4.3 Access Gateway Content Settings

One of the major benefits of using an Access Gateway to protect web resources is that 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 can significantly accelerate access to the information.

IMPORTANT:For caching to work correctly, the web servers must be configured to maintain a valid time. If possible, they must be configured to use an NTP server.

The object cache on an Access Gateway is quite 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

Access Gateway follow RFC directives. In addition, Access Gateway Service uses Apache Module mod_file_cache.

The following sections describe the features available to fine-tune this process for your network: