IBM BPM, V8.0.1, All platforms > Programming IBM BPM > Business rule management programming > Programming model
Rule set
A rule set is one type of business rule. Rule sets are typically used when multiple rules may need to be executed based on different conditional values. Rule sets are composed of a rule block and rule templates. The rule block ( RuleBlock) contains the different if-then and action rules which make up the logic of the rule set.
The RuleSet class provides methods that support the following:
- Retrieve a list of rule blocks for the rule set
- Retrieve a list of rule templates defined in the rules set
Currently each rule set can only have one rule block, while there can be multiple rule templates defined in the rule set. The rule block contains the set of rules that will be executed when the rule set is invoked. The rule block allows for the order of the rules to be modified. A rule block must have at least one rule defined. The rules ( Rule) can be defined as template instance rules (TemplateInstanceRule) or hard-coded. If an if-then or action rule has been defined with a template, it can be removed from the rule block. If a new instance of rule was created with a template, it can be added to the rule block.
If a rule is hard-coded and was not defined with a template, it cannot be modified or removed from the rule block. The expectation with these rules is that they have been designed to always be part of the rule set logic and are not to be changed or repeated within the logic.
When a new rule is created with a template, it must have a unique name value. The list of existing rules can be retrieved and checked first before creating the rule.
For hard-coded if-then and action rules, only the name and presentation can be retrieved. The presentation is a string which can be used to display information about the rule in client applications. For if-then or action rules that are defined with a template, the name and presentation can be retrieved as well as additional information. Specific parameter values can be retrieved and changed. With a template ( RuleSetRuleTemplate) defined in the rule set, another instance of the rule can be created within the rule set and parameter values can be set.
For example, if you have a rule saying that a customer of a particular status level receives a discount of a specific amount. This logic could be defined with a single rule template and then repeated with parameter values changed for the status level (gold, silver, bronze, and so on) and the discount amount (15%, 10%, 5%, and so on).
The parameters for a rule defined with a template are specific to the instance of the rule. The template only defines a standard presentation and the number of parameters for the rule. Each rule defined with a template can have different values as explained in the example on discounts for different customer status.
The RuleBlock class provides methods that support the following:
- Retrieve a rule by index
- Add a rule that was defined with a template
- Remove a rule defined with a template
- Modify the order of a rule by one place or to a specific index location
The RuleSetRule class provides methods that support the following:
- Retrieve the name of the rule
- Retrieve the display name of the rule
- Retrieve the user presentation
- Retrieve the rule block
The RuleSetRuleTemplate class provides methods that support the following:
- Create a rule template instance from this template definition
- Retrieve the parent rule set
The TemplateInstanceRule class provides methods that support the following:
- Retrieve the parameters for the rule
- Retrieve the template definition which defined the rule
The Template class provides methods that support the following:
- Retrieve the template ID
- Retrieve the name
- Retrieve and set the display name
- Retrieve and set the description
- Retrieve the parameters for this template
- Retrieve the user presentation
Figure 1. Class diagram of BusinessRule and related classes
