Operation

Although many distributed system components may depend upon rvcache, its caching operation remains transparent to them.

Other application programs do not send update messages specifically to rvcache. Instead, rvcache listens for a set of subjects, silently receiving messages and caching the most recent data on each subject as it arrives, as in Transparent Caching by rvcache.

Figure 139: Transparent Caching by rvcache

 

However, other application programs do send query requests to rvcache. Query and Response with rvcache illustrates this phase of rvcache operation:

Procedure 

1.

rvcache listens to the subject _SNAP.> for query messages.

2.

A program submits a query for the cached value of foo.bar by sending an empty message to the subject _SNAP.foo.bar (more generally, build the query subject on the template _SNAP.cached_subject).

3.

rvcache receives the query, and extracts the cache subject from the query subject name. It sends the cached value for that subject to the reply subject of the query message.

Figure 140: Query and Response with rvcache