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Wednesday, February 3, 2021

Presentation Layer

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 such that the data is sent to the receiver in such a way that the receiver will understand the information (data) and will be able to use the data.
  • Syntax may 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, to be defined and exchanged.

Functions of Presentation Layer

  1. 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.
  2. Encryption: It carries out encryption at the transmitter and decryption at the receiver.
  3. 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.

Design issues with Presentation Layer :

  1. Standard way of encoding data –
    The presentation layer follows a standard way to encode data when it needs to be transmitted. This encoded data is represented as character strings, integers, floating point numbers, and data structures composed of simple components. It is handled differently by different machines based on the encoding methods followed by them.
  2. Maintaining the Syntax and Semantics of distributed information –
    The presentation layer manages and maintains the syntax as well as logic and meaning of the information that is distributed.
  3. Standard Encoding on the wire –
    The data structures that are defined to be exchanged need to be abstract along with the standard encoding to be used “on the wire”.




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