 problems to watch out for:

Blocked ports - check your Access Control Lists (ACL) & firewalls
Quality of Service (QoS) settings. QoS is a feature of routers/switches that can prioritize traffic, and they can really muck things up. Learn more about QoS here .

The Transport Layer provides end-to-end transmission of a message by segmenting a message into multiple data packets; the layer supports connection-oriented and connectionless communication.

OSI Layer 5

Layer 5 is the session layer . This layer establishes, maintains, and terminates sessions.

A session is a mutually agreed upon connection that is established between two network applications. Not two nodes! Nope, we’ve moved on from nodes. They were so Layer 4.

Just kidding, we still have nodes, but Layer 5 doesn’t need to retain the concept of a node because that’s been abstracted out (taken care of) by previous layers.

So a session is a connection that is established between two specific end-user applications. There are two important concepts to consider here:

Client and server model: the application requesting the information is called the client, and the application that has the requested information is called the server.
Request and response model: while a session is being established and during a session, there is a constant back-and-forth of requests for information and responses containing that information or “hey, I don’t have what you’re requesting.”

Sessions may be open for a very short amount of time or a long amount of time. They may fail sometimes, too.

Depending on the protocol in question, various failure resolution processes may kick in. Depending on the applications/protocols/hardware in use, sessions may support simplex, half-duplex, or full-duplex modes.

Examples of protocols on Layer 5 include Network Basic Input Output System (NetBIOS) and Remote Procedure Call Protocol (RPC), and many others.

From here on out (layer 5 and up), networks are focused on ways of making connections to end-user applications and displaying data to the user.

How to Troubleshoot OSI Layer 5 Problems

Here are some Layer 5 problems to watch out for:

Servers are unavailable
Servers are incorrectly configured, for example Apache or PHP configs
Session failure - disconnect, timeout, and so on.

The Session Layer initiates, maintains, and terminates connections between two end-user applications. It responds to requests from the presentation layer and issues requests to the transport layer.

OSI Layer 6

Layer 6 is the presentation layer . This layer is responsible for data formatting, such as character encoding and conversions, and data encryption.

The operating system that hosts the end-user application is typically involved in Layer 6 processes. This functionality is not always implemented in a network protocol.

Layer 6 makes sure that end-user applications operating on Layer 7 can successfully consume data and, of course, eventually display it.

There are three data formatting methods to be aware of:

American Standard Code for Information Interchange (ASCII): this 7-bit encoding technique is the most widely used standard for character encoding. One superset is ISO-8859-1, which provides most of the characters necessary for languages spoken in Western Europe.
Extended Binary-Coded Decimal Interchange Code (EBDCIC): designed by IBM for mainframe usage. This encoding is incompatible with other character encoding methods.
Unicode: character encodings can be done with 32-, 16-, or 8-bit characters and attempts to accommodate every known, written alphabet.

Learn more about character encoding methods in this article , and also here .

Encryption: SSL or TLS encryption protocols live on Layer 6. These encryption protocols help ensure that transmitted data is less vulnerable to malicious actors by providing authentication and data encryption for nodes operating on a network. TLS is the successor to SSL.

How to Troubleshoot OSI Layer 6 Problems

Here are some Layer 6 problems to watch out for:

Non-existent or corrupted drivers
Incorrect OS user access level

The Presentation Layer formats and encrypts data.

OSI Layer 7

Layer 7 is the application layer .

True to its name, this is the layer that is ultimately responsible for supporting services used by end-user applications. Applications include software programs that are installed on the operating system, like Internet browsers (for example, Firefox) or word processing programs (for example, Microsoft Word).

Applications can perform specialized network functions under the hood and require specialized services that fall under the umbrella of Layer 7.

Electronic mail programs, for example, are specifically created to run over a network and utilize networking functionality, such as email protocols, which fall under Layer 7.

Applications will also control end-user interaction, such as security checks (for example, MFA), identification of two participants, initiation of an exchange of information, and so on.

Protocols that operate on this level include File Transfer Protocol (FTP), Secure Shell (SSH), Simple Mail Transfer Protocol (SMTP), Internet Message Access Protocol (IMAP), Domain Name Service (DNS), and Hypertext Transfer Protocol (HTTP).

While each of these protocols serve different functions and operate differently, on a high level they all facilitate the communication of information. ( Source )

How to Troubleshoot OSI Layer 7 Problems

Here are some Layer 7 problems to watch out for:

All issues on previous layers
Incorrectly configured software applications
User error (... we’ve all been there)

The Application Layer owns the services and functions that end-user applications need to work. It does not include the applications themselves.

Our Layer 1 koala is all grown up.

Learning check - can you apply makeup to a koala?

Don’t have a koala?

Well - answer these questions instead. It’s the next best thing, I promise.

What is the OSI model?
What are each of the layers?
How could I use this information to troubleshoot networking issues?

Congratulations - you’ve taken one step farther to understanding the glorious entity we call the Internet.

Learning Resources

Many, very smart people have written entire books about the OSI model or entire books about specific layers. I encourage readers to check out any O’Reilly-published books about the subject or about network engineering in general.

Here are some resources I used when writing this article:

The Illustrated Network, 2nd Edition
Protocol Data Unit (PDU): https://www.geeksforgeeks.org/difference-between-segments-packets-and-frames/
Troubleshooting Along the OSI Model: https://www.pearsonitcertification.com/articles/article.aspx?p=1730891
The OSI Model Demystified: https://www.youtube.com/watch?v=HEEnLZV2wGI
OSI Model for Dummies: https://www.dummies.com/programming/networking/layers-in-the-osi-model-of-a-computer-network/

Chloe Tucker is an artist and computer science enthusiast based in Portland, Oregon. As a former educator, she's continuously searching for the intersection of learning and teaching, or technology and art. Reach out to her on Twitter @_chloetucker and check out her website at chloe.dev .

If you read this far, thank the author to show them you care. Say Thanks

Learn to code for free. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Get started

Artificial Intelligence
Generative AI
Cloud Computing
CPUs and Processors
Data Center
Edge Computing
Enterprise Storage
Virtualization
Enterprise Buyer’s Guides
Internet of Things
Network Management Software
Network Security
United States
Newsletters
Foundry Careers
Terms of Service
Privacy Policy
Cookie Policy
Copyright Notice
Member Preferences
About AdChoices
E-commerce Links
Your California Privacy Rights

Our Network

Computerworld

What is the OSI model? How to explain and remember its 7 layers

A tutorial on the open systems interconnection (osi) networking reference model plus tips on how to memorize the seven layers..

AI image 7 layers of OSI model telecommunications network

The Open Systems Interconnect (OSI) model is a conceptual framework that describes networking or telecommunications systems as seven layers, each with its own function.

The layers help network pros visualize what is going on within their networks and can help network managers narrow down problems (is it a physical issue or something with the application?), as well as computer programmers (when developing an application, which other layers does it need to work with?). Tech vendors selling new products will often refer to the OSI model to help customers understand which layer their products work with or whether it works “across the stack”.

The 7 layers of the OSI model

The layers (from bottom to top) are: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

It wasn’t always this way. Conceived in the 1970s when computer networking was taking off, two separate models were merged in 1983 and published in 1984 to create the OSI model that most people are familiar with today. Most descriptions of the OSI model go from top to bottom, with the numbers going from Layer 7 down to Layer 1.

The layers, and what they represent, are as follows:

Layer 7: Application

The Application Layer in the OSI model is the layer that is the “closest to the end user”. It receives information directly from users and displays incoming data to the user. Oddly enough, applications themselves do not reside at the application layer. Instead the layer facilitates communication through lower layers in order to establish connections with applications at the other end. Web browsers (Google Chrome, Firefox, Safari, etc.) TelNet, and FTP, are examples of communications that rely on Layer 7.

Layer 6: Presentation

The Presentation Layer represents the area that is independent of data representation at the application layer. In general, it represents the preparation or translation of application format to network format, or from network formatting to application format. In other words, the layer “presents” data for the application or the network. A good example of this is encryption and decryption of data for secure transmission; this happens at Layer 6.

Layer 5: Session

When two computers or other networked devices need to speak with one another, a session needs to be created, and this is done at the Session Layer . Functions at this layer involve setup, coordination (how long should a system wait for a response, for example) and termination between the applications at each end of the session.

Layer 4: Transport

The Transport Layer deals with the coordination of the data transfer between end systems and hosts. How much data to send, at what rate, where it goes, etc. The best known example of the Transport Layer is the Transmission Control Protocol (TCP), which is built on top of the Internet Protocol (IP), commonly known as TCP/IP. TCP and UDP port numbers work at Layer 4, while IP addresses work at Layer 3, the Network Layer.

Layer 3: Network

Here at the Network Layer is where you’ll find most of the router functionality that most networking professionals care about and love. In its most basic sense, this layer is responsible for packet forwarding, including routing through different routers . You might know that your Boston computer wants to connect to a server in California, but there are millions of different paths to take. Routers at this layer help do this efficiently.

Layer 2: Data Link

The Data Link Layer provides node-to-node data transfer (between two directly connected nodes), and also handles error correction from the physical layer. Two sublayers exist here as well–the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. In the networking world, most switches operate at Layer 2. But it’s not that simple. Some switches also operate at Layer 3 in order to support virtual LANs that may span more than one switch subnet, which requires routing capabilities.

Layer 1: Physical

At the bottom of our OSI model we have the Physical Layer, which represents the electrical and physical representation of the system. This can include everything from the cable type, radio frequency link (as in a Wi-Fi network), as well as the layout of pins, voltages, and other physical requirements. When a networking problem occurs, many networking pros go right to the physical layer to check that all of the cables are properly connected and that the power plug hasn’t been pulled from the router, switch or computer, for example.

Why you need to know the 7 OSI layers

Most people in IT will likely need to know about the different layers when they’re going for their certifications, much like a civics student needs to learn about the three branches of the US government. After that, you hear about the OSI model when vendors are making pitches about which layers their products work with.

In a Quora post asking about the purpose of the OSI model, Vikram Kumar answered this way: “The purpose of the OSI reference model is to guide vendors and developers so the digital communication products and software programs they create will interoperate, and to facilitate clear comparisons among communications tools.”

While some people may argue that the OSI model is obsolete (due to its conceptual nature) and less important than the four layers of the TCP/IP model, Kumar says that “it is difficult to read about networking technology today without seeing references to the OSI model and its layers, because the model’s structure helps to frame discussions of protocols and contrast various technologies.”

If you can understand the OSI model and its layers, you can also then understand which protocols and devices can interoperate with each other when new technologies are developed and explained.

The OSI model remains relevant

In a post on GeeksforGeeks, contributor Vabhav Bilotia argues several reasons why the OSI model remains relevant, especially when it comes to security and determining where technical risks and vulnerabilities may exist.

For example, by understanding the different layers, enterprise security teams can identify and classify physical access, where the data is sitting, and provide an inventory of the applications that employees use to access data and resources.

“Knowing where the majority of your company’s data is held, whether on-premises or in cloud services, will help define your information security policy,” writes Bilotia. “You can invest in the correct solutions that provide you data visibility within the proper OSI layers once you have this knowledge.”

In addition, the OSI model can be used to understand cloud infrastructure migrations, particularly when it comes to securing data within the cloud.

And because the model has been around for so long and understood by so many, the uniform vocabulary and terms helps networking professionals understand quickly about the components of the networking system “While this paradigm is not directly implemented in today’s TCP/IP networks, it is a useful conceptual model for relating multiple technologies to one another and implementing the appropriate technology in the appropriate way,” Bilotia writes. We couldn’t agree more.

How to remember the OSI Model 7 layers: 8 mnemonic tricks

If you need to memorize the layers for a college or certification test, here are a few sentences to help remember them in order. The first letter of each word is the same as the first letter an OSI layer.

From Application to Physical (Layer 7 to Layer 1):

All People Seem To Need Data Processing
All Pros Search Top Notch Donut Places
A Penguin Said That Nobody Drinks Pepsi
A Priest Saw Two Nuns Doing Pushups

From Physical to Application (Layer 1 to Layer 7):

Please Do Not Throw Sausage Pizza Away
Pew! Dead Ninja Turtles Smell Particularly Awful
People Don’t Need To See Paula Abdul
Pete Doesn’t Need To Sell Pickles Anymore

More from this author

What is a network router how ai networking driving its evolution, bgp: what is border gateway protocol, and how does it work, what is a virtual machine, and why are they so useful, what is a network switch and how does it work, what is zero trust network access, what is sd-wan, and what does it mean for networking, security, cloud, what is beamforming and how does it make wireless better, colleges expand vpn capacity, conferencing to answer covid-19, show me more, bash command cheat sheet.

New brain-on-a-chip platform to deliver 460x efficiency boost for AI tasks

Data centers are now critical national infrastructure, says UK government

Has the hype around ‘Internet of Things’ paid off? | Ep. 145

Episode 1: Understanding Cisco’s Converged SDN Transport

Episode 2: Pluggable Optics and the Internet for the Future

How to determine if a string contains a regular expression

How to use the Grep command

How to see how many days passed since the beginning of the Linux epoch

Presentation Layer

The Presentation Layer is the sixth layer in the OSI model . It sits right above the Session Layer and below the Application Layer. Its main job is to handle how data is presented to the application . In other words, it ensures that the data is in a format that both the sending and receiving systems can understand.

Think of the Presentation Layer as a translator. Just like you might need a translator to understand a message in a foreign language, this layer translates data from one format to another. It ensures that the data sent from an application is correctly formatted and ready for the next layer in the OSI model to handle.

For example, when your computer sends a file over the Internet, it might be in a specific format like JPEG or PDF. The Presentation Layer translates that file into a format the receiving computer can understand and display correctly. It also ensures that any special characters or encryption are properly handled.

Functions of the Presentation Layer

The Presentation Layer has several vital functions that help ensure data is communicated effectively between systems.

Data Translation

One of the main jobs of the Presentation Layer is to translate data between different formats. When data is sent from one system to another, it might be in a format the receiving system does not understand. The Presentation Layer converts this data into an easily understood format, allowing different systems to work together smoothly.

Data Encryption/Decryption

Security is a big concern in data transmission. The Presentation Layer helps by encrypting data before it is sent. Encryption transforms data into a secure format so unauthorised people cannot easily read it. When the data reaches its destination, the Presentation Layer decrypts it, returning it to its original form to be used.

Data Compression/Decompression

The presentation layer can compress data to make data transfer faster and more efficient. Compression reduces the data's size, meaning it takes up less space and transfers more quickly. When the data arrives, the Presentation Layer decompresses it, restoring it to its original size and format.

These functions make the Presentation Layer essential for preparing data for proper communication and ensuring it is secure and efficient. This layer helps maintain smooth and reliable information exchanges across different systems by handling translation, encryption, and compression.

Examples of Presentation Layer Protocols and Formats

The Presentation Layer uses various protocols and formats to perform its tasks.

Regarding protocols, the SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are commonly used to encrypt and secure data transmitted across networks, ensuring that information remains confidential and protected from unauthorised access.

SSL and its successor, TLS, are protocols used to secure data transmission. They encrypt the data to protect it from being intercepted and read by unauthorised users. SSL/TLS ensures that information such as personal details or payment information remains private and secure as it travels across the internet.

Data Formats

Regarding data formats, the Presentation Layer is responsible for converting and optimising various data types—such as images, videos, and text—so they are displayed correctly and consistently across different platforms and devices.

JPEG and GIF

These are formats for image files. JPEG and GIF encode images for web display. The Presentation Layer helps convert these images into formats that can be viewed appropriately on different devices.

MPEG is a standard for video compression. It helps reduce the size of video files so they can be transmitted more efficiently. The Presentation Layer ensures that video data is compressed and decompressed correctly, allowing for smooth video playback.

ASCII and EBCDIC

These are character encoding standards. ASCII (American Standard Code for Information Interchange) and EBCDIC (Extended Binary Coded Decimal Interchange Code) define how text characters are represented in data. The Presentation Layer ensures that text is correctly converted from one encoding to another if needed.

These examples show how the Presentation Layer handles various data types and formats. This layer uses specific protocols and formats to ensure data is accurately translated, secured, and optimised for effective system communication.

Importance of the Presentation Layer in Networking

The Presentation Layer plays a key role in sharing data between different systems.

Ensures Proper Data Interpretation

Different systems might use different data formats. The Presentation Layer ensures that when data is sent from one system to another, it is translated into a format the receiving system can understand. This means that whether you are sending a file, a message, or any other type of data, it will be interpreted correctly on the other end.

Supports Data Security

With increasing concerns about data privacy, the Presentation Layer’s role in encryption is crucial. By encrypting data before it is sent and decrypting it when it is received, this layer helps protect sensitive information from being accessed by unauthorised individuals. This encryption ensures that data remains confidential and secure, which is especially important for secure online transactions, confidential communications, and personal information. Effective encryption within the Presentation Layer helps mitigate data breaches and unauthorised access risks, enhancing overall data security .

Improves Efficiency

The Presentation Layer also helps compress data to make transmission faster and more efficient. Compressed data takes up less space and travels more quickly across networks, making the communication process smoother and reducing the time it takes to send and receive information.

Relationship with Other Layers

The Presentation Layer doesn’t work alone; it relies on and interacts with other layers in the OSI model. Here’s how it connects with them.

Interaction with the Application Layer

The Application Layer is where software applications interact with the network. It sends data to the Presentation Layer, which prepares it for transmission. For example, when you send an email or upload a file, the Application Layer creates the data, and the Presentation Layer formats and possibly encrypts it before sending it out.

Connection with the Session Layer

The Session Layer manages sessions or connections between applications. It ensures that sessions are correctly established, maintained, and ended. Once a session is active, the Presentation Layer takes over, handling the data exchange by translating and preparing the data. It then hands the processed data back to the Session Layer for transmission.

Dependency on Lower Layers

The Presentation Layer relies on the layers below it for data transport. The Transport Layer handles the actual delivery of data across the network, ensuring it reaches the right destination. The Presentation Layer needs this layer’s services to get its formatted data to the receiving system.

The Presentation Layer deals with how data is formatted, encrypted, and compressed for system transmission. It ensures that data is prepared to be understood and used correctly by different systems. The Content Layer, on the other hand, refers to the actual data or information being conveyed, such as text, images, or video. Essentially, the Presentation Layer is concerned with how data is packaged for transfer, while the Content Layer focuses on the substance of the data itself.

In the context of an API (Application Programming Interface), the Presentation Layer handles how data is formatted and presented to the end-user or application. It takes the raw data from the API and structures it in a way that is easy to read and use. This can include converting data into formats like JSON or XML and ensuring it is displayed correctly according to the application's requirements.

The Presentation Layer offers several benefits. It ensures that data is correctly formatted so that different systems can understand it. It also provides security through data encryption, protecting sensitive information during transmission. Additionally, it improves efficiency by compressing data, which speeds up transfer times and reduces the amount of data that needs to be sent over the network.

The OSI model consists of seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer has a specific role in handling data as it moves through a network, from the physical transmission of signals to the final application interactions.

Articles you might enjoy

The OSI model is a conceptual framework that defines how different software and hardware components in a network communicate.

An application, commonly called an app or program, is a form of software that allows specific tasks to be performed on a device. "App" is a common term for an application. Applications run within the operating system until the application is closed.

what-is-an-api-application-programming-interface

An API, which stands for Application Programming Interface, is vital to modern technology. It serves as a bridge that enables different software systems to communicate and interact with each other seamlessly.

Staying up-to-date with the latest trends and technologies is paramount for technology and development. Single-page applications (SPAs) have emerged as a modern web application development cornerstone. Their ability to provide seamless user experiences and dynamic interactions has propelled them to the forefront of web development methodologies.

Piqued your interest?

We'd love to tell you more.

presentation layer in information technology

Unveiling the Interpreter: Fortifying the Presentation Layer’s Role in Cybersecurity

March 28, 2024

Cherise Esparza

Welcome back to Tea with C. As we navigate deeper into the OSI model, today’s spotlight shines on Layer 6: the Presentation Layer. The Presentation Layer, often likened to an adept interpreter in the digital realm, plays a pivotal role in the seamless transmission and reception of data across the network.

At its essence, the Presentation Layer is tasked with data translation, encryption, and compression. It ensures that the information sent from the application layer is suitably formatted for transmission across the network and can be accurately interpreted by the receiving system. This layer is a universal translator for network communications, bridging different data formats into a universally understood language.

Encryption protocols at this layer are vital for securing data at rest and in transit. They are the bedrock of data integrity and confidentiality, shielding sensitive information from prying eyes and potential cyber threats. This is where the magic of transforming data into a secure format occurs, making it an essential battleground for cybersecurity efforts.

However, the Presentation Layer is not without its vulnerabilities. Some of the most insidious security threats stem from weaknesses in the coding practices used to develop applications interacting at this layer. Buffer overflows, SQL injections, and cross-site scripting are prime examples of exploits that can lead to significant security breaches. These vulnerabilities underscore the critical importance of secure coding practices and robust input validation procedures to fend off attackers.

The roles vital to securing the Presentation Layer span a broad spectrum of cybersecurity expertise. Network security analysts play a key role in scrutinizing the data exchange protocols and ensuring that encryption measures are robust and correctly implemented. Developers adhere to a secure development lifecycle, ensuring that code is thoroughly vetted and sanitized before deployment. Lastly, the overarching vigilance of security analysts dedicated to network monitoring and logging forms the backbone of a comprehensive security strategy at this layer.

Ensuring the security of the Presentation Layer is a multifaceted challenge that requires a concerted effort from all parties involved in the development and deployment of network applications. As we gear up for our following discussion on the final layer of the OSI model , the Application Layer, remember that each layer presents unique challenges and opportunities for enhancing our cybersecurity posture. Join us next week as we conclude our exploration of the OSI model.

Share this post

SecurityGate Launches Version 4.0 of its Industry- Leading OT GRC Platform for OT Cyber Improvement

Major new features and enhancements set to transform user experience and performance SecurityGate, the provider of the leading SaaS platform for OT GRC, announced the

The Critical Role of Cybersecurity in the Automotive Industry

As the automotive industry accelerates its integration of digital technologies, vehicles are becoming more than just means of transportation; they are evolving into connected mobile

NIS2 Directive Compliance Checklist: Ensuring Robust Cybersecurity in Essential and Important Entities

The NIS2 Directive, a pivotal piece of legislation by the European Union, aims to enhance the cybersecurity posture of essential and important entities across the

SecurityGate Announces Integration with Claroty xDome.

Announcing SecurityGate’s latest integration with Claroty xDome.

Understanding the NIS2 Directive: A Comprehensive Overview

Learn about the background of the NIS2 Directive and the critical differences between NIS and NIS2.

SecurityGate Announces Integration with MicroSec to Provide Automatic Asset Inventory Synchronization

SecurityGate, the provider of the leading SaaS platform for OT cyber improvement, is excited to announce the launch of its latest technology integration with MicroSec,

5120 Woodway Dr. Suite 9003 Houston, TX 77056

SecurityGate c/o Talent Garden Calabiana Via Arcivescovo Calabiana, 6, 20139 Milano, Italy

Privacy Policy
Terms of Service
Support Terms

Platform Tour

Channel program, case studies, the business of cyber series.

Presentation Layer: Protocols, Examples, Services | Functions of Presentation Layer

Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model where all application programmer consider data structure and presentation, beyond of simply sending the data into form of datagram otherwise packets in between the hosts. Now, we will explain about what is presentation layer with its protocols, example, service ; involving with major functions of presentation Layer with ease. At the end of this article, you will completely educate about What is Presentation Layer in OSI Model without any hassle.

What is Presentation Layer?

Presentation layer is capable to handle abstract data structures, and further it helps to defined and exchange of higher-level data structures.

Presentation Layer Tutorial Headlines:

Let’s get started, functions of presentation layer.

Presentation layer performs various functions in the OSI model ; below explain each one –

Protocols of Presentation Layer

Example of presentation layer protocols:.

Here, we will discuss all examples of presentation layer protocols; below explain each one –

Multipurpose Internet Mail Extensions (MIME) : MIME protocol was introduced by Bell Communications in 1991, and it is an internet standard that provides scalable capable of email for attaching of images, sounds and text in a message.

Network News Transfer Protocol (NNTP) : This protocol is used to make connection with Usenet server and transmit all newsgroup articles in between system over internet.

Apple Filing Protocol (AFP ) : AFP protocol is designed by Apple company for sharing all files over the entire network .

NetWare Core Protocol (NCP) : NCP is a Novell client server model protocol that is designed especially for Local Area Network (LAN). It is capable to perform several functions like as file/print-sharing, clock synchronization, remote processing and messaging.

Network Data Representation (NDR) : NDR is an data encoding standard, and it is implement in the Distributed Computing Environment (DCE).

Tox : The Tox protocol is sometimes regarded as part of both the presentation and application layer , and it is used for sending peer-to-peer instant-messaging as well as video calling.

eXternal Data Representation (XDR) : This protocol provides the description and encoding of entire data, and it’s main goal is to transfer data in between dissimilar computer architecture.

Presentation Layer Services

Design issues with presentation layer, faqs (frequently asked questions), what is meant by presentation layer in osi model.

Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model that is the lowest layer, where all application programmer consider data structure and presentation, beyond of simply sending the data into form of datagram otherwise packets in between the hosts.

What protocols are used in the presentation layer?

Can you explain some presentation layer examples, what are the main functions of the presentation layer, what are services of presentation layer in osi.

Presentation layer has a responsibility for formatting, translation, and delivery of the information for getting to process otherwise display .

Now, i hope that you have completely learnt about what is presentation layer with its protocols, example, service ; involving with major functions of presentation Layer with ease. If this post is useful for you, then please share it along with your friends, family members or relatives over social media platforms like as Facebook, Instagram, Linked In, Twitter, and more.

Also Read: Data Link Layer: Protocols, Examples | Functions of Data Link Layer

OSI model (Open Systems Interconnection)

Andrew Froehlich, West Gate Networks
Linda Rosencrance
Kara Gattine, Director of Editorial Operations

What is OSI model (Open Systems Interconnection)?

OSI (Open Systems Interconnection) is a reference model for how applications communicate over a network. This model focuses on providing a visual design of how each communications layer is built on top of the other, starting with the physical cabling, all the way to the application that's trying to communicate with other devices on a network.

A reference model is a conceptual framework for understanding relationships. The purpose of the OSI reference model is to guide technology vendors and developers so the digital communications products and software programs they create can interoperate and to promote a clear framework that describes the functions of a networking or telecommunications system that's in use.

Most vendors involved in telecommunications try to describe their products and services in relation to the OSI model. This helps them differentiate among the various transport protocols, addressing schemes and communications packaging methods. And, although it's useful for guiding discussion and evaluation, the OSI model is theoretical in nature and should be used only as a general guide. That's because few network products or standard tools keep related functions together in well-defined layers, as is the case in the OSI model. The Transmission Control Protocol/Internet Protocol ( TCP/IP ) suite, for example, is the most widely used network protocol, but even it doesn't map cleanly to the OSI model.

History of the OSI model

In the 1970s, technology researchers began examining how computer systems could best communicate with each other. Over the next few years, several competing models were created and published to the community. However, it wasn't until 1984 when the International Organization for Standardization (ISO) took the best parts of competing networking reference models to propose OSI as a way to finally create a framework that technology companies around the world could use as the basis of their networking technologies .

From ISO's perspective, the easiest way to create a conceptual model was to organize the models into different abstraction layers required to organize and send data between computing systems. Looking inside each abstracted layer to see the details shows one part of this network communication process. Each layer can be thought of as a separate communication module or piece of the puzzle. But, to actually accomplish the goal of sending data from one device to another, each module must work together.

How the OSI model works

Information technology (IT) networking professionals use OSI to model or conceptualize how data is sent or received over a network. Understanding this is a foundational part of most IT networking certifications, including the Cisco Certified Network Associate (CCNA) and CompTIA Network+ certification programs. As mentioned, the model is designed to break down data transmission standards, processes and protocols over a series of seven layers, each of which is responsible for performing specific tasks concerning sending and receiving data.

The main concept of OSI is that the process of communication between two endpoints in a network can be divided into seven distinct groups of related functions, or layers. Each communicating user or program is on a device that can provide those seven layers of function.

In this architecture, each layer serves the layer above it and, in turn, is served by the layer below it. So, in a given message between users, there will be a flow of data down through the layers in the source computer, across the network and then up through the layers in the receiving computer. Only the application layer at the top of the stack doesn't provide services to a higher-level layer.

The seven layers of function are provided by a combination of applications, operating systems (OSes), network card device drivers, networking hardware and protocols that enable a system to transmit a signal over a network through various physical mediums, including twisted-pair copper, fiber optics, Wi-Fi or Long-Term Evolution (LTE) with 5G .

7 layers of the OSI model

What is the function of each layer of the OSI model? The seven Open Systems Interconnection layers are the following.

Layer 7. The application layer

The application layer enables the user -- human or software -- to interact with the application or network whenever the user elects to read messages, transfer files or perform other network-related tasks. Web browsers and other internet-connected apps, such as Outlook and Skype, use Layer 7 application protocols.

Layer 6. The presentation layer

The presentation layer translates or formats data for the application layer based on the semantics or syntax the application accepts. This layer also handles the encryption and decryption that the application layer requires.

Layer 5. The session layer

The session layer sets up, coordinates and terminates conversations between applications. Its services include authentication and reconnection after an interruption. This layer determines how long a system will wait for another application to respond. Examples of session layer protocols include X.225 and Zone Information Protocol (ZIP).

Layer 4. The transport layer

The transport layer is responsible for transferring data across a network and provides error-checking mechanisms and data flow controls. It determines how much data to send, where it gets sent and at what rate. TCP within the TCP/IP suite is the best-known example of the transport layer. This is where the communications select TCP port numbers to categorize and organize data transmissions across a network.

Layer 3. The network layer

The primary function of the network layer is to move data into and through other networks. Network layer protocols accomplish this by packaging data with correct network address information, selecting the appropriate network routes and forwarding the packaged data up the stack to the transport layer. From a TCP/IP perspective, this is where IP addresses are applied for routing purposes.

Layer 2. The data-link layer

The data-link , or protocol layer, in a program handles moving data into and out of a physical link in a network. This layer handles problems that occur as a result of bit transmission errors. It ensures that the pace of the data flow doesn't overwhelm the sending and receiving devices. This layer also permits the transmission of data to Layer 3, the network layer, where it's addressed and routed.

The data-link layer can be further divided into two sublayers. The higher layer, which is called logical link control (LLC), is responsible for multiplexing, flow control, acknowledgement and notifying upper layers if transmit/receive (TX/RX) errors occur.

The media access control sublayer is responsible for tracking data frames using MAC addresses of the sending and receiving hardware. It's also responsible for organizing each frame, marking the starting and ending bits and organizing timing regarding when each frame can be sent along the physical layer medium.

Layer 1. The physical layer

The physical layer transports data using electrical, mechanical or procedural interfaces. This layer is responsible for sending computer bits from one device to another along the network. It determines how physical connections to the network are set up and how bits are represented into predictable signals as they're transmitted either electrically, optically or via radio waves.

Cross-layer functions

Cross-layer functions, or services that may affect more than one layer, include the following:

security service telecommunication as defined by the International Telecommunication Union Standardization Sector (ITU-T) X.800 recommendation;
management functions that enable the configuration, instantiation, monitoring and terminating of the communications of two or more entities;
Multiprotocol Label Switching ( MPLS ), which operates at an OSI model layer that lies between the Layer 2 data-link layer and the Layer 3 network layer -- MPLS can carry a variety of traffic, including Ethernet frames and IP packets;
Address Resolution Protocol (ARP) translates IPv4 addresses (OSI Layer 3) into Ethernet MAC addresses (OSI Layer 2); and
domain name system (DNS), which is an application layer service that's used to look up the IP address of a domain name.

Pros and cons of the OSI model

The OSI model has a number of advantages, including the following:

It's considered a standard model in computer networking.
The model supports connectionless , as well as connection-oriented, services. Users can take advantage of connectionless services when they need faster data transmissions over the internet and the connection-oriented model when they're looking for reliability.
It has the flexibility to adapt to many protocols.
The model is more adaptable and secure than having all services bundled in one layer.

The disadvantages of the OSI model include the following:

It doesn't define any particular protocol.
The session layer, which is used for session management, and the presentation layer, which deals with user interaction, aren't as useful as other layers in the OSI model.
Some services are duplicated at various layers, such as the transport and data-link layers.
Layers can't work in parallel; each layer must wait to receive data from the previous layer.

OSI model vs. TCP/IP model

The OSI reference model describes the functions of a telecommunication or networking system, while TCP/IP is a suite of communication protocols used to interconnect network devices on the internet. TCP/IP and OSI are the most broadly used networking models for communication.

The OSI and TCP/IP models have similarities and differences. The main similarity is in their construction, as both use layers, although the OSI model consists of seven layers, while TCP/IP consists of just four layers.

Another similarity is that the upper layer for each model is the application layer, which performs the same tasks in each model but may vary according to the information each receives.

The functions performed in each model are also similar because each uses a network and transport layer to operate. The OSI and TCP/IP model are mostly used to transmit data packets, although they each use different means and paths to reach their destinations.

Additional similarities between the OSI and TCP/IP models include the following:

Both are logical models.
Both define standards for networking.
They each divide the network communication process in layers.
Both provide frameworks for creating and implementing networking standards and devices.
They enable one manufacturer to make devices and network components that can coexist and work with the devices and components made by other manufacturers.
Both divide complex functions into simpler components.

Differences between the OSI and TCP/IP models include the following:

OSI uses three layers -- application, presentation and session -- to define the functionality of upper layers, while TCP/IP uses only the application layer.
OSI uses two separate layers -- physical and data-link -- to define the functionality of the bottom layers, while TCP/IP uses only the link layer.
OSI uses the network layer to define the routing standards and protocols, while TCP/IP uses the internet layer.

Next: Explore 12 common network protocols all network engineers should know here .

Continue Reading About OSI model (Open Systems Interconnection)

What is the difference between TCP/IP model vs. OSI model?
Future of networking technology relies on 5G, edge computing
7 TCP/IP vulnerabilities and how to prevent them
Edge computing and 5G bring the edge to remote workers
SANs Institute OSI model overview

Related Terms

Dig deeper on network infrastructure.

An explanation of TCP/IP

Transmission Control Protocol (TCP)

encapsulation (object-orientated programming)

Microsoft 365 Copilot, an AI assistant, offers several promising features. Find out how to configure Copilot with Teams workflows...

With its AI capabilities, Microsoft Copilot provides several enhancements to Microsoft Teams functionality, including meeting ...

Organizations have ramped up their use of communications platform as a service and APIs to expand communication channels between ...

Auditing is a crucial part of mobile device security, but IT admins must ensure their approach is thorough and consistent. Learn ...

With the right software, almost any mobile device can be a payment terminal. Learn about the mobile point-of-sale options beyond ...

To keep corporate and user data safe, IT must continuously ensure mobile app security. Mobile application security audits are a ...

Lenovo adds to its AI portfolio with a new GPU-as-a-service offering, a move that challenges Dell and HPE. It also adds ...

AT&T claims its negotiated contract with VMware pre-Broadcom acquisition is not being honored, casting light on recent product ...

Rocky Linux and AlmaLinux are new distributions created after Red Hat announced the discontinuation of CentOS. These ...

Popular pricing models for managed service providers include monitoring only, per device, per user, all-you-can-eat or ...

Global IT consultancies take a multilayered approach to GenAI training by developing in-house programs, partnering with tech ...

IT service providers are upskilling a large portion of their workforces on the emerging technology. The campaign seeks to boost ...

What is the Presentation Layer in Programming?

Trevor Page

Get the Best Java Roadmap

Download the roadmap.

The presentation layer is one of the three main layers in object-oriented programming.

The three main layers include:

Presentation Layer
Business Layer

Now, these three layers are typically related to enterprise web applications. It's a design pattern used to help separate your code out in three distinct areas that (if need be) can easily be switched out with another programming language or technology.

So if you keep all of your presentation layer code in one area of your application, switching presentation layer technologies shouldn't be too difficult.

Same rules apply to the business and data layers. If you separated your code out properly, switching databases shouldn't be too big of an issue.

Having said that, we'll be focusing on the presentation layer.

The four big players (in terms of technology) in the presentation layer are as follows:

Let’s dive into the overviews of each of these big players, shall we?

HTML (HyperText Markup Language) is a technology used to communicate with web browsers. All browsers follow the rules laid out in HTML (currently in its 5th iteration).

HTML defines a bunch of different HTML elements known as tags that are put together to make up the basic layout of a web page. These tags are used to define things like the title of the webpage (which appears in the tab of your browser), the actual text that appears on the page, images, buttons and more.

Thankfully HTML isn’t too tough to learn as it’s more of a game of memorizing the most popular tags and using them to create your simple web pages. HTML is not a programming language, as it doesn’t define variables, data types, control structure or the like. This is also what makes it fairly easy to learn.

We’ll be diving into examples of HTML “code” later, so stay tuned.

CSS (cascading style sheets) is used to add some “pizazz” to your web pages. CSS is used to add a design look and feel to your web pages through the use of its cascading rules. We won’t get into the exact rules that CSS uses to apply its designs just yet, but again, stay tuned for a more in depth explanation.

All you need to know is that CSS is used to make a web page look nice. You can use it to choose which parts of the web page should be which color, how big or small elements should be, what fonts should be used and more.

If you’ve ever landed on a web page that wasn’t able to properly load its CSS, you’d likely think that the website was completely broken. It is often fixed by forcing the page to reload and then the CSS usually gets picked up the second time and everything loads properly and the website goes back to looking great. This situation is quite rare, but I thought I’d mention it because it’s a great example of just how powerful CSS is.

JavaScript is used to make your web pages interactive. It allows you to put some real programming functionality into web pages (as HTML is not a programming language and thus cannot add real programming elements to a page).

Examples of what JavaScript can do is when you’re logging into an application and you forget to provide information in one of the fields. JavaScript can detect that you’ve forgotten to type in your username or password and can provide you with a prompt explaining that you need to fill in your username and password before you can continue.

JavaScript shouldn’t be confused with Java, as they are two different technologies. Java is part of the business layer and has no place in the presentation layer. Java is known as a server side language, as it exists and runs on servers. JavaScript is known as a client side technology, and thus lives where the “clients” are, which is inside the actual web browsers.

A good way to think of the difference between the two languages is that when you land on a web page and it loads in your browser, it will also load any JavaScript code inside the page and you’ll actually be able to access that code and read it. Whereas, you’d never be able to read the Java code, as it’s not loaded in your browser because it’s a server side technology.

That simple distinction between the two languages makes for two very different languages in terms of their use and functionality.

The syntax for JavaScript, however, is fairly similar to Java. This is nice since you’ll be able to look at a piece of JavaScript code and more or less understand what’s going on. So you should be able to pick up the JavaScript language a lot quicker if you already have a good command of the Java language.

JQuery is a technology that’s used in tandem with JavaScript. JQuery makes your life as a web programmer so much easier for one reason, it allows you to write code once and have it work across all the browsers.

In today’s world we have so many browsers that can be downloaded for free and used to peruse the web. This actually makes building websites a bit challenging, as every browser has made up their own minds on how to “render” an HTML web page.

This means that a webpage loaded on Safari might not look the same as if it’s loaded on Internet Explorer, or Firefox, or Chrome.

These inconsistencies drive web programmers crazy, so that’s why jQuery was introduced. It allows you to write your JavaScript in a sort of “browser agnostic” way. You can write it once, and jQuery will execute the code appropriately depending on which browser it’s loaded it. VERY COOL!

The best part of all of these technologies is that they are all free to use.

And thankfully, they are also free to learn via these tutorials!

Do you want to get a job as a full-stack developer? Consider joining our Online Web Developer Bootcamp.

Free Java Roadmap

Discover exactly what you need to learn and where to start in order to become a professional coder.

Coders Campus

Launch your coding career..

151 Lyndhurst Drive, Kitchener, Ontario N2B 1B7 Canada

Computer Network

Introduction
Architecture
Computer Network Types
Transmission Modes
TCP/IP Model

Physical Layer

Digital Transmission
Transmission Media
Guided Media
UnGuided Media
Multiplexing
Switching Modes
Switching Techniques
Data Link layer
Error Detection
Error Correction
Data Link Controls
Network Layer
Network Addressing
Network Layer Protocols
Routing Algorithm
Distance Vector
Link State Routing
Transport Layer
Transport Layer Protocols
Application Layer
Client & Server Model

Application Protocols

Network security.

Digital Signature
What is Router
OSI vs TCP/IP
IPv4 vs IPv6
ARP Packet Format
Working of ARP
FTP Commands
I2P Protocol
Sliding Window Protocol
SPI Protocol
ARP Commands
ARP Request
ARP - Address Resolution Protocol
ARP and its types
TCP Retransmission
CAN Protocol
HTTP Status Codes
HTTP vs HTTPS
RIP Protocol
UDP Protocol
ICMP Protocol
MQTT Protocol
OSPF Protocol
Stop & Wait Protocol
IMAP Protocol
POP Protocol
Go-Back-N ARQ
Connection-Oriented vs Connectionless Service
CDMA vs GSM
What is MAC Address
Modem vs Router
Switch vs Router
USB 2.0 vs USB 3.0
CSMA CA vs CSMA CD
Multiple Access Protocols
IMAP vs. POP3
SSH Meaning
Status Code 400
MIME Protocol
What is a proxy server and how does it work
How to set up and use a proxy server
What is network security
WWW is based on which model
Proxy Server List
Fundamentals of Computer Networking
IP Address Format and Table
Bus topology vs Ring topology
Bus topology vs Star topology
Circuit Switching vs Packet switching
star vs ring topology
Router vs Bridge
TCP Connection Termination
Image Steganography
Network Neutrality
Onion Routing
ASA features
Relabel-to-front Algorithm
Types of Server Virtualization in Computer Network
Access Lists (ACL)
Digital Subscriber Line (DSL)
Operating system based Virtualization
Context based Access Control (CBAC)
Cristian's Algorithm
Service Set Identifier (SSID) in Computer Network
Voice over Internet Protocol (VoIP)
Challenge Response Authentication Mechanism (CRAM)
Extended Access List
Li-fi vs. Wi-fi
Reflexive Access List
Synchronous Optical Network (SONET)
Wifi protected access (WPA)
Wifi Protected Setup (WPS)
Standard Access List
Time Access List
What is 3D Internet
4G Mobile Communication Technology
Types of Wireless Transmission Media
Best Computer Networking Courses
Data Representation
Network Criteria
Classful vs Classless addressing
Difference between BOOTP and RARP in Computer Networking
What is AGP (Accelerated Graphics Port)
Advantages and Disadvantages of Satellite Communication
External IP Address
Asynchronous Transfer Mode (ATM) in Computer Network
Types of Authentication Protocols
What is a CISCO Packet Tracer
How does BOOTP work
Subnetting in Computer Networks
Mesh Topology Advantages and Disadvantages
Ring Topology Advantages and Disadvantages
Star Topology Advantages and Disadvantages
Tree Topology Advantages and Disadvantages
Zigbee Technology-The smart home protocol
Network Layer in OSI Model
Physical Layer in OSI Model
Data Link Layer in OSI Model
Internet explorer shortcut keys
Network Layer Security | SSL Protocols
Presentation Layer in OSI Model
Session Layer in OSI Model
SUBNET MASK
Transport Layer Security | Secure Socket Layer (SSL) and SSL Architecture
Functions, Advantages and Disadvantages of Network Layer
Functions, Advantages and Disadvantages of the Physical Layer
Types of Internet Connection
Noisy and Noiseless Channel
Advantages and Disadvantages of Bus Topology
Advantages and Disadvantages of Ring Topology
Advantages and Disadvantages of Star Topology
Protocols in Noiseless and Noisy Channel
Advantages and Disadvantages of Mesh Topology
Cloud Networking - Managing and Optimizing Cloud-Based Networks
Collision Domain and Broadcast Domain
Count to Infinity Problem in Distance Vector Routing
Difference Between Go-Back-N and Selective Repeat Protocol
Difference between Stop and Wait, GoBackN, and Selective Repeat
Network Function Virtualization (NFV): transforming Network Architecture with Virtualized Functions
Network-Layer Security | IPSec Modes
Network-Layer Security | IPSec Protocols and Services
Ping vs Traceroute
Software Defined Networking (SDN): Benefits and Challenges of Network Virtualization
Software Defined Networking (SDN) vs. Network Function Virtualization (NFV)
Virtual Circuits vs Datagram Networks
BlueSmack Attack in Wireless Networks
Bluesnarfing Attack in Wireless Networks
Direct Sequence Spread Spectrum
Warchalking in Wireless Networks
WEP (Wired Equivalent Privacy)
Wireless security encryption
Wireless Security in an Enterprise
Quantum Networking
Network Automation
Difference between MSS and MTU
What is MTU
Mesh Networks: A decentralized and Self-Organizing Approach to Networking
What is Autonomous System
What is MSS
Cyber security and Software security
Information security and Network security
Security Engineer and Security Architect
Protection Methods for Network Security
Trusted Systems in Network Security
What are Authentication Tokens in Network security
Cookies in Network Security
Intruders in Network Security
Network Security Toolkit (NST) in virtual box
Pivoting-Moving Inside a Network
Security Environment in Computer Networks
Voice Biometric technique in Network Security
Advantages and Disadvantages of Conventional Testing
Difference between Kerberos and LDAP
Cyber security and Information Security
GraphQL Attacks and Security
Application Layer in OSI Model
Applications of Remote Sensing
Seven Layers of IT Security
What is Ad Hoc TCP
What is Server Name Indication(SNI)
Difference Between Infrastructure and Infrastructure Less Network
Collision Avoidance in Wireless Networks
Difference Engine and Analytical Engine
Hotspot 2.0
Intrusion Prevention System (IPS)
Modes of Connection Bluetooth
Noisy Channel protocols
Parzen Windows density Estimation Technique
Principle of Information System Security
What are Bots, Botnets, and Zombies
Windows Memory Management
Wireless dos attack on Wifi
Design Principles of Security in Distributed Systems
MAC Filtering
Principles of Network Applications
Time-to-Live (TTL)
What is 1000 BASE-T
What is the difference between 802.11ac and 802.11ax
Differentiate between Circuit Switching, Message Switching, and Packet Switching
What is Web 3.0
Collision Detection in CSMA/CD
Ipv4 Header in Computer Networks
Layered Architecture in Computer Networks
Define URL in Computer Networks
MAN in Computer Networks
Routing Protocols in Computer Networks
Flooding in Computer Network
CRC in Computer Network
Application of Computer Network
Computer Network Architect
Design Issues for the Layers of Computer Networks
What is AMD (Advanced Micro Devices)
Protocol in Computer Network
Computer Network Projects
Different Types of Routers
Wireless Distribution System (WDS)
Network Time Protocol
Address Resolution Protocol (ARP) and its types in Computer Network
Automatic Repeat ReQuest (ARQ) in Computer Networks
Bluetooth in Computer Networks
Circuit Switching in Computer Network
Computer Hardware and Networking Course
Ring Topology in a Computer Network
Token Ring in Computer Networks
Medium Access Control in Computer Network
Need for Computer Network
Repeater in Computer Network
Computer Networking: a Top Down Approach
What is Multiplexing in Computer Network
Body Area Network (BAN)
INS AND OUT OF DATA STREAMING
Streaming stored video
Cellular Network
How can devices on a Network be identified
How Does the Internet Work
Authentication Server
What is Cloud Backup and How does it Work
Communication Protocols In System Design
Extensible Authentication Protocol (EAP)
Role-Based Access Control (RBAC)
Network Enumeration Tools
Network Protocol Testing
Windows Networking Commands
Advantages and Disadvantages of WLAN
Anonymous File Transfer Protocol (AFTP)
Automatic Private IP Addressing
What is Deep Web
USB-C (USB Type C)
User Authentication
What is a vCard
ipv4 Headers
Difference between Token ring and Ethernet Token Ring
Server Message Block protocol (SMB protocol)
Session Border Controllers (SBC)
Short Message Service Center (SMSC)
What is a Mail Server
What are Communication Networks
Initialization Vector
What is Fiber Optics
Open Networking
Access Ports Vs Trunk Ports
Edge Routers
IPTV (Internet Protocol Television)
Wireless Internet Service Provider (WISP)
Wireless Backhaul
Define Protocol in Computer Network
Virtual Network Adapter
Virtual Routing and Forwarding
Virtual Switches(vSwitches)
VLAN (Virtual LAN)
Wireless Mesh Network (WMN)
What is Gateway in Computer Network
Radio Access Network (RAN)
What is File Sharing
Passive Optical Network (PON)
Private IP address
Public Key Certificate
What is Bridge in Computer Network
Ping Sweep (ICMP Sweep)
Print Server
WIFI Pineapple
Walled Garden
Wireless ISP (wireless Internet service provider or WISP)
Bridge vs Repeater
Hardware Security Module (HSM)
Public Switched Telephone Network
Analog Telephone Adapter (ATA)
Host Bus Adapter (HBA)
ISCSI initiator
Simplest Protocol
Telecommunication Networks
What is WPS in Wi-Fi
What are the Most Important Email Security Protocols
What is Data Governance and Why does it Matter
Carrier Network
Most Secure Network Protocol
Network SMB
BGP vs. EIGRP: What's the Difference
Wireless Security: WEP, WPA, WPA2 and WPA3 differences
Cloud Radio Access Network (C-RAN)
Bits Per Second (bps or bit/sec)
Blade Server
command-and-control server (C&C server)
Computer Network MCQ
Computer Network MCQ Part2

Interview Questions

Networking Questions

The presentation layer is the 6 layer from the bottom in the OSI model. This layer presents the incoming data from the application layer of the sender machine to the receiver machine. It converts one format of data to another format of data if both sender and receiver understand different formats; hence this layer is also called the translation layer. It deals with the semantics and syntax of the data, so this layer is also called the syntax layer. It uses operations such as data compression, data encryption & decryption, data conversion, etc.

Data is sent from sender to receiver, but what if the sender device and receiver device understand different formats of code? For example, suppose one device understands ASCII code and another device understands EBCDIC code. In that case, the data must be translated into a code that the recipient understands to determine what data has been sent. The presentation layer is responsible for translating ASCII codes to EBCDIC or vice versa. With the help of the presentation layer, the receiver understands the data effectively and uses it efficiently. Whatever data is being transmitted between the sender and the receiver, that data must be secure because an intruder can hack the data passing between the sender and the receiver. Hackers can modify the data and send the modified data to the receiver to create false communication. The presentation layer is responsible for encrypting and decrypting data to avoid data leakage and data modification.
The plaintext data at the source is encrypted into ciphertext (unreadable format), then it is sent to the receiver, where the ciphertext is decrypted into plaintext. Now, if the hacker tries to hack the data, the hacker receives an encrypted, unreadable form, and if the hacker tries to send modified data, the receiver can detect the modification during decryption; thereby, the data remains safe. If the file size is large, it becomes difficult to transmit the large file over the network. File size can be decreased by compressing the file for easy transmission of data. Compression is the method of diminishing the size of a file to transmit data easily in less time. When the compressed data reaches the receiver, the data is reconstructed back to the original size, and this process is called decompression.

The presentation layer in the OSI model is classified into two sublayers:

This sublayer offers services to layer-7, i.e., the application layer, and requests services from layer-5, i.e., the session layer. It supports various application services, such as Reliable Transfer Service Element (RTSE), Remote Operation Service Element (ROSE), Association Control Service Element (ACSE), and Commitment Concurrency and Recovery (CCR). This sublayer offers application-specific protocols, such as Message Oriented Text Interchange Standard (MOTIS), Remote Database Access (RDA), File Transfer Access and Manager (FTAM), Common Management Information Protocol (CMIP), Virtual Terminal (VT), Distributed Transaction Processing (DTP), Job Transfer and Manipulation (JTM), and others. It is a presentation layer protocol in the OSI model, which was formed by Citrix Systems. It is used for transferring data from server to client. It is a very thin protocol as it does not require much overhead in order to transmit data from the server over to the client. It is well-optimized for the WAN. It is the protocol that is used to implement the presentation layer of the OSI model. It provides different kinds of data representation, such as images, video, audio, numbers, etc. It is used for Microsoft Remote Procedure Call (Microsoft RPC) and Distributed Computing Environment (DCE) / Remote Procedure Calls (RPC). It is a communication protocol that was specifically designed for macOS by Apple, Inc. It provides file services for Classic Mac OS and macOS. This protocol is used to share files over the network. It is a protocol that is associated with the client-server operating system. The user can access the directory, print, message, file, clock synchronization, etc., with the help of this protocol. It supports many platforms, such as Linux, Classic Mac OS, Windows NT, Mac OS X, and Microsoft Windows. It is a telecommunications equipment that splits a stream of data into separate packets and formats packet headers for asynchronous communication on X.25 networks. It receives packets from the network and converts them into a stream of data. The PAD provides many asynchronous terminal connectivities to a host computer. It is a computer network protocol that is used to transfer data between two systems. It was first published in 1987. XDR is used by various systems such as NDMP, Network File System, NetCDF, ZFS, Open Network Computer Remote Procedure Call, and others. It is a protocol that offers ISO presentation services over TCP/IP based networks. This protocol explains an approach to provide stream-line support for OSI over TCP/IP based networks.

Latest Courses

We provides tutorials and interview questions of all technology like java tutorial, android, java frameworks

Contact info

G-13, 2nd Floor, Sec-3, Noida, UP, 201301, India

[email protected] .

Online Compiler

Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers
Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand
OverflowAI GenAI features for Teams
OverflowAPI Train & fine-tune LLMs
Labs The future of collective knowledge sharing
About the company Visit the blog

Collectives™ on Stack Overflow

Find centralized, trusted content and collaborate around the technologies you use most.

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

Get early access and see previews of new features.

OSI model - What's the presentation and session layer for?

So I feel I pretty well understand the application layer, and everything below (and including) the transport layer.

The session and presentation layers, though, I don't fully understand. I've read the simplistic descriptions in Wikipedia, but it doesn't have an example of why separating out those layers is useful.

What is the session layer? What does it do, and under what circumstances is it better to have a session layer than simply talk to the transport with your app?
What is the presentation layer? (same questions as above)
network-programming

7 Answers 7

The session layer is meant to store states between two connections, like what we use cookies for when working with web programming.

The presentation layer is meant to convert between different formats. This was simpler when the only format that was worried about was character encoding, ie ASCII and EBCDIC. When you consider all of the different formats that we have today(Quicktime, Flash, Pdf) centralizing this layer is out of the question.

TCP/IP doesn't make any allocation to these layers, since they are really out of the scope of a networking protocol. It's up to the applications that take advantage of the stack to implement these.

The reasons there aren't any examples on wikipedia is that there aren't a whole lot of examples of the OSI network model, period.

OSI has once again created a standard nobody uses, so nobody really know how one should use it.

Layers 5-6 are not commonly used in today's web applications, so you don't hear much about them. The TCP/IP stack is slightly different than a pure OSI Model.

One of the reasons TCP/IP is used today instead of OSI is it was too bloated and theoretical, the session and presentation layer aren't really needed as separate layers as it turned out.

I think that presentation layer protocols define the format of data. This means protocols like XML or ASN.1. You could argue that video/audio codecs are part of the presentation layer Although this is probably heading towards the application layer.

I can't help you with the session layer. That has always baffled me.

To be honest, there are very vague boundaries in everything above the transport layer. This is because it is usually handled by a single software application. Also, these layers are not directly associated with transporting data from A to B. Layers 4 and below each have a very specific purpose in moving the data e.g. switching, routing, ensuring data integrity etc. This makes it easier to distinguish between these layers.

Presentation Layer The Presentation Layer represents the area that is independent of data representation at the application layer - in general, it represents the preparation or translation of application format to network format, or from network formatting to application format. In other words, the layer “presents” data for the application or the network. A good example of this is encryption and decryption of data for secure transmission - this happens at Layer 6.

Session Layer When two devices, computers or servers need to “speak” with one another, a session needs to be created, and this is done at the Session Layer. Functions at this layer involve setup, coordination (how long should a system wait for a response, for example) and termination between the applications at each end of the session.

For the presentation layer :because most of communication done between heterogeneous systems (Operating Systems,programing langages,cpu architectures)we need to use a unified idepedent specification .like ANS1 ans BRE.

Your Answer

Reminder: Answers generated by artificial intelligence tools are not allowed on Stack Overflow. Learn more

Sign up or log in

Post as a guest.

Required, but never shown

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy .

Not the answer you're looking for? Browse other questions tagged network-programming model stack osi or ask your own question .

The Overflow Blog
The world’s largest open-source business has plans for enhancing LLMs
Featured on Meta
User activation: Learnings and opportunities
Site maintenance - Mon, Sept 16 2024, 21:00 UTC to Tue, Sept 17 2024, 2:00...
What does a new user need in a homepage experience on Stack Overflow?
Announcing the new Staging Ground Reviewer Stats Widget

Hot Network Questions

how does the US justice system combat rights violations that happen when bad practices are given a new name to avoid old rulings?
Explicit Examples for Unrestricted Hartree Fock Calculations
Why did the Chinese government call its actual languages 'dialects'? Is this to prevent any subnational separatism?
Very simple CSV-parser in Java
How many engineers/scientists believed that human flight was imminent as of the late 19th/early 20th century?
Convert base-10 to base-0.1
How to change my document's font
Are positive definite linear operator always invertible?
Conservation of energy in cosmological redshift
Not great at regexs. Trying to code-golf this beast of a regex WITHOUT using string replacement (for G-Zip purposes)
Python script to renumber slide ids inside a pptx presentation
Can All Truths Be Scientifically Verified?
The consequence of a good letter of recommendation when things do not work out
Why is steaming food faster than boiling it?
What would a planet need for rain drops to trigger explosions upon making contact with the ground?
Little spikes on mains AC
Is it really a "space walk" (EVA proper) if you don't get your feet wet (in space)?
Inverses of Morphisms Necessarily Being Morphisms
Are these colored sets closed under multiplication?
Is Sagittarius A* smaller than we might expect given the mass of the Milky Way?
Smallest root of a degree 3 polynomial
Function with memories of its past life
Arduino Uno Serial.write() how many bits are actually transmitted at once by UART and effect of baudrate on other interrupts
If one is arrested, but has a baby/pet in their house, what are they supposed to do?

Application Architecture Guide - Chapter 10 - Presentation Layer Guidelines

Note - The patterns & practices Microsoft Application Architecture Guide, 2nd Edition is now live at http://msdn.microsoft.com/en-us/library/dd673617.aspx .

- J.D. Meier, Alex Homer, David Hill, Jason Taylor, Prashant Bansode, Lonnie Wall, Rob Boucher Jr, Akshay Bogawat

1 Objectives
3 Presentation Layer Components
5 Design Considerations
6 Presentation Layer Frame
8 Composition
9 Exception Management
12 Navigation
13 Presentation Entities
14 Request Processing
15 User Experience
16 UI Components
17 UI Process Components
18 Validation
19 Pattern Map
20 Pattern Descriptions
21.1 Mobile Applications
21.2 Rich Client Applications
21.3 Rich Internet Applications (RIA)
21.4 Web Applications
22 patterns & practices Solution Assets
23 Additional Resources
Understand how the presentation layer fits into typical application architecture.
Understand the components of the presentation layer.
Learn the steps for designing the presentation layer.
Learn the common issues faced while designing the presentation layer.
Learn the key guidelines for designing the presentation layer.
Learn the key patterns and technology considerations for designing the presentation layer.

The presentation layer contains the components that implement and display the user interface and manage user interaction. This layer includes controls for user input and display, in addition to components that organize user interaction. Figure 1 shows how the presentation layer fits into a common application architecture.

Figure 1 A typical application showing the presentation layer and the components it may contain

Presentation Layer Components

User interface (UI) components . User interface components provide a way for users to interact with the application. They render and format data for users. They also acquire and validate data input by the user.
User process components . User process components synchronize and orchestrate user interactions. Separate user process components may be useful if you have a complicated UI. Implementing common user interaction patterns as separate user process components allows you to reuse them in multiple UIs.

The following steps describe the process you should adopt when designing the presentation layer for your application. This approach will ensure that you consider all of the relevant factors as you develop your architecture:

Identify your client type . Choose a client type that satisfies your requirements and adheres to the infrastructure and deployment constraints of your organization. For instance, if your users are on mobile devices and will be intermittently connected to the network, a mobile rich client is probably your best choice.
Determine how you will present data . Choose the data format for your presentation layer and decide how you will present the data in your UI.
Determine your data-validation strategy . Use data-validation techniques to protect your system from untrusted input.
Determine your business logic strategy . Factor out your business logic to decouple it from your presentation layer code.
Determine your strategy for communication with other layers . If your application has multiple layers, such as a data access layer and a business layer, determine a strategy for communication between your presentation layer and other layers.

Design Considerations

There are several key factors that you should consider when designing your presentation layer. Use the following principles to ensure that your design meets the requirements for your application, and follows best practices:

Choose the appropriate UI technology. Determine if you will implement a rich (smart) client, a Web client, or a rich Internet application (RIA). Base your decision on application requirements, and on organizational and infrastructure constraints.
Use the relevant patterns. Review the presentation layer patterns for proven solutions to common presentation problems.
Design for separation of concerns. Use dedicated UI components that focus on rendering and display. Use dedicated presentation entities to manage the data required to present your views. Use dedicated UI process components to manage the processing of user interaction.
Consider human interface guidelines. Review your organization’s guidelines for UI design. Review established UI guidelines based on the client type and technologies that you have chosen.
Adhere to user-driven design principles. Before designing your presentation layer, understand your customer. Use surveys, usability studies, and interviews to determine the best presentation design to meet your customer’s requirements.

Presentation Layer Frame

There are several common issues that you must consider as your develop your design. These issues can be categorized into specific areas of the design. The following table lists the common issues for each category where mistakes are most often made.

Table 1 Presentation Layer Frame


	* Caching volatile data.
	* Failing to consider use of patterns and libraries that support dynamic layout and injection of views and presentation at runtime.
	* Failing to catch unhandled exceptions.
	* Failing to design for intuitive use, or implementing overly complex interfaces.
	* Using an inappropriate layout style for Web pages.
	* Inconsistent navigation.
	* Defining entities that are not necessary.
	* Blocking the UI during long-running requests.
	* Displaying unhelpful error messages.
	* Creating custom components that are not necessary.
	* Implementing UI process components when not necessary.
	* Failing to validate all input.

Caching is one of the best mechanisms you can use to improve application performance and UI responsiveness. Use data caching to optimize data lookups and avoid network round trips. Cache the results of expensive or repetitive processes to avoid unnecessary duplicate processing.

Consider the following guidelines when designing your caching strategy:

Do not cache volatile data.
Consider using ready-to-use cache data when working with an in-memory cache. For example, use a specific object instead of caching raw database data.
Do not cache sensitive data unless you encrypt it.
If your application is deployed in Web farm, avoid using local caches that need to be synchronized; instead, consider using a transactional resource manager such as Microsoft SQL Server® or a product that supports distributed caching.
Do not depend on data still being in your cache. It may have been removed.

Composition

Consider whether your application will be easier to develop and maintain if the presentation layer uses independent modules and views that are easily composed at run time. Composition patterns support the creation of views and the presentation layout at run time. These patterns also help to minimize code and library dependencies that would otherwise force recompilation and redeployment of a module when the dependencies change. Composition patterns help you to implement sharing, reuse, and replacement of presentation logic and views.

Consider the following guidelines when designing your composition strategy:

Avoid using dynamic layouts. They can be difficult to load and maintain.
Be careful with dependencies between components. For example, use abstraction patterns when possible to avoid issues with maintainability.
Consider creating templates with placeholders. For example, use the Template View pattern to compose dynamic Web pages in order to ensure reuse and consistency.
Consider composing views from reusable modular parts. For example, use the Composite View pattern to build a view from modular, atomic component parts.
If you need to allow communication between presentation components, consider implementing the Publish/Subscribe pattern. This will lower the coupling between the components and improve testability.

Exception Management

Design a centralized exception-management mechanism for your application that catches and throws exceptions consistently. Pay particular attention to exceptions that propagate across layer or tier boundaries, as well as exceptions that cross trust boundaries. Design for unhandled exceptions so they do not impact application reliability or expose sensitive information.

Consider the following guidelines when designing your exception management strategy:

Use user-friendly error messages to notify users of errors in the application.
Avoid exposing sensitive data in error pages, error messages, log files, and audit files.
Design a global exception handler that displays a global error page or an error message for all unhandled exceptions.
Differentiate between system exceptions and business errors. In the case of business errors, display a user-friendly error message and allow the user to retry the operation. In the case of system exceptions, check to see if the exception was caused by issues such as system or database failure, display a user-friendly error message, and log the error message, which will help in troubleshooting.
Avoid using exceptions to control application logic.

Design a user input strategy based on your application input requirements. For maximum usability, follow the established guidelines defined in your organization, and the many established industry usability guidelines based on years of user research into input design and mechanisms.

Consider the following guidelines when designing your input collection strategy:

Use forms-based input controls for normal data-collection tasks.
Use a document-based input mechanism for collecting input in Microsoft Office–style documents.
Implement a wizard-based approach for more complex data collection tasks, or for input that requires a workflow.
Design to support localization by avoiding hard-coded strings and using external resources for text and layout.
Consider accessibility in your design. You should consider users with disabilities when designing your input strategy; for example, implement text-to-speech software for blind users, or enlarge text and images for users with poor sight. Support keyboard-only scenarios where possible for users who cannot manipulate a pointing device.

Design your UI layout so that the layout mechanism itself is separate from the individual UI components and UI process components. When choosing a layout strategy, consider whether you will have a separate team of designers building the layout, or whether the development team will create the UI. If designers will be creating the UI, choose a layout approach that does not require code or the use of development-focused tools.

Consider the following guidelines when designing your layout strategy:

Use templates to provide a common look and feel to all of the UI screens.
Use a common look and feel for all elements of your UI to maximize accessibility and ease of use.
Consider device-dependent input, such as touch screens, ink, or speech, in your layout. For example, with touch-screen input you will typically use larger buttons with more spacing between them than you would with mouse or keyboard inputs.
When building a Web application, consider using Cascading Style Sheets (CSS) for layout. This will improve rendering performance and maintainability.
Use design patterns, such as Model-View-Presenter (MVP), to separate the layout design from interface processing.

Design your navigation strategy so that users can navigate easily through your screens or pages, and so that you can separate navigation from presentation and UI processing. Ensure that you display navigation links and controls in a consistent way throughout your application to reduce user confusion and hide application complexity.

Consider the following guidelines when designing your navigation strategy:

Use well-known design patterns to decouple the UI from the navigation logic where this logic is complex.
Design toolbars and menus to help users find functionality provided by the UI.
Consider using wizards to implement navigation between forms in a predictable way.
Determine how you will preserve navigation state if the application must preserve this state between sessions.
Consider using the Command Pattern to handle common actions from multiple sources.

Presentation Entities

Use presentation entities to store the data you will use in your presentation layer to manage your views. Presentation entities are not always necessary; use them only if your datasets are sufficiently large and complex to require separate storage from the UI controls.

Consider the following guidelines when designing presentation entities:

Determine if you require presentation entities. Typically, you may require presentation entities only if the data or the format to be displayed is specific to the presentation layer.
If you are working with data-bound controls, consider using custom objects, collections, or datasets as your presentation entity format.
If you want to map data directly to business entities, use a custom class for your presentation entities.
Do not add business logic to presentation entities.
If you need to perform data type validation, consider adding it in your presentation entities.

Request Processing

Design your request processing with user responsiveness in mind, as well as code maintainability and testability.

Consider the following guidelines when designing request processing:

Use asynchronous operations or worker threads to avoid blocking the UI for long-running actions.
Avoid mixing your UI processing and rendering logic.
Consider using the Passive View pattern (a variant of MVP) for interfaces that do not manage a lot of data.
Consider using the Supervising Controller pattern (a variant of MVP) for interfaces that manage large amounts of data.

User Experience

Good user experience can make the difference between a usable and unusable application. Carry out usability studies, surveys, and interviews to understand what users require and expect from your application, and design with these results in mind.

Consider the following guidelines when designing for user experience:

When developing a rich Internet application (RIA), avoid synchronous processing where possible.
When developing a Web application, consider using Asynchronous JavaScript and XML (AJAX) to improve responsiveness and to reduce post backs and page reloads.
Do not design overloaded or overly complex interfaces. Provide a clear path through the application for each key user scenario.
Design to support user personalization, localization, and accessibility.
Design for user empowerment. Allow the user to control how he or she interacts with the application, and how it displays data to them.

UI Components

UI components are the controls and components used to display information to the user and accept user input. Be careful not to create custom controls unless it is necessary for specialized display or data collection.

Consider the following guidelines when designing UI components:

Take advantage of the data-binding features of the controls you use in the UI.
Create custom controls or use third-party controls only for specialized display and data-collection tasks.
When creating custom controls, extend existing controls if possible instead of creating a new control.
Consider implementing designer support for custom controls to make it easier to develop with them.
Consider maintaining the state of controls as the user interacts with the application instead of reloading controls with each action.

UI Process Components

UI process components synchronize and orchestrate user interactions. UI processing components are not always necessary; create them only if you need to perform significant processing in the presentation layer that must be separated from the UI controls. Be careful not to mix business and display logic within the process components; they should be focused on organizing user interactions with your UI.

Consider the following guidelines when designing UI processing components:

Do not create UI process components unless you need them.
If your UI requires complex processing or needs to talk to other layers, use UI process components to decouple this processing from the UI.
Consider dividing UI processing into three distinct roles: Model, View, and Controller/Presenter, by using the MVC or MVP pattern.
Avoid business rules, with the exception of input and data validation, in UI processing components.
Consider using abstraction patterns, such as dependency inversion, when UI processing behavior needs to change based on the run-time environment.
Where the UI requires complex workflow support, create separate workflow components that use a workflow system such as Windows Workflow or a custom mechanism.

Designing an effective input and data-validation strategy is critical to the security of your application. Determine the validation rules for user input as well as for business rules that exist in the presentation layer.

Consider the following guidelines when designing your input and data validation strategy:

Validate all input data on the client side where possible to improve interactivity and reduce errors caused by invalid data.
Do not rely on client-side validation only. Always use server-side validation to constrain input for security purposes and to make security-related decisions.
Design your validation strategy to constrain, reject, and sanitize malicious input.
Use the built-in validation controls where possible, when working with .NET Framework.
In Web applications, consider using AJAX to provide real-time validation.

Pattern Map

Key patterns are organized by key categories, as detailed in the Presentation Layer Frame in the following table. Consider using these patterns when making design decisions for each category.

Table 2 Pattern Map


	* Cache Dependency
	* Composite View
	* Exception Shielding
	* Template View
	* Front Controller
	* Entity Translator
	* Asynchronous Callback
	* Model-View-Controller (MVC)

For more information on the Page Cache pattern, see “Enterprise Solution Patterns Using Microsoft .NET” at http://msdn.microsoft.com/en-us/library/ms998469.aspx
For more information on the Model-View-Controller (MVC), Page Controller, Front Controller, Template View, Transform View, and Two-Step View patterns, see “Patterns of Enterprise Application Architecture (P of EAA)” at http://martinfowler.com/eaaCatalog/
For more information on the Composite View, Supervising Controller, and Presentation Model patterns, see “Patterns in the Composite Application Library” at http://msdn.microsoft.com/en-us/library/cc707841.aspx
For more information on the Chain of responsibility and Command pattern, see “data & object factory” at http://www.dofactory.com/Patterns/Patterns.aspx
For more information on the Asynchronous Callback pattern, see “Creating a Simplified Asynchronous Call Pattern for Windows Forms Applications” at http://msdn.microsoft.com/en-us/library/ms996483.aspx
For more information on the Exception Shielding and Entity Translator patterns, see “Useful Patterns for Services” at http://msdn.microsoft.com/en-us/library/cc304800.aspx

Pattern Descriptions

Asynchronous Callback. Execute long-running tasks on a separate thread that executes in the background, and provide a function for the thread to call back into when the task is complete.
Cache Dependency. Use external information to determine the state of data stored in a cache.
Chain of Responsibility. Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request.
Composite View . Combine individual views into a composite representation.
Command Pattern. Encapsulate request processing in a separate command object with a common execution interface.
Entity Translator. An object that transforms message data types into business types for requests, and reverses the transformation for responses.
Exception Shielding. Prevent a service from exposing information about its internal implementation when an exception occurs.
Front Controller . Consolidate request handling by channeling all requests through a single handler object, which can be modified at run time with decorators.
Model-View-Controller . Separate the UI code into three separate units: Model (data), View (interface), and Presenter (processing logic), with a focus on the View. Two variations on this pattern include Passive View and Supervising Controller, which define how the View interacts with the Model.
Page Cache. Improve the response time for dynamic Web pages that are accessed frequently but change less often and consume a large amount of system resources to construct.
Page Controller . Accept input from the request and handle it for a specific page or action on a Web site.
Passive View . Reduce the view to the absolute minimum by allowing the controller to process user input and maintain the responsibility for updating the view.
Presentation Model . Move all view logic and state out of the view, and render the view through data-binding and templates.
Supervising Controller . A variation of the MVC pattern in which the controller handles complex logic, in particular coordinating between views, but the view is responsible for simple view-specific logic.
Template View . Implement a common template view, and derive or construct views using this template view.
Transform View . Transform the data passed to the presentation tier into HTML for display in the UI.
Two-Step View . Transform the model data into a logical presentation without any specific formatting, and then convert that logical presentation to add the actual formatting required.

Technology Considerations

The following guidelines will help you to choose an appropriate implementation technology. The guidelines also contain suggestions for common patterns that are useful for specific types of application and technology.

Mobile Applications

Consider the following guidelines when designing a mobile application:

If you want to build full-featured connected, occasionally connected, and disconnected executable applications that run on a wide range of Microsoft Windows®–based devices, consider using the Microsoft Windows Compact Framework.
If you want to build connected applications that require Wireless Application Protocol (WAP), compact HTML (cHTML), or similar rendering formats, consider using ASP.NET Mobile Forms and Mobile Controls.
If you want to build applications that support rich media and interactivity, consider using Microsoft Silverlight® for Mobile.

Rich Client Applications

Consider the following guidelines when designing a rich client application:

If you want to build applications with good performance and interactivity, and have design support in Microsoft Visual Studio®, consider using Windows Forms.
If you want to build applications that fully support rich media and graphics, consider using Windows Presentation Foundation (WPF).
If you want to build applications that are downloaded from a Web server and then execute on the client, consider using XAML Browser Applications (XBAP).
If you want to build applications that are predominantly document-based, or are used for reporting, consider designing a Microsoft Office Business Application.
If you decide to use Windows Forms and you are designing composite interfaces, consider using the Smart Client Software Factory.
If you decide to use WPF and you are designing composite interfaces, consider using the Composite Application Guidance for WPF.
If you decide to use WPF, consider using the Presentation Model (Model-View-ViewModel) pattern.
If you decide to use WPF, consider using WPF Commands to communicate between your View and your Presenter or ViewModel.
If you decide to use WPF, consider implementing the Presentation Model pattern by using DataTemplates over User Controls to give designers more control.

Rich Internet Applications (RIA)

Consider the following guidelines when designing an RIA:

If you want to build browser-based, connected applications that have broad cross-platform reach, are highly graphical, and support rich media and presentation features, consider using Silverlight.
If you decide to use Silverlight, consider using the Presentation Model (Model-View-ViewModel) pattern.

Web Applications

Consider the following guidelines when designing a Web application:

If you want to build applications that are accessed through a Web browser or specialist user agent, consider using ASP.NET.
If you want to build applications that provide increased interactivity and background processing, with fewer page reloads, consider using ASP.NET with AJAX.
If you want to build applications that include islands of rich media content and interactivity, consider using ASP.NET with Silverlight controls.
If you are using ASP.NET and want to implement a control-centric model with separate controllers and improved testability, consider using the ASP.NET MVC Framework.
If you are using ASP.NET, consider using master pages to simplify development and implement a consistent UI across all pages.

patterns & practices Solution Assets

Web Client Software Factory at http://msdn.microsoft.com/en-us/library/bb264518.aspx
Smart Client Software Factory at http://msdn.microsoft.com/en-us/library/aa480482.aspx
Composite Application Guidance for WPF at http://msdn.microsoft.com/en-us/library/cc707819.aspx
Smart Client - Composite UI Application Block at http://msdn.microsoft.com/en-us/library/aa480450.aspx

Additional Resources

For more information, see Microsoft Inductive User Interface Guidelines at http://msdn.microsoft.com/en-us/library/ms997506.aspx .
For more information, see User Interface Control Guidelines at http://msdn.microsoft.com/en-us/library/bb158625.aspx .
For more information, see User Interface Text Guidelines at http://msdn.microsoft.com/en-us/library/bb158574.aspx .
For more information, see Design and Implementation Guidelines for Web Clients at http://msdn.microsoft.com/en-us/library/ms978631.aspx .
For more information, see Web Presentation Patterns at http://msdn.microsoft.com/en-us/library/ms998516.aspx .

Personal tools

Community portal
Current events
Recent changes
Random page
What links here
Related changes
Special pages
Printable version
Permanent link
Page information

This page was last edited on 22 January 2010, at 07:50.
Privacy policy
About Guidance Share
Disclaimers

Our travels through the OSI seven layers of networking have shown that each layer has specific weaknesses and angles of attack. In turn, each has its best defenses. Now, we’ve come to the OSI presentation layer. Here translation, encryption and compression all happen.

What Is the Presentation Layer?

The simplest way to describe the OSI presentation layer is as follows: it is where machine-readable code gets processed into something the end user can use later in the application layer. This layer is where formatting, conversion and encryption happen. Without it, unless you’re a developer, you likely won’t know what you’re looking at.

Attacks and Threats

If you are using an HTTPS website, encryption would happen at the presentation layer. That means getting your encryption right matters here. Therefore threat actors look for exploits in encryption flaws within the OSI presentation layer. One of the most common tactics is SSL hijacking or sniffing.

Like we said in previous entries, man-in-the-middle (MitM) attacks are one of the go-to moves for threat actors. In conjunction with malware, SSL hijacking can be damaging at the OSI presentation layer. If an attacker has already installed malware on a machine, the MitM would use a proxy to serve as an untrusted certificate authority. If this is the case, the browser will trust the wrong certificate authority and now the attacker will be able to read all messages. For this reason, it is important that your antivirus is up to date and you are doing what you can to stop malware from entering your devices.

As mentioned in the previous piece on the session layer , attackers will take advantage of bad coding practices . That’s true at this layer as well. Keep this in mind when you choose and add software into your enterprise.

The Journey Through the OSI Seven-Layer Model

We’re almost done with the journey through the OSI seven-layer model. After the OSI presentation layer, we’ll look at the application layer. By far, this is where the widest range of attacks and breaches can occur. Therefore, it’s very important to understand.

More from Mobile Security

Juice jacking: is it a real issue or media hype.

4 min read - You get off a flight and realize your phone is almost out of battery, which will make getting an Uber at your destination a bit challenging. Then you see it — a public charging station at the next gate like a pot of gold at the end of the rainbow. As you run rom-com style to the USB port, you may briefly wonder if it’s actually safe from a cybersecurity perspective to plug in your phone. The answer is technically…

Third-party app stores could be a red flag for iOS security

4 min read - Even Apple can’t escape change forever. The famously restrictive company will allow third-party app stores for iOS devices, along with allowing users to “sideload” software directly. Spurring the move is the European Union’s (EU) Digital Markets Act (DMA), which looks to ensure open markets by reducing the ability of digital “gatekeepers” to restrict content on devices. While this is good news for app creators and end-users, there is a potential red flag: security. Here’s what the compliance-driven change means for…

A view into Web(View) attacks in Android

9 min read - James Kilner contributed to the technical editing of this blog. Nethanella Messer, Segev Fogel, Or Ben Nun and Liran Tiebloom contributed to the blog. Although in the PC realm it is common to see financial malware used in web attacks to commit fraud, in Android-based financial malware this is a new trend. Traditionally, financial malware in Android uses overlay techniques to steal victims’ credentials. In 2022, IBM Security Trusteer researchers discovered a new trend in financial mobile malware that targets…

Topic updates

Analysis and insights from hundreds of the brightest minds in the cybersecurity industry to help you prove compliance, grow business and stop threats.

Illustration with collage of pictograms of computer monitor, server, clouds, dots

Three-tier architecture is a well-established software application architecture that organizes applications into three logical and physical computing tiers: the presentation tier, or user interface; the application tier, where data is processed; and the data tier, where application data is stored and managed.

The chief benefit of three-tier architecture is that because each tier runs on its own infrastructure, each tier can be developed simultaneously by a separate development team. And can be updated or scaled as needed without impacting the other tiers.

For decades three-tier architecture was the prevailing architecture for client-server applications. Today, most three-tier applications are targets for modernization that uses cloud-native technologies such as containers and microservices and for migration to the cloud.

Connect and integrate your systems to prepare your infrastructure for AI.

Presentation tier

The presentation tier is the user interface and communication layer of the application, where the end user interacts with the application. Its main purpose is to display information to and collect information from the user. This top-level tier can run on a web browser, as desktop application, or a graphical user interface (GUI), for example. Web presentation tiers are developed by using HTML, CSS, and JavaScript. Desktop applications can be written in various languages depending on the platform.

Application tier

The application tier, also known as the logic tier or middle tier, is the heart of the application. In this tier, information that is collected in the presentation tier is processed - sometimes against other information in the data tier - using business logic, a specific set of business rules. The application tier can also add, delete, or modify data in the data tier.

The application tier is typically developed by using Python, Java, Perl, PHP or Ruby, and communicates with the data tier by using API calls.

The data tier, sometimes called database tier, data access tier or back-end, is where the information that is processed by the application is stored and managed. This can be a relational database management system such as PostgreSQL , MySQL, MariaDB, Oracle, Db2, Informix or Microsoft SQL Server, or in a NoSQL Database server such as Cassandra, CouchDB , or MongoDB .

In a three-tier application, all communication goes through the application tier. The presentation tier and the data tier cannot communicate directly with one another.

Tier versus layer

In discussions of three-tier architecture, layer is often used interchangeably – and mistakenly – for tier , as in 'presentation layer' or 'business logic layer'.

They aren't the same. A 'layer' refers to a functional division of the software, but a 'tier' refers to a functional division of the software that runs on infrastructure separate from the other divisions. The Contacts app on your phone, for example, is a three - layer application, but a single-tier application, because all three layers run on your phone.

The difference is important because layers can't offer the same benefits as tiers.

Again, the chief benefit of three-tier architecture is its logical and physical separation of functionality. Each tier can run on a separate operating system and server platform - for example, web server, application server, database server - that best fits its functional requirements. And each tier runs on at least one dedicated server hardware or virtual server, so the services of each tier can be customized and optimized without impacting the other tiers.

Other benefits (compared to single- or two-tier architecture) include:

Faster development : Because each tier can be developed simultaneously by different teams, an organization can bring the application to market faster. And programmers can use the latest and best languages and tools for each tier.
Improved scalability : Any tier can be scaled independently of the others as needed.
Improved reliability : An outage in one tier is less likely to impact the availability or performance of the other tiers.
Improved security : Because the presentation tier and data tier can't communicate directly, a well-designed application tier can function as an internal firewall, preventing SQL injections and other malicious exploits.

In web development, the tiers have different names but perform similar functions:

The web server is the presentation tier and provides the user interface. This is usually a web page or website, such as an ecommerce site where the user adds products to the shopping cart, adds payment details or creates an account. The content can be static or dynamic, and is developed using HTML, CSS, and JavaScript.
The application server corresponds to the middle tier, housing the business logic that is used to process user inputs. To continue the ecommerce example, this is the tier that queries the inventory database to return product availability, or adds details to a customer's profile. This layer often developed using Python, Ruby, or PHP and runs a framework such as Django, Rails, Symphony, or ASP.NET.
The database server is the data or backend tier of a web application. It runs on database management software, such as MySQL, Oracle, DB2, or PostgreSQL.

While three-tier architecture is easily the most widely adopted multitier application architecture, there are others that you might encounter in your work or your research.

Two-tier architecture

Two-tier architecture is the original client-server architecture, consisting of a presentation tier and a data tier; the business logic lives in the presentation tier, the data tier or both. In two-tier architecture the presentation tier - and therefore the end user - has direct access to the data tier, and the business logic is often limited. A simple contact management application, where users can enter and retrieve contact data, is an example of a two-tier application.

N-tier architecture

N-tier architecture - also called or multitier architecture - refers to any application architecture with more than one tier. But applications with more than three layers are rare because extra layers offer few benefits and can make the application slower, harder to manage and more expensive to run. As a result, n-tier architecture and multitier architecture are usually synonyms for three-tier architecture.

Move to cloud faster with IBM Cloud Pak solutions running on Red Hat OpenShift software—integrated, open, containerized solutions certified by IBM®.

Seamlessly modernize your VMware workloads and applications with IBM Cloud.

Modernize, build new apps, reduce costs, and maximize ROI.

IBM Consulting® application modernization services, which are powered by IBM Consulting Cloud Accelerator, offers skills, methods, tools, and initiatives that help determine the right strategy based on your portfolio. To modernize and containerize legacy system applications and accelerate the time-to-value of hybrid cloud environments.

Discover what application modernization is, the common benefits and challenges, and how to get started.

Learn about how relational databases work and how they compare to other data storage options.

Explore cloud native applications and how they drive innovation and speed within your enterprise.

Modernize your legacy three-tier applications on your journey to cloud. Whether you need assistance with strategy, processes, or capabilities—or want full-service attention—IBM can help. Start using containerized middleware that can run in any cloud—all bundled in IBM Cloud Paks.

IMAGES

Networking(DCCN): Presentation Layer
Presentation layer
Presentation Layer
Presentation Layer in OSI Model
layers_1
Presentation Layer

VIDEO

Technical Information (Part
OSI model
CCNA Course
Application Layer and Presentation Layer || OSI Model part 1
Steps to Create Presentation Layer and RPD Testing 03: By RR ITEC, Hyderabad, India
Working on a commission

COMMENTS

Presentation Layer in OSI model
Learn about the functions, features and protocols of the presentation layer in the OSI model, which is the 6th layer that translates data for network communication. The presentation layer formats, encrypts, compresses and converts data according to the network protocol and architecture.
Layer 6 Presentation Layer
The presentation layer (layer 6) sets the system-dependent representation of the data into an independent form, enabling the data exchange between different systems. It also performs functions such as data compression and encryption to ensure the data can be read by the application layer of another system.
Presentation layer
The presentation layer is layer 6 of the OSI model and serves as the data translator for the network. It ensures the information that the application layer of one system sends out is readable by the application layer of another system, and performs data conversion, character code translation, compression, encryption and decryption.
The OSI Model
Learn the OSI model and the 7 layers of networking, a conceptual framework that helps standardize how computer systems send information to each other. The OSI model does not enhance network communication, but it helps understand and troubleshoot it.
What is presentation layer?
The presentation layer resides at Layer 6 of the Open Systems Interconnection (OSI) communications model and ensures that communications that pass through it are in the appropriate form for the recipient application. In other words, the presentation layer presents the data in a readable format from an application layer perspective.
What is the OSI model? How to explain and remember its 7 layers
The OSI model is a conceptual framework that describes networking or telecommunications systems as seven layers, each with its own function. The presentation layer is responsible for preparing or ...
What is the presentation layer?
Learn what the presentation layer does in the OSI model, a reference model for network communication. It converts file formats, encrypts and decrypts data, and uses protocols like HTTP and FTP.
A Guide to the Presentation Layer
The presentation layer translates, compresses, and encrypts data across networks. It uses protocols like SSL, AFP, NCP, XDR, and NDR to perform these functions and ensure data security and compatibility.
What is a Presentation Layer?
Presentation Layer. The Presentation Layer is the sixth layer in the OSI model. It sits right above the Session Layer and below the Application Layer. Its main job is to handle how data is presented to the application. In other words, it ensures that the data is in a format that both the sending and receiving systems can understand.
Presentation Layer of the OSI Model
Learn about the presentation layer in the OSI model and its functions, protocols, and sub-layers. The presentation layer translates, encrypts, and compresses data for the application layer.
What is the Presentation Layer?
The presentation layer is the sixth layer of the OSI model that formats data for the application layer. It performs data encryption, conversion, compression and graphic handling.
Unveiling the Interpreter: Fortifying the Presentation Layer's Role in
The Presentation Layer, often likened to an adept interpreter in the digital realm, plays a pivotal role in the seamless transmission and reception of data across the network. At its essence, the Presentation Layer is tasked with data translation, encryption, and compression. It ensures that the information sent from the application layer is ...
OSI model
The OSI model is a reference model for networked communication that divides the flow of data into seven abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Learn about the history, functions, and protocols of each layer, and how the OSI model relates to the Internet protocol suite.
Presentation Layer: Protocols, Examples, Services
Learn about the 6th layer in the Open System Interconnection (OSI) model, which is responsible for data translation, encryption, compression, and formatting. Find out the common protocols, examples, and services of the presentation layer with this tutorial.
What is the OSI model? The 7 layers of OSI explained
Information technology (IT) networking professionals use OSI to model or conceptualize how data is sent or received over a network. Understanding this is a foundational part of most IT networking certifications, including the Cisco Certified Network Associate (CCNA) and CompTIA Network+ certification programs. ... The presentation layer.
What is the Presentation Layer in Programming?
The three main layers include: Presentation Layer. Business Layer. Data Layer. Now, these three layers are typically related to enterprise web applications. It's a design pattern used to help separate your code out in three distinct areas that (if need be) can easily be switched out with another programming language or technology.
Presentation Layer in OSI Model
The presentation layer is the 6th layer from the bottom in the OSI model. It converts one format of data to another format of data if both sender and receiver understand different formats; hence this layer is also called the translation layer. It deals with the semantics and syntax of the data, and uses operations such as data compression, data encryption & decryption, data conversion, etc.
OSI model
The session layer is meant to store states between two connections, like what we use cookies for when working with web programming. The presentation layer is meant to convert between different formats. This was simpler when the only format that was worried about was character encoding, ie ASCII and EBCDIC. When you consider all of the different ...
Chapter 10
Overview. The presentation layer contains the components that implement and display the user interface and manage user interaction. This layer includes controls for user input and display, in addition to components that organize user interaction. Figure 1 shows how the presentation layer fits into a common application architecture.
Multitier architecture
Learn about multitier architecture, a client-server model that separates presentation, logic and data functions. Find out the common layers, benefits and drawbacks of n-tier and 3-tier architectures, and how they are used in web development.
The OSI Model and You Part 6: Stopping Threats at the OSI Presentation
The OSI Model and You Part 6: Stopping Threats at the OSI Presentation Layer. Our travels through the OSI seven layers of networking have shown that each layer has specific weaknesses and angles ...
What Is Three-Tier Architecture?
The presentation tier is the user interface and communication layer of the application, where the end user interacts with the application. Learn how three-tier architecture separates functionality into presentation, application and data tiers, and how it differs from layer and other multitier architectures.