If there are many process instances in a system, it is also a lot of work to realign them, if necessary.

What do I mean by realignment of process instances?

For example, if there is a process instance – which is a simple example – that needs a one step approval in case of an order of below 1000€ and a two step approval in case of an order of 1000€ or above.

Now if there is an order of 900€ then there exists a process instance for a one step approval. If later the order is changed to have a value of 1500€, then the process instance needs to be realigned to have two steps of the approval.

The realignment can typically not be done from within the process instance itself.There is some logic needed, that does such a realignment and works in all cases. Furthermore as of my knowledge there is no generic algorithm to describe all needed realignments based on such changes. So the rule do assign one and two step approval to the values of below and above 1000€ is not enough. It is further necessary to describe the realignment logic.

This is especially challenging as it depends on the state of the process instance itself.For example if the one step approval is the manager approval and the two step approval is the revision department approval which has to take place before the manager approval. Then it may challenging to realign a process instance in the case of a value change, if the manager approval is already in progress, because a different step has to be inserted before.

So the process instance realignment problem is not simple, but a solution is needed, as soon as there are process instances in the system.