Search code examples
redisiot

EdgeX: Listen to IoT Messaging Bus from Redis Server

EdgeX uses Redis PubSub by default for its messaging bus (https://docs.edgexfoundry.org/2.3/microservices/application/Triggers/).

  1. I have started the Redis server locally.

  2. I have Core Data and/or Device Services running, which I believe is also configured defaultly to use Redis Pub/Sub.

  3. I have a Virtual Device Service that publishes data to the edgex/events/# topic (https://docs.edgexfoundry.org/2.3/microservices/device/virtual/Ch-VirtualDevice/).

  4. Finally, I have configured my Application Service to subscribe to the topic edgex/events/#, as shown in the example.

[Trigger.EdgexMessageBus]
Type = "redis" # message bus type (i.e "redis`, `mqtt` or `zero` for ZeroMQ)
    [Trigger.EdgexMessageBus.SubscribeHost]
        Host = "localhost"
        Port = 6379
        Protocol = "redis"
        SubscribeTopics="edgex/events/#"
    [Trigger.EdgexMessageBus.PublishHost]
        Host = "localhost"
        Port = 6379
        Protocol = "redis"
        PublishTopic="" # optional if publishing response back to the MessageBus

The Application Service is able to recieve all the messages sent to the topic.

However, when I go directly to the redis server (using redis-cli) and subscribe to SUBSCRIBE edgex/events/# or any other variant (edgex/events,edgex), nothing appears. Even checking PUBSUB CHANNELS shows that there are no active channels.

I am assuming that since EdgeX is using my localhost redis server (or any remote server, for that matter), that I'd be able to directly check with that redis server, subscribe to the topic that EdgeX is publishing to, and see the same messages.

Am I missing anything?

Thanks!

Solution

  • The EdgeX implementation is using PSUBSCRIBE with wildcards; the only command that will give you visibility is PUBSUB NUMPAT. You will need to identify the correct pattern for what you are trying to subscribe to AND have your subscriber running before anything is published as Redis PubSub is fire/forget.

    Rather than going directly to Redis, I recommend using the EdgeX Application Services to subscribe and then either operate on the results directly or feed that to an external service.