Messages create a well-defined interface between two different systems. Defining messages should be done by members of both teams. Establishing a common language can be tricky especially as terms are overloaded between different business units. What a sales department considers a customer may be totally different from what a shipping department considers a customer. Domain driven design provides some hints as to how boundaries can be established to avoid mixing terms.

There is a huge preponderance of queue technologies available. Each of them have a bunch of different properties around reliability, durability, and speed. Some of the queues support reading and writing JSON over HTTP: ideal for those interested in building JavaScript applications. Which queue is appropriate for your application is a topic for some research.