feat: Remove unnecessary dataset id references

[jimmarino]

This PR removes unnecessary use of the dsp:dataset attribute from the ContractOfferMessage and ContractRequestMessage but leaves it in the CatalogRequestMessage. For the former messages, the ODRL policy target attribute is used and the restriction to not allow that attribute in policies has been removed.

A new restriction is introduced to not allow target attributes on policy constraints as it does not make sense in our context but is permitted in ODRL.

Related Issues

Closes #192

[matgnt]

To my understanding this would introduce a redundant dataset id in the catalog, correct? 1 in the dataset itself and 1 in the enclosed offer->target

[ndr-brt]

To my understanding this would introduce a redundant dataset id in the catalog, correct? 1 in the dataset itself and 1 in the enclosed offer->target

yes, but that will avoid additional fields in the messages to specify the dataset: the offer will be self-contained and already able to tell to what dataset it's referring to. Same will be with the agreement.

Furthermore, not putting the target in the policy will be a violation of:

• A Permission MUST have one target property value of type Asset. (Other relation sub-properties MAY be used.)
• A Prohibition MUST have one target property value of type Asset. (Other relation sub-properties MAY be used.)

defining target at a root level is a way to tell "every rule has this target": https://www.w3.org/TR/odrl-model/#composition-compact

[jimmarino]

To my understanding this would introduce a redundant dataset id in the catalog, correct? 1 in the dataset itself and 1 in the enclosed offer->target

It would remove the redundant dataset property in the ContractOfferMessage and ContractRequestMessage. It would add the target attribute back to an Offer which must match the enclosing dataset id. This would make the Offer symmetrical with other policies. However, it would still allow referencing policies by URI and adding a target (so the referenced policy can be used generically):

"hasPolicy": {
   "@type": "Policy",
   "@id": "https://test.com/some-policy.json",
   "target": "datasetid"
}

[jimmarino]

Also the https://github.com/International-Data-Spaces-Association/ids-specification/blob/main/model/model.md file needs to be updated

I don't see where it needs to be updated beyond the changes I made in the PR. Did I miss something?

[ndr-brt]

Also the https://github.com/International-Data-Spaces-Association/ids-specification/blob/main/model/model.md file needs to be updated

I don't see where it needs to be updated beyond the changes I made in the PR. Did I miss something?

https://github.com/International-Data-Spaces-Association/ids-specification/blob/main/model/model.md?plain=1#L70

[jimmarino]

Also the https://github.com/International-Data-Spaces-Association/ids-specification/blob/main/model/model.md file needs to be updated

I don't see where it needs to be updated beyond the changes I made in the PR. Did I miss something?

https://github.com/International-Data-Spaces-Association/ids-specification/blob/main/model/model.md?plain=1#L70

Isn't that changed in the PR?

https://github.com/International-Data-Spaces-Association/ids-specification/pull/193/files#diff-759257c54564e8398e104d8ac97c57863a742dd341e12a45a9e8e492475b7398

[ndr-brt]

oh right, I overlooked that, sorry

[matgnt]

Please do not merge yet. We need to discuss this further, e.g. my comment in the original issu: https://github.com/International-Data-Spaces-Association/ids-specification/issues/192#issuecomment-1885135591

[ssteinbuss]

@jimmarino please revise/ turn back to old status as discussed