Application Layer Services and Its Protocols in Network Communication System

 An application layer is an abstraction layer that specifies the shared protocols and interface method used by hosts in a communications network. The application layer is used both of the standard models of computer networking: The internet protocol (TCP/IP) and the Open Systems Interconnection model (OSI). Although both models use the same term for their respective highest level layer, the detailed definitions and purposes are different. In (TCP/IP), the application layer contains the communications protocols and the application layer only standardizes communication. It establishes host-to-host data transfer channels and manage the data exchange in a client-server or peer-to-peer networking.  Application layer services to use network resources, like file transfer or network print spooling. Though transparent to the user, these services are the programs that interface with the network and prepare the data for transfer. Different types of data - whether it is text, graphics, or video - require different network services to ensure that it is properly prepared for processing by the functions occurring at the lower layers of OSI model. Each application or network service uses protocols which define the standards and data formats to be used. Without protocols, the data network would not have a common way to format and direct data. In order to understand the function of various network services, it is necessary to become familiar with the underlying protocols that govern their operation.

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