[jboss-jira] [JBoss JIRA] (DROOLS-2284) Implement an executable model for drools and a java dsl to instance it

[Mario Fusco (JIRA)]

    [ https://issues.jboss.org/browse/DROOLS-2284?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13537507#comment-13537507 ] 

Mario Fusco commented on DROOLS-2284:
-------------------------------------

The purpose of the executable model is to provide a pure Java-based representation of a rules set, together with a convenient Java DSL to programmatically create such a model. This model is generic enough to be independent from Drools but can be compiled into a plain Drools knowledge base. For this reason the implementation of the executable model has been split in 2 subprojects:
# *drools-canonical-model* is the canonical representation of a rule set model which is totally independent from Drools
# *drools-model-compiler* compile the canonical model into Drools internal data structures making it executable by the engine
The introduction of the executable model brings a set of benefits in different areas:
* *Compile time*: in Drools 6 a kjar contained, together with some pregenerated classes implementing the constraints and the consequences, the list of drl files and other Drools artifacts defining the rule base. Those drl files needed to be parsed and compiled from scratch, when the kjar is downloaded from the maven repository and installed in a KieContainer, making this process quite slow especially for large rules sets. Conversely it is now possible to package inside the kjar the Java classes implementing the executable model of the project rule base and recreate the KieContainer and its KieBases out of it in a much faster way. The kie-maven-plugin automatically generated the executable model classes from the drl files during the compilation process.
* *Runtime*: in the executable model all constraints are defined as Java lambda expressions. The same lambdas are also used for constraints evaluation and this allowed to get rid of both mvel for interpreted evaluation and of the jitting process transforming the mvel-based constraints in bytecode, resulting in a slow warming up process.
* *Future research*: the executable model will be also an enabler for experimenting with new features of the rule engine without the need of encoding these features in drl format and modify the parser to support them.

> Implement an executable model for drools and a java dsl to instance it
> ----------------------------------------------------------------------
>
>                 Key: DROOLS-2284
>                 URL: https://issues.jboss.org/browse/DROOLS-2284
>             Project: Drools
>          Issue Type: Bug
>          Components: core engine
>            Reporter: Mario Fusco
>            Assignee: Mario Fusco
>




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