5 Using a Streams Publisher

Each shard in the store publishes changes made to table data in the shard. Each of these publishing streams is combined into a single stream of table write operations, which the oracle.kv.pubsub.NoSQLPublisher class can access. This class constructs one or more NoSQLSubscription class objects, each of which can be used to manage a single subscription stream (where each subscription stream can include changes made to one or more tables in the store).

You configure NoSQLPublisher using oracle.kv.pubsub.NoSQLPublisherConfig, described next in this chapter. See Streams Example to see how the configuration is used within a streams application.

For any JVM, only one NoSQLPublisher instance can be created given identical NoSQLPublisherConfig objects. After creating an instance of NoSQLPublisher, the factory constructor returns the same instance of NoSQLPublisher for all subsequent construction requests, if the NoSQLPublisherConfig for those requests is identical.

Two NoSQLPublisherConfig objects are identical if all of the following information the same for both objects:

• Store name

• Shard timeout

• Maximum concurrent allowed subscriptions

• Security properties use identical username and credentials