Mqtt

Topic Structure

• User-defined topics in the form of tenant/obsType/custom/topic/parts
• Tenant and observation type explicitly required in all topic
• Topics created as activityCreator are only for configuration purposes and are saved in DB
  • They are used in reasoners configuration inside activity
  • They do not include tenant in their name (creator topics in the form of /amtech/things/eventsources/<topic>/<levels>)
• Topics created as follower or as part of the execution of an activity are not persistd in DB. They are mqtt topics to hold observations
• System topics in the form of prefix/tenant (ex. topic for OTA, for new digital twin, etc.)
• Core topics
  • Commands : _cmd/<tenant>/<thingtype>/<thingid>/<user-defined>/<path>
  • Crud : <tenant>/observationresourcecrud/<thingType>/<thingId>/<crudOp>
  • Bridge crud: _bridge/<tenant>/observationresourcecrud/amtechM2mBridge/<bridgeId>/_all/<propId>

Client applications required config

Client applications that want to send messages, and receive them all (including messages that were sent to topics when the client app was offline), must :

• Use the same client ID every time it reconnects, or use a MQTT client with the option automatic-reconnect set to true
• Connect with clean_session=False
• Subscribe to topics QoS>0
• Publish messages with QoS>0