10

In our project we have to implement business logic regarding mapping of certain objects to some actions. We will have a series of conditions for specific types of objects to be verified before a certain action finally gets resolved. In other words for 7 types of objects we can have a series of actions ( from out of almost 45 actions).

We were thinking of using Drools to write down the aforementioned rules. Does anyone have some positive / negative experience with using Drools as far as its efficiency is concerned? There is also the jBPM framework that can be used (if I am not mistaken Drools are used there) – anyone is familiar with that framework? Perhaps you have some other ideas of how to solve the problem?

Marcin Grzejszczak
  • 10,624
  • 1
  • 16
  • 32

4 Answers4

8

With regards efficiency, you should have no issues at all with Drools. That sounds like a pretty tiny set of facts and rules to me. The Rete engine on which it is based is almost certainly faster at making decisions than any pile of if-then-else statements you code up yourself. And a particular benefit that I noticed is that response times are extremely predictable.

Obviously all fact models and rules differe, but as an example, the application I'm currently building has hundreds of facts in working memory at any time, and more than 1000 rules. It's able to make decisions about incoming requests in about 20 milliseconds.

The full jBPM framework doesn't sound necessary for what you describe. However, it is good at what it does. For instance there is a process modelling GUI if you're looking to design workflows, and Guvnor can be usable for non-technical rules authors if the technical team puts in some up-front effort on writing DSLs and building decision tables.

For completeness, the main competitors are probably FICO Blaze Adviser or IBM ILog JRules. Generally when it comes to benchmarks those tend to be slightly ahead of Drools, but they are expensive. Admittedly, if you decide to pay for JBoss/RedHat service contracts then it's not much different, but if you're happy to take community support on Drools, then it's free!

Steve
  • 9,270
  • 5
  • 47
  • 61
  • Thank you for your response! We decided to use Drools in our project and we are really happy with it. A very good thing is that we keep our rules in DRL files and we don't have to redeploy the application each time. – Marcin Grzejszczak Feb 13 '13 at 14:57
4

My only concern about Drools is that there is no decent GUI for it that a non-IT business people could really use. Lots of products claim that they do provide such UI but it always turns out to be not really true. So, you have to accept the fact that your development team will end up creating and testing all those rules based on decision tables or some other formats.

Other than that, Drools is a great BRE used by governments, banks and large companies.

Kizz
  • 779
  • 1
  • 10
  • 15
  • 1
    100% true. But, according to the explanation he is giving, maybe a decision table could be a good candidate. If that is the case, rules could be managed by no IT guys with a small amount of pain. – Esteban Aliverti Dec 14 '12 at 15:07
  • 3
    @EstebanAliverti Theoretically you are absolutely correct. The whole premise of decision tables was to abstract IT from business. In reality this never works, though. I've been dealing with BREs for 15 years, went through all of the big ones. I have never seen a project where business people would create/edit tables with no help.assistance from IT. Format/actions/conditions get changed all the time, new business people come in, etc, etc. – Kizz Dec 14 '12 at 18:21
  • 1
    Thank you for your responses! We decided to use Drools in our project and we are really happy with it. Of course there is a problem with GUI but you can override it by using the decision tables in spreadsheets. I've got a post on it on my blog [link](http://toomuchcoding.blogspot.com/2013/02/drools-decision-tables-with-camel-and.html) – Marcin Grzejszczak Feb 13 '13 at 14:56
  • 1
    There are other open-source tools for decision rules with non-IT people in mind. You can check https://nussknacker.io. The main use cases are real-time marketing and fraud-detection rules. – dswiecki Feb 17 '22 at 15:45
2

Drools is very efficient and fast. But as with any technology & framework it will need an investment to integrate into your project and it is not a magic bullet. You need to consider:

  • How many rules will you have? I would not recommend any rule engine if there is less than 20 rules. It might not justify the effort you will spend for the compexity of adding a rule engine just for 7 objects and 45 actions...
  • Will you need DSL (Domain Specific Language) capabilities? Ie. will non-technical people write rules? IMHO this is not very usable in Drools in comparison to eg. Oracle OPA. But again I have not seen a non-technical person safely tinkering with a rule system yet. Apart from changing values in a decision table.
  • How often will your rules change? If you need a centralised system to manage, version, package, test your rules then Drools Guvnor is a very capable product.
ali köksal
  • 1,217
  • 1
  • 12
  • 19
1

jBPM is not a rule engine, it's a workflow engine. Drools is a rule engine. So Drools is what you're looking for.

Drools and jBPM are companion projects: they integrate really nicely if you need workflows with rules.

Drools is good well JBPM is bit complex as compared to other BPMN engines. I would suggest go for Activiti because it is bit easier and integration of anything say Spring, LDAP etc.; with Activiti is easier. Also you can integrate Drools with Activiti.. so go for Activiti as aworkflow engine and Drools for a rules engine.

Dhaval Shah
  • 9,042
  • 2
  • 14
  • 21