The more complex your problem gets, more technologies you will need to employ to solve it properly. Indeed Drools does not work "directly" with persistent storages, because its focus is on the efficient processing of business rules, processes and events, delegating the management of persistent and historical data to specialized tools (all kinds of databases, caches, etc). But Drools integrates with them by several different means, including pulling data from them on demand.

I suggest you watch the presentation "Drools and Large Data Sets" by Alexandre Porcelli, at the bootcamp in Argentina back in June: http://blog.athico.com/2011/08/drools-jbpm5-sessions-argentina-june.html . The solution is obviously tailored to the problem in question (constantly dealing with 30 million rows of historical data with high performance if I remember correctly), as any solutions for any major problems are. In other words, using each tool for what they do best and build the puzzle from there.

Regarding your second point, my understanding is that it has nothing to do with Drools per se. Does not matter if you implement your rules in Drools, in Java, or any other technology/language, you will have the same mapping problem. Solutions for that include a translator for the rules as you mentioned, or a translator for the data (smooks is a good open source one), or even use an adapter fact model that allows rules to work under the user friendly model, but execute actions on the engineering model.

Edson

On Fri, Nov 11, 2011 at 5:53 AM, kapokfly <ivan.jiang.ww@foxmail.com> wrote:

Not sure if these are also your questions you might have with the rule engine
adoption, but we have seen 2 showstopper issues for drools adoption in our
organization, or it is just because we are lack of some necessary knowledge.

Issue 1) : pattern match for large data

There are cases in a rule we need find matched records against a large
population of data and perform some actions.

Example:
From 2 millions employee directory, find those belongs to Depart1 and
with salary increased by 10% last year.

Inserting all these employee's data into WorkingMemory is HUGE and
mission impossible, we can't simply load the entire db into the working
memory, do we have any other approach to accomplish or this is just not a
use case can be resolved by a rule engine?

Issue 2): Map business object to real engineering implementation

What we are trying to do is to build a rule UI which a business user without
engineering background of our codebase can work with; the business object we
show on the UI might be different with the real engineering objects already
in system, for example, on the UI a user might be able to able to see
something like person.address.addressLine1 but the actually implementation
might not be an object traverse implementation.

Example, the model could be Long Person.addressId ; then referring to his
address we need another lookup and we want to hide such complexity to the
end user.

The approach we took is to design a translation layer to translate the user
input to drools rule string, is this the right approach?

If not, any suggestions? I know Drools is mainly designed for developers but
just trying to see if there is any way we can work it around.

Thanks and looking forward to your recommendations.

Ivan

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Ivan, your Panda, forever
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Edson Tirelli
JBoss Drools Core Development
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