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Release: CX-Saturn (Preview)

CX-0018 Dataspace Connectivity v.4.0.0

ABSTRACT​

This document specifies the communication requirements for data exchange between participants in the Catena-X data ecosystem. The aim is to ensure interoperability and data sovereignty at the same time.

COMPARISON WITH THE PREVIOUS VERSION OF THE STANDARD​

  • Update to DSP version 2025-1 and DCP version 1.0
  • Switch identifier in DSP communication from BPN to DID
  • Add management domain concepts and introducing the reference in the DID document
  • Add protocol version handling
  • Add section on backward compatibility

1 INTRODUCTION​

1.1 AUDIENCE & SCOPE​

This section is non-normative

AUDIENCE​

The role definition is based on the definition of the CX Operating Model.

The standard is relevant for the following roles, as they must be certified against it:

  • Core Service Provider (A/B)
  • Enablement Service Provider
  • Business Application Provider
  • Data Provider/Consumer

Note: The normative section of this standard uses the DSP-definitions of "Consumer" and "Provider". Any of the aforementioned Catena-X-roles can assume either DSP-role.

The standard is relevant for the following role, as they must certify against this standard:

  • Conformity Assessment Body

The standard is relevant for the following role, as they carry out their advisory on the basis of this standard.

  • Advisory Provider

SCOPE​

This document covers the requirements for dataspace connectivity. It describes

  • how communication between dataspace participants must take place,
  • which transfer type profiles have to be supported by any Provider or Consumer,
  • how communication with credential services must take place,
  • which conventions apply with regard to policy constraints,
  • and which conventions apply to datasets.

1.2 CONTEXT AND ARCHITECTURE FIT​

This section is non-normative

The connector is the main technical component that implements dataspace connectivity including data sovereignty and interorganizational interoperability. It is part of the enablement services, which are intended to enable participation in the Catena-X ecosystem.

The following figure shows how the connector fits into the overall framework of Catena-X to exchange data.

Framework of data exchange

Figure 1: Framework of data exchange

1.3 CONFORMANCE AND PROOF OF CONFORMITY​

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words MAY, MUST, MUST NOT, OPTIONAL, RECOMMENDED, REQUIRED, SHOULD and SHOULD NOT in this document are to be interpreted as described in BCP 14 RFC2119, RFC8174 when, and only when, they appear in all capitals, as shown here.

1.4 TERMINOLOGY​

TermDescriptionReference
International Data Spaces Association (IDSA)Organisation that provides standards and architecture solutions for secure, sovereign data sharing within so-called dataspaceshttps://internationaldataspaces.org
Eclipse Dataspace Working Group (EDWG)Eclipse Foundation Working Group that develops and maintains specifications for the data exchange within a dataspacehttps://dataspace.eclipse.org
Dataspace Protocol (DSP)Protocol specification, designed to facilitate interoperable data sharing within a dataspace, currently governed by the EDWGhttps://github.com/eclipse-dataspace-protocol-base/DataspaceProtocol
Decentralized Claims Protocol (DCP)Protocol specification for the exchange of verifiable credentials and presentations between a connector and a wallet as well as the issuance of such credentials by an identity providerhttps://github.com/eclipse-dataspace-dcp/decentralized-claims-protocol
Connector(Catena-X) Technical component that allows business applications to interact with each other within a dataspacehttps://github.com/eclipse-tractusx/tractusx-edc
(Catena-X) Business Applications(Catena-X) Applications that enable functionality of different use cases, hosted by a data provider or consumer itself or by a business application providerhttps://eclipse-tractusx.github.io/developer
Catena-X MarketplaceThe Marketplace inside a portal, allowing participants of the Catena-X network to search and select Catena-X Business Applicationshttps://catena-x.net/en/offers/portal-marketplace
Data Catalog Vocabulary (DCAT)RDF vocabulary designed to facilitate interoperability between data catalogs published on the Webhttps://www.w3.org/TR/vocab-dcat-3
Open Data Rights Language (ODRL)Policy expression language that provides a flexible and interoperable information model, vocabulary, and encoding mechanisms for representing statements about the usage of content and serviceshttps://www.w3.org/TR/odrl-model, https://www.w3.org/TR/odrl-vocab, https://w3c.github.io/odrl/bp
  • The terms Connector, Provider, Participant Agent are adopted from the DSP.
  • The term Credential Service is adopted from the DCP.
  • The terms Core Service Provider A/B (CSP A/B), Onboarding Service Provider (OSP), Enablement Service Provider ( ESP), Business Application Provider (BAP), Advisory Provider (AP) and Conformity Assessment Body (CAB) are adopted from the CX Operating Model

2 MAIN CONTENT​

This section is normative

This section uses the following prefixes as abbreviations for namespaces

  • "dct": "http://purl.org/dc/terms/"
  • "dspace": "https://w3id.org/dspace/2024/1/"
  • "odrl": "https://www.w3.org/ns/odrl/2/"
  • "dcat": "http://www.w3.org/ns/dcat#"
  • "cx-common": "https://w3id.org/catenax/ontology/common#"

2.1 Communication between Dataspace Participants​

Dataspace Participants exchange data via their Participant Agents. They are a logical component that communicates via a set of well-defined messages.

Participant Agents MUST facilitate data exchange according to the HTTPS binding defined in the Dataspace Protocol.

Providers and Consumer MUST expose the specified endpoints for the

  • Catalog Protocol
  • Contract Negotiation Protocol
  • Transfer Process Protocol
  • Version Metadata

as specified in the HTTPS binding of the Dataspace Protocol.

2.1.1 Usage of DID in the data exchange​

A Participant Agent MUST use the DID in all protocol message properties that identify a Participant. This includes properties such as dspace:participantId in the Catalog response message, odrl:assigner and odrl:assignee in the dspace:ContractAgreementMessage.

2.2 Transfer Type Profiles​

In their dcat:Catalog response to a dspace:CatalogRequestMessage, for each Dataset, a Provider MUST return a dcat:Distribution signifying what Transfer Profile a Consumer can use to obtain data.

Providers MUST be able to serve data according to that signal when data transfer is requested by a consumer via a dspace:TransferRequestMessage.

Despite the IRIs dspace:HttpData-PULL and dspace:AmazonS3-PUSH are not yet included in the DSP-context, they will be used as preliminary identifiers.

Providers MUST offer at least one Transfer Type Profile. The remainder of this section provides regulations for a non-exhaustive selection of Transfer Type Profiles. Further profiles can be defined by consecutive standards.

2.2.1 HttpData-PULL​

A Consumer MUST send a dspace:TransferRequestMessage with "dct:format":"HttpData-PULL". A Provider is not required to process the dspace:dataAddress property.

A Provider MUST send a dspace:TransferStartMessage with sufficient information in the dspace:dataAddress property so that an HTTP request to the dspace:endpoint may succeed. The dspace:endpointType property MUST be https://w3id.org/idsa/v4.1/HTTP. The following endpointProperties are to be added to the object as specified in the table below:

Namedescription
https://w3id.org/edc/v0.0.1/ns/authorizationREQUIREDThe access token to access data. To be included in the Authorization header.
https://w3id.org/edc/v0.0.1/ns/authTypeREQUIREDPrefix for the Authorization header's content.
https://w3id.org/tractusx/auth/refreshEndpointOPTIONALEndpoint to refresh the access token using the refreshToken. It behaves as defined in RFC6749 section 6 using an STS-token for authentication.
https://w3id.org/tractusx/auth/refreshTokenOPTIONALThe refresh token to present to the refreshEndpoint in conjunction with the old access token.
https://w3id.org/tractusx/auth/expiresInREQUIREDTime to live for the access token after issuance.

A Provider Connector MUST ensure that the requested backend system has sufficient context from the negotiation to evaluate the legitimacy of the request.

A Consumer may then use the provided data to execute requests against the endpoint.

Despite the token, the endpoint still has the right to refuse serving a request. This may occur for instance when a consumer attempts to PUT against a resource but is only allowed to GET.

2.2.2 AmazonS3-PUSH​

A Consumer MUST send a dspace:TransferRequestMessage with dct:format:AmazonS3-PUSH and dspace:dataAddress property so that triggering a transfer to the dspace:endpoint may succeed. The dspace:endpointType property MUST be AmazonS3. The dspace:endpointType MUST be decorated with the data relevant dspace:endpointProperties as follows:

Namedescription
regionREQUIREDRegion the bucket resides in.
bucketNameREQUIREDName of the bucket.
https://w3id.org/tractusx/auth/folderNameREQUIREDname of the folder to be transferred.
https://w3id.org/tractusx/auth/keyNameREQUIREDpath to the resource to be transferred.
https://w3id.org/edc/v0.0.1/ns/secretREQUIREDjson object as string with \ escaped double-quotes holding accessKeyId, secretAccessKey, sessionToken and expiration properties.

A Provider MUST send a dspace:TransferStartMessage and an empty dspace:dataAddress property. They MUST execute a transfer as specified by the received request.

2.3 Communication with a Credential Service​

This standard assumes that each Participant has been issued a set of Verifiable Credentials (VCs) according to the relevant Catena-X standards. These VCs are stored in a Credential Service.

A Consumer MUST be able to retrieve an access token according to the Verifiable Presentation Protocol (VPP) that is part of the Decentralized Claims Protocol (DCP). This corresponds to Request 1 in the presentation flow where this Consumer acts as Client.

A Provider MUST be able to receive and securely verify an access token and derive information on a Consumer's Credential Service in order to execute the DCP VPP Request 4. This corresponds to the role of Verifier.

A Consumer MUST include an appropriately scoped STS-Token in the Authorization header in all DSP messages sent to the provider (see DSP) and in addition in the refresh message (see HttpData-PULL)

2.4 Conventions for Policy Constraints​

odrl:Offer objects contained in a dcat:Catalog SHOULD carry odrl:Constraints that are specified in the CX-ODRL-Profile. Subsequent standards are encouraged to specify further restrictions of said profile, especially on the odrl:rightOperands. The following list compiles a set of well-defined policies that Data Providers and Data Consumers SHOULD include in their offers and guidance on how to check them. Application Providers MUST support all constraints of the following table.

NameleftOperand (expanded IRI)operator
(compacted IRI)		valid rightOperands (literal)validation mechanism
MembershipConstrainthttps://w3id.org/catenax/policy/Membershipodrl:eqactiveMembership Credential (CX - 0149)
UseCaseConstraintshttps://w3id.org/catenax/policy/FrameworkAgreementodrl:eq[usecasename]:[version]UseCaseFrameworkAgreementCredential (CX - 0050)
The exact mapping logic is specified in the section Framework Agreement to Verifiable Credential Mapping
ContractReferenceConstrainthttps://w3id.org/catenax/policy/ContractReferenceodrl:eq[string]:[version]The value comparison necessary for validation SHOULD be based on CX-ODRL-Profile
UsagePurposeConstrainthttps://w3id.org/catenax/policy/UsagePurposeodrl:eq[string]:[version]The value comparison used necessary for validation SHOULD be based on CX-ODRL-Profile

Note: The list is available in machine-readable form with links to the respective legal documents in the CX-ODRL-Profile.

Each Data Offer visible in a Provider's dcat:Catalog MUST include at least an odrl:Constraint according to the definition of UseCaseContraint as defined above.

Providers SHOULD chain constraints (if necessary) via odrl:and. Examples can be found in CX-ODRL-Profile.

Providers MUST perform access control checks based on CX credentials on their data offers as a dcat:Catalog object may expose information restricted by governance and regulation.

Framework Agreement to Verifiable Credential Mapping​

The mapping between the rightOperands of a cx-policy:FrameworkAgreement to its referring Verifiable Credential ( described in CX-0050) is done via the credential type and its version.

  • The given rightOperand needs to be separated by the first “:” to separate the version term. Only one separator is allowed.

  • Thereafter, the term “Credential” needs to be appended to identify the relevant credential via its credential type.

  • The version maps the “contractVersion” property inside the relevant credential.

Example (rightOperand to Credential):

  • DataExchangeGovernance:x.x -> DataExchangeGovernanceCredential with contractVersion “x.x”

Note: Versions are to be handled as strings / literals and do not require any semantic comparison.

Catena-X ODRL Profile​

To clearly identify the relevant Catena-X ODRL Profile, every policy (and their subclasses) MUST use the ODRL ‘profile’ property with an IRI referring to the Catena-X ODRL Profile as defined in ODRL policy The current version is: https://w3id.org/catenax/policy/profile2405 or in compact form: cx-policy:profile2405.

2.5 Conventions for Datasets​

A Provider MUST annotate all instances dcat:Dataset in a dcat:Catalog with the following properties:

  • dct:type holding an object with at least an @id property pointing to a concept describing what type of API this Dataset represents. Subsequent standards define the exact value this property shall hold, depending on the Business scenario. The set of concepts is maintained in the taxonomy https://w3id.org/catenax/taxonomy# and MUST extend the concept https://w3id.org/catenax/taxonomy#Asset.
  • cx-common:version holding a string with SemVer semantics indicating the API version of the API that was typed by the dct:type property. It is allowed to use version information that is incomplete according to SemVer. Subsequent standards define the exact value this property shall hold, depending on the Business scenario.

2.6 Participant Agent Management​

A Provider SHOULD organize his participant agents in a way, that there is exactly one participant agent providing a root catalog. Further participant agents SHOULD be provided as dcat:Catalog entry in the root catalog referring to the catalog endpoint of the second participant agent.

A provider MUST publish all participant agents that should be detectable by a Consumer for an initial contact by specifying the participants catalog endpoint address in the DID document as specified in the CX-0049 DID Document standard. The endpoint address has the format https://provider-connector.provider-domain.com/subpath/versionpath/catalog. The path parts are defined by

  • subpath: The address https://provider-connector.provider-domain.com/subpath defines the root endpoint of the providers participant agent.
  • versionpath: The path part that is returned by the well-known version metadata endpoint (see DSP).
  • catalog: The catalog endpoint of a participant agent (see DSP).

The definition of the service reference reflects the section Discovery of Catalog Services in the DSP.

2.7 Protocol Version Handling​

Prior to any DSP communication, a Consumers participant agent MUST evaluate the protocol versions supported by the targeted Providers participant agent by calling the well-known version metadata endpoint (see DSP). He MUST use a protocol version supported by both participant agents.

A Providers participant agent MUST be capable to identify by the called DSP api, which version the Consumers participant agents is using for the communication and MUST answer with the right response formats according to that version.

The reference of a participant in the DID Document MUST refer to the catalog service of the latest version supported following the format specified in section 2.6.

3 BACKWARD COMPATIBILITY​

Backward compatibility is handled by the Dataspace Protocol version used for the communication between two participant agents. All differences are handled by explicit versioning of the protocol. This includes changes in details that are not motivated by the Dataspace Protocol itself but by semantic changes attached to the protocol version update.

Based on this constraint, backward compatibility is handled by the mechanism specified in section 2.7.

4 REFERENCES​

4.1 NORMATIVE REFERENCES​

Dataspace Protocol​

The Dataspace Protocol is an external reference. A Participant Agent MUST implement the referenced version to comply to this standard version.

Decentralized Claims Protocol​

The Decentralized Claims Protocol is an external reference. A Participant Agent MUST implement the referenced version to comply to this standard version.

RFC 6749​

https://www.rfc-editor.org/rfc/rfc6749#section-6

Decentralized Identifiers (DID)​

Framework Agreement Credential​

DID Document​

Verified Company Identity​

ODRL Profile​

CX Operating Model​

4.2 NON-NORMATIVE REFERENCES​

This section is non-normative

4.3 REFERENCE IMPLEMENTATIONS​

This section is non-normative

ANNEXES​

FIGURES​

Figure 1: Framework of data exchange