Schedulers

The schedulers are the heart of the order system. They manage the callbacks and the orders that arrive from the CPEE and the user. The figure below describes the interaction between the different modules and the CPEE.

callback_scheduler

The callback_scheduler module is designed to provide interaction with the CPEE by managing callback URLs. It is integrated closely with the ``order_scheduler’’ module to allow seamless processing of new orders and callbacks. The module provides a mechanism for registering new callback URLs, which are then used to notify the CPEE of new orders. If no new orders are available when a callback is registered, the callback URL is placed in a thread-safe queue until it can be processed. This module includes functionality to add and retrieve callbacks to the queue, allowing efficient communication with the CPEE.

The callback_scheduler supports a RESTful API implemented using Flask. See below for detailed documentation of its API endpoints and functionality.

API Endpoints:

Set Callback

• URL: /set_callback (configurable via conf_callback.URL_SET)

• Method: GET

• Description: Adds a new callback URL to the queue if there are no immediate orders to process. If an order is available, the order data is sent back immediately.

• Headers: Must include Cpee-Callback with the callback URL.

• Success Response:

  If an order is available:

  HTTP/1.1 200 OK
  Content-Type: application/json
  
  {
     "id": "...",
     "orderbot_id": -1,
     "status": "Order Initiated"
  }
  

  If no order is available and the callback is queued:

  HTTP/1.1 200 OK
  Content-Type: application/json
  CPEE-CALLBACK: true
  
  {
     "message": "Callback URL added to the queue"
  }
  

• Error Response:

  Code: 400 (Bad Request), Content: {"error": "No Cpee-Callback header found"}

  Code: 500 (Internal Server Error), Content: {"error": "<error_message>"}

Get Callback

• URL: /get_callback (configurable via conf_callback.URL_GET)

• Method: GET

• Description: Retrieves and removes the next callback URL from the queue if available.

• Success Response: If a callback URL is available:

  HTTP/1.1 200 OK
  Content-Type: application/json
  
  {
     "callback_url": "CPEE Callback URL"
  }
  

  If no callback URL is available:

  HTTP/1.1 204 OK
  Content-Type: application/json
  
  {
     "message": "There are currently no callbacks available"
  }
  

• Error Response:

  Code: 204 (No Content), Content: {"message": "There are currently no callbacks available"}

Get All Callbacks (Debug)

• URL: /get_all_callbacks (configurable via conf_callback.URL_DEBUG)

• Method: GET

• Description: Returns a list of all callback URLs currently in the queue. This endpoint is intended for debugging purposes.

• Success Response:

  HTTP/1.1 200 OK
  Content-Type: application/json
  
  {
     "all_callbacks": "[<callback_url_1>, <callback_url_2>, ...]"
  }
  

Module Implementation:

callback_scheduler.get_all_callbacks()

Returns all the callbacks currently in the queue (for debugging purposes) :return: All the callbacks currently in the queue

callback_scheduler.get_callback()

Returns a callback URL from the queue if available and removes it from the queue :return: Callback URL if available, message indicating no callbacks available otherwise

callback_scheduler.get_order()

Fetches an order from the Order Service (if available) :return: Order data if available, None otherwise

callback_scheduler.set_callback()

Adds a callback to the queue if there are no orders available, otherwise it returns the order data :return: Order data if available, message indicating the callback was added to the queue otherwise

order_scheduler

The order_scheduler module is designed to provide interaction between the order_management_system and the callback_scheduler. The module provides a mechanism for registering a new orders or getting new set orders from a que. After registering a new order, it first checks the callback_scheduler if there are currently any callback URLs available. If so it fetches a new callback URL and sends the order back to the CPEE using the callback URL. If there are currently no callback URLs available, it stores the new order inside a thread safe que until the order can be further processed by the callback_scheduler. This module includes functionality to add and retrieve orders to the queue, allowing efficient communication with the CPEE.

The order_scheduler supports a RESTful API implemented using Flask. See below for detailed documentation of its API endpoints and functionality.

API Endpoints:

Set Order

• Endpoint: /set_order (configurable via conf_order.URL_SET)

• Method: POST

• Description: Adds a new order to the queue. If a callback URL is available, the order is sent directly to the callback URL.

• Request Body: The expected JSON payload containing the order data:

  {
    "drink": "Gin Tonic",
    "size": "Medium",
    "name": "John Doe"
  }
  

• Success Response:

  If the order is added to the queue:

  HTTP/1.1 200 OK
  Content-Type: application/json
  
  {
      "message": "Order added to the queue",
      "order_id": 1
  }
  

  If the order is sent to a callback URL:

  HTTP/1.1 200 OK
  Content-Type: application/json
  
  {
      "message": "Order sent to callback URL",
      "order_id": 1
  }
  

• Error Response:

  If no order data is provided or data is incomplete:

  HTTP/1.1 400 Bad Request
  Content-Type: application/json
  
  {
      "error": "No order data provided/Missing order details"
  }
  

  If there is an error with the request to the callback URL:

  HTTP/1.1 500 Internal Server Error
  Content-Type: application/json
  
  {
      "error": "Error message describing the issue"
  }
  

Get Order

• Endpoint: /get_order (configurable via conf_order.URL_GET)

• Method: GET

• Description: Retrieves the next order from the queue and removes it.

• Success Response:

  If an order is available:

  HTTP/1.1 200 OK
  Content-Type: application/json
  
  {
      "order_id": 1,
      "drink": "Gin Tonic",
      "size": "Medium",
      "name": "John Doe",
  }
  

  If the queue is empty:

  HTTP/1.1 204 No Content
  Content-Type: application/json
  
  {
      "message": "No orders in the queue"
  }
  

Get All Orders (Debug)

• Endpoint: /get_all_orders (configurable via conf_order.URL_DEBUG)

• Method: GET

• Description: Retrieves all orders currently in the queue. Intended for debugging purposes.

• Success Response:

Allways returns a list of all orders currently in the queue.

HTTP/1.1 200 OK
Content-Type: application/json

{
    "all_orders": [
        {
            "order_id": 1,
            "drink": "Gin Tonic",
            "size": "Medium",
            "name": "John Doe",
        },
        "..."
    ]
}

Module Implementation:

order_scheduler.get_all_orders()

Fetches all orders from the queue (for debugging purposes) :return: A list of all orders in the queue

order_scheduler.get_callback_url()

Fetches the callback URL from the callback service (if available) :return: The callback URL or None if not available

order_scheduler.get_order()

Fetches the next order from the queue and removes it :return: The next order in the queue or a message if the queue is empty

order_scheduler.set_order()

Adds a new order to the queue or sends it to the callback URL if available :return: A response message and status code