Subscribe and decode Sparkplug B payloads with custom code

Chariot MQTT Server
1

Hi there,
We would like to create a custom app that subscribes to topics in the MQTT broker in Ignition Distribution module. Are there any examples in your developer docs that demonstrate how to do this ?
Specifically, how to decode the Sparkplug B payloads ?
Most of the examples I have seen demonstrate how to connect and publish data.

Many thanks,
Damien.

2

Take a look at this example: tahu/sparkplug_b/tools/java_sparkplug_b_listener at develop · eclipse/tahu · GitHub

This example only shows how to print the payload in a JSON format. But, the decoded payload can be picked apart after it is in the SparkplugBPayload object.

3

Thanks for the fast response Wes.
Looking into the code example you provided, it has a dependency on the SparkplugBPayloadDecoder module which encapsulates the detail about decoding the payload.
Do you know if there is an equivilent module available for .Net ?
Failing that, is the specification for the encoding/decoding algorithm published somewhere ( I can’t seem to find anything in the official spec?

4

There is the rudimentary C# library here: tahu/client_libraries/c_sharp at develop · eclipse/tahu · GitHub

This is purely Google Protobuf generated code based on the proto definition file here (which is used for all Sparkplug B payloads): tahu/sparkplug_b.proto at develop · eclipse/tahu · GitHub

I know people have used that C# library to build apps. But, we haven’t yet gotten any contributions around C# into Eclipse Tahu. It would be nice to have a wrapper library like we do for Java :wink: