In the context of the OSI reference model, the application
layer (Layer 7) supports the communicating component of an application. The application
layer is responsible for the following:
- identifying and establishing the availability of intended communication partners
- synchronizing cooperating applications
- establishing agreement on procedures for error recovery
- controlling data integrity
The application layer is the OSI layer closest to the end system. This determines whether sufficient resources exist for communication between systems.
Without the
application layer, there would be no network communication support. The application layer does not provide services to any other OSI layer. It does provide services to application processes lying outside the scope of the OSI model.
Examples of such
application processes include spreadsheet programs, word processing programs, and banking
terminal programs. Additionally, the application layer provides a direct
interface for the rest of the OSI model by using network applications
(e.g. Browser, e-mail, FTP, Telnet), or an indirect interface by using
standalone applications (e.g. word processors, spreadsheets,
presentation managers) with a network redirector.
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