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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.



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Presentation layer and Session layer of the OSI model

There are two popular networking models: the OSI layers model and the TCP/IP layers model. The presentation layer and session layer exist only in the OSI layers models. The TCP/IP layers model merges them into the application layer.

The Presentation Layer

The presentation layer is the sixth layer of the OSI Reference model. It defines how data and information is transmitted and presented to the user. It translates data and format code in such a way that it is correctly used by the application layer.

It identifies the syntaxes that different applications use and formats data using those syntaxes. For example, a web browser receives a web page from a web server in the HTML language. HTML language includes many tags and markup that have no meaning for the end user but they have special meaning for the web browser. the web browser uses the presentation layer's logic to read those syntaxes and format data in such a way the web server wants it to be present to the user.

presentation layer

On the sender device, it encapsulates and compresses data before sending it to the network to increase the speed and security of the network. On the receiver device, it de-encapsulates and decompresses data before presenting it to the user.

Examples of the presentation layer

Example standards for representing graphical information: JPEG, GIF, JPEG, and TIFF.

Example standards for representing audio information: WAV, MIDI, MP3.

Example standards for representing video information: WMV, MOV, MP4, MPEG.

Example standards for representing text information: doc, xls, txt, pdf.

Functions of the presentation layer

  • It formats and presents data and information.
  • It encrypts and compresses data before giving it to the session layer.
  • It de-encrypts and decompresses the encrypted and compressed data it receives from the session layer.

Session layer

The session layer is the fifth layer of the OSI layers model. It is responsible for initiating, establishing, managing, and terminating sessions between the local application and the remote applications.

It defines standards for three modes of communication: full duplex, half-duplex, and simplex.

duplex modes

In the full duplex mode, both devices can send and receive data simultaneously. The internet connection is an example of the full duplex mode.

In the half duplex mode, only one device can send data at a time. A telephone conversation is an example of the half-duplex mode.

In the simplex mode, only one device can send data. A radio broadcast is an example of the simplex mode.

Functions of the session layer

  • It is responsible for terminating sessions, creating checkpoints, and recovering data when sessions are interrupted.
  • It opens and maintains logical communication channels between network applications running on the local host and network applications running on the remote host.
  • If a network application uses an authentication mechanism before it opens a logical communication channel (session) with the remote host, it handles the authentication process.

Examples of the session layer

Structure Query Language (SQL), Remote Procedure Call (RPC), and Network File System (NFS) are examples of the session layer.

By ComputerNetworkingNotes Updated on 2024-09-24

ComputerNetworkingNotes CCNA Study Guide Presentation layer and Session layer of the OSI model

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Presentation Layer

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What is the Presentation Layer?

Presentation Layer is the Layer 6 of the seven-layer Open Systems Interconnection (OSI) reference model . The presentation layer structures data that is passed down from the application layer into a format suitable for network transmission. This layer is responsible for data encryption, data compression, character set conversion, interpretation of graphics commands, and so on. The network redirector also functions at this layer.

Presentation Layer

Presentation Layer functions

  • Translation:  Before being transmitted, information in the form of characters and numbers should be changed to bit streams. Layer 6 is responsible for interoperability between encoding methods as different computers use different encoding methods. It translates data between the formats the network requires and the format the computer.
  • Encryption:  Encryption at the transmitter and decryption at the receiver
  • Compression:  Data compression to reduce the bandwidth of the data to be transmitted. The primary role of  data compression  is to reduce the number of bits to be transmitted. Multimedia files, such as audio and video, are bigger than text files and compression is more important.

Role of Presentation Layer in the OSI Model

This layer is not always used in network communications because its functions are not always necessary. Translation is only needed if different types of machines need to talk with each other. Encryption is optional in communication. If the information is public there is no need to encrypt and decrypt info. Compression is also optional. If files are small there is no need for compression.

Explaining Layer 6 in video

Most real-world protocol suites, such as TCP/IP , do not use separate presentation layer protocols. This layer is mostly an abstraction in real-world networking.

An example of a program that loosely adheres to layer 6 of OSI is the tool that manages the Hypertext Transfer Protocol (HTTP) — although it’s technically considered an application-layer protocol per the TCP/IP model.

However, HTTP includes presentation layer services within it. HTTP works when the requesting device forwards user requests passed to the web browser onto a web server elsewhere in the network.

It receives a return message from the web server that includes a multipurpose internet mail extensions (MIME) header. The MIME header indicates the type of file – text, video, or audio – that has been received so that an appropriate player utility can be used to present the file to the user.

In short, the presentation layer

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.

  • ensures proper formatting and delivery to and from the application layer;
  • performs data encryption; and
  • manages serialization of data objects.

Presentation Layer In OSI Model : A Comprehensive Guide

In the vast landscape of computer networks, the OSI (Open Systems Interconnection) model stands as a fundamental framework for understanding how data is transmitted from one device to another. Among its seven layers, the presentation layer holds an important place, acting as a translator and formatter to ensure seamless communication between different systems. Through this article, we will try to know what is presentation layer in OSI model, what is its role in the field of networking and what is its importance.

Table of Contents

What is the Presentation Layer?

The Presentation Layer, within the OSI (Open Systems Interconnection) model, is the sixth layer. It focuses on the representation of data, ensuring that information exchanged between applications is formatted appropriately for transmission and receipt across a network. This layer handles tasks such as data translation, encryption, compression, and formatting. Its primary function is to ensure that data remains readable and understandable by both the sender and receiver, regardless of differences in data formats. In essence, the Presentation Layer acts as a translator and formatter, facilitating seamless communication between different systems and enhancing the reliability and security of data transmission.

Working of Presentation Layer

The Presentation Layer acts like a language translator and document formatter in the OSI model. It takes data from applications and prepares it for transmission over the network by translating it into a language that both the sender and receiver understand. Think of it as converting a letter into a universal format before mailing it overseas. Additionally, the Presentation Layer ensures that the data looks right by formatting it properly, like adjusting the font and spacing in a document. It also adds extra security by encrypting the data if needed, making it like a secret code that only the intended recipient can understand. Lastly, it might shrink the data down to save space during transmission, similar to compressing a file before emailing it. In short, the Presentation Layer makes sure data is ready for its journey across the network, keeping it secure, readable, and efficient along the way.

Functions of the Presentation Layer

  • Data Translation : Converting data from the format used by the application into a format suitable for transmission over the network, and vice versa, ensuring interoperability between different systems.
  • Encryption and Decryption : Securing data during transmission by encrypting it before sending and decrypting it upon reception, ensuring confidentiality and integrity of the information.
  • Data Compression : Reducing the size of data before transmission to optimize bandwidth usage and speed up the transfer process, improving network efficiency.
  • Data Formatting: Formatting data according to predefined standards for transmission, including character encoding, data structure, and multimedia representation, ensuring compatibility between sender and receiver applications.
  • Protocol Conversion : Adapting data between different network protocols or data formats, facilitating communication between systems with varying requirements or standards.
  • Character Code Translation: Converting characters between different character sets or encoding schemes to ensure proper interpretation of text-based data across systems with different language or encoding preferences.

Protocols are Use in Presentation layer

The Presentation Layer primarily focuses on data representation and formatting rather than specific protocols. However, some protocols or standards are commonly associated with the Presentation Layer due to their role in data representation and formatting. Here are a few examples.

  • MIME : MIME stands for Multipurpose Internet Mail Extensions. It’s a protocol that broadens the scope of email messages, enabling the use of text in various character sets beyond ASCII. Additionally, MIME facilitates the inclusion of attachments such as audio, video, images, and application programs within emails.
  • SSL/TLS : SSL/TLS protocols provide secure communication over a computer network by encrypting data between the client and server, ensuring data confidentiality and integrity. While SSL/TLS operate at the Transport Layer, they often involve encryption and decryption processes associated with the Presentation Layer.
  • ASCII (: ASCII and Unicode are character encoding standards that represent text characters using numerical codes. These standards ensure consistent representation of text characters across different systems and platforms, which is crucial for data interchange.
  • JPEG, GIF, PNG : These image file formats are commonly used for encoding and transmitting images over networks. While the specifics of image compression and encoding are often handled by the Application Layer, the Presentation Layer ensures proper interpretation and formatting of these image data.
  • PDF : PDF is a file format used to present and exchange documents reliably, independent of software, hardware, or operating systems. The Presentation Layer ensures proper interpretation and rendering of PDF documents for display or printing

the Presentation Layer of the OSI Model acts as a translator and formatter, ensuring that data exchanged between applications remains readable and compatible across diverse systems. By handling tasks such as data translation, encryption, compression, and formatting, it enhances the reliability, efficiency, and security of data transmission over networks. Essentially, the Presentation Layer plays a crucial role in facilitating seamless communication between different systems, ensuring that information is accurately represented and securely transmitted, thus contributing to the smooth functioning of modern networking environments.

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Last Updated on March 7, 2024 by Abhishek Sharma

presentation layer task

The OSI (Open Systems Interconnection) model is a conceptual framework used to understand the functions of a telecommunication or computing system. It consists of seven layers, each responsible for specific tasks. The sixth layer, known as the Presentation Layer, plays a crucial role in ensuring that data exchanged between systems is readable and usable. Let’s explore the functions and importance of the Presentation Layer in the OSI model.

What is Presentation Layer in OSI Model?

The Presentation Layer, the sixth layer of the OSI (Open Systems Interconnection) model, is responsible for ensuring that data exchanged between systems is in a format that can be interpreted and used by the receiving system. It performs various functions, including data translation, encryption, compression, and formatting, to facilitate efficient and secure communication between networked devices.

Functions of the Presentation Layer

Below are some of the functions of the Presentation Layer in OSI Model:

  • Data Translation: The Presentation Layer translates data from the format used by the application layer into a format that can be transmitted over the network. This includes encoding, compression, and encryption.
  • Data Formatting: It ensures that data is formatted according to the specifications of the application layer. This includes converting between different character sets, such as ASCII and Unicode.
  • Data Compression: The Presentation Layer compresses data to reduce the amount of bandwidth required for transmission, improving network efficiency.
  • Data Encryption: It encrypts data to ensure that it remains secure during transmission, protecting it from unauthorized access.
  • Data Syntax: The Presentation Layer defines the syntax for data representation, ensuring that both the sender and receiver understand the structure of the data being exchanged.

Importance of the Presentation Layer

Importance of Presentation Layer are:

  • Data Integrity: By ensuring that data is formatted correctly and encrypted, the Presentation Layer helps maintain the integrity of data during transmission.
  • Interoperability: The Presentation Layer enables different systems to communicate with each other by ensuring that data is translated into a common format that both systems understand.
  • Efficiency: Data compression reduces the amount of data that needs to be transmitted, improving network efficiency and reducing bandwidth requirements.
  • Security: Encryption provided by the Presentation Layer ensures that data remains secure and protected from unauthorized access.

Conclusion The Presentation Layer is a crucial component of the OSI model, responsible for ensuring that data exchanged between systems is in a format that can be understood and used. By performing functions such as data translation, formatting, compression, and encryption, the Presentation Layer plays a vital role in maintaining data integrity, facilitating interoperability, and ensuring the security of data during transmission.

FAQs related to Presentation Layer in OSI Model

Here are some of the FAQs related to Presentation Layer in OSI Model:

Q1: What is the role of the Presentation Layer in the OSI model? The Presentation Layer ensures that data exchanged between systems is in a usable format, performing functions such as data translation, encryption, compression, and formatting.

Q2: How does the Presentation Layer ensure data security? The Presentation Layer encrypts data before transmission, making it unreadable to unauthorized parties, thus ensuring data security.

Q3: Why is data compression important in the Presentation Layer? Data compression reduces the size of data packets, leading to faster transmission speeds and optimized bandwidth usage, which is crucial in high-traffic networks.

Q4: How does the Presentation Layer facilitate interoperability between systems? By translating data into a common format that both sender and receiver understand, the Presentation Layer enables different systems to communicate with each other seamlessly.

Q5: Can the Presentation Layer be bypassed in data transmission? While it is possible to bypass the Presentation Layer in some cases, doing so can lead to compatibility issues between systems and is not recommended.

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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.

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The presentation layer is the sixth layer of the OSI Reference Model protocol stack, and second from the top. It is different from the other layers in two key respects. First, it has a much more limited and specific function than the other layers; it's actually somewhat easy to describe, hurray! Second, it is used much less often than the other layers; in many types of connections it is not required.

The name of this layer suggests its main function as well: it deals with the presentation of data. More specifically, the presentation layer is charged with taking care of any issues that might arise where data sent from one system needs to be viewed in a different way by the other system. It also takes care of any special processing that must be done to data from the time an application tries to send it until the time it is sent over the network.

Here are some of the specific types of data handling issues that the presentation layer handles:

The reason that the presentation layer is not always used in network communications is that the jobs mentioned above are simply not always needed. Compression and encryption are usually considered “optional”, and translation features are also only needed in certain circumstances. Another reason why the presentation layer is sometimes not mentioned is that its functions may be performed as part of the application layer.

The fact that the translation job done by the presentation layer isn't always needed means that it is common for it to be “skipped” by actual protocol stack implementations. This means that protocols at layer seven may talk directly with those at layer five. Once again, this is part of the reason why all of the functions of layers five through seven may be included together in the same software package, as described in the overview of layers and layer groupings .

The sixth OSI model layer is called the . Protocols at this layer take care of manipulation tasks that transform data from one representation to another, such as translation, compression and encryption. In many cases, no such functions are required in a particular networking stack; if so, there may not be any protocol active at layer six.

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Presentation Layer - OSI Reference Model

The primary goal of this layer is to take care of the syntax and semantics of the information exchanged between two communicating systems. Presentation 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. Languages(syntax) can be different of the two communicating systems. Under this condition presentation layer plays a role translator.

In order to make it possible for computers with different data representations to communicate, the data structures to be exchanged can be defined in an abstract way. The presentation layer manages these abstract data structures and allows higher-level data structures(eg: banking records), to be defined and exchanged.

Functions of Presentation Layer

  • Translation: Before being transmitted, information in the form of characters and numbers should be changed to bit streams. The presentation layer is responsible for interoperability between encoding methods as different computers use different encoding methods. It translates data between the formats the network requires and the format the computer.
  • Encryption: It carries out encryption at the transmitter and decryption at the receiver.
  • Compression: It carries out data compression to reduce the bandwidth of the data to be transmitted. The primary role of Data compression is to reduce the number of bits to be 0transmitted. It is important in transmitting multimedia such as audio, video, text etc.

Presentation Layer in ISO-OSI Model

Design Issues with Presentation Layer

  • To manage and maintain the Syntax and Semantics of the information transmitted.
  • Encoding data in a standard agreed upon way. Eg: String, double, date, etc.
  • Perform Standard Encoding on wire.
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Presentation Layer: What It Is, Design Issues, Functionalities

Description and Functions of Presentation Layer in the OSI model: In this tutorial, we are going to learn what the Presentation layer is and the Functions of the Presentation Layer in the OSI model in Computer Networking. We will also discuss the Design issues with the Presentation Layer and the working of the Presentation Layer with the help of its diagram. By Monika Jha Last updated : May 05, 2023

What is Presentation Layer?

The Presentation Layer is concerned with the syntax and semantics of the information exchanged between two communicating devices.

  • The presentation layer takes care that the data is sent in that way the receiver of the data will understand the information (data) and will be able to use the data.
  • Languages that are syntax can be different from the two communicating machines. In this condition, the presentation layer plays the role of translator between them.
  • It is possible for two machines to communicate with different data representations, data structures to be exchanged can be defined in an abstract way.
  • These abstract data structures will be managed by the presentation layer and this layer allows higher-level data structures (For example banking records), to be defined and exchanged.

This figure shows the relationship of the presentation layer to the session layer and application layer.

presentation layer

Design Issues with Presentation Layer

The following are the design issues with presentation layer:

  • To manage and maintain the Syntax and Semantics of the information transmitted.
  • Encoding data in a standard agreed-upon way just like a string, double, date, etc.
  • It Performs Standard Encoding scheme on the wire.

Functionalities of the Presentation Layer

Specific functionalities of the presentation layer are as follows:

1. Translation

  • The processes or running programs in two machines are usually exchanging the information in the form of numbers, character strings and so on before being transmitted. The information should be changed to bitstreams because different computers use different encoding schemes.
  • The Presentation layer is responsible for compatibility between these encoding methods.
  • The Presentation layer at the sender's side changes the information from its sender dependent format.
  • The Presentation layer at the receiving machine changes the common format into its receivers dependent format.

Example: Convert ASCII code to EBCDIC code.

2. Encryption

  • The system must be able to assure privacy regarding the message or information as it also carries sensitive information.
  • Encryption means that the sender transforms the original information or message to another form, this data after encryption is known as the ciphertext and this ciphertext sends the resulting message out over the network.
  • Decryption concerned with the transform of the message back to its original form. This decrypted data is known as plain text.

3. Compression

  • Data Compression means reduces the number of bits to be transmitted by this reduce the bandwidth of the data.
  • Data Compression becomes particularly important in the transmission of multimedia such as audio, video, text, etc.

Related Tutorials

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

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:

Image

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?

Cave, Dragon's Lair, mountains

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:

Closeup of 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.

Koala with Photoshopped makeup

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

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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.

presentation layer task

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 .

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OSI Presentation and Application Layers

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presentation layer task

  • Paul D. Bartoli 3  

Part of the book series: Applications of Communications Theory ((ACTH))

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This chapter discusses the Application and Presentation Layers of the Reference Model of Open Systems Interconnection (OSI) [1]. The Application and Presentation Layers perform functions necessary to exchange information between application processes; the Application Layer is concerned with the semantic aspects of the information exchange, while the Presentation Layer is concerned with the syntactic aspects. The ability to manage the semantic and syntactic elements of the information to be exchanged is key to ensuring that the information can be interpreted by the communicants.

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ISO 7498, “Information processing systems—Open Systems Interconnection—Basic Reference Model,” 1984. CCITT Recommendation X.200, “Reference model of open systems interconnection for CCITT applications,” 1984 (updated expected in 1988).

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ISO DIS 9545, “Information processing systems—Open Systems Interconnection—Application Layer structure,” September 1988.

ISO TR 9007, “Concepts and terminology for the conceptual schema and the information base,” 1985.

ISO 8649, “Information processing systems—Open systems interconnection—Service definition for the association control service element,” 1988. ISO 8650, “Information processing systems—Open systems interconnection—Protocol specification for the association control service element,” 1988. CCITT Recommendation X.217, “Association control service definition for open systems interconnection for CCITT applications,” 1988. CCITT Recommendation X.227, “Association control protocol specification for open systems interconnection for CCITT applications,” final text December, 1987.

ISO 8571, “Information processing systems—Open systems interconnection—File transfer, access, and management,” Parts 1–4, 1988.

ISO/DIS 9804, “Information processing systems”Open systems interconnection—Service definition for commitment, concurrency, and recovery,” 1988 (text in SC 21 N 2573, March, 1988). ISO DIS 9805, “Information processing systems—Open systems interconnection—Protocol specification for commitment, concurrency, and recovery,” 1988 (text in SC 21 N 2574, March, 1988). CCITT Recommendation X.237, “Commitment, concurrency, and recovery service definition,” Draft Text, 1988. CCITT Recommendation X.247, “Commitment, concurrency, and recovery protocol specification, Draft Text, 1988.

ISO DIS 9040, “Information processing systems—Open systems interconnection—Virtual terminal service—Basic class,” 1988 (text in SC 21 N 2615, March, 1988). ISO DIS 9041, “Information processing systems—Open systems interconnection—Virtual terminal protocol—Basic class,” 1988 (text in SC 21 N 2616, March, 1988).

ISO DIS 9066–1, “Reliable transfer service”, 1988 (text in SC 18 N 1408, March, 1988). ISO DIS 9066–2, “Reliable transfer protocol specification,” 1988 (text in SC 18 N 1409). CCITT Recommendation X.218, “Reliable transfer: Model and service definition,” 1988. CCITT Recommendation X.228, “Reliable transfer: Protocol specification,” 1988.

ISO DIS 9072–1, “Remote operations service,” 1988 (text in SC 18 N 1410, March, 1988). ISO DIS 9072–2, “Remote operations protocol specification,” 1988 (text in SC 18 N 1411, March, 1988). CCITT Recommendation X.219, “Remote operations: Model, notation, and service definition,” 1988. CCITT Recommendation X.229, “Remote operations: Protocol specification,” 1988.

ISO DIS 9594, “Information processing—Open systems interconnection—The directory,” parts 1–8, 1988 (text in SC 21 N 2751 through N 2758, April, 1988). CCITT X.500, “Series recommendations on directory,” November, 1987.

ISO DIS 10021, “Information processing—Text communication—Message oriented text interchange system,” 1988 (text in SC 18 N 1487 through N 1493, May, 1988). CCITT X.400, “Series recommendations for message handling systems,” 1988.

ISO 8613/1–8, “Office document architecture and interchange format,” 1988, awaiting publication. CCITT T.400, “Series recommendations for document architecture, transfer, and manipulation,” 1988.

ISO 8824, “Information processing systems—Open systems interconnection—Specification of abstract syntax notation one (ASN.1),” 1987; and ISO 8824/PDAD 1, “Information processing systems—Open systems interconnection—Specification for ASN.1: Proposed draft Addendum 1 on ASN.1 extensions,” 1988 (final text in SC 21 N 2341 Revised, April, 1988). CCITT Recommendation X.208, “Specification of abstract syntax notation one (ASN.1),” 1988.

ISO 8822, “Information processing systems—Open systems interconnection—Connection oriented presentation service definition,” 1988. CCITT Recommendation X.216, “Presentation service definition for open systems interconnection for CCITT applications,” 1988.

ISO 8825, “Information processing—Open systems interconnection—Specification of basic encoding rules for abstract syntax notation one (ASN.1),” 1987; and ISO 8825/ PDAD 1, “Information processing systems—Open systems interconnection—Specification of basic encoding rules for ASN.1: Proposed draft addendum 1 on ASN.1 extensions,” 1988 (text in SC 21 N 2342 Revised, April, 1988). CCITT Recommendation X.209, “Specification of basic encoding rules for abstract syntax notation one (ASN.1),” 1988.

ISO 8823, “Information processing systems—Open systems interconnection—Connection oriented presentation protocol specification,” 1988. CCITT Recommendation X.226, “Presentation protocol specification for open systems interconnection for CCITT applications,” 1988.

ISO 8326, “Information processing systems—Open systems interconnection—Basic connection oriented session service definition,” 1987; and ISO 8326/AD 2, “Information processing systems—Open systems interconnection—Basic connection oriented session service definition—Addendum 2: Incorporation of unlimited user data,” 1988. ISO 8327, “Information processing systems—Open systems interconnection—Basic connection oriented session protocol specification,” 1987; and ISO 8327/AD 2, “Information processing systems—Open systems interconnection—Basic connection oriented session protocol specification—Addendum 2: Unlimited session user data protocol specification,” 1988.

CCITT Recommendation X.215, “Session service definition for open systems interconnection for CCITT applications,” 1988. CCITT Recommendation X.225, “Session protocol specification for open systems interconnection for CCITT applications,” 1988.

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Bartoli, P.D. (1989). OSI Presentation and Application Layers. In: Sunshine, C.A. (eds) Computer Network Architectures and Protocols. Applications of Communications Theory. Springer, Boston, MA. https://doi.org/10.1007/978-1-4613-0809-6_13

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Application Layer in OSI Model

The Application Layer of OSI (Open System Interconnection) model, is the top layer in this model and takes care of network communication. The application layer provides the functionality to send and receive data from users. It acts as the interface between the user and the application. The application provides services like file transmission, mail service, and many more.

In this article we will explore the application layer in the OSI model, application layer functions, the working of the application layer, and services provided by the application layer.

Table of Content

  • What is Application Layer in OSI Model?

Functions of Application Layer

Working of application layer in osi model, features provided by application layer protocols.

  • Services Provided by Application Layer Protocols

Application Layer Protocols

What is an application layer in osi model.

Application Layer is the topmost layer in the Open System Interconnection (OSI) model . This layer provides several ways for manipulating the data (information) which actually enables any type of user to access network with ease. This layer also makes a request to its bottom layer, which is presentation layer for receiving various types of information from it.

The Application Layer interface directly interacts with application and provides common web application services. This layer is basically highest level of open system, which provides services directly for application process.

The Application Layer, as discussed above, being topmost layer in OSI model, performs several kinds of functions which are requirement in any kind of application or communication process. Following are list of functions which are performed by Application Layer of OSI Model:

  • Application Layer provides a facility by which users can forward several emails and it also provides a storage facility.
  • This layer allows users to access, retrieve and manage files in a remote computer.
  • It allows users to log on as a remote host.
  • This layer provides access to global information about various services.
  • This layer provides services which include: e-mail, transferring files, distributing results to the user, directory services, network resources and so on.
  • It provides protocols that allow software to send and receive information and present meaningful data to users.
  • It handles issues such as network transparency, resource allocation and so on.
  • This layer serves as a window for users and application processes to access network services.
  • Application Layer is basically not a function, but it performs application layer functions.
  • The application layer is actually an abstraction layer that specifies the shared protocols and interface methods used by hosts in a communication network.
  • Application Layer helps us to identify communication partners, and synchronizing communication.
  • This layer allows users to interact with other software applications.
  • In this layer, data is in visual form, which makes users truly understand data rather than remembering or visualize the data in the binary format (0’s or 1’s).
  • This application layer basically interacts with Operating System (OS) and thus further preserves the data in a suitable manner.
  • This layer also receives and preserves data from it’s previous layer, which is Presentation Layer (which carries in itself the syntax and semantics of the information transmitted).
  • The protocols which are used in this application layer depend upon what information users wish to send or receive.
  • This application layer, in general, performs host initialization followed by remote login to hosts.

The application layer in the OSI model generally acts only like the interface which is responsible for communicating with host-based and user applications. This is in contrast with TCP/IP protocol, wherein the layers below the application layer, which is Session Layer and Presentation layer, are clubbed together and form a simple single layer which is responsible for performing the functions, which includes controlling the dialogues between computers, establishing as well as maintaining as well as ending a particular session, providing data compression and data encryption and so on.

Working of Application Layer

  • At first, client sends a command to server and when server receives that command, it allocates port number to client.
  • Thereafter, the client sends an initiation connection request to server and when server receives request, it gives acknowledgement (ACK) to client through client has successfully established a connection with the server.
  • Therefore, now client has access to server through which it may either ask server to send any types of files or other documents or it may upload some files or documents on server itself.

To ensure smooth communication, application layer protocols are implemented the same on source host and destination host. The following are some of the features which are provided by Application layer protocols-

  • The Application Layer protocol defines process for both parties which are involved in communication.
  • These protocols define the type of message being sent or received from any side (either source host or destination host).
  • These protocols also define basic syntax of the message being forwarded or retrieved.
  • These protocols define the way to send a message and the expected response.
  • These protocols also define interaction with the next level.

Services Provided by Application Layer

The services provided by application layer in OSI model are:

  • It provides interface between user and application.
  • It is used for remote login.
  • It is used for file transfer.
  • It is used for mail services and transfers.
  • It is also used to transfer multimedia files.
  • It is used for resource sharing.
  • It is used for data synchronization.
  • It is used for authentication services.

The application layer provides several protocols which allow any software to easily send and receive information and present meaningful data to its users. The following are some of the application layer protocols .

  • TELNET: Telnet stands for Telecommunications Network. This protocol is used for managing files over the Internet. It allows the Telnet clients to access the resources of Telnet server. Telnet uses port number 23.
  • DNS: DNS stands for Domain Name System. The DNS service translates the domain name (selected by user) into the corresponding IP address. For example- If you choose the domain name as www.abcd.com, then DNS must translate it as 192.36.20.8 (random IP address written just for understanding purposes). DNS protocol uses the port number 53.
  • DHCP: DHCP stands for Dynamic Host Configuration Protocol. It provides IP addresses to hosts. Whenever a host tries to register for an IP address with the DHCP server, DHCP server provides lots of information to the corresponding host. DHCP uses port numbers 67 and 68.
  • FTP: FTP stands for File Transfer Protocol. This protocol helps to transfer different files from one device to another. FTP promotes sharing of files via remote computer devices with reliable, efficient data transfer. FTP uses port number 20 for data access and port number 21 for data control.
  • SMTP: SMTP stands for Simple Mail Transfer Protocol. It is used to transfer electronic mail from one user to another user. SMTP is used by end users to send emails with ease. SMTP uses port numbers 25 and 587.
  • HTTP: HTTP stands for Hyper Text Transfer Protocol. It is the foundation of the World Wide Web (WWW). HTTP works on the client server model. This protocol is used for transmitting hypermedia documents like HTML. This protocol was designed particularly for the communications between the web browsers and web servers, but this protocol can also be used for several other purposes. HTTP is a stateless protocol (network protocol in which a client sends requests to server and server responses back as per the given state), which means the server is not responsible for maintaining the previous client’s requests. HTTP uses port number 80.
  • NFS: NFS stands for Network File System. This protocol allows remote hosts to mount files over a network and interact with those file systems as though they are mounted locally. NFS uses the port number 2049.
  • SNMP: SNMP stands for Simple Network Management Protocol. This protocol gathers data by polling the devices from the network to the management station at fixed or random intervals, requiring them to disclose certain information. SNMP uses port numbers 161 (TCP) and 162 (UDP).

From the above discussion we can conclude that application layer is the topmost layer in the OSI Model and acts as an interface between end user software like a web browser (or any other application that needs network communication) to send or receive data over network. By offering support for multiple protocols like SMTP, FTP, SNMP and DHCP the stack helps in effective communication of data. Every one who is at network management and application development should also have the idea about what are basic functions of Application Layer and Protocols.

Frequently Asked Questions on Application Layer in OSI Model – FAQ’s

What is the function of the application layer.

The function of application layer is to provide an interface to send and receive data from user.

Which is an Application Layer Service?

The application layer services are remote login, email services and file transmission.

How does the Application Layer ensure data integrity?

It uses protocols and error-checking mechanisms to detect and correct transmission errors.

Can the Application Layer handle multiple protocols simultaneously?

Yes, it supports concurrent protocols like HTTP, FTP, SMTP, and DNS for seamless network operations.

How does the Application Layer interact with other OSI model layers?

It requests data formatting from the Presentation Layer and relies on lower layers for connection and data transmission.

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  1. Presentation Layer in 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. ... This model consists of total of seven layers and each of layers performs specific task or particular netw. 4 min read. How Communication ...

  2. Presentation layer

    The presentation layer ensures the information that the application layer of one system sends out is readable by the application layer of another system. On the sending system it is responsible for conversion to standard, transmittable formats. [7] On the receiving system it is responsible for the translation, formatting, and delivery of ...

  3. Presentation Layer of the OSI Model

    Open Systems Interconnect (OSI): has seven layers and each layer performs a specific and supportive communicative task ; Presentation layer: primarily responsible for managing protocol and ...

  4. Presentation Layer

    Layer 6 is known as the presentation layer. The main purpose of the presentation layer is to deliver and present data to the application layer. This data must be formatted so that the application layer can understand and interpret it. The presentation layer is responsible for items such as: . Encryption and decryption of messages.

  5. Presentation Layer in OSI Model

    The presentation layer is the 6 th 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 ...

  6. Presentation layer and Session layer of the OSI model

    The presentation layer is the sixth layer of the OSI Reference model. It defines how data and information is transmitted and presented to the user. It translates data and format code in such a way that it is correctly used by the application layer. It identifies the syntaxes that different applications use and formats data using those syntaxes.

  7. Presentation Layer

    Presentation Layer is the Layer 6 of the seven-layer Open Systems Interconnection (OSI) reference model. The presentation layer structures data that is passed down from the application layer into a format suitable for network transmission. This layer is responsible for data encryption, data compression, character set conversion, interpretation ...

  8. Presentation Layer In OSI Model : A Comprehensive Guide

    The Presentation Layer, within the OSI (Open Systems Interconnection) model, is the sixth layer. It focuses on the representation of data, ensuring that information exchanged between applications is formatted appropriately for transmission and receipt across a network. This layer handles tasks such as data translation, encryption, compression ...

  9. Presentation Layer in OSI Model

    The Presentation Layer is a crucial component of the OSI model, responsible for ensuring that data exchanged between systems is in a format that can be understood and used. By performing functions such as data translation, formatting, compression, and encryption, the Presentation Layer plays a vital role in maintaining data integrity ...

  10. 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.

  11. The TCP/IP Guide

    Presentation Layer (Layer 6) The presentation layer is the sixth layer of the OSI Reference Model protocol stack, and second from the top. It is different from the other layers in two key respects. First, it has a much more limited and specific function than the other layers; it's actually somewhat easy to describe, hurray! Second, it is used ...

  12. Presentation Layer of OSI Reference Model

    Presentation Layer - OSI Reference Model. The primary goal of this layer is to take care of the syntax and semantics of the information exchanged between two communicating systems. Presentation 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.

  13. A Guide to the Presentation Layer

    Understanding the layers of the Open Systems Interconnect (OSI) model can help users conceptualize data communication over a network. Layer 6 in the OSI model - the presentation layer - translates, compresses, and encrypts data across networks. In this article, we'll explain what the presentation layer is, how it works, and its functions and protocols.

  14. Presentation Layer: What It Is, Design Issues, Functionalities

    Functionalities of the Presentation Layer. Specific functionalities of the presentation layer are as follows: 1. Translation. The processes or running programs in two machines are usually exchanging the information in the form of numbers, character strings and so on before being transmitted. The information should be changed to bitstreams ...

  15. The OSI Model

    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 ...

  16. What is OSI Model?

    Presentation Layer - Layer 6 . The presentation layer is also called the Translation layer . The data from the application layer is extracted here and manipulated as per the required format to transmit over the network. ... This model consists of total of seven layers and each of layers performs specific task or particular netw. 4 min read ...

  17. 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.

  18. Presentation Layer of the OSI Model: Definition and Function

    The presentation layer is the sixth layer of the Open Systems Interconnection (OSI), model. In computer networking, the OSI model is a concept that describes the transmission of data from one computer to another. Each layer in the model is a packet of protocols, or procedures that govern data transmission, which allow the layer to execute ...

  19. PDF 13 OSI Presentation and Application Layers

    13. ion LayersPaul D. BartoliI. IntroductionThis chapter discusses the Application and Presentation Layers of the Reference Model. of Open Systems Interconnection (OSI) [1]. The Applica tion and Presentation Layers perform functions necessary to exchange information between application processes; the Application Layer is con cerned with the ...

  20. Application Layer in OSI Model

    Application Layer is the topmost layer in the Open System Interconnection (OSI) model. This layer provides several ways for manipulating the data (information) which actually enables any type of user to access network with ease. This layer also makes a request to its bottom layer, which is presentation layer for receiving various types of ...