Current Value Cache
In many distributed applications new processes can join the system at any time. Often these new processes need access to the current information state of the system in order to function properly. In many cases a straightforward cache program can fill that need.
The Rendezvous distribution includes a utility program called rvcache, which caches the data from messages sent to each subject name. Whenever a Rendezvous program begins listening to a subject name, it can query rvcache to send it the current data for that subject.
The data cached for a subject can be either the most recent whole message on that subject, or a composite set containing the most recent value of each field sent on that subject.
Although rvcache resembles a simple database program in some respects, it differs in an important way. Namely, updates are implicit; that is, rvcache monitors message activity and automatically caches the data. Application components query for data by subject.
We recommend that administrators arrange for correct operation of rvcache. This section describes administrative considerations; for a command summary, see rvcache.