Re: [droolers] Trying to get a clue.

[bob mcwhirter]

> This is a new area for me ( but exciting! ).

Glad to have you on board!

> I'm experimenting with using drools for filtering datasets.
> 
> In my case so far, I have basically 4 rules with varying parameters.
> 
> One of the rules looks something like this:
> 
> loop over a collection of beans
>  - for each bean check it against the conditions.
> 
> The conditions are name/value pairs with an operation ( >, <, =, etc...)
> Each name may have several values that are ORed together.
> 
> So for example: return true IF name=1 OR 2 OR 3 ... etc.

Would it be possible (maybe inconvenient) to break these into multiple
rules, one for each portion of the condition?

ie;

rule-1:
                name = 1

rule-2:
                name = 2

rule-3:
                name = 3

...etc...

> Also, each rule may have more than one name/value pair.
> And if the number of name/value pairs > 1 then AND them together
> 
> Example:
> 
>    nameX=1 OR 2 OR 3 
>      AND
>    nameY= A OR B OR etc...

I guess this may result in combinatorial explosion, no, using the
method I just prescribed above...

rule-1a:

        nameX = 1
        nameY = A

rule-1b:

        nameX = 1
        nameY = B

... etc ...

> Since the variable data is coming from a database and I've narrowed it down 
> to 4 rules, I figured that the best approach would be to program (using the 
> spi ) the rules rather than XML.

Are you doing it against all things in the database, effectively being
a query?  Are you doing a SELECT * first, creating objects, and then
intending to pass them through drools?

> Can anyone give me a pointer or suggestion on how I can express the above 
> using drools, especially the operators? 

Thus far, I haven't allowed OR expressions in the rules-file syntax,
due to analysis complexities.  Some OR expressions should/will be
allowed, but only those that result in the same 'active' objects,
regardless of which portion of the OR expression matched.

ie, this would be BAD.

        if name="bob" OR age=28

This should be okay:

        name="bob" OR name="billy"

Using the SPI, though, you are not limited to what I've allowed with
the rules-file analysis.  You can do anything you want, including 
a Condition that does OR type expressions internally.  

        -bob


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