Presentation Layer

This is the sixth in the seven layers of OSI model of computer networking which serves the data translator for the network. At times this presentation layer is also referred to as the syntax layer. The duty of the presentation layer is to deliver and format the information to the application layer for future processing or display. This reduces the application of concern regarding syntactical differences in data representation inside the end-user systems.

The presentation layer is the buck layer at which application programmers think about data structure and presentation, instead of simply transferring data in form of datagram or packets between hosts. This layer concerns with issues of string representation and whether they use the Pascal method or the C++. The opinion is that the application layer should be able to indicate at the data to be shifted, and the presentation layer will deal with the rest. 

The key Functions of the Presentation Layer

The main function of the presentation layer is to serialize the complex data structures into flat byte-strings using mechanisms such as TLV or XML. Another part of execution encryption is performed at this level though these can be performed on the Application, Session, Transport or even the Network layers. However, performing at different stages will have its own positive and negative implications. Along with these Decryption is also dealt at this layer.  For instance, when signing in bank account pages the presentation layer will decrypt the data as it is obtained. In addition to this, representing structure which is usually standardized at this level frequently is done by XML.

Some of the Examples for Clarity

Even the easy fragments of data such as strings and more complicated things are standardized in this layer. The best examples can be the objects in object oriented programming and the same way that streaming video is transmitted. In several applications and protocols in use, no difference is made between the presentation and application layers. To give an example, HTTP commonly considered as application layer protocol has presentation layer features like the ability to detect the character encoding for proper conversion which is later performed in the application layer.

Inside the service layering semantics of the OSI network build up, the presentation layer replies to service needs from the application layer and releases service requests to the session layer. A suitable example of a program which is usually stick to the presentation layer of OSI is that manages the Web's Hypertext Transfer Protocol.

Questions:

• What is presentation layer?
• List down some of the key functions of the presentation layer.