Multicast Request/Reply Interactions
Like request/reply interactions, multicast request/reply interactions are driven by demand for data. While traditional request/reply interactions involve one requestor and one server, in multicast request/reply interactions multiple servers can receive the request and respond as appropriate. Communication flows in both directions, and only some servers respond to the client request, as in Multicast Request/Reply Interaction. The complete interaction consists of one multicast request message, and any number of point-to-point reply messages.
Figure 12: Multicast Request/Reply Interaction
Example applications:
| • | Database query with multiple servers. |
| • | Distribution of computing sub-tasks to the first available server. |
| • | Network management applications that multicast requests for test information. |
In multicast request/reply interactions, data producers coordinate closely with data consumers. A server does not send data until a client requests it. Servers send point-to-point replies to the specific client program.
If a server has the information the consumer requested, it sends a reply. The requesting client listens until it receives one or more replies. The client stops listening by destroying the reply inbox listener.
Rendezvous software supports multicast request/reply interactions with a combination of multicast and point‑to‑point communication.