[AIP-151] Long-running operations

[aip-dev]

[AIP-151] Long-running operations

[lukesneeringer]

Documenting a conversation so it is not lost:

Is there a convention for how to set response for LRO?
Specifically, if the LRO is done:

1. If successful, do we still set metadata?
2. How about cancelled? do we set metadata in this case?

We currently always set metadata, but we don't know if this is the correct way to do it.
My concern is that there are always duplicate information in metadata and response.
Thanks.

Are you saying that the LRO might return immediately? If you return immediately for either an immediately completed or cancelled LRO, it should be marked as done and have the response (or error) included.

The metadata could be included if it has relevant information (maybe metadata stores CPU-hours consumed for billing purposes, or perhaps the cancelled one has a progress indicator of how many items were inspected before the cancellation happened), but if there's nothing relevant, it need not be included.

@lukesneeringer: Can we add this to the AIP for LROs ?