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.