# Semantic conventions for messaging client metrics **Status**: [Development][DocumentStatus] - [Common metrics](#common-metrics) - [Metric: `messaging.client.operation.duration`](#metric-messagingclientoperationduration) - [Producer metrics](#producer-metrics) - [Metric: `messaging.client.sent.messages`](#metric-messagingclientsentmessages) - [Consumer metrics](#consumer-metrics) - [Metric: `messaging.client.consumed.messages`](#metric-messagingclientconsumedmessages) - [Metric: `messaging.process.duration`](#metric-messagingprocessduration) > [!Warning] > > Existing messaging instrumentations that are using > [v1.24.0 of this document](https://github.com/open-telemetry/semantic-conventions/blob/v1.24.0/docs/messaging/messaging-spans.md) > (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. ## Common metrics ### Metric: `messaging.client.operation.duration` When this metric is reported alongside a messaging span, the metric value SHOULD be the same as the corresponding span duration. This metric is [required][MetricRequired]. This metric SHOULD be specified with [`ExplicitBucketBoundaries`](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.45.0/specification/metrics/api.md#instrument-advisory-parameters) of `[ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ]`. | Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations | | -------- | --------------- | ----------- | -------------- | --------- | ------ | | `messaging.client.operation.duration` | Histogram | `s` | Duration of messaging operation initiated by a producer or consumer client. [1] |  | | **[1]:** This metric SHOULD NOT be used to report processing duration - processing duration is reported in `messaging.process.duration` metric. | Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability | |---|---|---|---|---|---| | [`messaging.operation.name`](/docs/registry/attributes/messaging.md) | string | The system-specific name of the messaging operation. | `send`; `receive`; `ack` | `Required` |  | | [`messaging.system`](/docs/registry/attributes/messaging.md) | string | The messaging system as identified by the client instrumentation. [1] | `activemq`; `aws_sqs`; `eventgrid` | `Required` |  | | [`error.type`](/docs/registry/attributes/error.md) | string | Describes a class of error the operation ended with. [2] | `amqp:decode-error`; `KAFKA_STORAGE_ERROR`; `channel-error` | `Conditionally Required` If and only if the messaging operation has failed. |  | | [`messaging.consumer.group.name`](/docs/registry/attributes/messaging.md) | string | The name of the consumer group with which a consumer is associated. [3] | `my-group`; `indexer` | `Conditionally Required` if applicable. |  | | [`messaging.destination.name`](/docs/registry/attributes/messaging.md) | string | The message destination name [4] | `MyQueue`; `MyTopic` | `Conditionally Required` [5] |  | | [`messaging.destination.subscription.name`](/docs/registry/attributes/messaging.md) | string | The name of the destination subscription from which a message is consumed. [6] | `subscription-a` | `Conditionally Required` if applicable. |  | | [`messaging.destination.template`](/docs/registry/attributes/messaging.md) | string | Low cardinality representation of the messaging destination name [7] | `/customers/{customerId}` | `Conditionally Required` if available. |  | | [`messaging.operation.type`](/docs/registry/attributes/messaging.md) | string | A string identifying the type of the messaging operation. [8] | `create`; `send`; `receive` | `Conditionally Required` If applicable. |  | | [`server.address`](/docs/registry/attributes/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. |  | | [`messaging.destination.partition.id`](/docs/registry/attributes/messaging.md) | string | The identifier of the partition messages are sent to or received from, unique within the `messaging.destination.name`. | `1` | `Recommended` |  | | [`server.port`](/docs/registry/attributes/server.md) | int | Server port number. [10] | `80`; `8080`; `443` | `Recommended` |  | **[1] `messaging.system`:** The actual messaging system may differ from the one known by the client. For example, when using Kafka client libraries to communicate with Azure Event Hubs, the `messaging.system` is set to `kafka` based on the instrumentation's best knowledge. **[2] `error.type`:** The `error.type` SHOULD be predictable, and SHOULD have low cardinality. When `error.type` is set to a type (e.g., an exception type), its canonical class name identifying the type within the artifact SHOULD be used. Instrumentations SHOULD document the list of errors they report. The cardinality of `error.type` within one instrumentation library SHOULD be low. Telemetry consumers that aggregate data from multiple instrumentation libraries and applications should be prepared for `error.type` to have high cardinality at query time when no additional filters are applied. If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`. If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes), it's RECOMMENDED to: - Use a domain-specific attribute - Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not. **[3] `messaging.consumer.group.name`:** Semantic conventions for individual messaging systems SHOULD document whether `messaging.consumer.group.name` is applicable and what it means in the context of that system. **[4] `messaging.destination.name`:** Destination name SHOULD uniquely identify a specific queue, topic or other entity within the broker. If the broker doesn't have such notion, the destination name SHOULD uniquely identify the broker. **[5] `messaging.destination.name`:** if and only if `messaging.destination.name` is known to have low cardinality. Otherwise, `messaging.destination.template` MAY be populated. **[6] `messaging.destination.subscription.name`:** Semantic conventions for individual messaging systems SHOULD document whether `messaging.destination.subscription.name` is applicable and what it means in the context of that system. **[7] `messaging.destination.template`:** Destination names could be constructed from templates. An example would be a destination name involving a user name or product id. Although the destination name in this case is of high cardinality, the underlying template is of low cardinality and can be effectively used for grouping and aggregation. **[8] `messaging.operation.type`:** If a custom value is used, it MUST be of low cardinality. **[9] `server.address`:** Server domain name of the broker if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. **[10] `server.port`:** 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. | Value | Description | Stability | |---|---|---| | `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. |  | --- `messaging.operation.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. | Value | Description | Stability | |---|---|---| | `create` | A message is created. "Create" spans always refer to a single message and are used to provide a unique creation context for messages in batch sending scenarios. |  | | `process` | One or more messages are processed by a consumer. |  | | `receive` | One or more messages are requested by a consumer. This operation refers to pull-based scenarios, where consumers explicitly call methods of messaging SDKs to receive messages. |  | | `send` | One or more messages are provided for sending to an intermediary. If a single message is sent, the context of the "Send" span can be used as the creation context and no "Create" span needs to be created. |  | | `settle` | One or more messages are settled. |  | --- `messaging.system` 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. | Value | Description | Stability | |---|---|---| | `activemq` | Apache ActiveMQ |  | | `aws_sqs` | Amazon Simple Queue Service (SQS) |  | | `eventgrid` | Azure Event Grid |  | | `eventhubs` | Azure Event Hubs |  | | `gcp_pubsub` | Google Cloud Pub/Sub |  | | `jms` | Java Message Service |  | | `kafka` | Apache Kafka |  | | `pulsar` | Apache Pulsar |  | | `rabbitmq` | RabbitMQ |  | | `rocketmq` | Apache RocketMQ |  | | `servicebus` | Azure Service Bus |  | ## Producer metrics ### Metric: `messaging.client.sent.messages` This metric is [required][MetricRequired]. | Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations | | -------- | --------------- | ----------- | -------------- | --------- | ------ | | `messaging.client.sent.messages` | Counter | `{message}` | Number of messages producer attempted to send to the broker. [1] |  | | **[1]:** This metric MUST NOT count messages that were created but haven't yet been sent. | Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability | |---|---|---|---|---|---| | [`messaging.operation.name`](/docs/registry/attributes/messaging.md) | string | The system-specific name of the messaging operation. | `send`; `schedule`; `enqueue` | `Required` |  | | [`messaging.system`](/docs/registry/attributes/messaging.md) | string | The messaging system as identified by the client instrumentation. [1] | `activemq`; `aws_sqs`; `eventgrid` | `Required` |  | | [`error.type`](/docs/registry/attributes/error.md) | string | Describes a class of error the operation ended with. [2] | `amqp:decode-error`; `KAFKA_STORAGE_ERROR`; `channel-error` | `Conditionally Required` If and only if the messaging operation has failed. |  | | [`messaging.destination.name`](/docs/registry/attributes/messaging.md) | string | The message destination name [3] | `MyQueue`; `MyTopic` | `Conditionally Required` [4] |  | | [`messaging.destination.template`](/docs/registry/attributes/messaging.md) | string | Low cardinality representation of the messaging destination name [5] | `/customers/{customerId}` | `Conditionally Required` if available. |  | | [`server.address`](/docs/registry/attributes/server.md) | string | Server domain name if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. [6] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | `Conditionally Required` If available. |  | | [`messaging.destination.partition.id`](/docs/registry/attributes/messaging.md) | string | The identifier of the partition messages are sent to or received from, unique within the `messaging.destination.name`. | `1` | `Recommended` |  | | [`server.port`](/docs/registry/attributes/server.md) | int | Server port number. [7] | `80`; `8080`; `443` | `Recommended` |  | **[1] `messaging.system`:** The actual messaging system may differ from the one known by the client. For example, when using Kafka client libraries to communicate with Azure Event Hubs, the `messaging.system` is set to `kafka` based on the instrumentation's best knowledge. **[2] `error.type`:** The `error.type` SHOULD be predictable, and SHOULD have low cardinality. When `error.type` is set to a type (e.g., an exception type), its canonical class name identifying the type within the artifact SHOULD be used. Instrumentations SHOULD document the list of errors they report. The cardinality of `error.type` within one instrumentation library SHOULD be low. Telemetry consumers that aggregate data from multiple instrumentation libraries and applications should be prepared for `error.type` to have high cardinality at query time when no additional filters are applied. If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`. If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes), it's RECOMMENDED to: - Use a domain-specific attribute - Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not. **[3] `messaging.destination.name`:** Destination name SHOULD uniquely identify a specific queue, topic or other entity within the broker. If the broker doesn't have such notion, the destination name SHOULD uniquely identify the broker. **[4] `messaging.destination.name`:** if and only if `messaging.destination.name` is known to have low cardinality. Otherwise, `messaging.destination.template` MAY be populated. **[5] `messaging.destination.template`:** Destination names could be constructed from templates. An example would be a destination name involving a user name or product id. Although the destination name in this case is of high cardinality, the underlying template is of low cardinality and can be effectively used for grouping and aggregation. **[6] `server.address`:** Server domain name of the broker if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. **[7] `server.port`:** 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. | Value | Description | Stability | |---|---|---| | `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. |  | --- `messaging.system` 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. | Value | Description | Stability | |---|---|---| | `activemq` | Apache ActiveMQ |  | | `aws_sqs` | Amazon Simple Queue Service (SQS) |  | | `eventgrid` | Azure Event Grid |  | | `eventhubs` | Azure Event Hubs |  | | `gcp_pubsub` | Google Cloud Pub/Sub |  | | `jms` | Java Message Service |  | | `kafka` | Apache Kafka |  | | `pulsar` | Apache Pulsar |  | | `rabbitmq` | RabbitMQ |  | | `rocketmq` | Apache RocketMQ |  | | `servicebus` | Azure Service Bus |  | ## Consumer metrics ### Metric: `messaging.client.consumed.messages` This metric is [required][MetricRequired]. | Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations | | -------- | --------------- | ----------- | -------------- | --------- | ------ | | `messaging.client.consumed.messages` | Counter | `{message}` | Number of messages that were delivered to the application. [1] |  | | **[1]:** Records the number of messages pulled from the broker or number of messages dispatched to the application in push-based scenarios. The metric SHOULD be reported once per message delivery. For example, if receiving and processing operations are both instrumented for a single message delivery, this counter is incremented when the message is received and not reported when it is processed. | Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability | |---|---|---|---|---|---| | [`messaging.operation.name`](/docs/registry/attributes/messaging.md) | string | The system-specific name of the messaging operation. | `receive`; `peek`; `poll`; `consume` | `Required` |  | | [`messaging.system`](/docs/registry/attributes/messaging.md) | string | The messaging system as identified by the client instrumentation. [1] | `activemq`; `aws_sqs`; `eventgrid` | `Required` |  | | [`error.type`](/docs/registry/attributes/error.md) | string | Describes a class of error the operation ended with. [2] | `amqp:decode-error`; `KAFKA_STORAGE_ERROR`; `channel-error` | `Conditionally Required` If and only if the messaging operation has failed. |  | | [`messaging.consumer.group.name`](/docs/registry/attributes/messaging.md) | string | The name of the consumer group with which a consumer is associated. [3] | `my-group`; `indexer` | `Conditionally Required` if applicable. |  | | [`messaging.destination.name`](/docs/registry/attributes/messaging.md) | string | The message destination name [4] | `MyQueue`; `MyTopic` | `Conditionally Required` [5] |  | | [`messaging.destination.subscription.name`](/docs/registry/attributes/messaging.md) | string | The name of the destination subscription from which a message is consumed. [6] | `subscription-a` | `Conditionally Required` if applicable. |  | | [`messaging.destination.template`](/docs/registry/attributes/messaging.md) | string | Low cardinality representation of the messaging destination name [7] | `/customers/{customerId}` | `Conditionally Required` if available. |  | | [`server.address`](/docs/registry/attributes/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. |  | | [`messaging.destination.partition.id`](/docs/registry/attributes/messaging.md) | string | The identifier of the partition messages are sent to or received from, unique within the `messaging.destination.name`. | `1` | `Recommended` |  | | [`server.port`](/docs/registry/attributes/server.md) | int | Server port number. [9] | `80`; `8080`; `443` | `Recommended` |  | **[1] `messaging.system`:** The actual messaging system may differ from the one known by the client. For example, when using Kafka client libraries to communicate with Azure Event Hubs, the `messaging.system` is set to `kafka` based on the instrumentation's best knowledge. **[2] `error.type`:** The `error.type` SHOULD be predictable, and SHOULD have low cardinality. When `error.type` is set to a type (e.g., an exception type), its canonical class name identifying the type within the artifact SHOULD be used. Instrumentations SHOULD document the list of errors they report. The cardinality of `error.type` within one instrumentation library SHOULD be low. Telemetry consumers that aggregate data from multiple instrumentation libraries and applications should be prepared for `error.type` to have high cardinality at query time when no additional filters are applied. If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`. If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes), it's RECOMMENDED to: - Use a domain-specific attribute - Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not. **[3] `messaging.consumer.group.name`:** Semantic conventions for individual messaging systems SHOULD document whether `messaging.consumer.group.name` is applicable and what it means in the context of that system. **[4] `messaging.destination.name`:** Destination name SHOULD uniquely identify a specific queue, topic or other entity within the broker. If the broker doesn't have such notion, the destination name SHOULD uniquely identify the broker. **[5] `messaging.destination.name`:** if and only if `messaging.destination.name` is known to have low cardinality. Otherwise, `messaging.destination.template` MAY be populated. **[6] `messaging.destination.subscription.name`:** Semantic conventions for individual messaging systems SHOULD document whether `messaging.destination.subscription.name` is applicable and what it means in the context of that system. **[7] `messaging.destination.template`:** Destination names could be constructed from templates. An example would be a destination name involving a user name or product id. Although the destination name in this case is of high cardinality, the underlying template is of low cardinality and can be effectively used for grouping and aggregation. **[8] `server.address`:** Server domain name of the broker if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. **[9] `server.port`:** 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. | Value | Description | Stability | |---|---|---| | `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. |  | --- `messaging.system` 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. | Value | Description | Stability | |---|---|---| | `activemq` | Apache ActiveMQ |  | | `aws_sqs` | Amazon Simple Queue Service (SQS) |  | | `eventgrid` | Azure Event Grid |  | | `eventhubs` | Azure Event Hubs |  | | `gcp_pubsub` | Google Cloud Pub/Sub |  | | `jms` | Java Message Service |  | | `kafka` | Apache Kafka |  | | `pulsar` | Apache Pulsar |  | | `rabbitmq` | RabbitMQ |  | | `rocketmq` | Apache RocketMQ |  | | `servicebus` | Azure Service Bus |  | ### Metric: `messaging.process.duration` When this metric is reported alongside a messaging process span, the metric value SHOULD be the same as the corresponding span duration. This metric is [required][MetricRequired] for push-based message delivery and is [recommended][MetricRecommended] for processing operations instrumented for pull-based scenarios. This metric SHOULD be specified with [`ExplicitBucketBoundaries`](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.45.0/specification/metrics/api.md#instrument-advisory-parameters) of `[ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ]`. | Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations | | -------- | --------------- | ----------- | -------------- | --------- | ------ | | `messaging.process.duration` | Histogram | `s` | Duration of processing operation. [1] |  | | **[1]:** This metric MUST be reported for operations with `messaging.operation.type` that matches `process`. | Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability | |---|---|---|---|---|---| | [`messaging.operation.name`](/docs/registry/attributes/messaging.md) | string | The system-specific name of the messaging operation. | `process`; `consume`; `handle` | `Required` |  | | [`messaging.system`](/docs/registry/attributes/messaging.md) | string | The messaging system as identified by the client instrumentation. [1] | `activemq`; `aws_sqs`; `eventgrid` | `Required` |  | | [`error.type`](/docs/registry/attributes/error.md) | string | Describes a class of error the operation ended with. [2] | `amqp:decode-error`; `KAFKA_STORAGE_ERROR`; `channel-error` | `Conditionally Required` If and only if the messaging operation has failed. |  | | [`messaging.consumer.group.name`](/docs/registry/attributes/messaging.md) | string | The name of the consumer group with which a consumer is associated. [3] | `my-group`; `indexer` | `Conditionally Required` if applicable. |  | | [`messaging.destination.name`](/docs/registry/attributes/messaging.md) | string | The message destination name [4] | `MyQueue`; `MyTopic` | `Conditionally Required` [5] |  | | [`messaging.destination.subscription.name`](/docs/registry/attributes/messaging.md) | string | The name of the destination subscription from which a message is consumed. [6] | `subscription-a` | `Conditionally Required` if applicable. |  | | [`messaging.destination.template`](/docs/registry/attributes/messaging.md) | string | Low cardinality representation of the messaging destination name [7] | `/customers/{customerId}` | `Conditionally Required` if available. |  | | [`server.address`](/docs/registry/attributes/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. |  | | [`messaging.destination.partition.id`](/docs/registry/attributes/messaging.md) | string | The identifier of the partition messages are sent to or received from, unique within the `messaging.destination.name`. | `1` | `Recommended` |  | | [`server.port`](/docs/registry/attributes/server.md) | int | Server port number. [9] | `80`; `8080`; `443` | `Recommended` |  | **[1] `messaging.system`:** The actual messaging system may differ from the one known by the client. For example, when using Kafka client libraries to communicate with Azure Event Hubs, the `messaging.system` is set to `kafka` based on the instrumentation's best knowledge. **[2] `error.type`:** The `error.type` SHOULD be predictable, and SHOULD have low cardinality. When `error.type` is set to a type (e.g., an exception type), its canonical class name identifying the type within the artifact SHOULD be used. Instrumentations SHOULD document the list of errors they report. The cardinality of `error.type` within one instrumentation library SHOULD be low. Telemetry consumers that aggregate data from multiple instrumentation libraries and applications should be prepared for `error.type` to have high cardinality at query time when no additional filters are applied. If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`. If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes), it's RECOMMENDED to: - Use a domain-specific attribute - Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not. **[3] `messaging.consumer.group.name`:** Semantic conventions for individual messaging systems SHOULD document whether `messaging.consumer.group.name` is applicable and what it means in the context of that system. **[4] `messaging.destination.name`:** Destination name SHOULD uniquely identify a specific queue, topic or other entity within the broker. If the broker doesn't have such notion, the destination name SHOULD uniquely identify the broker. **[5] `messaging.destination.name`:** if and only if `messaging.destination.name` is known to have low cardinality. Otherwise, `messaging.destination.template` MAY be populated. **[6] `messaging.destination.subscription.name`:** Semantic conventions for individual messaging systems SHOULD document whether `messaging.destination.subscription.name` is applicable and what it means in the context of that system. **[7] `messaging.destination.template`:** Destination names could be constructed from templates. An example would be a destination name involving a user name or product id. Although the destination name in this case is of high cardinality, the underlying template is of low cardinality and can be effectively used for grouping and aggregation. **[8] `server.address`:** Server domain name of the broker if available without reverse DNS lookup; otherwise, IP address or Unix domain socket name. **[9] `server.port`:** 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. | Value | Description | Stability | |---|---|---| | `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. |  | --- `messaging.system` 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. | Value | Description | Stability | |---|---|---| | `activemq` | Apache ActiveMQ |  | | `aws_sqs` | Amazon Simple Queue Service (SQS) |  | | `eventgrid` | Azure Event Grid |  | | `eventhubs` | Azure Event Hubs |  | | `gcp_pubsub` | Google Cloud Pub/Sub |  | | `jms` | Java Message Service |  | | `kafka` | Apache Kafka |  | | `pulsar` | Apache Pulsar |  | | `rabbitmq` | RabbitMQ |  | | `rocketmq` | Apache RocketMQ |  | | `servicebus` | Azure Service Bus |  | [DocumentStatus]: https://opentelemetry.io/docs/specs/otel/document-status [MetricRequired]: /docs/general/metric-requirement-level.md#required [MetricRecommended]: /docs/general/metric-requirement-level.md#recommended