1. We expose public constants for the verticle configuration parameters: the HTTP port number and the name of the event bus destination to post messages to the database verticle.

The rest of the class is mostly an extract of the HTTP-only code, with what was previously database code being replaced with event bus messages. Here is the indexHandler method code:

As we can see, an event bus message consists of a body, options, and it can optionally expect a reply. In the event that no response is expected there is a variant of the send method that does not have a handler.

The rest of the verticle code consists in the router handlers that also use the event-bus to fetch and store data: