# Resolution (DCP)

{% hint style="info" %}
Specifications and best practice implementations for Verifiable Credentials are currently being developed. This page is expected to be updated, closely following these developments.
{% endhint %}

The `POST` request to the `/presentations/query` endpoint queries the holder for credentials, after which the holder sends a set of Verifiable Presentations as a response.

{% hint style="info" %}
The `POST` request to the `/presentations/query` is an **OPTIONAL** endpoint and is part of the iSHARE Framework's Verifiable Credentials support in line with the **Decentralised Claims Protocol (DCP)**.
{% endhint %}

## Verifier requests Verifiable Presentation from holder

> The Resolution API defines the Credential Service endpoint for querying credentials and returning a set of Verifiable Presentations. More information in the \[DCP specification]\(<https://eclipse-dataspace-dcp.github.io/decentralized-claims-protocol/v1.0/#resolution-api>.

```json
{"openapi":"3.1.0","info":{"title":"iSHARE Decentralized Claims Protocol (DCP) API specifications","version":"3.0"},"tags":[{"name":"Holder","description":"Endpoints relevant for the VC Holder role (e.g., storing credentials, receiving offers)."}],"security":[{"BearerAuth":[]}],"components":{"securitySchemes":{"BearerAuth":{"type":"http","scheme":"bearer","bearerFormat":"JWT","description":"iSHARE JWT Bearer token authentication"}}},"paths":{"/presentations/query":{"post":{"tags":["Holder"],"summary":"Verifier requests Verifiable Presentation from holder","description":"The Resolution API defines the Credential Service endpoint for querying credentials and returning a set of Verifiable Presentations. More information in the [DCP specification](https://eclipse-dataspace-dcp.github.io/decentralized-claims-protocol/v1.0/#resolution-api.","operationId":"post-vp-request","requestBody":{"required":true,"content":{"application/json":{"schema":{"$ref":"#/x-ext/5c2969b"}}}},"responses":{"200":{"description":"VP request received successfully","content":{"application/json":{"schema":{"$ref":"#/x-ext/5dff8d7"}}}},"400":{"description":"Bad Request - possibly because both PresentationQueryMessage and presentationDefinition are provided (only one is allowed)"},"500":{"description":"Internal Server Error"}}}}}}
```

### Request model

The model for the PresentationQueryMessage is defined in: <https://eclipse-dataspace-dcp.github.io/decentralized-claims-protocol/v1.0/resources/presentation/presentation-query-message-schema.json>. Verifiable presentations containing credentials may be requested using [scopes](https://eclipse-dataspace-dcp.github.io/decentralized-claims-protocol/v1.0/#scopes) or using a [presentation definition](https://identity.foundation/presentation-exchange/spec/v2.1.1/#presentation-definition).

* `@context`\
  **Array of Strings**. Root level. <mark style="color:red;">(Required)</mark>\
  Specifies a valid Json-Ld context. Must contain `"https://w3id.org/dspace-dcp/v1.0/dcp.jsonld"`
* `type`\
  **String**. Root level. <mark style="color:red;">(Required)</mark>\
  A string specifying the PresentationQueryMessage type. Must contain `"PresentationQueryMessage"`
* `scope`\
  **Array of Strings**. Root level.\
  A non-empty array of scopes.
* `presentationDefinition`\
  **Object**. Root level.\
  An object containing the definition of the requested presentation. Further details on <https://identity.foundation/presentation-exchange/spec/v2.1.1/#presentation-definition>.

A `PresentationQueryMessage` *MUST* contain either a `presentationDefinition` or a `scope` parameter. If both parameters are present it is an error and the client *MUST* return an `HTTP 400 BAD REQUEST` response.

### Example request

#### Example using scopes

```json
POST /presentations/query
Authorization: Bearer YOUR_SECRET_TOKEN
Content-Type: application/json

{
  "@context": [
    "https://w3id.org/dspace-dcp/v1.0/dcp.jsonld"
  ],
  "type": "PresentationQueryMessage",
  "scope": [
    "presentation1",
    "presentation2"
  ]
}
```

#### Example using presentation definition

```json
POST /presentations/query
Authorization: Bearer YOUR_SECRET_TOKEN
Content-Type: application/json

{
  "@context": [
    "https://w3id.org/dspace-dcp/v1.0/dcp.jsonld"
  ],
  "type": "PresentationQueryMessage",
  "presentationDefinition": {
    "id": "ishareFrameworkCompliance",
    "name": "iSHARE Framework Compliance",
    "purpose": "Request proof of compliance with the iSHARE Framework",
    "input_descriptors": [
      {
        "id": "ishareFrameworkComplianceFrameworkIdAndStatus",
        "format": {
          "ldp_vc": {
            "proof_type": [
              "Ed25519Signature2018"
            ]
          }
        },
        "constraints": {
          "fields": [
            {
              "path": [
                "$.type"
              ],
              "filter": {
                "type": "string",
                "pattern": "FrameworkCompliance"
              }
            },
            {
              "path": [
                "$.frameworkId"
              ],
              "filter": {
                "type": "string",
                "pattern": "iSHARE"
              }
            },
            {
              "path": [
                "$.status"
              ],
              "filter": {
                "type": "string",
                "pattern": "active"
              }
            }
          ]
        }
      }
    ]
  }
}
```

### Response model

On succesfull receipt of the PresentationRequestMessage, the holder must return a 200 code and a PresentationResponseMessage. A `PresentationResponseMessage` should only include valid (non-expired, non-revoked, non-suspended) credentials. The model for the PresentationQueryMessage is defined in: <https://eclipse-dataspace-dcp.github.io/decentralized-claims-protocol/v1.0/resources/presentation/presentation-response-message-schema.json>.

* `@context`\
  **Array of Strings**. Root level. <mark style="color:red;">(Required)</mark>\
  Specifies a valid Json-Ld context. Must contain `"https://w3id.org/dspace-dcp/v1.0/dcp.jsonld"`
* `type`\
  **String**. Root level. <mark style="color:red;">(Required)</mark>\
  A string specifying the PresentationResponseMessage type. Must contain `"PresentationResponseMessage"`
* `presentation`\
  **Array of Strings**. Root level.\
  An array of Verifiable Presentations. The Verifiable Presentations may be strings, JSON objects, or a combination of both depending on the format.
* `presentationSubmission`\
  **Object**. Root level.\
  A valid Presentation Submission. Further details on <https://identity.foundation/presentation-exchange/spec/v2.1.1/>.

Implementations that support the `presentationDefinition` parameter *MUST* include the `presentationSubmission` parameter.

### Example response

#### Example including presentations

```json
{
  "@context": [
    "https://w3id.org/dspace-dcp/v1.0/dcp.jsonld"
  ],
  "type": "PresentationResponseMessage",
  "presentation": [
    "presentation1",
    "presentation2"
  ]
}
```

#### Example including presentation and presentationSubmission

```json
{
  "@context": [
    "https://w3id.org/dspace-dcp/v1.0/dcp.jsonld"
  ],
  "type": "PresentationResponseMessage",
  "presentation": [
    "jwtPresentation"
  ],
  "presentationSubmission": {
    "id": "ishareFrameworkCompliancePresentation",
    "definition_id": "ishareFrameworkCompliance",
    "descriptor_map": [
      {
        "id": "ishareFrameworkComplianceFrameworkIdAndStatus",
        "format": "jwt_vp",
        "path": "$.presentation[0]"
      }
    ]
  }
}
```