[BUG] EH SDK: Enqueued Time on root activity, not on the links

[Dmitry-Matveev]

Describe the bug
This recent PR has added attribute "x-opt-enqueued-time" to the Diagnostic Scope activity.
While debugging this new behavior with new version of Application Insights SDK that reads this attribute, I noticed that there is disconnect between the two SDKs on the expected attribute location:

• AI SDK looks through the links of the Activity in Diagnostic Source event;
• EH SDK stores that time in the tags of the main Activity instead.

Side note: AI SDK reads "enqueueTime" attribute while value is posted to "x-opt-enqueued-time" attribute, one of the SDKs would need to fix that too (I guess, AI?).

Expected behavior
I had a conversation with original developer on AI SDK side and the expected behavior seem to be to store enqueued time in the links of the activity because it's the way to post that time for each separate message. (+ Both SDKs should agree on the attribute name :) )

Actual behavior (include Exception or Stack Trace)
EH SDK stores enqueued time on the main Activity propagated with DS event.

To Reproduce

• Debug LineCounter application (make sure both projects are marked as startup).
• Ensure latest AI SDK is installed (or build from local source)
• Ensure latest EH SDK is installed (or build from local source)
• Set BP on AI reading EH DS event, check that root Activity has tag, not linked activities.

Environment:

• Latest master from source, EH SDK, commit 257703e.
• Win10, .NET Core 3.0
• Visual Studio 16.4.5

[Dmitry-Matveev]

@kinelski , not sure what's the right approach here, I touched base with @lmolkova and her expectation was to have enqueued time on links rather than main activity. I do lack context of the feature, though, I simply debugged the behavior to help one of the internal teams who tried this new feature out - let me know what you think.

[lmolkova]

Here is the spec https://gist.github.com/lmolkova/e4215c0f44a49ef824983382762e6b92#processing-messages

I confirm that each linked activity should have enqueued time in case there is more than one message in the batch.

[kinelski]

Hello, @Dmitry-Matveev. That was definitely a mistake on my part. Thanks for pointing it out!

I have just opened a PR that will allow us to add attributes to linked activities (#10368). Once that's merged, I'll get the Event Hubs SDK fixed.