[rules-users] Question about Rete Tree example with NotNode in "Drools JBoss Rules 5.0 Developers Guide"

[Michal Bali]

Hi Tina,

the "address == $address" condition is added to an existing Join node
(accounts contains $account) so the rete tree doesn't change.

Best regards,
Michal

On Thu, Oct 28, 2010 at 11:31 PM, Tina Vießmann
<tviessmann at stud.hs-bremen.de> wrote:
> You're talking about the follwing errata, aren't you?
>
>     rule noCustomerWithLowAccountBalance
>     when
>       $address : Address( addressLine1 == "Rossa Avenue" )
>       not ( $account : Account( balance < 100 )
>             and Customer( accounts contains $account ) )
>     then
>       System.out.println("No customers with low balance in "+ "their
> accounts live at Rossa Avenue");
>     end
>
>     Should be changed to:
>
>     rule noCustomerWithLowAccountBalance
>     when
>       $address : Address( addressLine1 == "Rossa Avenue" )
>       not ( $account : Account( balance < 100 )
>              and Customer( accounts contains $account, address ==
> $address ) )
>     then
>       System.out.println("No customers with low balance in "+ "their
> accounts live in Rossa Avenue");
>     end
>
>
>
> If the new version is correct, why is the condition  "address ==
> $address" still missing in the related figure? Or do I not see something?
>
>
>
>> see book errata at
>> https://www.packtpub.com/support?nid=4009
>>
>> ________________________________________
>> From: rules-users-bounces at lists.jboss.org [rules-users-bounces at lists.jboss.org] On Behalf Of Tina Vießmann [tviessmann at stud.hs-bremen.de]
>> Sent: Wednesday, 27 October 2010 1:24 p.m.
>> To: Rules Users List
>> Subject: [rules-users] Question about Rete Tree example with NotNode in "Drools JBoss Rules 5.0 Developers Guide"
>>
>> Hi,
>>
>> I'm working through the explanations about Rete Trees in chapter 12 of
>> "Drools JBoss Rules 5.0 Developers Guide" on page 264-265. I have a
>> problem in understanding the input of the NotNode.
>>
>> The rule says:
>>       when
>>         $address : Address ( addressLine == "Rossa Avenue" )
>>         not (
>>           $account : Account ( balance<  100 ) and
>>           Customer ( accounts contains $account )
>>         )
>>       then
>>          ...
>>
>> The related figure shows:
>> 1. The Address object being processed and a tuple will be created by a
>> LeftInputAdapterNode.
>> 2. The tuple of 1. will be joined with the Account fact with no
>> constraints (so that there's a tuple of size two?).
>> 3. The tuple of 2. will be joined with the Customer fact with the
>> restriction 'accounts contains $account'. (That results in a tuple with
>> size 3!?)
>> 4. The tuple of 3. will then be processed by a RightInputAdapterNode.
>> 5. The tuple/fact from 3. will be processed using a NotNode together
>> with the Address-tuple from 1.
>>
>> I don't understand while the tuple from 1. will in step 2 be joined with
>> the Account fact. I would have expected something like:
>> 1. // same
>> 2. The Account fact will be processed and a tuple will be created by a
>> LeftInputAdapterNode.
>> 3. The Customer fact will be joined with the Account tuple with the
>> constraint 'accounts contains $address'. Resulting in a tuple.
>> 4. // somehow the tuple from step 3 will be negated and joined with the
>> tuple from step 1.
>>
>> Could anybody explain to me why it's done the way its drawn in the book?
>>
>> Thank you! :)
>> Tina
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>
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