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asyncapi

What is Correlation ID in AsyncAPI?

I'm trying to understand what correlation ids are in the AsyncAPI spec https://www.asyncapi.com/docs/specifications/v2.0.0#correlationIdObject

There is a full example dedicated to this, but I still have no idea what's the purpose of this property https://github.com/asyncapi/spec/blob/3470a6386736cf6002846d8eb7535308b79c75e8/examples/correlation-id.yml

I'm interested in:

  • Is this information relevant for the data producer (server) or the consumer (client)?
  • What information can we derive from it?
  • For what practical use case should I use it?
Solution

  • correlationid purpose is to specify where in the message you can find the correlation identifier. Sometimes this information is part of the header, sometimes can be in message payload. So the correlationid prop is to unify the way such information is presented to the API description, it is a place where you specify where exactly identifier is located.

    Why would you need it? at all. The main reason for me is always tracing. Correlation Identifier is also known as tracing-id or request-id. Please do call it differently. Basically, this is the id of the event that helps you trace the event in the system, through logs and tracing tools like Jeager and others. So you can trace the flow of the event in the system from point A to Z, to for example identify why it didn't get to Z, where did it stack.

    It is also useful in request/reply pattern in event driven architecture. Where producer of the event wants to make sure the event it got in reply is a response from a consumer to this specific event.