In a post to his site Robert Basic continues his series looking at the Phrooph package, this time focusing on the query bus. This functionality allows you to dispatch an event to a single "finder" in the CQRS/event souring framework.

Continuing on with the The query bus allows the handler to do whatever it needs to do to return the result, synchronously or asynchronously.

He starts by talking about the return value of the bus - a ReactPHP promise for the async handling - and the plugin system that allows for more advanced handling. He then starts on the example, showing how to create a simple bus object and define the routing to a specific query handler. This is then dispatched and a closure is defined as the "done" operation. From this basic example he then moves to something a bit more useful - an example query to determine how may Calls for Papers are currently open on the Joind.in service (fetched via the API).