Custom Joiners

On this section, we are trying to explain how to develop your own joiners.

All the joiners classes implement the Joiner interface.

If you want to build your own joiners, you only need to implement some of different abstract classes and add de JAR into the lib folder inside the enricher distribution.

BaseJoiner

The base abstract class that you need to implement your own BaseJoiner is BaseJoiner class.

Using this class you can develop your joiners like:

• StreamPreferredJoiner
• TablePreferredJoiner

The BaseJoiner allow us join both stream and table with same key. If the stream message cannot be joined then any message is sent.

The abstract class has one method:

    public Map<String, Object> join(Map<String, Object> stream, Map<String, Object> table) {
        // Join logic that return a new Map
    }

On each join call the enricher gives you a table and a stream that is the deserialized json. You must return a Map object with the new content.

QueryableJoiner

The base abstract class that you need to implement your own QueryableJoiner is QueryableJoiner class.

The QueryableJoiner works like BaseJoiner. The difference is that a QueryableJoiner will notify to __enricher_queryable topic, if received message cannot be join it with other with same key.

The abstract class has same method that BaseJoiner

QueryableBackJoiner

The base abstract class that you need to implement your own QueryableJoiner is QueryableBackJoiner class.

The QueryableBackJoiner works like QueryableJoiner. The difference is that a QueryableBackJoiner will notify to __enricher_queryable topic and will resend unjoined messages to source topic, if received message cannot be join it with other with same key.

The abstract class has same method that BaseJoiner