Application layer

What is the application layer?
The application layer is the top layer of the TCP / IP protocols group. In the layer Of applications, we will find network and services applications that communicate with layers Bottom via TCP and UDP ports. The question arises as to why the application layer is judged Part of all the glass, while TCP and UDP ports form a well-defined interface with network. But it is important to remember that in a layer architecture like TCP / IP, each layer Is a network interface. The TCP / IP application layer is really a kind of network software component that Sends and receives information from TCP and UDP ports. These components of the layer Applications are not really parallel in sencin that are logically the same or equivalent. Some of the components in the application layer are simple elements you gather Information about network configuration. Other components of the application layer can A user interface system (such as a window interface) or an interface of an application program (API) that supports an operating action. Some components of the application layer provide Network services such as file and print services or name resolution services (NRS). it The part explains some of the types of services and applications that are commonly found in the layer applications. The actual implementation of these components has essentially the details of programming and Software design. First we will begin with a quick comparison of the layer of TCP / IP application with the layer Corresponding to the OSI model

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Layer of TCP / IP and OSI model applications As we have mentioned, TCP / IP does not exactly match the seven layers of the OSI network model. The OSI model, however, has become very influential in the development of the network system, and the trend Current networking with multiprotocols increases security in the concepts and terminology of OSI. The application layer can be structured from a wide range of operations and environments Networks, and in many of these areas, the OSI model is an important element for it Define and describe the network system. A look at the axis model will help us understand Processes occurring in the layer of TCP / IP applications. The TCP / IP application layer matches the application, presentation, and layer layer Sessions in the OSI model (see Figure 7.1). The subdivision of the OSI model (three layers in the country Of one) provides some additional organization of the theoretic elements

The description of the OSI model that corresponds to the TCP / IP Application layer is as follows:  The application layer - the OSI application layer has components that provide services For user applications and supports network access.  Presentation layer - presentation layer translates data into program format - Neutral and enables encryption and compression of data.  Session Layer - session layer manages communication between apps in us Network computers. This layer provides some functions that refer to links that you can not To be realized from the Transport layer, for example. Knowledge of name and security. All these services are not required for all applications and implementations. we The TCP / IP implementation model is not required to follow OSI partitioning, but In general, the tasks assigned to the Application, the presentation and the session of the OSI model, Are within the boundaries of the TCP / IP Application layer layer.