Configuring Custom Cache Control Headers; Understanding How Custom Cache Control Headers Work; Section 5.3, "Configuring Custom Cache Control Headers - Novell ACCESS MANAGER 3.1 SP2 - ACCESS GATEWAY GUIDE 2010 Manual

5.3 Configuring Custom Cache Control Headers

(Access Gateway Appliance) In addition to fine-tuning cache freshness by using the HTTP timers,
as explained in Section 5.1, "Configuring Caching Options," on page
proxy service to recognize custom headers in HTTP packets. Your Web server can then use these
headers for transmitting caching instructions that only the Access Gateway can recognize and
follow.
Section 5.3.1, "Understanding How Custom Cache Control Headers Work," on page 173
Section 5.3.2, "Enabling Custom Cache Control Headers," on page 174
5.3.1 Understanding How Custom Cache Control Headers
Work
Only the proxy service containing the custom header definition follows the cache policies specified
in the custom headers.
All other proxy services, requesting browsers, and external proxy caches such as transparent caches
and client accelerators do not recognize the custom headers. They follow only the cache policies
specified 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 external caches cannot cache the objects, but the proxy
service can.
This lets you off-load request processing from the origin Web server while still requiring that
users 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 and
specifying a header string such as MYCACHE (see
Control Headers," on page
Configure the Web servers of the proxy service to send an HTTP header containing the defined
string 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 following
headers:
Cache-Control: public
Cache-Control: max-age=number
If 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 that
browsers 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 an
object for two minutes.
Section 5.3.2, "Enabling Custom Cache
174).
170, you can configure each
Configuring the Content Settings 173