Give exhaustive specification of span kinds for messaging spans (#1171)

Co-authored-by: Liudmila Molkova <[email protected]>
Co-authored-by: Joao Grassi <[email protected]>

.chloggen/1112.yaml

@@ -0,0 +1,4 @@
+change_type: enhancement
+component: messaging
+note: Define span kind for unspecified cases of messaging `publish` and `process` spans.
+issues: [1112]

docs/messaging/messaging-spans.md

@@ -208,21 +208,13 @@ Span kind SHOULD be set according to the following table, based on the operation
 
 | Operation type | Span kind|
 |----------------|-------------|
-| `create`       | `PRODUCER` |
-| `publish`      | `PRODUCER` if the context of the "Publish" span is used as creation context. |
-| `receive`      | `CONSUMER` |
-| `process`      | `CONSUMER` for push-based scenarios where no "Receive" span exists. |
-
-For cases not covered by the table above, the span kind should be set according
-to the [generic specification about span kinds](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.35.0/specification/trace/api.md#spankind),
-e. g. it should be set to CLIENT for the "Publish" span if its context is not
-used as creation context and if the "Publish" span models a synchronous call to
-the intermediary.
-
-Setting span kinds according to this table ensures that span links between
-consumers and producers always exist between a PRODUCER span on the producer
-side and a CONSUMER span on the consumer side. This allows analysis tools to
-interpret linked traces without the need for additional semantic hints.
+| `create`       | `PRODUCER`  |
+| `publish`      | `PRODUCER` if the context of the "Publish" span is used as creation context, otherwise `CLIENT`. |
+| `receive`      | `CLIENT`    |
+| `process`      | `CONSUMER`  |
+
+Setting span kinds according to this table allows analysis tools to interpret spans
+and relationships between them without the need for additional semantic hints.
 
 ### Trace structure