Since version 1.4, HiveMQ offers a free and open source plugin SDK with service provider interfaces. This allows everyone to extend HiveMQ and add custom functionality via plugins.
With custom HiveMQ plugins, it’s easy to add functionality like writing messages to databases, integrate with other service buses, collect statistics, add fine-grained security and virtually anything else you can imagine.
Since version 1.5, there is even deeper integration to the HiveMQ core with the HiveMQ Services concept. See the HiveMQ Services chapter for more information.
HiveMQ 3.0 brought major improvements for the plugin system in all aspects and allows even deeper integration into HiveMQ message processing and lifecycle.
Plugin development for HiveMQ is as easy as writing a Java main method once you grasp the core concepts. This documentation covers all relevant topics to get you started as quickly as possible. If you prefer to learn from real world plugins, visit the HiveMQ Github page or use the Maven Archetype for plugins.
If you’re looking for information how to upgrade your plugins in order to work with newer HiveMQ versions, take a look at the HiveMQ Upgrade Guide.