Licensing Use Cases

To help us determine the proper work flows to use during user authentication and authorization it will be helpful to run though several typical usage scenarios.


The following terms and abbreviations will be used in the remainder of this document:

protected resource
Any resource that requires specific authorization before a user can be granted access.
access constraints
A set of constraints end users must agree to before they are allowed to access to a particular protected resource.
access token
Essentially a session id. An access token allows an authorized user to access a protected resource for a limited time (e.g. 24 hours) without having to authenticate with every request.
The application (composer or pipeline planner) the end user is using to access a protected resource.
An authentication and authorization service. Any service that can authenticate a user and determine if they are authorized to access a particular protected resource. The AAS must also return any access constraints that apply to the protected resource.
The LDC’s Authentication and Authorization Service.

Authorization Use Cases

Authorized User Requests a Gigaword Document

Jane Austen has signed the required licenses and paid all required fees. Jane creates a pipeline and selects Gigaword as the data source.

  1. Since Gigaword is a resource at the LDC the application forwards Jane to the LAAS with the ID of the document she wishes to access.
  2. The LAAS requests Jane’s username and password and determines if Jane has access to the requested resource.
  3. Since Jane is an authorized user of the resource the LAAS returns a JSON document containing an access token and any access constraints required by the resource.
  4. When Jane attempts to run her pipeline the application will validate the pipeline by:
    1. Ensuring none of the selected web services violate the access constraints specified by the protected resource.
    2. Asking Jane to agree to any access constraints that must be agreed to at runtime. For example, not to redistribute the output.
  5. If the pipeline is valid then the application will begin running the pipeline:
    1. The application will send a request to the LDC datasource with the access token and desired document ID.
    2. The LDC will verify that the access token has not expired and is valid for the requested protected resource. If the access token is valid the LDC will return the requested document, otherwise the LDC will return an error message.
    3. The application will check that the request succeeded.
      • If the request succeeded the application will invoke each web service in turn.
      • If the request failed the error message will be displayed and Jane will be returned to the pipeline construction page.

Unauthorized User Requests a Protected Resource

Alice Cooper is a member of the LDC but has not paid the required fees to access CorpusX, which is a protected resource.

  1. The application will forward Alice to the LAAS with ID of the document he wishes to access.
  2. The LAAS prompts Alice for his username and password and determines that he is not an authorized user of CorpusX.
    • The LAAS returns an “permission denied” message.

Access Constraints Use Cases

Authorized User Constraints Violation

Dave Bowman is a registered member of the LDC with authorization at access CorpusX. Dave has constructed a pipeline that creates a derivative work but CorpusX does not allow derivative works.

  1. The application will forward Dave to the LAAS with the ID of the document he wishes to access.
  2. Since Dave is an authorized user the LAAS returns a JSON document containing an access token and the access constraints NO_DERIVATIVES.
  3. When the application validates the pipeline it will notify Dave that the protected resource does not permit derivative works.