Status: Experimental
Warning Existing Messaging instrumentations that are using v1.20.0 of this document (or prior):
- SHOULD NOT change the version of the networking attributes that they emit until the HTTP semantic conventions are marked stable (HTTP stabilization will include stabilization of a core set of networking attributes which are also used in Messaging instrumentations).
- SHOULD introduce an environment variable
OTEL_SEMCONV_STABILITY_OPT_INin the existing major version which is a comma-separated list of values. The only values defined so far are:
http- emit the new, stable networking attributes, and stop emitting the old experimental networking attributes that the instrumentation emitted previously.http/dup- emit both the old and the stable networking attributes, 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 networking attributes the instrumentation was emitting previously.
- SHOULD maintain (security patching at a minimum) the existing major version for at least six months after it starts emitting both sets of attributes.
- SHOULD drop the environment variable in the next major version (stable next major version SHOULD NOT be released prior to October 1, 2023).
Although messaging systems are not as standardized as, e.g., HTTP, it is assumed that the following definitions are applicable to most of them that have similar concepts at all (names borrowed mostly from JMS):
A message is an envelope with a potentially empty payload. This envelope may offer the possibility to convey additional metadata, often in key/value form.
A message is sent by a message producer to:
- Physically: some message broker (which can be e.g., a single server, or a cluster, or a local process reached via IPC). The broker handles the actual delivery, re-delivery, persistence, etc. In some messaging systems the broker may be identical or co-located with (some) message consumers. With Apache Kafka, the physical broker a message is written to depends on the number of partitions, and which broker is the leader of the partition the record is written to.
- Logically: some particular message destination.
Messages can be delivered to 0, 1, or multiple consumers depending on the dispatching semantic of the protocol.
The "producer" is a specific instance, process or device that creates and publishes a message. "Publishing" is the process of sending a message or batch of messages to the intermediary or consumer.
A "consumer" receives the message and acts upon it. It uses the context and data to execute some logic, which might lead to the occurrence of new events.
The consumer receives, processes, and settles a message. "Receiving" is the process of obtaining a message from the intermediary, "processing" is the process of acting on the information a message contains, "settling" is the process of notifying an intermediary that a message was processed successfully.
An "intermediary" receives a message to forward it to the next receiver, which might be another intermediary or a consumer.
A destination represents the entity within a messaging system where messages are published to and consumed from.
A destination is usually uniquely identified by its name within the messaging system instance. Examples of a destination name would be an URL or a simple one-word identifier.
Typical examples of destinations include Kafka topics, RabbitMQ queues and topics.
The consumption of a message can happen in multiple steps. First, the lower-level receiving of a message at a consumer, and then the logical processing of the message. Often, the waiting for a message is not particularly interesting and hidden away in a framework that only invokes some handler function to process a message once one is received (in the same way that the listening on a TCP port for an incoming HTTP message is not particularly interesting).
In some messaging systems, a message can receive one or more reply messages that answers a particular other message that was sent earlier. All messages that are grouped together by such a reply-relationship are called a conversation. The grouping usually happens through some sort of "In-Reply-To:" meta information or an explicit conversation ID (sometimes called correlation ID). Sometimes a conversation can span multiple message destinations (e.g. initiated via a topic, continued on a temporary one-to-one queue).
Some messaging systems support the concept of temporary destination (often only temporary queues) that are established just for a particular set of communication partners (often one to one) or conversation. Often such destinations are also unnamed (anonymous) or have an auto-generated name.
Given these definitions, the remainder of this section describes the semantic conventions for Spans describing interactions with messaging systems.
A message may traverse many different components and layers in one or more intermediaries when it is propagated from the producer to the consumer(s). To be able to correlate consumer traces with producer traces using the existing context propagation mechanisms, all components must propagate context down the chain.
Messaging systems themselves may trace messages as the messages travels from producers to consumers. Such tracing would cover the transport layer but would not help in correlating producers with consumers. To be able to directly correlate producers with consumers, another context that is propagated with the message is required.
A message creation context allows correlating producers with consumers of a message and model the dependencies between them, regardless of the underlying messaging transport mechanism and its instrumentation.
The message creation context is created by the producer and should be propagated to the consumer(s). Consumer traces cannot be directly correlated with producer traces if the message creation context is not attached and propagated with the message.
A producer SHOULD attach a message creation context to each message. If possible, the message creation context SHOULD be attached in such a way that it cannot be changed by intermediaries.
This document does not specify the exact mechanisms on how the creation context is attached/extracted to/from messages. Future versions of these conventions will give clear recommendations, following industry standards including, but not limited to Trace Context: AMQP protocol and Trace Context: MQTT protocol once those standards reach a stable state.
The span name SHOULD be set to the message destination name and the operation being performed in the following format:
<destination name> <operation name>
The destination name SHOULD only be used for the span name if it is known to be of low cardinality (cf. general span name guidelines).
This can be assumed if it is statically derived from application code or configuration.
Wherever possible, the real destination names after resolving logical or aliased names SHOULD be used.
If the destination name is dynamic, such as a conversation ID or a value obtained from a Reply-To header, it SHOULD NOT be used for the span name.
In these cases, an artificial destination name that best expresses the destination, or a generic, static fallback like "(anonymous)" for anonymous destinations SHOULD be used instead.
The values allowed for <operation name> are defined in the section Operation names below.
If the format above is used, the operation name MUST match the messaging.operation attribute defined for message consumer spans below.
Examples:
shop.orders publishshop.orders receiveshop.orders processprint_jobs publishtopic with spaces processAuthenticationRequest-Conversations process(anonymous) publish((anonymous)being a stable identifier for an unnamed destination)
A producer of a message should set the span kind to PRODUCER unless it synchronously waits for a response: then it should use CLIENT.
The processor of the message should set the kind to CONSUMER, unless it always sends back a reply that is directed to the producer of the message
(as opposed to e.g., a queue on which the producer happens to listen): then it should use SERVER.
The following operations related to messages are defined for these semantic conventions:
| Operation name | Description |
|---|---|
publish |
A message is sent to a destination by a message producer/client. |
receive |
A message is received from a destination by a message consumer/server. |
process |
A message that was previously received from a destination is processed by a message consumer/server. |
| Attribute | Type | Description | Examples | Requirement Level |
|---|---|---|---|---|
messaging.system |
string | A string identifying the messaging system. | kafka; rabbitmq; rocketmq; activemq; AmazonSQS |
Required |
messaging.operation |
string | A string identifying the kind of messaging operation as defined in the Operation names section above. [1] | publish |
Required |
messaging.batch.message_count |
int | The number of messages sent, received, or processed in the scope of the batching operation. [2] | 0; 1; 2 |
Conditionally Required: [3] |
messaging.client_id |
string | A unique identifier for the client that consumes or produces a message. | client-5; myhost@8742@s8083jm |
Recommended: If a client id is available |
messaging.destination.anonymous |
boolean | A boolean that is true if the message destination is anonymous (could be unnamed or have auto-generated name). | Conditionally Required: [4] | |
messaging.destination.name |
string | The message destination name [5] | MyQueue; MyTopic |
Conditionally Required: [6] |
messaging.destination.template |
string | Low cardinality representation of the messaging destination name [7] | /customers/{customerId} |
Conditionally Required: [8] |
messaging.destination.temporary |
boolean | A boolean that is true if the message destination is temporary and might not exist anymore after messages are processed. | Conditionally Required: [9] | |
messaging.message.conversation_id |
string | The conversation ID identifying the conversation to which the message belongs, represented as a string. Sometimes called "Correlation ID". | MyConversationId |
Recommended: [10] |
messaging.message.id |
string | A value used by the messaging system as an identifier for the message, represented as a string. | 452a7c7c7c7048c2f887f61572b18fc2 |
Recommended: [11] |
messaging.message.payload_compressed_size_bytes |
int | The compressed size of the message payload in bytes. | 2048 |
Recommended: [12] |
messaging.message.payload_size_bytes |
int | The (uncompressed) size of the message payload in bytes. Also use this attribute if it is unknown whether the compressed or uncompressed payload size is reported. | 2738 |
Recommended: [13] |
network.protocol.name |
string | OSI Application Layer or non-OSI equivalent. The value SHOULD be normalized to lowercase. | amqp; mqtt |
Recommended |
network.protocol.version |
string | Version of the application layer protocol used. See note below. [14] | 3.1.1 |
Recommended |
network.transport |
string | OSI Transport Layer or Inter-process Communication method. The value SHOULD be normalized to lowercase. | tcp; udp |
Recommended |
network.type |
string | OSI Network Layer or non-OSI equivalent. The value SHOULD be normalized to lowercase. | ipv4; ipv6 |
Recommended |
server.address |
string | Logical server hostname, matches server FQDN if available, and IP or socket address if FQDN is not known. [15] | example.com |
Conditionally Required: If available. |
server.socket.address |
string | Physical server IP address or Unix socket address. If set from the client, should simply use the socket's peer address, and not attempt to find any actual server IP (i.e., if set from client, this may represent some proxy server instead of the logical server). | 10.5.3.2 |
Recommended: If different than server.address. |
server.socket.domain |
string | The domain name of an immediate peer. [16] | proxy.example.com |
Recommended: [17] |
server.socket.port |
int | Physical server port. | 16456 |
Recommended: If different than server.port. |
[1]: If a custom value is used, it MUST be of low cardinality.
[2]: Instrumentations SHOULD NOT set messaging.batch.message_count on spans that operate with a single message. When a messaging client library supports both batch and single-message API for the same operation, instrumentations SHOULD use messaging.batch.message_count for batching APIs and SHOULD NOT use it for single-message APIs.
[3]: If the span describes an operation on a batch of messages.
[4]: If value is true. When missing, the value is assumed to be false.
[5]: Destination name SHOULD uniquely identify a specific queue, topic or other entity within the broker. If the broker does not have such notion, the destination name SHOULD uniquely identify the broker.
[6]: If span describes operation on a single message or if the value applies to all messages in the batch.
[7]: 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]: If available. Instrumentations MUST NOT use messaging.destination.name as template unless low-cardinality of destination name is guaranteed.
[9]: If value is true. When missing, the value is assumed to be false.
[10]: Only if span represents operation on a single message.
[11]: Only for spans that represent an operation on a single message.
[12]: Only if span represents operation on a single message.
[13]: Only if span represents operation on a single message.
[14]: 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 used has a version of 0.27.2, but sends HTTP version 1.1, this attribute should be set to 1.1.
[15]: This should be the IP/hostname of the broker (or other network-level peer) this specific message is sent to/received from.
[16]: Typically observed from the client side, and represents a proxy or other intermediary domain name.
[17]: If different than server.address and if server.socket.address is set.
messaging.operation 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 |
|---|---|
publish |
publish |
receive |
receive |
process |
process |
Additionally server.port from the network attributes is recommended.
Furthermore, it is strongly recommended to add the network.transport attribute and follow its guidelines, especially for in-process queueing systems (like Hangfire, for example).
These attributes should be set to the broker to which the message is sent/from which it is received.
messaging.message: Contains attributes that describe individual messagesmessaging.destination: Contains attributes that describe the logical entity messages are published to and received from. See Destinations for more detailsmessaging.batch: Contains attributes that describe batch operationsmessaging.consumer: Contains attributes that describe application instance that consumes a message. See consumer for more details
Communication with broker is described with general network attributes.
Messaging system-specific attributes MUST be defined in the corresponding messaging.{system} namespace
as described in Attributes specific to certain messaging systems.
The receive span is used to track the time used for receiving the message(s), whereas the process span(s) track the time for processing the message(s).
Note that one or multiple Spans with messaging.operation = process may often be the children of a Span with messaging.operation = receive.
The distinction between receiving and processing of messages is not always of particular interest or sometimes hidden away in a framework (see the Message consumption section above) and therefore the attribute can be left out.
For batch receiving and processing (see the Batch receiving and Batch processing examples below) in particular, the attribute SHOULD be set.
Even though in that case one might think that the processing span's kind should be INTERNAL, that kind MUST NOT be used.
Instead span kind should be set to either CONSUMER or SERVER according to the rules defined above.
All messaging operations (publish, receive, process, or others not covered by this specification) can describe both single and/or batch of messages.
Attributes in the messaging.message or messaging.{system}.message namespace describe individual messages. For single-message operations they SHOULD be set on corresponding span.
For batch operations, per-message attributes are usually different and cannot be set on the corresponding span. In such cases the attributes MAY be set on links. See Batch Receiving and Batch Processing for more information on correlation using links.
Some messaging systems (e.g., Kafka, Azure EventGrid) allow publishing a single batch of messages to different topics. In such cases, the attributes in messaging.destination MAY be
set on links. Instrumentations MAY set destination attributes on the span if all messages in the batch share the same destination.
All attributes that are specific for a messaging system SHOULD be populated in messaging.{system} namespace. Attributes that describe a message, a destination, a consumer, or a batch of messages SHOULD be populated under the corresponding namespace:
messaging.{system}.message.*: Describes attributes for individual messagesmessaging.{system}.destination.*: Describes the destination a message (or a batch) are published to and received from respectively. The combination of attributes in these namespaces should uniquely identify the entity and include properties significant for this messaging system. For example, Kafka instrumentations should include partition identifier.messaging.{system}.consumer.*: Describes message consumer propertiesmessaging.{system}.batch.*: Describes message batch properties
In RabbitMQ, the destination is defined by an exchange and a routing key.
messaging.destination.name MUST be set to the name of the exchange. This will be an empty string if the default exchange is used.
| Attribute | Type | Description | Examples | Requirement Level |
|---|---|---|---|---|
messaging.rabbitmq.destination.routing_key |
string | RabbitMQ message routing key. | myKey |
Conditionally Required: If not empty. |
For Apache Kafka, the following additional attributes are defined:
| Attribute | Type | Description | Examples | Requirement Level |
|---|---|---|---|---|
messaging.kafka.message.key |
string | Message keys in Kafka are used for grouping alike messages to ensure they're processed on the same partition. They differ from messaging.message.id in that they're not unique. If the key is null, the attribute MUST NOT be set. [1] |
myKey |
Recommended |
messaging.kafka.consumer.group |
string | Name of the Kafka Consumer Group that is handling the message. Only applies to consumers, not producers. | my-group |
Recommended |
messaging.kafka.destination.partition |
int | Partition the message is sent to. | 2 |
Recommended |
messaging.kafka.message.offset |
int | The offset of a record in the corresponding Kafka partition. | 42 |
Recommended |
messaging.kafka.message.tombstone |
boolean | A boolean that is true if the message is a tombstone. | Conditionally Required: [2] |
[1]: If the key type is not string, it's string representation has to be supplied for the attribute. If the key has no unambiguous, canonical string form, don't include its value.
[2]: If value is true. When missing, the value is assumed to be false.
For Apache Kafka producers, peer.service SHOULD be set to the name of the broker or service the message will be sent to.
The service.name of a Consumer's Resource SHOULD match the peer.service of the Producer, when the message is directly passed to another service.
If an intermediary broker is present, service.name and peer.service will not be the same.
messaging.client_id SHOULD be set to the client-id of consumers, or to the client.id property of producers.
Specific attributes for Apache RocketMQ are defined below.
| Attribute | Type | Description | Examples | Requirement Level |
|---|---|---|---|---|
messaging.rocketmq.namespace |
string | Namespace of RocketMQ resources, resources in different namespaces are individual. | myNamespace |
Required |
messaging.rocketmq.client_group |
string | Name of the RocketMQ producer/consumer group that is handling the message. The client type is identified by the SpanKind. | myConsumerGroup |
Required |
messaging.rocketmq.message.delivery_timestamp |
int | The timestamp in milliseconds that the delay message is expected to be delivered to consumer. | 1665987217045 |
Conditionally Required: [1] |
messaging.rocketmq.message.delay_time_level |
int | The delay time level for delay message, which determines the message delay time. | 3 |
Conditionally Required: [2] |
messaging.rocketmq.message.group |
string | It is essential for FIFO message. Messages that belong to the same message group are always processed one by one within the same consumer group. | myMessageGroup |
Conditionally Required: If the message type is FIFO. |
messaging.rocketmq.message.type |
string | Type of message. | normal |
Recommended |
messaging.rocketmq.message.tag |
string | The secondary classifier of message besides topic. | tagA |
Recommended |
messaging.rocketmq.message.keys |
string[] | Key(s) of message, another way to mark message besides message id. | [keyA, keyB] |
Recommended |
messaging.rocketmq.consumption_model |
string | Model of message consumption. This only applies to consumer spans. | clustering |
Recommended |
[1]: If the message type is delay and delay time level is not specified.
[2]: If the message type is delay and delivery timestamp is not specified.
messaging.rocketmq.message.type MUST be one of the following:
| Value | Description |
|---|---|
normal |
Normal message |
fifo |
FIFO message |
delay |
Delay message |
transaction |
Transaction message |
messaging.rocketmq.consumption_model MUST be one of the following:
| Value | Description |
|---|---|
clustering |
Clustering consumption model |
broadcasting |
Broadcasting consumption model |
messaging.client_id SHOULD be set to the client ID that is automatically generated by the Apache RocketMQ SDK.
Given is a process P, that publishes a message to a topic T on messaging system MS, and two processes CA and CB, which both receive the message and process it.
Process P: | Span Prod1 |
--
Process CA: | Span CA1 |
--
Process CB: | Span CB1 |
| Field or Attribute | Span Prod1 | Span CA1 | Span CB1 |
|---|---|---|---|
| Span name | "T publish" |
"T process" |
"T process" |
| Parent | Span Prod1 | Span Prod1 | |
| Links | |||
| SpanKind | PRODUCER |
CONSUMER |
CONSUMER |
| Status | Ok |
Ok |
Ok |
server.address |
"ms" |
"ms" |
"ms" |
server.port |
1234 |
1234 |
1234 |
messaging.system |
"rabbitmq" |
"rabbitmq" |
"rabbitmq" |
messaging.destination.name |
"T" |
"T" |
"T" |
messaging.operation |
"process" |
"process" |
|
messaging.message.id |
"a1" |
"a1" |
"a1" |
Given is a process P, that publishes a message to a topic T1 on Apache Kafka. One process, CA, receives the message and publishes a new message to a topic T2 that is then received and processed by CB.
Frameworks such as Quarkus and Spring Boot separate processing of a received message from producing subsequent messages out.
For this reason, receiving (Span Rcv1) is the parent of both processing (Span Proc1) and producing a new message (Span Prod2).
The span representing message receiving (Span Rcv1) should not set messaging.operation to receive,
as it does not only receive the message but also converts the input message to something suitable for the processing operation to consume and creates the output message from the result of processing.
Process P: | Span Prod1 |
--
Process CA: | Span Rcv1 |
| Span Proc1 |
| Span Prod2 |
--
Process CB: | Span Rcv2 |
| Field or Attribute | Span Prod1 | Span Rcv1 | Span Proc1 | Span Prod2 | Span Rcv2 |
|---|---|---|---|---|---|
| Span name | "T1 publish" |
"T1 receive" |
"T1 process" |
"T2 publish" |
"T2 receive" |
| Parent | Span Prod1 | Span Rcv1 | Span Rcv1 | Span Prod2 | |
| Links | |||||
| SpanKind | PRODUCER |
CONSUMER |
CONSUMER |
PRODUCER |
CONSUMER |
| Status | Ok |
Ok |
Ok |
Ok |
Ok |
peer.service |
"myKafka" |
"myKafka" |
|||
service.name |
"myConsumer1" |
"myConsumer1" |
"myConsumer2" |
||
messaging.system |
"kafka" |
"kafka" |
"kafka" |
"kafka" |
"kafka" |
messaging.destination.name |
"T1" |
"T1" |
"T1" |
"T2" |
"T2" |
messaging.operation |
"process" |
"receive" |
|||
messaging.client_id |
"5" |
"5" |
"5" |
"8" |
|
messaging.kafka.message.key |
"myKey" |
"myKey" |
"myKey" |
"anotherKey" |
"anotherKey" |
messaging.kafka.consumer.group |
"my-group" |
"my-group" |
"another-group" |
||
messaging.kafka.partition |
"1" |
"1" |
"1" |
"3" |
"3" |
messaging.kafka.message.offset |
"12" |
"12" |
"12" |
"32" |
"32" |
Given is a process P, that publishes two messages to a queue Q on messaging system MS, and a process C, which receives both of them in one batch (Span Recv1) and processes each message separately (Spans Proc1 and Proc2).
Since a span can only have one parent and the propagated trace and span IDs are not known when the receiving span is started, the receiving span will have no parent and the processing spans are correlated with the producing spans using links.
Process P: | Span Prod1 | Span Prod2 |
--
Process C: | Span Recv1 |
| Span Proc1 |
| Span Proc2 |
| Field or Attribute | Span Prod1 | Span Prod2 | Span Recv1 | Span Proc1 | Span Proc2 |
|---|---|---|---|---|---|
| Span name | "Q publish" |
"Q publish" |
"Q receive" |
"Q process" |
"Q process" |
| Parent | Span Recv1 | Span Recv1 | |||
| Links | Span Prod1 | Span Prod2 | |||
| SpanKind | PRODUCER |
PRODUCER |
CONSUMER |
CONSUMER |
CONSUMER |
| Status | Ok |
Ok |
Ok |
Ok |
Ok |
server.address |
"ms" |
"ms" |
"ms" |
"ms" |
"ms" |
server.port |
1234 |
1234 |
1234 |
1234 |
1234 |
messaging.system |
"rabbitmq" |
"rabbitmq" |
"rabbitmq" |
"rabbitmq" |
"rabbitmq" |
messaging.destination.name |
"Q" |
"Q" |
"Q" |
"Q" |
"Q" |
messaging.operation |
"receive" |
"process" |
"process" |
||
messaging.message.id |
"a1" |
"a2" |
"a1" |
"a2" |
|
messaging.batch.message_count |
2 |
Given is a process P, that publishes two messages to a queue Q on messaging system MS, and a process C, which receives them separately in two different operations (Span Recv1 and Recv2) and processes both messages in one batch (Span Proc1).
Since each span can only have one parent, C3 should not choose a random parent out of C1 and C2, but rather rely on the implicitly selected parent as defined by the tracing API spec. Depending on the implementation, the producing spans might still be available in the meta data of the messages and should be added to C3 as links. The client library or application could also add the receiver span's SpanContext to the data structure it returns for each message. In this case, C3 could also add links to the receiver spans C1 and C2.
The status of the batch processing span is selected by the application. Depending on the semantics of the operation. A span status Ok could, for example, be set only if all messages or if just at least one were properly processed.
Process P: | Span Prod1 | Span Prod2 |
--
Process C: | Span Recv1 | Span Recv2 |
| Span Proc1 |
| Field or Attribute | Span Prod1 | Span Prod2 | Span Recv1 | Span Recv2 | Span Proc1 |
|---|---|---|---|---|---|
| Span name | "Q publish" |
"Q publish" |
"Q receive" |
"Q receive" |
"Q process" |
| Parent | Span Prod1 | Span Prod2 | |||
| Links | [Span Prod1, Span Prod2 ] | ||||
| Link attributes | Span Prod1: messaging.message.id: "a1" |
||||
Span Prod2: messaging.message.id: "a2" |
|||||
| SpanKind | PRODUCER |
PRODUCER |
CONSUMER |
CONSUMER |
CONSUMER |
| Status | Ok |
Ok |
Ok |
Ok |
Ok |
server.address |
"ms" |
"ms" |
"ms" |
"ms" |
"ms" |
server.port |
1234 |
1234 |
1234 |
1234 |
1234 |
messaging.system |
"rabbitmq" |
"rabbitmq" |
"rabbitmq" |
"rabbitmq" |
"rabbitmq" |
messaging.destination.name |
"Q" |
"Q" |
"Q" |
"Q" |
"Q" |
messaging.operation |
"receive" |
"receive" |
"process" |
||
messaging.message.id |
"a1" |
"a2" |
"a1" |
"a2" |
|
messaging.batch.message_count |
1 | 1 | 2 |