How Caching Works

Caching reduces network traffic and offers faster response time for clients who are using the proxy server instead of going directly to remote servers.

When a client requests a web page or document from the proxy server, the proxy server copies the document from the remote server to its local cache directory structure while sending the document to the client.

When a client requests a document that was previously requested and copied into the proxy cache, the proxy returns the document from the cache instead of retrieving the document from the remote server again (see Figure 12–1). If the proxy determines the file is not up to date, it refreshes the document from the remote server and updates its cache before sending it to the client.

Figure 12–1 Proxy Document Retrieval

Files in the cache are automatically maintained by the Sun Java System Web Proxy Server garbage collection utility (CacheGC). The CacheGC automatically cleans the cache on a regular basis to ensure that the cache does not get cluttered with out-of-date documents.