7.2. Rule Language Keywords

7.2.1. Hard Keywords

Hard keywords are words which you cannot use when naming your domain objects, properties, methods, functions and other elements that are used in the rule text. The hard keywords are true, false, and null.
Report a bug

7.2.2. Soft Keywords

Soft keywords can be used for naming domain objects, properties, methods, functions and other elements. The rules engine recognizes their context and processes them accordingly.
Report a bug

7.2.3. List of Soft Keywords

Rule attributes can be both simple and complex properties that provide a way to influence the behavior of the rule. They are usually written as one attribute per line and can be optional to the rule. Listed below are various rule attributes:
Rule attributes chart for BRMS Development Guide 6.0.2

Figure 7.1. Rule Attributes

Table 7.1. Soft Keywords

Name Default Value Type Description
no-loop false Boolean When a rule's consequence modifies a fact, it may cause the rule to activate again, causing an infinite loop. Setting 'no-loop' to "true" will skip the creation of another activation for the rule with the current set of facts.
lock-on-active false Boolean Whenever a 'ruleflow-group' becomes active or an 'agenda-group' receives the focus, any rule within that group that has 'lock-on-active' set to "true" will not be activated any more. Regardless of the origin of the update, the activation of a matching rule is discarded. This is a stronger version of 'no-loop' because the change is not only caused by the rule itself. It is ideal for calculation rules where you have a number of rules that modify a fact, and you do not want any rule re-matching and firing again. Only when the 'ruleflow-group' is no longer active or the 'agenda-group' loses the focus, those rules with 'lock-on-active' set to "true" become eligible again for their activations to be placed onto the agenda.
salience 0 integer Each rule has an integer salience attribute which defaults to zero and can be negative or positive. Salience is a form of priority where rules with higher salience values are given higher priority when ordered in the activation queue. BRMS also supports dynamic salience where you can use an expression involving bound variables like the following: 
rule "Fire in rank order 1,2,.."
        salience( -$rank )
    when
        Element( $rank : rank,... )
    then
        ...
end
ruleflow-group N/A String Ruleflow is a BRMS feature that lets you exercise control over the firing of rules. Rules that are assembled by the same ''ruleflow-group' identifier fire only when their group is active. This attribute has been merged with 'agenda-group' and the behaviours are basically the same.
agenda-group MAIN String Agenda groups allow the user to partition the agenda, which provides more execution control. Only rules in the agenda group that have acquired the focus are allowed to fire. This attribute has been merged with 'ruleflow-group' and the behaviours are basically the same.
auto-focus false Boolean When a rule is activated where the 'auto-focus' value is "true" and the rule's agenda group does not have focus yet, it is automatically given focus, allowing the rule to potentially fire.
activation-group N/A String Rules that belong to the same 'activation-group' identified by this attribute's String value, will only fire exclusively. More precisely, the first rule in an 'activation-group' to fire will cancel all pending activations of all rules in the group, i.e., stop them from firing.
dialect specified by package String Java and MVEL are the possible values of the 'dialect' attribute. This attribute specifies the language to be used for any code expressions in the LHS or the RHS code block. While the 'dialect' can be specified at the package level, this attribute allows the package definition to be overridden for a rule.
date-effective N/A String, date and time definition A rule can only activate if the current date and time is after the 'date-effective' attribute. An example 'date-effective' attribute is displayed below: 
rule "Start Exercising"
date-effective "4-Sep-2014"
when
$m : org.drools.compiler.Message()
then
$m.setFired(true);
end
date-expires N/A String, date and time definition A rule cannot activate if the current date and time is after the 'date-expires' attribute. An example 'date-expires' attribute is displayed below: 
rule "Run 4km"
date-effective "4-Sep-2014"
date-expires "9-Sep-2014"
when
$m : org.drools.compiler.Message()
then
$m.setFired(true);
end
duration no default long If a rule is still "true", the 'duration' attribute will dictate that the rule will fire after a specified duration.

Note

The attributes 'ruleflow-group' and 'agenda-group' have been merged and now behave the same. The GET methods have been left the same, for deprecations reasons, but both attributes return the same underlying data.
Report a bug