Ranking/Prioritization of Tasks Through DMN

BPMN & Modeling Discussion & Questions
1

Dear all, we have a usecase where once or more often a day, we want to analyze each user task in task pools and dynamically assign a ranking (from 1 to the total no. of tasks) to each. I’ve been wondering, he algorithm for that could be made with DMN. What do you think about that?

2

Hi @IdemenB,

The ranking or prioritization would be based on what? Can you elaborate more…

3

Sorry for not giving enough details. Let’s say this is a pizza store. What I have in mind is something as follows:

  • Inputs to be given to the DMN model: Total Number of Orders In Queue (int) , Price Of Pizza Ordered (decimal) , is Returning Customer (bool), Time Since Order Given in mins (int)
  • Output: Ranking of which pizza to cook first from 1 to n (where n = total number of orders in queue)

So, I’ll have some rules using those inputs and for each pizza in the queue, I’ll run that decision to come up with a ranking.

4

Hİ @Philipp_Ossler , I see that the DMN hit policy “priority” could be good use case here, but currently not supported. Any quick idea coming to your mind worth trying?

5

This is an interesting question!

To sum it up, you have a list of orders. For each order, you want to assign a rank. And you want to sort the orders based on the rank.

{
"orders": [
		{
			"priceOfPizza": 20.0,
			"isReturningCustomer": true,
			"orderTime": "2021-07-11T14:00:00Z"
		},
		{
			"priceOfPizza": 25.0,
			"isReturningCustomer": true,
			"orderTime": "2021-07-11T14:01:00Z"
		},
		{
			"priceOfPizza": 30.0,
			"isReturningCustomer": false,
			"orderTime": "2021-07-11T14:02:00Z"
		}
	]
}

These are multiple steps and not so easy to model with one DMN. The challenge here is also that a decision table can’t be applied to a list of orders.

Option 1)

Model a decision table to rank a order.

Evaluate the decision for each order by using a multi-instance business rule task.

Collect the output of the business rule task and sort the list based on the rank. For example, by using a script (expression).

Option 2)

Use a complex FEEL expression to rank and sort the orders.

Cons: the ranking function is not as easy to understand as a decision table.

{
  ranking: function (order) {
    time: 3 * (now() - date and time(order.orderTime)) / duration("PT1M"),
    isReturning: if order.isReturningCustomer then 10 else 0,
    price: 1 * order.priceOfPizza,
    rank: time + isReturning + price
  }.rank,	
  rankedOrders: sort(orders, function(x,y) ranking(x) > ranking(y))
}.rankedOrders

Option 3)

Use a DMN engine that supports BKMs.

Model the ranking as decision table.

Call the decision table in a context decision and sort the results.

Read more about it in the blog post: DMN is more than a Decision Table - Camunda

A decision table with the hit policy priority would not help here. It is only to order the matched rules. But it can’t be applied to a list of orders.

Does this help you?

6

Thank you so much for the valuable insight @Philipp_Ossler , I’ll give them a try and share the results.

7