Explain about Client server architecture?

Question

Defininition of Client server architecture and Advantages as well as disadvantages?

Answer 1

As you probably know, a _server_ is a computer or process that hosts a service. In this case, Yahoo is the server, and the Yahoo Answers web site is the service.

The software that the user is running are running to use this service is the _client_.  So in this case your browser that you're using to browse the site is the client.

Advantages: Single point of maintenance. Say you need to make an update to the site. You only need to change the program running on the server(s) which is of course going to be a LOT less work then changing every client. This is of course assuming that you don't have to patch the client (and ideally your client has to do as little of the work as possible, to prevent having to do this.)

Another advantage is you have a single point of control.  Say you have a web site that deals with sensitive information.  Because your users all have to access the web site through a server or a few servers, it's easier to enforce policies and control the flow of information through less points of distribution than many.

The disadvantage to client / server is the fact that since we're running our service in a centralized fashion, i.e. on a server or handful of server(s), there is also a centralized point of failure.  When one of these servers goes down for whatever reason, a LOT of clients lose access to the service.  Compare this to Peer-to-peer architecture in which the users of the service run a client, but also host a piece of the overall service, so there is no central 'server'.  In P2P, as long as a few users are signed on to the service, it will continue to run smoothly.

There are actual several different ways client / server is put into use, and you can look up these terms to find out more: 3-tier, 4-tier or n-tier architecture, clustering / server farms, 'cloud' computing is in vogue right now.