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Distributed Tracing extension

This extension embeds context from Distributed Tracing so that distributed systems can include traces that span an event-driven system. This extension is meant to contain historical data of the parent trace, in order to diagnose eventual failures of the system through tracing platforms like Jaeger, Zipkin, etc.

Attributes

traceparent

  • Type: String
  • Description: Contains a version, trace ID, span ID, and trace options as defined in section 3.2
  • Constraints
    • REQUIRED

tracestate

  • Type: String
  • Description: a comma-delimited list of key-value pairs, defined by section 3.3.
  • Constraints
    • OPTIONAL

Using the Distributed Tracing Extension

The Distributed Tracing Extension is not intended to replace the protocol specific headers for tracing, like the ones described in W3C Trace Context for HTTP.

Given a single hop event transmission (from sink to source directly), the Distributed Tracing Extension, if used, MUST carry the same trace information contained in protocol specific tracing headers.

Given a multi hop event transmission, the Distributed Tracing Extension, if used, MUST carry the trace information of the starting trace of the transmission. In other words, it MUST NOT carry trace information of each individual hop, since this information is usually carried using protocol specific headers, understood by tools like OpenTelemetry.

Middleware between the source and the sink of the event could eventually add a Distributed Tracing Extension if the source didn't include any, in order to provide to the sink the starting trace of the transmission.

An example with HTTP:

CURL -X POST example/webhook.json \
-H 'ce-id: 1' \
-H 'ce-specversion: 1.0' \
-H 'ce-type: example' \
-H 'ce-source: http://localhost' \
-H 'ce-traceparent:  00-0af7651916cd43dd8448eb211c80319c-b9c7c989f97918e1-01' \
-H 'traceparent:  00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01' \
-H 'tracestate: rojo=00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01,congo=lZWRzIHRoNhcm5hbCBwbGVhc3VyZS4`