Structure of a message

Core identifiers

traceId

Trace identifier for one full distributed flow.

correlationId

Correlation identifier for one request/response or one stream session.

id

Unique message id.

instanceId

Unique event bridge instance id (sender side).

principalId and tenantId

Optional security/tenant metadata propagated through the flow.

Shared message fields

field	required	meaning
messageType	yes	command/response/custom/info/stream
id	yes	message id
timestamp	yes	unix time in ms
traceId	yes	distributed trace id
sender	yes	sender address (serviceName, serviceVersion, serviceTarget, instanceId)
receiver	depends	target address for directed messages
payload	depends	message body
otp	no	OpenTelemetry propagation payload

Stream message model

messageType: 'stream' uses frame-oriented payloads:

• open: open request with payload + parameter
• start: producer accepted and stream started
• chunk: one incremental result item
• complete: terminal success (optional final payload)
• error: terminal failure
• cancel: terminal cancellation
• heartbeat: optional keepalive frame

A stream session is keyed by correlationId.

Practical debugging tips

• use traceId for end-to-end flow views
• use correlationId for one command call or stream session
• inspect sender/receiver address to verify routing correctness
• verify eventName for subscription matching and event-driven fan-out