drools 6.0中的未知KieSession名称（同时尝试将流水添加到现有的maven / eclipse项目） [英] Unknown KieSession name in drools 6.0 (while trying to add drools to existing maven/eclipse project)
问题描述
我没有需要学习流口水或maven（虽然他们是我之前的项目的一部分），足以说我迷失在我想做的事情。
根据我的理解（googling），java类文件根据包名（？）挂钩到规则。这需要处理编译时问题。但是在运行时我看到空指针异常。为了将流口水适应我现有的代码库：I 1）创建helloworld drools项目，成功运行2）将java文件复制到我现有的包中，3）使用正确的包在Eclipse中创建规则文件：FIle-> New-> other - >规则资源; 3）通过右键单击项目将配置文件转换为drools包，并配置 - >转换为drools项目
这一切都负责编译问题，但是我得到以下运行时错误
[main] ERROR org.drools.compiler.kie.builder.impl.KieContainerImpl - Unknown KieSession name：ksession-rules
java.lang.NullPointerException
在main.java.com.harmonia.cbm.afloat.dataaquisition.dql.DroolsTest.main（DroolsTest.java:23）
这是因为从kcontainer返回的ksession为null，并在最后一行抛出空指针异常
KieServices ks = KieServices.Factory.get（）;
KieContainer kContainer = ks.getKieClasspathContainer（）;
KieSession kSession = kContainer.newKieSession（ksession-rules）;
//以上行返回null
消息消息= new Message（）;
message.setMessage（Hello World）;
message.setStatus（Message.HELLO）;
kSession.insert（message）;
已经花了一天多的时间来弄清楚流口水如何工作，以及如何修复。 Pl建议
1）我采取正确的方法将现有项目转换为drools项目。我想要我的代码库的所有现有功能;但是希望为未来的增强添加基于规则的方法。来到以下链接，但不清楚，如果它有助于我的情况
http://drools.46999.n3.nabble.com/Retrofitting-a-project-with-JBoss-Rules-td48656.html
2）任何有用的drools教程，以更好地理解以下3行（除了java文档）
KieServices ks = KieServices.Factory.get（）;
KieContainer kContainer = ks.getKieClasspathContainer（）;
KieSession kSession = kContainer.newKieSession（ksession-rules）;
3）解决空指针异常的任何提示（假设我采取正确和简单的转换方法现有项目进入流水项目）
更新
@David：感谢详细的帖子。我意识到，将现有项目转换为maven项目，同时工作，并没有吸引我，因为现有的目录结构/命名被保留（很可能不同于maven默认创建的）。我发布了替代解决方案，我认为这个问题与类路径问题有关 http://drools.46999.n3.nabble.com/Null-pointer-exception-when-adding-drools-to-existing-project-td4027944.html# a4028011
我遇到类似的问题。
我认为这个问题的一部分是试图生活在这两个世界。 JBoss Drools eclipse插件世界和maven世界。
我有安装了各种Jboss / Drools插件的Eclipse 4.3.1（Kepler）。
我采取了一个工作的日食示例，并确保我可以在maven中运行它。
- 创建一个演示流口水项目文件 - >新建 - >其他..-> Drools-> Drools项目
- 确保您可以运行测试程序DroolsTest
- 将项目转换为maven项目 - 配置 - >转换为Maven项目
（这将创建一个具有许多依赖关系的pom.xml文件，可以是prunes） - 从构建中删除Drools库路径 - 在项目属性中构建路径 - >库 - 选择Drools库并单击删除
- 禁用Drools构建器 - 在项目属性中构建器 - >取消选中Drools Builder
- 从pom.xml中注释出依赖关系jsr94（不可检索）
- 从命令行mvm clean install运行maven。
这应该给你一个完全从Maven构建和运行的项目。
添加到您的pom.xml
< plugin>
< groupId> org.codehaus.mojo< / groupId>
< artifactId> exec-maven-plugin< / artifactId>
< version> 1.2.1< / version>
< / plugin>
和
<依赖性>
< groupId> org.slf4j< / groupId>
< artifactId> slf4j-simple< / artifactId>
< version> 1.7.2< / version>
< scope>运行时< / scope>
< / dependency>
尝试：
mvn -e exec ：java -Dexec.mainClass =com.sample.DroolsTest
它应该产生：
...
[com.sample.DroolsTest.main（）] INFO org.drools.compiler.kie.builder.impl.ClasspathKieProject - 找到kmodule ：file：/Users/davidbernard/Projects/action-deducing-diff/xx/target/classes/META-INF/kmodule.xml
[com.sample.DroolsTest.main（）] INFO org.drools.compiler .kie.builder.impl.KieRepositoryImpl - 添加了KieModule：FileKieModule [ReleaseId = x：x：1.0file = / Users / davidbernard / Projects / action-deducing-diff / xx / target / classes]
[ sample.DroolsTest.main（）] INFO org.drools.compiler.kie.builder.impl.ClasspathKieProject - Found kmodule：file：/ Users / davidbernard / Projects / action-deducing-diff / xx / target / classes / META-INF /kmodule.xml
[com.sample.DroolsTest.main（）] INFO org.drools.compiler.kie.builder.impl.KieRepositoryImpl - 添加了KieModule：FileKieModule [ReleaseId = x：x：1.0file = /用户/天avidbernard / Projects / action-deducing-diff / xx / target / classes]
Hello World
再见残酷世界
...
您现在还可以从eclipse运行DroolsTest。
您将拥有规则 - > Sample.drl文件和kmodule.xml文件。
<？xml version =1.0encoding = UTF-8\" >？;
< kmodule xmlns =http://jboss.org/kie/6.0.0/kmodule>
< kbase name =rulespackages =rules>
< ksession name =ksession-rules/>
< / kbase>
< / kmodule>
ksession名称应与创建ksession的代码相匹配：
KieSession kSession = kContainer.newKieSession（ksession-rules）;
包应与规则文件所在的目录相匹配。
I am trying to adapt drools6.0 for an existing code base (it is maven project under eclipse). I didnt had need to learn drools or maven before (though they were part of my previous project), suffice to say I am lost in what I wanted to do. Based on my understanding (googling), java class files get hooked to rules based on the package name(?). That takes care of compile time issues. But I am seeing null pointer exception at run time. Inorder to adapt drools into my existing code base: I 1)created helloworld drools project, ran it successfully 2)copied the java file to my existing package, 3)created rule file in Eclipse with correct package: FIle->New->other->Rule Resource; 3)converted existing project into drools package by right clicking project and configure->convert to drools project
This all takes care of compilation issues, but I get following run time error
[main] ERROR org.drools.compiler.kie.builder.impl.KieContainerImpl - Unknown KieSession name: ksession-rules
java.lang.NullPointerException
at main.java.com.harmonia.cbm.afloat.dataaquisition.dql.DroolsTest.main(DroolsTest.java:23)
This is because ksession that is returned from kcontainer is null and throws null pointer exception in last line
KieServices ks = KieServices.Factory.get();
KieContainer kContainer = ks.getKieClasspathContainer();
KieSession kSession = kContainer.newKieSession("ksession-rules");
// above line is returning null
Message message = new Message();
message.setMessage("Hello World");
message.setStatus(Message.HELLO);
kSession.insert(message);
Already spent more than a day trying to figure out how drools works and how above can be fixed. Pl suggest
1) am I taking the right approach to convert existing project into drools project. I want all existing functionality of my code base; but want to add rules based approach for future enhancements. Came across following link, but not clear if it helps my situation http://drools.46999.n3.nabble.com/Retrofitting-a-project-with-JBoss-Rules-td48656.html
2)Any useful drools tutorials in better understanding following 3 lines (besides java docs)
KieServices ks = KieServices.Factory.get();
KieContainer kContainer = ks.getKieClasspathContainer();
KieSession kSession = kContainer.newKieSession("ksession-rules");
3)Any hints on resolving null pointer exception (assuming I am taking the right and easy approach of converting existing project into drools project)
UPDATE @David: thanks for detailed post. I realized that converting existing project into maven project, while works, did not appeal to me since existing directory structure/naming is preserved (most likely different from what maven creates by default). I posted alternative solution where I thought this problem has to do with classpath issues http://drools.46999.n3.nabble.com/Null-pointer-exception-when-adding-drools-to-existing-project-td4027944.html#a4028011
I hit similar problems.
I think that part of the problem is trying to live in both worlds. The JBoss Drools eclipse plugin world and the maven world.
I have Eclipse 4.3.1 (Kepler) with various Jboss/Drools plugins installed.
I took a working eclipse example and made sure I could run it in maven.
- Created a demo drools project File->New->Other..->Drools->Drools Project
- Ensured you could run the test programs DroolsTest
- Converted project to maven project - Configure->Convert To Maven Project (This will create a pom.xml file with many dependencies. These can be prunes)
- Removed the Drools Library from the build path - in the project properties Build Path -> Libraries - select Drools Library and click Remove
- Disable the Drools builder - in project properties Builders -> uncheck Drools Builder
- Comment out dependancy jsr94 from the pom.xml(not retrievable)
- Run maven from the command line "mvm clean install".
This should give you a project that builds and runs entirely from Maven.
Add to your pom.xml
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.2.1</version>
</plugin>
And
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.2</version>
<scope>runtime</scope>
</dependency>
Try:
mvn -e exec:java -Dexec.mainClass="com.sample.DroolsTest"
It should produce:
...
[com.sample.DroolsTest.main()] INFO org.drools.compiler.kie.builder.impl.ClasspathKieProject - Found kmodule: file:/Users/davidbernard/Projects/action-deducing-diff/xx/target/classes/META-INF/kmodule.xml
[com.sample.DroolsTest.main()] INFO org.drools.compiler.kie.builder.impl.KieRepositoryImpl - KieModule was added:FileKieModule[ ReleaseId=x:x:1.0file=/Users/davidbernard/Projects/action-deducing-diff/xx/target/classes]
[com.sample.DroolsTest.main()] INFO org.drools.compiler.kie.builder.impl.ClasspathKieProject - Found kmodule: file:/Users/davidbernard/Projects/action-deducing-diff/xx/target/classes/META-INF/kmodule.xml
[com.sample.DroolsTest.main()] INFO org.drools.compiler.kie.builder.impl.KieRepositoryImpl - KieModule was added:FileKieModule[ ReleaseId=x:x:1.0file=/Users/davidbernard/Projects/action-deducing-diff/xx/target/classes]
Hello World
Goodbye cruel world
...
You should now also be able to run DroolsTest from eclipse.
You will have a rules->Sample.drl file and a kmodule.xml file.
<?xml version="1.0" encoding="UTF-8"?>
<kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule">
<kbase name="rules" packages="rules">
<ksession name="ksession-rules"/>
</kbase>
</kmodule>
The "ksession" name should match the code creating the ksession:
KieSession kSession = kContainer.newKieSession("ksession-rules");
The "packages" should match the directory the rule file is in.
这篇关于drools 6.0中的未知KieSession名称（同时尝试将流水添加到现有的maven / eclipse项目）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
