[rules-users] Design Question

[Anstis, Michael (M.)]

Is this not a more viable solution?

Global HibernateFacade hibernate;

Rule "free food"
    when
       $food: Food() from hibernate.getFoodForTheDay()
       $person: Person( favouriteFood == $food )
    then
       System.out.println( $person.getName() + " gets a hamburger" );
End

Where HibernateFacade is a façade for using Hibernate named queries?

-----Original Message-----
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of bchrist2
Sent: 24 January 2008 19:02
To: rules-users at lists.jboss.org
Subject: Re: [rules-users] Design Question


That makes sense. 
So,  if you have a rule with 2 different requirements (changes daily versus
yearly ) 

if a persons favourite food is equal to the free food (for the day  .changes
once per day) then you would load it into the working memory as a fact 

BUT if for the same rule 
if a persons favourite food is equal to the free food (for the day which is
basically immutable..changes once per year) then you would load it into the
global list. 
 




Mark Proctor wrote:
> 
> Christie, Blair wrote:
>>
>> Does anyone have any examples of using  the new 'from' element it is 
>> now common to pass a Hibernate session as a global, to allow 'from' to 
>> pull data from a named Hibernate query.
>>
>>  
>>
>> Would it be good design to store the values for a condition in a 
>> database so they can be changed without having to go into the .drl file?
>>
>>  
>>
>> i.e.
>>
>> So instead of ..
>>
>>  
>>
>>  Rule "free food"
>>
>>     when
>>
>>         Food( $food : name == "hamburger" )
>>
>>         $: Person( favouriteFood == $food )
>>
>>     then
>>
>>         System.out.println( $person.getName() + " gets a hamburger" );
>>
>>     End
>>
>>  
>>
>> You would have
>>
>>  
>>
>> global Food food //where food is inserted as a global but populated 
>> from a db.
>>
>>  
>>
>> Rule "free food"
>>
>>     when
>>
>>        $food : food
>>
>>         $person: Person( favouriteFood == $food )
>>
>>     then
>>
>>         System.out.println( $person.getName() + " gets a " + 
>> $food.getName() );
>>
>>     End
>>
>>  
>>
>> Cheers,
>>
>>  
>>
>> Blair
>>
> No that isn't good, due to indexing. If $food changes value without the 
> engine knowing about it, then you get a memory leak. So you have to 
> assert the value. Globals really are for immutable vars or containers to 
> collect results.
>>
>>  
>>
>>  
>>
>> ------------------------------------------------------------------------
>>
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>>   
> 
> 
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> 
> 

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