Create Access Requests/Grants

AccessGrantClient

The inrupt-client-accessgrant module provides an AccessGrantClient that interacts with the ESS Access Grant Service to create/verify/query/fetch Access Requests and Grants.

To interact with the service, the AccessGrantClient has the following methods:

Method	Description
AccessGrantClient.requestAccess	Creates Access Requests.
AccessGrantClient.grantAccess	Creates Access Grants.
AccessGrantClient.revoke	Updates the status of the Access Requests/Grantss to revoked.
AccessGrantClient.query	Queries for Access Requests and Grants.
AccessGrantClient.denyAccess	Creates Access Request denials.
AccessGrantClient.verify	Performs validation checks on Access Requests/Grantss, such as signature validation, date validation, etc.

To instantiate an AccessGrantClient, you need to pass in the URI of the ESS Access Grant Service. For example, the Access Grant service for Inrupt’s PodSpaces runs at https://vc.inrupt.com.

Create an Access Request

An application can use AccessGrantClient.requestAccess to create an Access Request.

For example, a user visits an ExamplePrinter’s website which provides photo printing services. When the ExamplePrinter’s web application asks for the photos to print, the user enters the URLs of the photos that are located in the user’s Pod. To continue, the ExamplePrinter’s backend server uses AccessGrantClient.requestAccess to create Access Requests to read the photos.

1. Instantiate the Requestor’s AccessGrantClient

To instantiate an AccessGrantClient, call the constructor with the following parameters:

Parameters	Descriptions
Access Grant Service URI	The root URL of the ESS Access Grant service.
Authenticated Session	The authenticated session of the requestor.

For example, the following instantiates an AccessGrantClient for ExamplePrinter using the Inrupt PodSpaces Access Grant Service URI and ExamplePrinter’s authenticated session:

public class ExamplePrinterRequestingClass {

   private final URI PS_ACCESS_GRANT_URI = URI.create("https://vc.inrupt.com");
   private Session session;  // Session for ExamplePrinter.
   // ... Logic to initialize the ExamplePrinter's session has been omitted for brevity.

   private final AccessGrantClient accessgrantClient = new AccessGrantClient(PS_ACCESS_GRANT_URI)
         .session(session);

   // ...
   // ...

}

In these examples, logic to initialize an authenticated session for ExamplePrinter has been omitted for brevity.

2. Create the Access Request

To create an Access Request, call AccessRequest.requestAccess with the request details:

Parameters	Descriptions
Resource Owner	The WebID of the agent who controls access to the requested resource(s).
Requested resource(s)	Resource(s) to which the access is being requested.
Requested access mode(s).	Requested access modes. Available modes are: "Read", "Write", and "Append".
Optional. Purpose(s) for the request.	URI(s) indicating the stated purpose(s) for the request.
Optional (but Recommended) Expiration Date.	Expiration date of the Access Request and subsequent Access Grant, if approved. ESS Access Grant Service may be configured to issue Access Requests and Grants with earlier expiration date.

The AccessRequest.requestAccess accepts:

• request details as AccessRequest.RequestParameters, which is a collection of the request parameters; or

• request details as individual parameters.

Request Parameters

AccessGrantClient.requestAccess(AccessRequest.RequestParameters) accepts the Access Request details as AccessRequest.RequestParameters. To build the AccessRequest.RequestParameters object, you can use AccessRequest.RequestParameters.Builder and its methods.

For example, the following code uses:

• AccessRequest.RequestParameters.Builder to specify the request details (i.e., the resource owner, the resources, the modes, the purposes, and the expiration); and

• ExamplePrinter’s instantiated AccessGrantClient to create the request (i.e., the requestor is ExamplePrinter).

public AccessRequest createReadRequest(List<String> resourceURLs, String resourceOwner) {
    URI resourceOwnerURI = URI.create(resourceOwner);
    Set<URI> resourcesURIs = resourceURLs.stream().map(URI::create).collect(Collectors.toSet());

    Set<String> modes = Set.of("Read"); // Available modes are "Read", "Write", and "Append".

    Set<URI> purposes = Set.of(
                URI.create("https://purpose.example.com/PhotoPrinting"),
                URI.create("https://purpose.example.com/ServiceProvision"));

    Instant currentInstant = Instant.now();
    Instant expiration = currentInstant.plus(30, ChronoUnit.MINUTES);

    AccessRequest.RequestParameters requestParams = AccessRequest.RequestParameters.newBuilder()
            .recipient(resourceOwnerURI)
            .resources(resourcesURIs)
            .modes(modes)
            .purposes(purposes)
            .expiration(expiration)
            .build();

    AccessRequest accessRequest = accessgrantClient.requestAccess(requestParams).toCompletableFuture().join();

    return accessRequest;
}

Individual Request Parameters

Create an Access Grant

Resource owners can use their access management application to view Access Requests made to them and decide whether to grant the requested access or not. If the resource owner decides to grant an Access Request, the access management application can call AccessGrantClient.grantAccess to create an Access Grant. Optionally, the application can also call AccessGrantClient.verify to verify the Access Request before displaying it to the user.

For example, the user (the resource owner) who visited ExamplePrinter’s website to print pictures can login to a trusted access management application. The access management application can display the Access Request made to the user by the ExamplePrinter. If the user decides to grant the requested access, the application can create an Access Grant. The access manage application has a backend server that uses various AccessGrantClient methods, namely:

1. Instantiate the Grantor’s AccessGrantClient

To instantiate an AccessGrantClient for the grantor/resource owner, call the constructor with the following parameters:

Parameters	Descriptions
Access Grant Service URL	The root URL of the ESS Access Grant service
Authenticated Session	The authenticated session of the user (the resource owner).

For example, the following instantiates an AccessGrantClient using Inrupt PodSpaces Access Grant Service URI and the resource owner’s session:

public class AccessManagementAppRequestHandler {

   private final URI PS_ACCESS_GRANT_URI = URI.create("https://vc.inrupt.com");
   private Session userSession;  // Session for a resource owner.
   // ... Logic to initialize a session for a resource owner has been omitted for brevity.

   AccessGrantClient agClientForUser = new AccessGrantClient(PS_ACCESS_GRANT_URI)
      .session(userSession);

   // ...
   // ...

}

2. Get the Access Requests Made to the User

The user can only retrieve Access Requests where the user is either the requestor (creator of the Access Request) or the resource owner (recipient of the Access Request).

If the Access Request’s id is known, the application can directly retrieve the Access Request using AccessGrantClient.fetch with the Access Request’s id.

The fetch operation can return expired or future Access Requests.

// String requestID = "https://vc.{ESS DOMAIN}/vc/xxxxxx...";
AccessRequest accessRequest = agClientForUser.fetch(URI.create(requestID), AccessRequest.class)
      .toCompletableFuture()
      .join();

3. Verify the Requested Access

To verify the Access Request, use AccessGrantClient.verify, passing it the Access Request.

For example, the following example uses AccessGrantClient.verify to verify an Access Request, checking for errors and warning.

// AccessRequest accessRequest = ...;

AccessCredentialVerification verification = agClientForUser.verify(accessRequest).toCompletableFuture().join();

if (verification.getChecks().isEmpty() || !verification.getErrors().isEmpty()) {
   // Handle invalid Access Request
}

if (!verification.getWarnings().isEmpty()) {
   // Handle warnings
}

4. Create the Access Grant

For a valid Access Request, if the resource owner decides to grant the requested access, the application can call AccessGrantClient.grantAccess, passing in the specific Access Request to grant.

For example:

AccessGrant accessGrant = agClientForUser.grantAccess(accessRequest).toCompletableFuture().join();