Delivery Assurance: Topology

When using a persistence store for delivery assurance, the store is similar to a second transport. Like the direct path, it mediates message communication among a network of endpoints. It operates in parallel with direct-path transports, as an additional path from publishers to subscribers.

Because the store offers a redundant path, one can say that the store backs the direct paths. Depending on the focus, one can also say that the store backs the network of endpoints, or that it backs the message stream that travels among those endpoints.

Persistence Store as Redundant Message Path

The preceding diagram depicts a direct path through the transport bus, and another path from endpoint to endpoint through a store. (Conceptually, communications to and from the store travel through the endpoint instances. TIBCO FTL software arranges a communication mechanism for this path.)

Direct Path Requirement for Standard Durables

For delivery assurance, you must configure a direct path. TIBCO FTL software does not support configurations in which a persistence store is the only path between a publishing endpoint and a subscribing endpoint.

(This requirement does not apply when using a store to apportion a message stream, nor for last-value availability, only for delivery assurance.)