SCIENCE DIRECT

Application Layer is a term used in categorizing protocols and methods in architectural models of computer networking. Both the OSI model and the Internet Protocol Suite (TCP/IP) contain an application layer.In TCP/IP, the Application Layer contains all protocols and methods that fall into the realm of process-to-process communications via an Internet Protocol (IP) network using the Transport Layer protocols to establish underlying host-to-host connections.

In the OSI model, the definition of its Application Layer is narrower in scope, distinguishing explicitly additional functionality above the Transport Layer at two additional levels: Session Layer and Presentation Layer. OSI specifies strict modular separation of functionality at these layers and provides protocol implementations for each layer. The common application layer services provide semantic conversion between associated application processes. Note: Examples of common application services of general interest include the virtual file, virtual terminal, and job transfer and manipulation protocols.