Chapter 47 Introduction to the Request-Reply Communication Pattern

As applications become more complex, it often becomes necessary to use other communication patterns in addition to the DDS data-centric publish-subscribe pattern. The data-centric publish-subscribe pattern is well-suited to situations where the same data must flow from one producer to many consumers, or when data is streaming continuously from producers to consumers. But sometimes an application needs to get a one-time snapshot of information—for example, to make a query into a database or retrieve configuration parameters that never change. Other times an application needs to ask a remote application to perform an action on its behalf; for example, to invoke a remote procedure call or a service.

To support these scenarios, Connext includes support for the request-reply communication pattern.

Figure 47.1: Publish-Subscribe Overview

Sending temperature updates using the publish-subscribe pattern

 

Figure 47.2: Request-Reply Overview

Request-Reply communication pattern using a Requester and a Replier