Design goals

A Distributed Web Server System (DWSS) consists of a large number of servers with some mechanism to distribute the incoming client requests among those servers. We have the following design goals for the DWSS architecture:

• Components used should be compatible with current protocol and network elements, i.e. they can be deployed in current infrastructure and protocol suite very easily.

• It should not require change of components at client side or components on which website administrator has no control, i.e. change in only server side components is allowed.

• System should be geographically scalable, i.e. more servers in clusters can be added when needed in LAN environment and besides that more clusters (that may be geographically far apart) can be added in web server system on WAN.

• System should give better performance in terms of latency perceived at client side, i.e. time lag between request submission by user and content reaching at client side software should be minimized.

• System should be user transparent, i.e. single virtual interface to access website should be provided at the URL level, request should be directed to appropriate server automatically by web server system.

• System should be fault tolerant, i.e. system should continue working (may be with degraded performance) even if some servers or clusters fail or taken off-line.

• System should avoid overloading of any server, i.e. requests beyond capacity of any server should not reach to it, since it may result in crashing of servers.

• System should not incur too much additional overhead for its functioning, in terms of computation required or network traffic generated.