19 Introduction to Coherence Topics

Topics introduces a publish and subscribe messaging functionality in Oracle Coherence

This chapter includes the following sections:

Topics Overview

The Topics API enables the building of data pipelines between loosely coupled producers and consumers.

One or more publishers publish a stream of values to a topic. One to many subscribers consume the stream of values to a topic. The topic values are spread evenly across all Oracle Coherence data servers, enabling high throughput processing in a distributed and fault tolerant manner. Each direct subscriber to a topic receives all values published to the topic.

In publish and subscribe messaging, messages are only delivered to active subscribers of the topic. Subscriber groups add queue processing capabilities to topics. Once a subscriber group is created on a topic, all values sent to the topic are accumulated for the subscriber group. One or more subscribers can subscribe to a subscriber group. For the stream of values accumulated by a subscriber group, each value is only delivered to one of its subscriber group members, thus enabling distributed, parallel processing of these values.

Figure 19-2 Topic Values in a Subscriber Group

Description of Figure 19-2 follows
Description of "Figure 19-2 Topic Values in a Subscriber Group"