[rules-users] How to traverse a hierarchy?

[Charles Binford]

Thanks for the suggestion.  I'll try a slight variation on the theme and
see what that does to my overall throughput.

cb


Wolfgang Laun wrote:
> Let me propose a somewhat different approach which avoids changing
> your objects.
>  
> Define a new class Marker that combines a "mark" with the Object to be
> classified:
>    private String mark;
>    private final Object object;
>    public Marker( Object o ){ this.object = o; mark = ""; }
>    // getter for object
>    // getter & setter for mark
>  
> For every new Object, create and insert a marker object. This could be
> done by the (Java) code inserting the new objet, or by a rule that
> fires on an unmarked and unclassified Object. (This depends somewhat
> upon the ultimate fate of the Object facts. If they are left in WM, it
> might be preferable to used the first technique.)
>  
> Rules would be written as
>    rule r1.2.4
>    when
>        $m : Marker( mark == "1.2", $object : object )
>        Object( this == $object,... )
>    then
>        $m.setMark( "1.2.4" );
>        update( $m );
> end
>  
> Leaf rules would have to retract the marker (and dispose of the Object
> fact).
>  
> A low salience rule should be provided to match left-over Marker
> objects so you can catch Objects that aren't matched by any rule.
>  
> -W
>  
>  
>  
>  
>  
>  
>  
>
>
>  
> On 4/13/09, *Charles Binford* <Charles.Binford at sun.com
> <mailto:Charles.Binford at sun.com>> wrote:
>
>     All,  I'm trying to figure out a better way to solve this problem.  I
>     have a batch of objects that I want matched against a hierarchy of
>     rules.  I check the rules in order, and as soon as I find a match I'm
>     done for that level of the hierarchy.  In other words, If the object
>     matches a rule, we'll check the rules children, but not the siblings.
>     Example:
>
>     rule 1
>     rule 1.1
>     rule 1.2
>        rule 1.2.1
>        rule 1.2.2
>     rule 1.3
>     rule 2
>
>     If an object matches rule 1, check for a match at level "1.*", but
>     rule
>     2 will never be checked.  If an object matches 1, 1.2, and 1.2.1,
>     we're
>     done as 1.2.1 has no children.
>
>     My current implementation with drools works, but is very
>     inefficient.  I
>     have a "level" string in the objects and whenever I find a match I
>     update the level of the object and force an object update.  Each rule
>     tests that the level string is correct, e.g. rule 1.2.1 works as
>     follows:
>     rule "1.2.1"
>     when
>        obj(level matches "1.2.*",.....)
>        ...
>     then
>        objSetLevel("1.2.1.*");
>        ....
>     end
>
>     I'm also using saliance to keep the evaluation order like I want it.
>
>     Changing the contents of the object and doing the update is not
>     good for
>     drools performance as I understand it so I'm looking for a better way.
>     The hierarchy and the order of the matching is key to my
>     application so
>     I'm not wanting to redesign that part of things.
>
>     I tried using activation-groups.  That worked great as long as I only
>     had a single object to run through the hierarchy, but given the
>     way the
>     rest of the system is design I need to load up 10-100 objects before
>     each call to fireallrules() for performance purposes.
>
>     Any suggestions are appreciated.
>
>     Charles Binford
>
>
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