# Semantic Conventions for Messaging Systems **Status**: [Experimental][DocumentStatus] This document defines semantic conventions for messaging systems spans, metrics and logs. > [!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 which is a comma-separated list of values. > 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. Semantic conventions for messaging systems are defined for the following signals: * [Messaging Spans](messaging-spans.md): Semantic Conventions for messaging *spans*. * [Messaging Metrics](messaging-metrics.md): Semantic Conventions for messaging *metrics*. Technology specific semantic conventions are defined for the following messaging systems: * [Kafka](kafka.md): Semantic Conventions for *Apache Kafka*. * [RabbitMQ](rabbitmq.md): Semantic Conventions for *RabbitMQ*. * [RocketMQ](rocketmq.md): Semantic Conventions for *Apache RocketMQ*. * [Google Cloud Pub/Sub](gcp-pubsub.md): Semantic Conventions for *Google Cloud Pub/Sub*. * [Azure Service Bus](azure-messaging.md#azure-service-bus): Semantic Conventions for *Azure Service Bus*. * [Azure Event Hubs](azure-messaging.md#azure-event-hubs): Semantic Conventions for *Azure Event Hubs*. [DocumentStatus]: https://opentelemetry.io/docs/specs/otel/document-status