VERSION 1.0.0 MANDATORY
The Evidence Exchange section describes the scope and goals of the Exchange Data Models (EDM) that support the communication between two competent authorities. It provides the business requirements for the Evidence Request (Request from Evidence Requester to Evidence Provider to request certain evidence data or documents) and the Evidence Response (Response from Evidence Provider to Evidence Requester to deliver the requested evidence data or documents). The Query Model is always based on these request-response pattern and supports the execution of document queries including eventual Error Responses that may occur during the execution. The syntax mapping for the Exchange Data Models to form XML-based messages is also provided, including examples.
In this chapter, the Exchange Data Models are being detailed. Three main messages are defined:
- Evidence Request;
- Evidence Response;
- Error Response.
The Evidence Request is the message created by the Evidence Requester, containing all the necessary information for requesting an Evidence. Depending on the preference and availability, the Evidence Request can be used to query documents, that are either structured and unstructured pieces of evidence. In preparation to the request, the Evidence Broker helps to determine which evidence types can be accepted for a particular procedure. A list of Evidence Providers that issue the required Evidence Type together with associated metadata can be looked up in the Data Service Directory. The Evidence Requests is then addressed to a specific Evidence Provider that has been identified in the Data Service Directory (DSD).
The Evidence Response is the answer to an Evidence Request created by the Evidence Provider and sent to the Evidence Requester. It contains necessary information of the Evidence Provider and data for the correlation of the Evidence Response with the respective Evidence Request. The response messages distinguish between three different status:
- Success: The Evidence Response message is delivered together with the requested Evidence and its associated Metadata.
- Unavailable: The Evidence Response message points to a date when the requested Evidence will be available. The Evidence Requester then can define a new Evidence Request at the time of availability.
- Failure: The response message is defined as Error Response that points to an exception that occurred during the processing of an Evidence Request such as a missing authorization, an object that cannot be found or the need for preview on the side of the Evidence Provider. The Evidence Requester then can define a new Evidence Request who fulfills the requirements.
The Evidence Exchange specification firstly illustrates the scope, goals and architecture requirements of the Exchange Data Models, and the underlying business requirements for Evidence Requests, Evidence Responses and Error Responses.
The Exchange Data Models make use of the functional capabilities of the OASIS RegRep V4 Query Protocol, and therefore the request and response messages are being modeled in the form of query models. The query models are illustrated together with a mapping to the appropriate syntax elements of the OASIS RegRep V4 Query Protocol and the syntax elements of the SDG metadata profile, a generic metadata model for the OOTS that is used to enhance the capability of the OASIS RegRep V4 Query Protocol (Syntax Mapping). In this way, for each Exchange Data Model, a specific SDGR Application Profile is defined that consists of syntax mappings to all necessary information entities for Evidence Requests, Evidence Responses and Error Responses. Class diagrams, tables and XML examples of the Evidence Exchange illustrate the shape of the Exchange Data Models.
In the further course of the document, business rules formalize the constraints associated to the Exchange Data Models and their information entities. Business rules therewith control the correct structure and use of information entities and are in the process of being implemented as executable Schematron rules that can be used for testing and validation.
At the end of the document, additional components such as eDelivery configuration, Evidence Exchange Logging and Evidence Preview are specified.