The creation and handling of the remote request dispatcher
(RRD) message and the transfer of this data across a network creates
substantial overhead. To improve performance, the local machine can
receive the cache rules of the remote server and know when to cache
the response locally to prevent the RRD call altogether.
About this task
Unsupported rules are cached remotely. However, remote request
dispatcher does not support the entire set of rules of the
cachespec.xml file
for local caching. The following rules for the
cachespec.xml file
are supported for local caching.
- parameters
- Retrieves the named parameter value.
- cookie
- Retrieves the named cookie value.
- header
- Retrieves the named request header.
- locale
- Retrieves the request locale.
- requestType
- Retrieves the HTTP request method from the request.
Complete the following steps to enable RRD dynamic
cache support.
Procedure
- Enable servlet caching on the local server Refer
to the Configuring servlet caching article for more information.
- Construct and install an application with a valid cachespec.xml
file policy with RRD supported rules. See the article,
Configuring cacheable objects with the cachespec.xml file, for additional
information.
- Enable servlet caching on the remote server. Refer
to the Configuring servlet caching article for more information.
- Restart WebSphere® Application Server.
Refer to the Managing application servers article for more information.
Results
To verify that dynamic cache is enabled locally, you can enable
RRD trace and verify that there is a CACHE HIT printed out for multiple
requests to a resource that has an appropriate cache policy. You also
have the option to use CacheMonior instead of turning on tracing.
If the CacheMonitor on the remote machine is not receiving cache hits,
then the response is cached locally. The local CacheMonitor will not
receive hits because RRD uses its own custom cache.