[rules-users] Anyway to get Failed Reason for Failed Rule?

[Wolfgang Laun]

For a simplified scenario, it is easily possible to determine which rules
fire and which don't. This scenario assumes that you have
 - a set of rules
 - some static facts (which may be modified in the process or not)
 - one transactional fact
and the simple sequence
  kSession.insert( transFact );
  kSession.fireAllRules();
repeated for each fact.

Set up an agenda event listener and register which rules fired - all
the others did not.

Analysing why some fact does not trigger a rule R is much more complex
than rule R itself. Consider: rule R constrains n properties, and each
of these values can be out of the "hot" range. Lets say we are
investigating boxes with height, width, depth, colour, material, and
weight. When your rule looks for h>10, w>20, d>5, colour == RED,
material == WOOD, weight < 100 then you have 6 individual
possibilities for this rule to fire.

If you really need to have a detailed analysis you will have to
redesign your rule base with individual rules checking individual
properties, one rule each for width, height, depth, colour, material
and weight. Each of these rules would add a property (WIDTH_OK,
HEIGHT_OK,... WEIGHT_OK) to the investigated box. Then, at the end of
the firings you look at the collected properties and can determine
what is there and what isn't. If it is the full set, you have a
matching box; otherwise the missing properties tell you what
prohibited a full match. (Again, this assumes that you are
investigating one transactional fact at a time.)

Of course it will get even more complicated if you need to investigate
combinations of facts, but I think it can be done, but it'll need some
extensive work.

-W









On 09/08/2012, Rana <ven12344 at yahoo.com> wrote:
> Hi Davide, your second guess is right. Sorry I should have said failed
> condition.
>
> I wanted to know which rule got fired and which one did not (because the
> condition failed in when clause).
>
> I wanted to know those, because we have requirement which asks for what are
> the rules which have passed and failed copnditions, so that we can make
> some
> decisions.
>
> Also, I wanted to know that in a rule
>
> rule "name"
> when
>     //condition
> then
>    //consequence
> end
>
> when the condition is failed will the rule goes to consequence or not.  (I
> am fairely new to Drools. sorry).
>
> Thanks.
>
>
>
> --
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