Add session.previous_id

[breedx-splk]

Changes

Introduces a convention to represent the previous session id for client instrumentation. This can be used by telemetry backends to create links from the old/expired session to the new one.

Existing art exists in Android via the SessionIdChangeTracer.

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• CHANGELOG.md updated for non-trivial changes.
• schema-next.yaml updated with changes to existing conventions.

[AlexanderWert]

I think I get the idea of this proposal. But I think it would help if we had mobile- or client-specific semantic conventions that would describe how these attributes are intended to be used. I think it's clear for session.id (i.e. it would be just an attribute that's being added to all mobile/client signals/events, except for metrics due to cardinality).

But, what about session.previous_id? Would that be set on every signal/event as well (e.g. every mobile span would always have session.id and session.previous_id)? Or, is the intention rather to send a specific event that would indicate a "session transition" from old session to new session that would contain those two attributes?

I think documenting this reasoning as mobile semantic conventions would be great!

[breedx-splk]

But, what about session.previous_id? Would that be set on every signal/event as well (e.g. every mobile span would always have session.id and session.previous_id)? Or, is the intention rather to send a specific event that would indicate a "session transition" from old session to new session that would contain those two attributes?

Yeah, I linked to the tracer in android to demonstrate, but yeah, the idea is to send a session change event. I can add some text in this same file to give more of an explanation of intent. Is this the right place for that, or, because it's behavioral does it belong in the spec repo?

[AlexanderWert]

Yeah, I linked to the tracer in android to demonstrate, but yeah, the idea is to send a session change event. I can add some text in this same file to give more of an explanation of intent. Is this the right place for that, or, because it's behavioral does it belong in the spec repo?

I think a new area of semantic conventions under /docs/mobile/ would make sense (in addition to this PR, where just the session is being defined). In /docs/mobile/ we then can describe all the mobile-specific conventions such as types of mobile spans and their attributes to capture, description of mobile events to send, etc.

With #197 the definition of the session attributes would go into the registry anyways and the mobile semantic conventions would just reference it.

[AlexanderWert]

@open-telemetry/semconv-mobile-approvers Can we get more reviews on this one please?

[breedx-splk]

Hi @open-telemetry/specs-semconv-maintainers -- we have 4 approvals on this. Any reason to hold this up? 🙏🏻