Application layer

Definition:

 

     The application layer serves as the window for users and application processes to access network services.  

Commonly Needed functions:


  •   * Resource sharing and device redirection
  •   * Remote file access
  •   * Remote printer access
  •   * Inter-process communication
  •   * Network management
  •   * Directory services
  •   * Electronic messaging (such as mail)
  •   * Network virtual terminals

 

Other Functions:

 

The application layer interacts with software applications (such as Netscape or Outlook Express) that implement a communicating component. Such application programs are outside of the scope of the OSI model, but they translate an enduser's typing into a Layer 7 request. Application layer functions typically include the following:

 

Identifying communication partners - The application layer identifies and determines the availability of communication partners for an application with data to transmit.

 

  • Determining resource availability - The application layer must determine whether sufficient network resources for the requested communication are available.

 

  • Synchronizing communication - Communication between applications requires cooperation that is managed by the application layer.

 

    Example:The Application layer is responsible for identifying that there is a web server answering on port 80 in order for HTTP communication to happen.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OSI Layers