Clustering

[Shailesh Narkhede]

I read in HFSJ,
There is mutiple instances of servlet when clustered environment is used.
i.e. Instance per JVM.

In this what is mean by clustered environment ?
and What is advantages of that?

Thanks in advance.

[kurt hanni]

A clustered environment is a cluster of computers (hardware), for example 2 or more servers are clustered to run a single application, each server must have a copy of the application (same set-up) running on separate JVMs.

advantages of clustered environment is that it spreads out the work load to multiple machines, improving performance and speed of your application. May include fail-over, if one cluster is down your application will still run on different clusters.

for every cluster everything in your application (objects) is duplicated except for your session objects.

[Shailesh Narkhede]

Thank you kurt.

[Geetha Arthanari]

Is clustering and distributed web apps same or different?

[Shailesh Narkhede]

I think it is same.
Please correct me If I am wrong.

[Christophe Verré]

There's an interesting definition here.

[Shailesh Narkhede]

Thanks Christophe,
this is I got from that link.

A cluster consists of multiple stand-alone machines acting in parallel across a local high speed network.
Distributed computing differs from cluster computing in that,
Computers in a distributed computing environment are typically not exclusively running "group" tasks, whereas clustered computers are usually much more tightly coupled. Distributed computing also often consists of machines which are widely separated geographically.

[Amit Ghorpade]

If we are talking about clustering, then lets talk it in the General Computing forum.