Status: Experimental
In OpenTelemetry spans can be created freely and it’s up to the implementor to annotate them with attributes specific to the represented operation. Spans represent specific operations in and between systems. Some of these operations represent calls that use well-known protocols like HTTP or database calls. Depending on the protocol and the type of operation, additional information is needed to represent and analyze a span correctly in monitoring systems. It is also important to unify how this attribution is made in different languages. This way, the operator will not need to learn specifics of a language and telemetry collected from polyglot (multi-language) micro-service environments can still be easily correlated and cross-analyzed.
The following semantic conventions for spans are defined:
- General: General semantic attributes that may be used in describing different kinds of operations.
- HTTP: Spans for HTTP client and server.
- Database: Spans for SQL and NoSQL client calls.
- RPC/RMI: Spans for remote procedure calls (e.g., gRPC).
- Messaging: Spans for interaction with messaging systems (queues, publish/subscribe, etc.).
- FaaS: Spans for Function as a Service (e.g., AWS Lambda).
- Exceptions: Attributes for recording exceptions associated with a span
Apart from semantic conventions for traces and metrics, OpenTelemetry also defines the concept of overarching Resources with their own Resource Semantic Conventions.