[rules-users] advice is needed: rule based processing ofinter connected facts
Edson Tirelli
tirelli at post.com
Fri Feb 2 17:08:34 EST 2007
Vlad,
That's what the engine does... it's like SQL. Imagine you have an
"Account" table that has a "number" field. You could write a SQL like:
select * from account a
where (number % 10) < 5
and number < 9000
and 0 = (select count(*) from account b where b.number =
(a.number+1000) )
I'm writing it from my head, so there may be syntax errors... :) but
I think you got the idea.
You don't say write an algorithm saying:
"for each record in account table..."
The SQL engine iterates the table for you.
The same happens with Rule Engines. In the case of JBoss Rules,
instead of tables, you have classes (Account). Instead of columns, you
have class attributes (number).
If you write a rule like this:
rule "missing accounts"
when
$a : Account( $number : number -> ( $number % 10 < 5 ), number < 9000 )
not Account( number == ( $number + 1000 ) )
then
// $a does not have a matching primary account
end
You are saying the engine to iterate over all Account instances, and
for each of them bind the variable and apply constraints, and when a
full match is found, the consequence is executed.
[]s
Edson
Olenin, Vladimir (MOH) wrote:
>Hi, Edson,
>
>I was going through your rule sniplets and I couldn't understand very well
>one thing:
>
>-------------
>when
> $a : Account( $number : number -> ( number % 10 < 5 ), number < 9000 )
> not Account( number == ( $number + 1000 ) ) then
>-------------
>
>The 'number' variable refers to the 'fact' in the working memory, correct?
>Basically it means I have only one particular number to compare ALL accounts
>(from the data sheet) with?
>
>If so, it's not what I actually need to achieve. I need to compare all
>accounts with 'each other', all of them coming from the same data sheet. So,
>I guess it has to be an iteration through all the facts, comparing each fact
>with every other one.
>
>Or is the sniplet above does exactly that? Ie, iterating through all the
>facts?
>
>In other words, I'd be initializing working memory ONLY with the facts
>below:
>
> for (Iterator it = accountsFromDataSheet.iterator(); it.hasNext(); ) {
> Account account = (Account)it.next();
> workingMemory.assertObject(account);
> }
>
>After which the rules must operate on the facts loaded...
>
>Thanks.
>
>Vlad
>
>
>-----Original Message-----
>From: rules-users-bounces at lists.jboss.org
>[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Edson Tirelli
>Sent: 02 February 2007 11:13
>To: Rules Users List
>Subject: Re: [rules-users] advice is needed: rule based processing ofinter
>connected facts
>
> Hi Vlad,
>
> This is a case where you can apply business rules with good results.
> In the end, it all depends on how you model your Business Objects,
>but lets get some examples:
>
>
>
>>1) for all primary accounts 'zxxy' where y < 5, there should be a matching
>>primary account '(z+1)xxy'
>> - [this one is true for the dataset above]
>>
>>
>
> My understanding is that you are validating your accounting plan, so
>you may have an Account object in your model. So, if you want to report
>inconsistencies, you can do something like:
>
>rule "missing accounts"
>when
> $a : Account( $number : number -> ( number % 10 < 5 ), number < 9000 )
> not Account( number == ( $number + 1000 ) )
>then
> // $a does not have a matching primary account
>end
>
> Please, note that the "formulas" I used above may not be the best way
>to do it... they are only a possible representation of what you said.
>
>
>
>>2) sumOfDebit(primary + matching_primary + secondary_account) -
>>sumOfCredit(primary + matching_primary + secondary_account) must be = 0
>> - [this one is also true]
>>
>>
>
> Here, it seems you are refering to a set of transactions, so you
>might have a set of transaction objects to represent the transaction in
>your sample. So, a possible representation would be:
>
>rule "transaction consistency"
>when
> Transaction( $id : id )
> $credits: Double( )
> from accumulate( TransactionEntry( id == $id, operation ==
>"credit", $amount : amount ),
> init( double balance = 0 ),
> action( balance += $amount ),
> result( new Double( balance ) ) );
> $debits: Double( )
> from accumulate( TransactionEntry( id == $id, operation ==
>"debit", $amount : amount ),
> init( double balance = 0 ),
> action( balance -= $amount ),
> result( new Double( balance ) ) );
> eval( ! $credits.equals( $debits ) )
>then
> // inconsistency for transaction $id
>end
>
> Again, this is not the only way or the best way... it is just an example.
>
> Also, for the above examples, I used syntax/features of the jbrules
>3.1 version.
>
> Hope it helps.
>
> []s
> Edson
>
>
>Olenin, Vladimir (MOH) wrote:
>
>
>
>>Ok, approx data set:
>>
>>Primary Account | Secondary Account | Operation | Amount | Type | Owner
>>------------------------------------------------------------------------
>>0001 | | debit | 100 | A | M
>>1001 | | credit | 80 | A | F
>>1001 | | credit | 20 | X | F
>>0002 | 2002 | debit | 50 | B | M
>>2002 | | dedit | 20 | B | M
>>1002 | | credit | 70 | C | M
>>
>>Rules:
>>
>>1) for all primary accounts 'zxxy' where y < 5, there should be a matching
>>primary account '(z+1)xxy'
>> - [this one is true for the dataset above]
>>2) sumOfDebit(primary + matching_primary + secondary_account) -
>>sumOfCredit(primary + matching_primary + secondary_account) must be = 0
>> - [this one is also true]
>>3) OwnerOf (primary_account, matching_primary, secondary_account) must be
>>
>>
>of
>
>
>>the same gender
>> - [this one is false - 0001 owner must be 'F']
>>
>>.... The kind of the rules above... The dataset is more complex and the
>>rules are a bit more involved, but this should give an idea.
>>
>>Thanks for all suggestions!
>>
>>Vlad
>>
>>-----Original Message-----
>>From: rules-users-bounces at lists.jboss.org
>>[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Michael Rhoden
>>Sent: 01 February 2007 17:49
>>To: 'Rules Users List'
>>Subject: RE: [rules-users] advice is needed: rule based processing
>>ofinterconnected facts
>>
>>Can you post a couple of example conditions with a dataset you want to
>>check?
>>
>>-Michael
>>
>>-----Original Message-----
>>From: rules-users-bounces at lists.jboss.org
>>[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Olenin, Vladimir
>>(MOH)
>>Sent: Thursday, February 01, 2007 4:04 PM
>>To: rules-users at lists.jboss.org
>>Subject: [rules-users] advice is needed: rule based processing
>>ofinterconnected facts
>>
>>Hi,
>>
>>
>>
>>I need some pointer as to where to start with the problem below.
>>
>>
>>
>>The system should be able to validate the balancing data based on around
>>
>>
>400
>
>
>>different rules. To simplify the task, the data facts are essentially the
>>debit/credit transactions on different accounts. The rules describe the
>>correlation between different facts:
>>
>>- eg, all debit transactions minus all credit transaction must be
>>equal 0
>>
>>- if one account got credited, there should be another account
>>(within the same dataset) which was debited
>>
>>- if there are accounts starting with some letter combination,
>>there also should be
>>
>>- etc
>>
>>
>>
>>In other words, each rule describes
>>
>>- the subset of facts to be analyzed
>>
>>- the rules to be checked against this subset
>>
>>
>>
>>It seems basically like each fact is a set of Account Number, Transaction
>>Type, Transaction Amount information, Secondary Account Number (which
>>sometimes needs to be validated against some other account number within
>>
>>
>the
>
>
>>same data set). But I couldn't find a way to relate between multiple data
>>facts.
>>
>>
>>
>>On one hand rule engine seems to be a good solution in here, but I'm not
>>sure how to deal with 'dynamic selection' of the subset of facts. Can this
>>kind of task be reformulated somehow?
>>
>>
>>
>>Any pointers into the DROOLS documentation or hints on a general approach
>>would be greatly appreciated!
>>
>>
>>
>>Thanks.
>>
>>
>>
>>Vlad
>>
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>>
>>
>>
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>>
>>
>>
>
>
>
>
--
Edson Tirelli
Software Engineer - JBoss Rules Core Developer
Office: +55 11 3124-6000
Mobile: +55 11 9218-4151
JBoss, a division of Red Hat @ www.jboss.com
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