[jboss-jira] [JBoss JIRA] Commented: (JBRULES-600) "Otherwise" feature to catch scenarios when no rules fired

[Michael Neale (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBRULES-600?page=comments#action_12349610 ] 
            
Michael Neale commented on JBRULES-600:
---------------------------------------

Have an initial implementation of this, based on using an Otherwise fact (org.drools.Otherwise) which will be automatically asserted, the fire loop retried, and retracted when done.

This is simple, and works by only needing a "Otherwise()" declaration in the LHS, but it could be confusing should either the LHS include more constraints, have multiple rules, or modify working memory (so its not without its downsides).

BUT, if you can have rules that declare Otherwise() and nothing else, and its perfectly safe. You can also have as many rules that use Otherwise() with other constraints as long as 
a) the rule action does not modify working memory or b) the other conditions to not overlap.

There are many other much more complex ways to implement this if needed (most likely a different type of terminal node, driven by a rule attribute).

> "Otherwise" feature to catch scenarios when no rules fired
> ----------------------------------------------------------
>
>                 Key: JBRULES-600
>                 URL: http://jira.jboss.com/jira/browse/JBRULES-600
>             Project: JBoss Rules
>          Issue Type: Feature Request
>      Security Level: Public(Everyone can see) 
>          Components: Reteoo
>    Affects Versions: 3.0.5
>            Reporter: Michael Neale
>         Assigned To: Michael Neale
>             Fix For: 3.1-m1
>
>   Original Estimate: 1 day
>  Remaining Estimate: 1 day
>
> Have had a few requests for features when "otherwise" is needed. Basically, in a rule set, when fireAllRules is called, an no "normal" rules activate and fire, rules declared as "otherwise" will then activate, presumably to cater for scenarios that have "fallen through the cracks" in typical business applications.

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