The rule engine of Combinum CPQ is non-sequential which means that the user is not required to set the parameters of a configuration model in a certain order - the rule engine works independently on in which order the parameters are set and prevents or solves rule conflicts automatically.

Even if the rule engine is non-sequential it can sometimes be beneficial to guide inexperienced users by not showing all options at once. This can, for example, be done by using the Inclusion expression of tabs and showing the next tab when the user is ready with the previous tab. Then use the expression function IsSet() to verify which parameters that the user has set.

Unidirectional and bidirectional rules

Most types of rules consist of a triggering side and an action side and can therefore be considered unidirectional - when the triggering condition is fulfilled the action takes place.

However, in the case of template rules, which consists of a trigger and actions, the rule engine is aware about which parameters will be set to which values if the rule is triggered and if this is not allowed the rule engine will prevent the trigger condition by disallowing triggering values when needed, so the template rule is bidirectional.

Another bidirectional type of rule is the disallowed combination rule. This rule is activated when it's one step from being fulfilled, but it doesn't matter in which order the parameters are set. So, if for example a disallowed combination rule consists of three parameters then the rule is activated when two of these parameters have got values that are disallowed to combine for all three parameters, and the rule engine now prevents the remaining parameter from also getting its disallowed value.