How does Web Cache improves scalability of a website?

The Web Cache accelerates delivery of data to the users.

Apache’s Limitations

An Apache web listener is restricted in terms of the number of concurrent connections that it can service. The standard distribution can only handle 256 connections. The Apache distributed with Oracle Application Server can handle 1,024 concurrent Connections. The Web Cache can address the scalability limitations of Apache in two ways.

First, it can handle thousands of concurrent connections.

Second, it can distribute these connections across a pool of Apache web listeners.

Thus, the Web Cache can improve response times to end users and reduce the workload on the Apache web listener.

Webcache Architecture

The Web Cache is a specialized web listener.It monitors one or more ports on one or more addresses for incoming URLs.If it can satisfy the URL from its memory cache, it will do so; otherwise, it will pass the request back to a web listener.

There are certainly issues to consider with using a Web Cache, but provided that the rules it uses to determine which documents to cache and for how long are appropriate, it can improve the performance perceived by end users dramatically, reducing the strain on the application server(s) behind it.

By putting one, or several, Web Caches in front of your web site, you should be able to improve performance and reliability dramatically. For this reason, the Web Cache is enabled by default on all middle tier Oracle Application Server instances. It comes preconfigured with a set of caching rules that will certainly help all web sites; but if you choose to customize these rules to your own environment, the benefits will be even greater.