Creating a follows_from reference

I’m trying to write an implementation, but I’m not sure how to go about implementing follows_from.

It looks like this isn’t implemented in startSpan() in tracer.js.

I’ve had a read through the git history and it looks like this may have been implemented at some point.

Can someone show how this should be done in an implementation, as well as an example of how to use it in practice.

I would expect it to work like this, based on how childOf works.

const parentSpan = tracer.startSpan('parentOperation');
const childSpan = tracer.startSpan('childOperation', { followsFrom: parentSpan });

Thanks!

[yurishkuro]

Are you asking as a user of the API or as the implementor of the tracer? For the latter what you have above makes sense, but it’s not part of the official API which only defines fields.childOf, not fields.followsFrom. As a user of the API, you would need to do

tracer.startSpan("operation name", {
    references: [opentracing.followsFrom(parentContext)]
})

[yurishkuro]

https://github.com/opentracing/opentracing-javascript/pull/62

cc @ojkelly @bhs