[rules-users] Using Java Rule Engine JSR-94

[Stephen Masters]

JSR-94 is just an API, not an implementation. A bit like if you use JPA, you still need to have an implementation layer such as Hibernate, and DB-specific drivers underneath.

The theoretical benefit is that you should be able to swap rule engine implementations such as Drools, JRules, or Blaze, without changing your API code.

The reality is that most of these rules engines have a lot of functionality additional to the JSR-94 spec, and may not even be a particularly good fit to it. So using the JSR-94 API means that you need to accept a cut-down interface to the rules engine, which prevents you from accessing much of the functionality that you really need.

To evaluate whether it's worth it, take a look at your code. What is the ratio of Drools API code to actual Drools DRL? I'm pretty sure that in any real-world application, re-writing the API code to an alternative platform is trivial in comparison to re-writing all of the rules code.

Steve


On 16 May 2013, at 10:09, abhinay_agarwal <abhinay_agarwal at infosys.com> wrote:

> Hey,
> 
> I read about JSR-94 and found it quite useful, so was trying to do a POC on
> its usage. These are the steps which i followed.
> 
> 1. Made a new java application.
> 2. Added the JSR-94 api jars in its build path.
> 3. Made a rule as myRuleFile.drl
> 4. Wrote a RuleAdapter class as shown in drools expert document Chapter 5.
> The Java Rule Engine
> API (JSR94).
> 
> But when i tried to run the piece of code, it kept giving me errors related
> to Class missing related to drools.
> 
> Are are the drools jar required to run this example,if yes, then what is the
> avantage of using jsr-94 api ?
> 
> If any specific jars, can you please list them out?
> 
> If I am doing anything wrong, then, can you please point me to the correct
> direction.
> 
> Thanks,
> Abhinay
> 
> 
> 
> --
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