Practical Microservices

Fleshing Out Message Structure

In Chapter 2, ​Writing Messages​, we showed some example messages. That’s what they look like before being written to the Message Store. The act of writing them adds some additional fields:

streamName

A string and the name of the stream this event belongs to. We discussed the importance of streams and how they’re namedhere.

position

This is used for optimistic locking, a method for dealing with concurrent writes. It denotes a particular message’s position within its stream. The Message Store will generate these values.

globalPosition

Just as position records a message’s position within its stream, globalPosition records a message’s position within the entire Message Store. This field enables real-time consumption ...