Configuring the Content Settings 145novdocx (en) 19 February 20105.3.1 Understanding How Custom Cache Control HeadersWorkOnly the proxy service containing the custom header definition follows the cache policies specifiedin the custom headers.All other proxy services, requesting browsers, and external proxy caches (transparent caches, clientaccelerators, etc.), do not recognize the custom headers. They follow only the cache policiesspecified by the standard cache control headers.This means that you have the following options for configuring your Web server: You can specify that browsers and/or external caches cannot cache the objects, but the proxyservice can.This lets you offload request processing from the origin Web server while still requiring thatusers return to the site each time they request an object. You can also specify separate cache times for browsers, external caches, and the proxy service.To implement custom cache control headers, you must do the following: Configure a proxy service to use custom cache control headers by enabling the feature andspecifying a header string such as MYCACHE (see Section 5.3.2, “Enabling Custom CacheControl Headers,” on page 146). Configure the Web servers of the proxy service to send an HTTP header containing the definedstring and the time in seconds that the object should be retained in cache (for example,MYCACHE: 60).If the number is non-zero, the Access Gateway treats the reply as if it has the followingheaders:Cache-Control: publicCache-Control: max-age=numberIf the number is zero (0), the Access Gateway treats the reply as if it has the following header:Cache-Control: no-cache Ensure that the Web server continues to send standard HTTP cache-control headers so thatbrowsers and external caches follow the caching policies you intend them to.For example, you can configure the following: Use an Expires or Cache-Control: Max-Age header to specify that browsers should cache anobject for two minutes. Use a Cache-Control: Private header to prevent external caches from caching the object at all. Use a custom cache control header, such as MYCACHE: 1800, to indicate that the proxyservice should cache the object for 30 minutes.Custom Cache Control Headers override the following standard HTTP cache-control headers on theAccess Gateway, but they do not affect how browsers and external caches respond to them:
