AccessQueueService/README.md

AccessQueueService

AccessQueueService is a microservice API for managing access to a resource with limited capacity. When a user requests access, they are either granted access immediately (if there is available capacity) or placed in a queue. The service also allows for revoking access.

API Routes

Request Access

• GET /access/{id}
  • Description: Request access for a user with the specified id.
  • Response: Returns an AccessResponse object indicating whether access was granted or the user's position in the queue.

Revoke Access

• DELETE /access/{id}
  • Description: Revoke access for a user with the specified id. This will remove the user from the active list or queue and may allow the next user in the queue to gain access.
  • Response: Returns a boolean indicating success.

Configuration Variables

Configuration is set in appsettings.json or via environment variables. The main configuration section is AccessQueue:

• CapacityLimit: The maximum number of users that can have access at the same time (default: 100).
• ActivitySeconds: How long (in seconds) a user can remain active before being considered inactive (default: 900).
• ExpirationSeconds: How long (in seconds) before an access ticket expires (default: 43200).
• RollingExpiration: If true, the expiration timer resets on activity (default: true).
• CleanupIntervalSeconds: How often (in seconds) the background cleanup runs to remove expired/inactive users (default: 60).

Example appsettings.json:

{
  "AccessQueue": {
    "CapacityLimit": 100,
    "ActivitySeconds": 900,
    "ExpirationSeconds": 43200,
    "RollingExpiration": true,
    "CleanupIntervalSeconds": 60
  }
}

How the Service Works

1. Requesting Access:

   • When a user requests access, the service checks if the current number of active users is below MaxCapacity.
   • If there is capacity, the user is granted access immediately.
   • If not, the user is added to a queue and receives their position in the queue.

2. Revoking Access:

   • When a user revokes access (or their access times out), their slot is freed.

3. Queue Management:

   • Users in the queue are managed in a FIFO (first-in, first-out) order.
   • If a user is removed from the queue but they are inactive, they are not granted access and their position in the queue is lost.

AccessResponse Object

The AccessResponse object returned by the API contains the following properties:

• ExpiresOn (DateTime?): The UTC timestamp when the user's access will expire. null if the user does not have access.
• RequestsAhead (int): The number of requests ahead of the user in the queue. 0 if the user has access.
• HasAccess (bool): Indicates whether the user currently has access (true if ExpiresOn is set and in the future).

Running the Service

1. Build and run the project using .NET 8.0 or later:

   dotnet run --project AccessQueueService/AccessQueueService.csproj
   

2. By default, the API will be available at:
   • HTTP: http://localhost:5199
   • HTTPS: https://localhost:7291 (See AccessQueueService/Properties/launchSettings.json for details.)

Running the Tests

Unit tests for the service are located in the AccessQueueServiceTests project. To run all tests, use the following command from the root of the repository:

# Run all tests in the solution
 dotnet test

Test results will be displayed in the terminal. You can also use Visual Studio's Test Explorer for a graphical interface.

AccessQueuePlayground (Demo UI)

The AccessQueuePlayground project provides a simple web-based UI for interacting with the AccessQueueService API. This is useful for testing and demonstration purposes.

Running the Playground

1. Build and run the playground project:

   dotnet run --project AccessQueuePlayground/AccessQueuePlayground.csproj
   

2. By default, the playground will be available at:
   • HTTP: http://localhost:5108
   • HTTPS: https://localhost:7211 (See AccessQueuePlayground/Properties/launchSettings.json for details.)

Using the Playground

• Open the provided URL in your browser.
• Use the UI to request and revoke access for different user IDs.
• The UI will display your access status, queue position, and expiration time.

This playground is intended only for local development and demonstration.

License

See LICENSE.txt for license information.