MPX Cache Agent Operations

The following sections provide information for understanding how MPX Cache Agent operates with the Message Broker, other MPX Cache Agents, and the client.

• When a server configuration starts, so does the File Transmitter. The File Transmitter generates and maintains a CacheJournal.dat file for that configuration.
• When a Root MPX Cache Agent starts up for the first time, it reads the CacheJournal.dat file from beginning to end. This makes the MPX Cache Agent aware of the most recently added and modified files and objects and, thereby, able to return them in fetch requests. The Root MPX Cache Agent then scans the server configuration's hives for additional archive files and, if the Precharge and ObjectTypes options are set, it also scans the configuration's database for additional objects not described in the CacheJournal.dat file. The hive and database scans are done in the background because they may take several minutes.
• When a Remote MPX Cache Agent starts, depending on its settings, it can update its cache with data from its logical "parent" MPX Cache Agent, usually the Root MPX Cache Agent. It also adds data to its cache as it receives file and object update messages from the Message Broker.
• When a client or another MPX Cache Agent requests a file or object that the Remote MPX Cache Agent has, it returns the file or object. When asked for a file or object that it does not have but can get from a parent, it adds the new file or object to its cache and then returns it to the requesting client or MPX Cache Agent.
• If the Remote MPX Cache Agent cannot get a file or object from a parent, it sends a "miss" indicator back. After receiving "miss" indicators, clients request those files or objects from StarTeam Server in a non-MPX fetch.
• When the Remote MPX Cache Agent's total cache size exceeds the MaxCacheSize parameter, it removes the oldest contents in the cache. It repeats this check until the total cache size is within limits.
• Remote MPX Cache Agents provide project filtering capabilities. Specifically, you can specify a list of Project parameters in the ContentSource section of the Remote MPX Cache Agent configuration file. This list can either be explicit project names or can include a "wildcard" character, such as "*" to match partial strings.