[rules-users] Using Drools as a glorified Hashmap

[John Peterson]

How many match rules do you have?  You could always set a single
"invalid" rule with a low salience (at least lower than your match
rules) that is always true and sets the flag that it is invalid.  Then
put all the rules into the same activation-group so that only one can
fire.  If the invalid flag is set, that means that the 'no match' rule
was the only one that could have fired.  If it matches, the
activation-group will prevent the 'no match' rule from firing....

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Message: 3
Date: Tue, 18 May 2010 02:56:21 -0700 (PDT)
From: djb <dbrownell83 at hotmail.com>
Subject: [rules-users] Using Drools as a glorified Hashmap
To: rules-users at lists.jboss.org
Message-ID: <1274176581461-825851.post at n3.nabble.com>
Content-Type: text/plain; charset=us-ascii


Hi Drools users,

I've got a situation where I've got a list of Drug codes which can only
be
used for certain prescription codes.

The traditional method for implementing this is to simply pre-load the
values in a static Hashmap.  Then if get() returns null, it is not a
valid
combination.  O(1), blazingly fast. 

The issue with using Drools for this, is that Drools can match a code to
a
code, and mark it as valid, but cannot call it invalid, as another rule
may
still be relevant.  Therefore, using Drools for this would require
marking
combinations as valid, and afterwards, doing a linear traversal of the
prescriptions to see if there are any combinations that are not valid.

Is this the case?  I would like to try implement it in Drools just for
the
sake of consistency, but it seems a bit of a hack.

Thanks,
Daniel
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