Application Layer is the layer 7 of the OSI model. It is the interface between the user and the system. It provides a high level of abstraction and services to the end users and applications. There are several applications and protocols that work on this layer. The application layer, takes the data from the end user or application and passes it on to the presentation layer which takes care of heterogeneous networks, compression and encryption.
Normally applications that involve a communication component, fall outside the scope of the OSI model. The application layer makes this possible. Imagine you have a full scree editor which you wish to deploy in a network. The issue is that these networks have several terminals each with different characteristics such as layouts and so on. One way to solve this issue is to set up a virtual terminal. It acts as an intermediate layer between the application and the real terminal. This way different terminal communication is possible, but the overhead involved is various softwares involved for mapping the functions on the virtual terminal to the real terminal.
Some functions of the application layer
- File transfer
- Remote job entry
- Directory lookup
- Application support
The application layer has many generic and application specific functions as well.
