Documentation does not state how to create long running spans

### Type of issue

Missing information

### Description

The documentation does not state any possibility to start long-running `Activity` for a (very) long-running, asynchronous task. Example: An API starts an operation / distributed trace, but this operation requires user feedback. I.e. a mail is sent to a user, and the user - at a later time - clicks on a link. This link comes back to the API to finish the activity.

How can the API start the Activity, but not end it when the initial API call is finished and the Activity instance is disposed? Because the actual Activity (approval process) that is still running / waiting. What does the code need to do, to recreate the activity object for the very same activity when the user clicked the link, to `.Stop()` the actual activity then?

### Page URL

https://learn.microsoft.com/en-us/dotnet/core/diagnostics/distributed-tracing-concepts

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/core/diagnostics/distributed-tracing-concepts.md

### Document Version Independent Id

f3c7815e-7bd4-19ef-72c8-0a12dd2622c6

### Article author

@tommcdon

### Metadata

* ID: f172877e-feb4-cd62-3179-9335db8d70bd
* Service: **dotnet-fundamentals**