How to understand Opentracing ? about opentracing-java

[yurishkuro]

If you use OpenTracing, it's always two spans. Whether they have unique span IDs or share the same (as Zipkin does) is the implementation detail of the tracer.

[tomgithub2016]

@yurishkuro ,
Ok I understand;

Service A will build span1  and  inject to request header send to the ServiceB.
ServiceB will extract request header ,and build span2

```My question is:
 span2 must be the asChildOf span1?   I do not think so. 

[yurishkuro]

yes, you would start span2 with

spanCtx = tracer.extract(...)
span2 := tracer.start_span("endpoint name", child_of=spanCtx)

If you don't do that, span2 will have a completely different trace ID.

[bhs]

(closing since this isn't really an OT-Java issue... @tomgithub2016 please reopen against the opentracing/specification repo if you think additional clarification is needed)