Semantic conventions for messaging systems

Existing messaging instrumentations that are using v1.24.0 of this document (or prior):

• SHOULD NOT change the version of the messaging conventions that they emit by default until the messaging semantic conventions are marked stable. Conventions include, but are not limited to, attributes, metric and span names, span kind and unit of measure.
• SHOULD introduce an environment variable OTEL_SEMCONV_STABILITY_OPT_IN in the existing major version as a comma-separated list of category-specific values (e.g., http, databases, messaging). The list of values includes:
  • messaging - emit the new, stable messaging conventions, and stop emitting the old experimental messaging conventions that the instrumentation emitted previously.
  • messaging/dup - emit both the old and the stable messaging conventions, allowing for a seamless transition.
  • The default behavior (in the absence of one of these values) is to continue emitting whatever version of the old experimental messaging conventions the instrumentation was emitting previously.
  • Note: messaging/dup has higher precedence than messaging in case both values are present
• SHOULD maintain (security patching at a minimum) the existing major version for at least six months after it starts emitting both sets of conventions.
• SHOULD drop the environment variable in the next major version.
• SHOULD emit the new, stable values for span name, span kind and similar “single” valued concepts when messaging/dup is present in the list.