BaSyx / Documentation / Components / Registry / Features / Hierarchical MQTT

Hierarchical MQTT Eventing

User Story & Use Case

As AAS Components user

I want hierarchical MQTT topics in the AAS Registry Component

so that I can subscribe precisely to the topics of interest without having to filter on client side

MQTT supports hierarchical topics with wildcard subscription support. For example, if the topics a/b/x and a/b/y exist, subscribing to a/b/+ subscribes to all events broadcasted on both topics.

Feature Overview

The following hierarchical topics with their respective payloads are implemented:

• aas-registry/<reg-id>/shells/created
• aas-registry/<reg-id>/shells/updated
  • Payload: New AAS-Descriptor

• aas-registry/<reg-id>/shells/removed
  • Payload: Old AAS-Descriptor

• aas-registry/<reg-id>/submodels/added
• aas-registry/<reg-id>/submodels/updated
  • Payload: New SM-Descriptor

• aas-registry/<reg-id>/submodels/deleted
  • Payload: Old SM-Descriptor

• aas-registry/<reg-id>/shells/<encoded-aas-identifier>/submodels/added
• aas-registry/<reg-id>/shells/<encoded-aas-identifier>/submodels/deleted
  • Payload: New SM-Descriptor

• /aas-registry/<reg-id>/shells/<encoded-aas-identifier>/submodels/deleted
  • Payload: Old SM-Descriptor

For AAS-Identifier encoding, Base64URL encoding and URL encoding are available.

Feature Configuration

The feature can be configured in the registry.properties file by setting registry.events = MQTTV2 for Base64URL encoding or registry.events = MQTTV2_SIMPLE_ENCODING for URL encoding. Additionally, the Registry id needs to be configured via registry.id = <repo-id>.

An example configuration for this feature could be:

registry.events = MQTTV2
registry.id = product-aas-registry

The MQTT broker connectivity is configured via mqtt.properties