Got it to work J Actually I was inserting the RAM facts in a different “knowledge session” .. which was causing the “collect” to return no record .. anyways. Thanks for you help J

Regards,

Abhay Chaware

P Please consider the environment before printing this e-mail

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Michael Anstis
Sent: Monday, May 09, 2011 4:27 PM
To: Rules Users List
Subject: Re: [rules-users] FW: Basic rules question

Yes :)

2011/5/9 Abhay B. Chaware <Abhay.Chaware@kpitcummins.com>

Mike,

What I meant was, There are say 10 objects of RAM in memory whose type is DDR. Now my “Product” object has a member variable named “compatibleRAMs”, and I would like to set an arraylist containing these 10 objects to the “compatibleRAMs” variable of “Product” object in memory.

I am reading about the “collect” which can be used to create collections from fact objects in memory. Something like.

When

$prod : Product (type==’laptop’)

$compatibleRAMs : ArrayList() from collect (RAM (type == ‘DDR’))

Then

$prod.setCompatibleRAMs($compatibleRAMs);

Am I on the right track ?

-abhay

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Michael Anstis
Sent: Monday, May 09, 2011 3:52 PM
To: Rules Users List
Subject: Re: [rules-users] FW: Basic rules question

Abhay,

Do you need a list?

You can assign RAM to COMPUTERS with this:-

when
    $c : Computer( $type : type )
    $r : RAM( compatibleWith == $type )
then
   $c.addRAM( $r );
end

This would add all RAM (in Working Memory) compatible with COMPUTER to computer.

You could use a list of RAM as a Fact in WM and change your rule to use that:-

when
    $l : MyList( )
    $c : Computer( $type : type )
    $r : RAM( compatibleWith == $type ) from $l
then
    $c.addRAM( $r );
end

Or you can define a rule to construct the list too:-

when
    $l : MyList( $t : typeRAM )
    RAM( $c : $t )
then
    $l.add( $r )
end

I assume you'd need to differentiate different lists for different types; so I have shown use of "MyList" which could subclass ArrayList and have a "Type of RAM" attribute. Drools doesn't "do" generics.

With kind regards,

Mike

2011/5/9 Abhay B. Chaware <Abhay.Chaware@kpitcummins.com>

Wendy,

Thanks for helping me out so far.

I have another question. What if I have all my “RAM” objects inserted into working memory. How should I write my rule’s “when” portion to get a collection of all the RAM objects matching type “DDR” ? In other words, can I get collection of facts assigned to a variable and use it in the “then” part ?

Thanks

Abhay

==================================

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Wendy Mungovan
Sent: Friday, May 06, 2011 5:47 PM
To: Rules Users List
Subject: Re: [rules-users] Basic rules question

Q2:
So the rule would be something like:

rule "RAM type"
when
     $product: Product(type == "laptop");
then
     //you are looking for the best way to set valid RAM types in the then part of the rule?
    $product.setRamType("DDR");
    //or
   $product.setValidRamOptions( getValidRamOptions("DDR"));
end

where getValidRamOptions would be a custom function included through 'import function' so you can then load the choices from some where else. Or if RamOptions were an object in memory you could have a rule like:

rule "RAM type"
when
     $product: Product(type == "laptop");
     $ramOptions: RAMOptions(type == "DDR");

then
   $product.setValidRamOptions( $ramOptions.getList());
end

Wendy

==================================

Regards,

Abhay Chaware

P Please consider the environment before printing this e-mail

Abhay,
Q1: I think that this will depend on how many different products you have. If there is a small number it is more straight forward to have a rule for each one (so the 2nd option). This allows all you logic to be in one place. If there are a large number of products and writing a rule for each one is intractable you probably would want to look into some generalizations of the rules. Is that helpful?

Q2: I'm not quite sure what you are getting at in Q2. Are you trying to write validation rules or rules that are modifying the facts?

Wendy

From: Abhay B. Chaware <Abhay.Chaware@kpitcummins.com>
To: "rules-users@lists.jboss.org" <rules-users@lists.jboss.org>
Sent: Fri, May 6, 2011 4:59:46 AM
Subject: [rules-users] Basic rules question

I am a newbie to rule based applications and trying to get the concept of rules. I have couple of questions about rules to start with, not specifically about Drools though.

Q1 - Should rules be data/model specific or can/should they be generic or both

==========================================================

e.g.

If selected product “TYPE” is “laptop”, then category “RAM” should have all “DDR” type items compatible ( selecting items matching certain property )

If selected product is “IBM T42”, then category “RAM” should have “512MB DDR” , “1024MB DDR”, “2048MB DDR” compatible. ( assigning individual items in rules )

Combination of both

Q2 – How should be the data modeled in above case

==========================================================

e.g.

in product master, each item ( e.g. T40, T42 ) should have a “TYPE” ( e.g. desktop or laptop ) , all items in category “RAM” should have a “TYPE” ( e.g. DDR ) and then control the assignment of RAM options to the PRODUCT through Rule using “DDR” type ?

in product master, each item ( e.g. T40, T42 ) should have a “TYPE” ( e.g. desktop or laptop ) , all items in category “RAM” should have a “compatibleProduct” column ( e.g. desktop or laptop ) and control the assignment of RAM to PRODUCT through “dynamic” rules by selecting all the RAMs by passing the “TYPE” of the product to the database handler.

Am I making my point clear ?

Thanks

Abhay

This message contains information that may be privileged or confidential and is the property of the KPIT Cummins Infosystems Ltd. It is intended only for the person to whom it is addressed. If you are not the intended recipient, you are not authorized to read, print, retain copy, disseminate, distribute, or use this message or any part thereof. If you receive this message in error, please notify the sender immediately and delete all copies of this message. KPIT Cummins Infosystems Ltd. does not accept any liability for virus infected mails.

_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users