The easiest way to view drools is as an in memory relational database.
Rules are a type of efficient triggers that as soon as data changes causes actions to
occur in nearly real time. (Sorry for making people cringe with this overly simplified
explanation).
The use case you gave sounds like you are trying to perform a scheduled task which every
so often queries a database to select a category of people to perform some actions on.
This is most likely to be most efficiently done by just doing a sql query to get the
relevant data and processing it in the traditional way, though you may want to use Flow to
manage the perfoming and defining of the actions. Of course if your use case is actually
more complicated than this then you may want either a hybrid approach (a simplified sql
query to produce a superset of who will be effected and then more complex rules to pick
out individual customers with more specific criteria), or CEP approach may work - although
you will need to be careful that your CEP rules don't have the effect of keeping all 6
months worth of data in memory.
Thomas
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-
bounces(a)lists.jboss.org] On Behalf Of bellios
Sent: 09 September 2010 09:28
To: rules-users(a)lists.jboss.org
Subject: Re: [rules-users] Loading facts and memory size limits
In my application I would to model the Customers-Sales domain and I thought
that drools could help me to express a set of rules to capture (or execute
on-demand) some "special" customers (e.g. take the customers which not
have/have bought some products of category X in the last 6 months).
To do this i'm loading the last 6 months sales into WM, afterwards on demand
i execute the rules. This process fails due the memory requirements. I
thought that Drools would use an hibernate/JPA/ or an incremental
mechanisms to load and process the facts.
@Swindells, Thomas: Do you think that it's the right approach?
@Michael Anstis-2: I will try to study in deep the event
processing\CEP\streaming methods.
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