WebSphere Application Server V7.0: Concepts ... - IBM Redbooks

4.2.2 Caching
6. Reevaluate.
Recognize that any system is dynamic. The initial infrastructure will at some
point need to be reviewed and possibly expanded. Changes in the nature of
the workload can create a need to reevaluate the current environment. Large
increases in traffic will require examination of the machine configurations.
Scalability is not a one time design consideration, It is part of the growth of the
environment.
The developerWorks article Design for Scalability - an Update provides a
detailed discussion about these steps. It can be accessed at the following Web
page:
http://www.ibm.com/developerworks/websphere/library/techarticles/hipods
/scalability.html
We expand on some of the scaling techniques in Chapter 7, “Performance,
scalability, and high availability” on page 229.
Caching is a widely used technique to improve performance of application server
environments. If planning for a high volume web site, caching will most likely be
required to achieve satisfying performance results at acceptable cost.
WebSphere Application Server provides many different caching features at
different locations in the architecture.
WebSphere Application Network Deployment provides caching features at each
possible layer of the infrastructure:
► Infrastructure edge:
– Caching Proxy provided by the Edge Components
– WebSphere Proxy Server
► HTTP server layer:
– Edge Side Include (ESI) fragment caching capabilities provided by the
WebSphere plug-in
– Caching capabilities of the HTTP server itself (like the Fast Response
Cache Accelerator (FRCA) as provided by most implementations of IBM
HTTP Server)
► Application server layer:
– Dynamic caching service inside the application server’s JVM
– WebSphere Proxy Server
98 WebSphere Application Server V7.0: Concepts, Planning, and Design