A verticle contributed by a GeoRocket extension.

Implementations should be registered through the Java Service Provider Interface (SPI). Upon startup, GeoRocket will instantiate and start registered implementations and then publish messages to the event bus at the address EXTENSION_VERTICLE_ADDRESS. The messages will be JSON objects with the attribute type set to either MESSAGE_ON_INIT or MESSAGE_POST_INIT, depending on whether the extension is notified during GeoRocket's initialization process or at the end, respectively. The initialization process itself consists of deploying GeoRocket's internal verticles such as the importer and the indexer, as well as mounting all endpoints. This includes internal GeoRocket endpoints and those contributed by extensions.

Note: The messages are sent asynchronously. If you want to execute code before GeoRocket's initialization process is started, just implement Verticle.start(Future).