Client  Server Architecture

There is an  always  on host  called  server  which  provides  service requests to many other hosts  called  clients. In other words  client program is  running  on one end system  that request and  receives a service from a server program running on another  end  system. The web email file transfer remote login news groups and many other popular applications which  adopt the client  server model. With the client  server  architecture  clients do not  directly communicate with  each other for e g  in the web  application two browsers do not  directly communicate.

Another characteristic of the client  server architecture is  that the  server has a fixed  well know  address  and because the server has a fixed well know address and because the server is always on thus a client  can always contact to the  server by sending  a packet to the server a address. Some  of the better know  application  with a client server architecture include the web file transfer remote login  and e mail. The client  server architecture is shown  in figure.

Since  a client  program  typically runs ones  computer  and the server  program runs on another compute client server internet applications are distributed applications. The client  program and the server program  interact by  sending  each other massage over  the internet. at  this level  of abstraction  the routers links  and other components  of the  internet  that transfer  message between  the distributed  communicating  components of an internet applications.