Java Programming Forum - Learn Java Programming - Blogs - Drools http://www.java-forums.org/blogs/drools/ Java Programming Forum - Learning Java easily en Tue, 18 Jun 2013 04:55:00 GMT vBulletin 60 http://www.java-forums.org/images/misc/rss.jpg Java Programming Forum - Learn Java Programming - Blogs - Drools http://www.java-forums.org/blogs/drools/ Drools Components http://www.java-forums.org/blogs/drools/998-drools-components.html Sun, 04 Mar 2012 08:57:14 GMT 1. *Rules* – Where conditions are specified (If a then b) 2. *Facts* – Simple objects (POJOs). E.g, a Bank Account fact consists of an account... 1. Rules – Where conditions are specified (If a then b)
2. Facts – Simple objects (POJOs). E.g, a Bank Account fact consists of an account number, someone’s id and balance.
3. Knowledge Base –is where rules are built and loaded into a structure that gets implemented by the Rete algorithm.
4. Session – Here facts are placed. Facts are inserted into a session. A session can be State less or State full. Facts in the statefull shall be present in a constant rule alignment once they are inserted.
5. Activation – It might be a rule’s “then” part. When you find a rule to be true then place Agenda into activation. It shall be noticed that all the activations are only placed in Agenda.
6. Agenda –Activations wait to get fired in agenda. For state full sessions, all rules are being fired. Once a fact is inserted all of the activations are placed in agenda, already. When fire rules of session are called explicitly the execution of activations take place. When activation gets executed once facts might be update or retracted that may place new activations in agenda. New activations will be fired by the Drools engine until the agenda gets empty.

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Drools Components
 ]]> Drools http://www.java-forums.org/blogs/drools/998-drools-components.html How is JBoss Drools is made up http://www.java-forums.org/blogs/drools/997-how-jboss-drools-made-up.html Sun, 04 Mar 2012 08:54:37 GMT There are 2 main parts of Drools:

Authoring & Runtime

Creation Rules files (.DRL) are involved in authoring process. They consists of rules that are being fed to a parser. Correct syntax of rules is checked by parser which creates intermediate structure so that to describe certain rules. Then it is passed on to Package Builder that creates the packages. After this, any code generation as well as compilation is undertaken that is essential to create package.

RuleBase, being a runtime component is built from 1 or more then 1 packages. At any time, more than one working memories could be instantiated by the RuleBase. Numbers of sub components are present in working memory which includes Truth Maintenance system, Working Memory Event Support & Agenda and Agenda Event Support. ]]> Drools http://www.java-forums.org/blogs/drools/997-how-jboss-drools-made-up.html Why using a Rule Engine ? http://www.java-forums.org/blogs/drools/996-why-using-rule-engine.html Sun, 04 Mar 2012 08:53:11 GMT Rule systems are able to solve hard problems by providing the detail of the arrival of the solution and also why every decision was been taken along... Rule systems are able to solve hard problems by providing the detail of the arrival of the solution and also why every decision was been taken along the way.

Major benefits of Rule Engine are:

Logic & Data Separation
To break down the domain objects from business rules could make it possible to easily maintain the application. This is possible because it may shield from the future alterations.

Speed & Scalability
Several times, “if” condition is applied this is not actually needed. The Rete algorithm makes the replacement of all “ifs”…(as implemented by Drools) and then statements along with a network that is optimized.

Knowledge Centralization
Repository of knowledge is created by using the rules. For business policy, it could be the single point of truth. Rules are ideally so readable that they might serve the purpose of documentations.

Tool’s Integration
To write the rules actually means to be accustomed to the Rule debugging, validation and language. Eclipse is found to give an excellent delivery tool which tests your rules. ]]> Drools http://www.java-forums.org/blogs/drools/996-why-using-rule-engine.html Drools Components and Terminology http://www.java-forums.org/blogs/drools/995-drools-components-terminology.html Sun, 04 Mar 2012 08:51:30 GMT Objects used by the Drools are market out by the rules and patterns which are responsible for invoking the certain actions: * Drool objects are... Objects used by the Drools are market out by the rules and patterns which are responsible for invoking the certain actions:

  • Drool objects are considered as the Java objects. They are usually presented by the XML schemas or instances of the Java classes.
  • A patter being a coded expression is involved in the manipulation of 1 or more than 1 objects so that to create a pattern for making, adapting behavior, according to the designed logic.
  • Working Memory drools stores its objects in working memory.
  • Actions are basically those operations which might alter the working memory.
  • A rule can perform different actions, like:

– Add/remove object, from the working memory
– Modification of an object might take place.
– Execute one method at one of the objects
]]> Drools http://www.java-forums.org/blogs/drools/995-drools-components-terminology.html Advantages of the Drools rule engine http://www.java-forums.org/blogs/drools/994-advantages-drools-rule-engine.html Sun, 04 Mar 2012 08:48:15 GMT Drools rule engine offers these advantages. * It separates conditions and applications * They are present in separated files * Different... Drools rule engine offers these advantages.
  • It separates conditions and applications

  • They are present in separated files
  • Different people groups can modify them
  • After changing a rule, recompilation is not needed. Redeployment is also not needed in the whole application.
  • To control an application’s flow, put rules at one place
  • All the complexed statements can be replaced by rules in an easier or understandable way

  • Rule language is not tough to be learnt.
  • An “Eclipse plug in” makes it an easy task to write down the rules and also makes it possible to look at the RETE tree.
  • Complicated problems are solved by using rules that doesn’t solve the complex algorithms. Rules are easily understandable in comparison to code.

  • Focus is at what, not how, in case of declarative programming.
  • Rules easily solve group of problems
]]> Drools http://www.java-forums.org/blogs/drools/994-advantages-drools-rule-engine.html Drools Overview http://www.java-forums.org/blogs/drools/993-drools-overview.html Sun, 04 Mar 2012 08:46:05 GMT Drools, BRMS i.e. business rule management system consists of a forward chaining inference based rule engine. Correctly, it is called production rule... Drools, BRMS i.e. business rule management system consists of a forward chaining inference based rule engine. Correctly, it is called production rule system which uses enhanced Rete algorithm implementation.
For its business rule engine as well as its enterprise framework, Drools provides support to JSR-94 standard. This is done for maintenance, construction & enforcement of organization’s business policies, services or applications.

Pluggable language implementations are being allowed by the Drools. Now rules are written in Groovy, MVEL, Java and python. Declarative programming is provided by the drools and it is quite flexible to match the problem domain’s semantics with the DSL i.e. domain specific languages through XML, by using a schema that has been define particularly for sake of problem domain. Domain specific languages possess XML elements as well attributes that present the problem domain. ]]> Drools http://www.java-forums.org/blogs/drools/993-drools-overview.html