How to add open telemetry traces

[RichardWright]

Has anyone ever made a suggestion on how to add spans/traces to an rxjs observable? Specifically on something like receiving data from a websocket?

[abarke]

You can create a new serialize and deserialize methods to intercept all messages before/after they are received/transmitted.

The functions can be set in the WebSocketSubjectConfig

[RichardWright]

an id would allow for a central place to store the actual span/tracer. It could equally be the actual span.

I feel like i'm asking the wrong questions and this has already been solved in rxjs somewhere else.

[scvnc]

I was thinking about the { tracer: {spanId}, data: dataToReturn } pattern too. In typescript it could be handled like a

type Envelope<T> {
  data: T,
  _span: Span
}

Might be a way to build a toolset of RxJS operators that notice such an Envelope signature and create a child span off of it.

const {startSpan, finalizeSpan} =  createRxJsTracer()

someEvent$.pipe(
  startTrace('some-interesting-service-call'),
  // do some remote call
  switchMap((envelope) => ajax('/some/api', data: { id: envelope.data.id }),
  finalizeSpan, // handles on stream errors too
)

but still figuring it out.

let me know if you'd like to collaborate on this in further detail. I am curious to build/find some tooling/patterns to bolt in tracing/spans into a rxjs heavy SPA UI.

[RichardWright]

I'd love to work on this. I was mostly battling my current type system, would love to be able to explore the problem with someone similarly motivated.

[RichardWright]

@scvnc

[scvnc]

Hi @RichardWright

Since I was last here, I've been experimenting working on an Rxjs OperatorFn that uses a javascript mixin behind the scenes. Allows a span to be created/completed/error-handled when something subscribes and data flows through.

Everyones use case may be different, but so far this is working for me... gotta figure out nested spans.. E.g. that doHttpCall might also create a span.

   id$.pipe(
       withSpan('span-name', optionsObj, _id$ =>
           _id$.pipe(
               // Do work in this composition and it will be tracked in the context of this span
               switchMap((id) => doHttpCall(id)),
               map(transformResult)
           )
       ),
      someWorkOutsideOfSpan()
   );