Implement ScopeManager

[sebnow]

Requirement - what kind of business use case are you trying to solve?

Support in-context propagation of the active span, to make span management easier.

Problem - what in Jaeger blocks you from solving the requirement?

From the RFC:

For platforms where the call-context is explicitly propagated down the execution chain -such as Go-, such context can be used to store the active Span at all times.

For platforms not propagating the call-context, it's inconvenient to pass the active Span from function to function manually, so OpenTracing should require, for those platforms, that Tracer contains a Scope Manager that grants access to the active Span through a container, called Scope (using some call-context storage, such as thread-local or coroutine-local).

Proposal - what do you suggest to solve the problem or improve the existing situation?

Implement the ScopeManager RFC

[yurishkuro]

afaik the ScopeManager is not yet defined in OpenTracing Javascript, so we can't start it here.

[yurishkuro]

I see you opened the OT issue: opentracing/opentracing-javascript#112. It needs to be addressed first before we can do something here.