Changing the Web Agent Caching Behavior

Each web agent maintains a cache that stores the policies for every user’s session. The cache can be updated by a cache polling mechanism.

Cache Updates

A web agent maintains a cache of all active sessions involving content that the agent protects. Once an entry is added to an agent's cache, it remains valid for a period of time after which the entry is considered expired and later purged.

The property com.sun.am.policy.am.polling.interval in the web agent AMAgent.properties configuration file determines the number of minutes an entry will remain in the web agent cache. Once the interval specified by this property has elapsed, the entry is dropped from the cache. By default, the expiration time is set to three minutes.

In a normal deployment situation, policy changes on the server are frequent, which requires sites to accept a certain amount of latency for web agents to reflect policy changes. Each site decides the amount of latency time that is acceptable for the site’s specific needs. When setting the com.sun.am.policy.am.polling.interval property, set it to the lower of the two:

• The session idle timeout period

• Your site’s accepted latency time for policy changes

Sun Java System Policy Agent 2.2 for Apache HTTP Server does not support notifications. Therefore, updating the cache through a notification mechanism is not an available feature. However, since the notification mechanism is available for other agents in the Policy Agent 2.2 software set, a property exists in the web agent AMAgent.properties configuration file to control this feature. The property that controls the notification mechanism, com.sun.am.notification.enable, is set to false for this agent. Do not set this property to true for this agent as it might result in unexpected behavior.