Make network.protocol.name conditionally required for messaging

CHANGELOG.md

@@ -13,6 +13,8 @@ release.
   ([#484](https://github.com/open-telemetry/semantic-conventions/pull/484))
 - Depluralize labels for pod (`k8s.pod.labels.*`) and container (`container.labels.*`) resources
   ([#625](https://github.com/open-telemetry/semantic-conventions/pull/625))
+- Make `network.protocol.name` conditionally required for messaging
+  ([#644](https://github.com/open-telemetry/semantic-conventions/pull/644))
 - BREAKING: Generate process metrics from YAML
   ([#330](https://github.com/open-telemetry/semantic-conventions/pull/330))
   - Rename `process.threads` to `process.thread.count`

docs/messaging/messaging-metrics.md

@@ -29,10 +29,10 @@ All messaging metrics share the same set of attributes:
 | [`messaging.destination.name`](../attributes-registry/messaging.md) | string | The message destination name [3] | `MyQueue`; `MyTopic` | Conditionally Required: [4] |
 | [`messaging.destination.template`](../attributes-registry/messaging.md) | string | Low cardinality representation of the messaging destination name [5] | `/customers/{customerId}` | Conditionally Required: if available. |
 | [`messaging.system`](../attributes-registry/messaging.md) | string | An identifier for the messaging system being used. See below for a list of well-known identifiers. | `activemq` | Required |
-| [`network.protocol.name`](../attributes-registry/network.md) | string | [OSI application layer](https://osi-model.com/application-layer/) or non-OSI equivalent. [6] | `amqp`; `mqtt` | Recommended |
-| [`network.protocol.version`](../attributes-registry/network.md) | string | Version of the protocol specified in `network.protocol.name`. [7] | `3.1.1` | Recommended |
-| [`server.address`](../attributes-registry/server.md) | string | Server domain name if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. [8] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | Conditionally Required: If available. |
-| [`server.port`](../attributes-registry/server.md) | int | Server port number. [9] | `80`; `8080`; `443` | Recommended |
+| [`network.protocol.name`](../attributes-registry/network.md) | string | [OSI application layer](https://osi-model.com/application-layer/) or non-OSI equivalent. [6] | `amqp`; `mqtt` | Conditionally Required: [7] |
+| [`network.protocol.version`](../attributes-registry/network.md) | string | Version of the protocol specified in `network.protocol.name`. [8] | `3.1.1` | Recommended |
+| [`server.address`](../attributes-registry/server.md) | string | Server domain name if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. [9] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | Conditionally Required: If available. |
+| [`server.port`](../attributes-registry/server.md) | int | Server port number. [10] | `80`; `8080`; `443` | Recommended |
 
 **[1]:** The `error.type` SHOULD be predictable and SHOULD have low cardinality.
 Instrumentations SHOULD document the list of errors they report.
@@ -61,11 +61,13 @@ the broker doesn't have such notion, the destination name SHOULD uniquely identi
 
 **[6]:** The value SHOULD be normalized to lowercase.
 
-**[7]:** `network.protocol.version` refers to the version of the protocol used and might be different from the protocol client's version. If the HTTP client has a version of `0.27.2`, but sends HTTP version `1.1`, this attribute should be set to `1.1`.
+**[7]:** Only for messaging systems and frameworks that support more than one protocol.
 
-**[8]:** This should be the IP/hostname of the broker (or other network-level peer) this specific message is sent to/received from.
+**[8]:** `network.protocol.version` refers to the version of the protocol used and might be different from the protocol client's version. If the HTTP client has a version of `0.27.2`, but sends HTTP version `1.1`, this attribute should be set to `1.1`.
 
-**[9]:** When observed from the client side, and when communicating through an intermediary, `server.port` SHOULD represent the server port behind any intermediaries, for example proxies, if it's available.
+**[9]:** This should be the IP/hostname of the broker (or other network-level peer) this specific message is sent to/received from.
+
+**[10]:** When observed from the client side, and when communicating through an intermediary, `server.port` SHOULD represent the server port behind any intermediaries, for example proxies, if it's available.
 
 `error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
 

docs/messaging/messaging-spans.md

@@ -302,12 +302,12 @@ as described in [Attributes specific to certain messaging systems](#attributes-s
 | [`messaging.system`](../attributes-registry/messaging.md) | string | An identifier for the messaging system being used. See below for a list of well-known identifiers. | `activemq` | Required |
 | [`network.peer.address`](../attributes-registry/network.md) | string | Peer address of the network connection - IP address or Unix domain socket name. | `10.1.2.80`; `/tmp/my.sock` | Recommended |
 | [`network.peer.port`](../attributes-registry/network.md) | int | Peer port number of the network connection. | `65123` | Recommended: If `network.peer.address` is set. |
-| [`network.protocol.name`](../attributes-registry/network.md) | string | [OSI application layer](https://osi-model.com/application-layer/) or non-OSI equivalent. [14] | `amqp`; `mqtt` | Recommended |
-| [`network.protocol.version`](../attributes-registry/network.md) | string | Version of the protocol specified in `network.protocol.name`. [15] | `3.1.1` | Recommended |
-| [`network.transport`](../attributes-registry/network.md) | string | [OSI transport layer](https://osi-model.com/transport-layer/) or [inter-process communication method](https://wikipedia.org/wiki/Inter-process_communication). [16] | `tcp`; `udp` | Recommended |
-| [`network.type`](../attributes-registry/network.md) | string | [OSI network layer](https://osi-model.com/network-layer/) or non-OSI equivalent. [17] | `ipv4`; `ipv6` | Recommended |
-| [`server.address`](../attributes-registry/server.md) | string | Server domain name if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. [18] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | Conditionally Required: If available. |
-| [`server.port`](../attributes-registry/server.md) | int | Server port number. [19] | `80`; `8080`; `443` | Recommended |
+| [`network.protocol.name`](../attributes-registry/network.md) | string | [OSI application layer](https://osi-model.com/application-layer/) or non-OSI equivalent. [14] | `amqp`; `mqtt` | Conditionally Required: [15] |
+| [`network.protocol.version`](../attributes-registry/network.md) | string | Version of the protocol specified in `network.protocol.name`. [16] | `3.1.1` | Recommended |
+| [`network.transport`](../attributes-registry/network.md) | string | [OSI transport layer](https://osi-model.com/transport-layer/) or [inter-process communication method](https://wikipedia.org/wiki/Inter-process_communication). [17] | `tcp`; `udp` | Recommended |
+| [`network.type`](../attributes-registry/network.md) | string | [OSI network layer](https://osi-model.com/network-layer/) or non-OSI equivalent. [18] | `ipv4`; `ipv6` | Recommended |
+| [`server.address`](../attributes-registry/server.md) | string | Server domain name if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. [19] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | Conditionally Required: If available. |
+| [`server.port`](../attributes-registry/server.md) | int | Server port number. [20] | `80`; `8080`; `443` | Recommended |
 
 **[1]:** The `error.type` SHOULD be predictable and SHOULD have low cardinality.
 Instrumentations SHOULD document the list of errors they report.
@@ -354,19 +354,21 @@ size should be used.
 
 **[14]:** The value SHOULD be normalized to lowercase.
 
-**[15]:** `network.protocol.version` refers to the version of the protocol used and might be different from the protocol client's version. If the HTTP client has a version of `0.27.2`, but sends HTTP version `1.1`, this attribute should be set to `1.1`.
+**[15]:** Only for messaging systems and frameworks that support more than one protocol.
 
-**[16]:** The value SHOULD be normalized to lowercase.
+**[16]:** `network.protocol.version` refers to the version of the protocol used and might be different from the protocol client's version. If the HTTP client has a version of `0.27.2`, but sends HTTP version `1.1`, this attribute should be set to `1.1`.
+
+**[17]:** The value SHOULD be normalized to lowercase.
 
 Consider always setting the transport when setting a port number, since
 a port number is ambiguous without knowing the transport. For example
 different processes could be listening on TCP port 12345 and UDP port 12345.
 
-**[17]:** The value SHOULD be normalized to lowercase.
+**[18]:** The value SHOULD be normalized to lowercase.
 
-**[18]:** This should be the IP/hostname of the broker (or other network-level peer) this specific message is sent to/received from.
+**[19]:** This should be the IP/hostname of the broker (or other network-level peer) this specific message is sent to/received from.
 
-**[19]:** When observed from the client side, and when communicating through an intermediary, `server.port` SHOULD represent the server port behind any intermediaries, for example proxies, if it's available.
+**[20]:** When observed from the client side, and when communicating through an intermediary, `server.port` SHOULD represent the server port behind any intermediaries, for example proxies, if it's available.
 
 `error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
 

model/messaging-common.yaml

@@ -18,6 +18,8 @@ groups:
       - ref: server.port
       - ref: network.protocol.name
         examples: ['amqp', 'mqtt']
+        requirement_level:
+          conditionally_required: Only for messaging systems and frameworks that support more than one protocol.
         tag: connection-level
       - ref: network.protocol.version
         tag: connection-level