# General

GCMB is a global message broker. It uses the MQTT protocol. In MQTT messages are published and subscribed to in the context of a topic. Topics are organized hierarchically. Topics look like this:

In GCMB, all users share a single topic namespace. Each user or organization gets a sub-namespace. Projects, which are below users and organizations, each have a sub-sub-namespace. So a topic in GCMB looks like this:

myorg/myproject/sometopic/someotherthing

• myorg is the organization
• myproject is the project
• sometopic and someotherthing are examples for topics in myproject

Since everyone is in the same topic namespace, sharing data becomes easy as does combining data from multiple sources.