How to map EDC to IDS within an extension?

[carlos-schmidt]

Hello,
from an extension point of view:

• How do I map/transform EDC assets and contracts onto the IDS Infomodel (Resource, Artifact, Contract, ...)?

• In the folder /data-protocols/ids/ids-transform-v1 there are various of these transformers. How can/should they be used inside of an extension?

Thanks in advance

[juliapampus]

Hi @carlos-schmidt!

Please take a look at e.g. org.eclipse.dataspaceconnector.ids.api.multipart.dispatcher.sender.MultipartContractAgreementSender lines 99-103. You can use the transformer by handing over the object that should be transformed, and the class of the resulting object.

var transformationResult = getTransformerRegistry().transform(contractAgreement, ContractAgreement.class);
if (transformationResult.failed()) {
    throw new EdcException("Failed to create IDS contract agreement");
}

The right transformer will be automatically detected by input and output type. You can add own transformers by implementing IdsTypeTransformer and adding the new class to the list in IdsTransformServiceExtension. We currently provide some tranformers for converting IDS objects to EDC objects and vice versa. There, you can also find e.g. asset to IDS resource/representation/artifact and IDS resource/representation/artifact to asset.

[juliapampus]

In the initialize method of your extensions class, you need to create the TransformerRegistry and add in to the context. See an example in e.g. org.eclipse.dataspaceconnector.ids.core.IdsCoreServiceExtension.

[carlos-schmidt]

Hello,

thanks for the answer!
In org.eclipse.dataspaceconnector.ids.api.multipart.handler.description.ArtifactDescriptionRequestHandler, an Artifact is being fetched from the AssetIndex, and later transformed to an artifact.
This means, the requestor must know which (asset) ID belongs to what kind of IDS object type, right?

[DominikPinsel]

To make it easier to see whether an object belongs to the edc or ids domain I will add a prefix in this comment. There is no meaning beyond this.

This means, the requestor must know which (asset) ID belongs to what kind of IDS object type, right?

In case of the IDS transformation the edc:Asset is always transformed into a triplet of 1x ids:Resource, 1x ids:Representation and 1x ids:Artifact. Therefore, it is not necessary to know the asset ID to transform it into the correct ids object

How do I map/transform EDC assets and contracts onto the IDS Infomodel (Resource, Artifact, Contract, ...)?

The edc / ids mapping of contracts is probably a little bit more complicated. I will try to showcase it here using the contract offer generation. (Maybe I don't get the relationship between all the classes 100% right.)

Contract Offer Generation:

The edc:ContractOffer are generated on the fly and not persisted anywhere. When the connector is asked about its ids:ContractOffers it checks the edc:ContractDefinitions, that contain the contract details and a AssetSelectorExpression. The AssetSelectorExpression can be used to query the AssetIndex for all the edc:Assets, the edc:ContractOffer should be generated for. For each edc:Asset a new edc:ContractOffer is created. The creation of edc:ContractOffers is be done by the ContractOfferService.
The edc:ContractOffer are then converted to ids:ContractOffer using the TransformerRegistry.