Implement dataSink and dataSource API.

[csadorf]

Implements all dataSink and dataSource-related operations in compliance with the OpenStack Swift object storage API on the container level. That means the operations for creating, replacing, and deleting datasets (objects) are in compliance with the API specified by Swift and it is assumed that one dataSink/dataSource is equivalent to a object storage container.

[csadorf]

@yoavnash @pablo-de-andres This is my proposal for the dataSink and dataSource API. It is based on the OpenStack SWIFT API which is largely compatible with S3 for core functions. I only specified operations for the purpose of MarketPlace that appeared most important to me.

Finally, you may notice that some functions have "optional path parameters". To my knowledge neither FastAPI nor Flask support optional path parameters since they conceptually represent different endpoints. However, you can associate
multiple endpoints with one response handler function – which I did. In that case the corresponding function parameter must be optional which FastAPI picks up and then annoyingly represents as an optional query parameter for the endpoint without path parameter. I think that's a tolerable nuisance for the sake of implementational simplicity. I primarily wanted to alert you of that, but please feel free to disagree with my assessment.

[yoavnash]

In addition to the above, it seems that capabilities for querying (queryDataset, queryCollection) are also planned to be dropped. I wonder how much they are needed.

[csadorf]

In addition to the above, it seems that capabilities for querying (queryDataset, queryCollection) are also planned to be dropped. I wonder how much they are needed.

I don't plan to drop anything. I am just introducing the objectStorage API here. Capabilities for querying can be added later.

[csadorf]

@yoavnash @pablo-de-andres As discussed, I will implement the container-level API. After I'm done I will re-request your review.

[csadorf]

@yoavnash @pablo-de-andres Ready for another review iteration.

[yoavnash]

Sorry for the delay. I think that looks very good.