When Access Gateway is configured to protect web resources, it can cache the requested information and send it directly to the client browser rather than contacting the origin web resource and waiting for the requested information to be sent. This accelerates access to the information.
IMPORTANT:For caching to work correctly, web servers must be configured to maintain a valid time. These must be configured to use an NTP server.
The object cache on an Access Gateway is different from a browser’s cache, which all users access when they click the Back button and which can serve stale content that does not accurately reflect the fresh content on the origin web server.
Access Gateway caching system uses a number of methods to ensure cache freshness. Most time-sensitive web content is flagged by Webmasters in such a way that it cannot become stale unless a caching system ignores the Webmaster’s settings. Access Gateway honors all RFC 2616 directives that affect cache freshness such as Cache-Control, If-Modified-Since, and Expires.
Access Gateway can be fine-tuned for cache freshness in the following ways:
Accelerated checking of objects that have longer than desirable Time to Expire headers
Delayed checking of objects that have shorter than desirable Time to Expire headers
Checking for freshness of objects that do not include Time to Expire headers
Both Access Gateway Appliance and Access Gateway Service follow RFC directives. In addition, Access Gateway Service uses “Apache Module mod_file_cache”.