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Feature Request
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Resolution: Unresolved
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L3 - Default
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User Story (Required on creation):
As a user, in modeling resources (e.g., on sequence flows), I can define expressions that call methods on a bean.
Functional Requirements (Required before implementation):
E.g., in a sequence flow camunda:expression attribute, I can use the following expression:
${myService.checkCondition('foo')}
Technical Requirements (Required before implementation):
Quarkus ArC does not support the API method BeanManager#getELResolver. Replace it with something else.
Limitations of Scope (Optional):
Hints (Optional):
Right now, only a simple JUEL expression referencing a delegate bean directly can be resolved: ${myDelegateBean}. Referencing a delegate bean via a more complex expression is not possible ${myBean.getDelegateBean()} due to missing support in Quarkus ArC of BeanManager#getELResolver. Let's evaluate if and how we can fix this.
Solution ideas
- Shade de.odysseus.juel into the Quarkus extension like we already do it in the legacy JUEL FEEL Engine.
- Or even cleaner: create a shaded jar containing de.odysseus.juel the DMN legacy FEEL Engine, as well as Quarkus, uses.
- Identify Quarkus environment by catching the UnsupportedOperationException when BeanManager#getELResolver is called in CdiResolver#getWrappedResolver.
- Register the javax.el.BeanELResolver instead.
- Tries to create a ExpressionFactory by looking up the SPI.
- Register an ExpressionFactory SPI in the Qurkus extension pointing to de.odysseus.el.ExpressionFactoryImpl.
- See prototypical implementation (shading is missing): fix-quarkus-el-support.patch.txt
- Wait until Quarkus supports BeanManager#getELResolver
This is the controller panel for Smart Panels app
[CAM-13637] Support JUEL delegate expressions in Quarkus
Even though this feature request is yet not resolved, it is possible to already use the alternative solution by applying the following configurations to your Quarkus Application.
1. Configure the process engine accordingly:
@ApplicationScoped public class MyConfig { @Produces public QuarkusProcessEngineConfiguration customEngineConfig() { return new QuarkusProcessEngineConfiguration() { @Override protected void initExpressionManager() { expressionManager = new ExpressionManager() { protected ELResolver createElResolver() { CompositeELResolver compositeElResolver = new CompositeELResolver(); compositeElResolver.add(new VariableScopeElResolver()); compositeElResolver.add(new VariableContextElResolver()); compositeElResolver.add(new CdiResolver() { protected javax.el.ELResolver getWrappedResolver() { return new javax.el.BeanELResolver(); } }); compositeElResolver.add(new ArrayELResolver()); compositeElResolver.add(new ListELResolver()); compositeElResolver.add(new MapELResolver()); compositeElResolver.add(new BeanELResolver()); return compositeElResolver; } }; this.expressionManager.addFunctionMapper(new CommandContextFunctionMapper()); this.expressionManager.addFunctionMapper(new DateTimeFunctionMapper()); } }; } }
2. Add a JUEL implementation by adding the following dependencies to your `pom.xml` file:
<dependency> <groupId>de.odysseus.juel</groupId> <artifactId>juel-api</artifactId> <version>2.2.7</version> </dependency> <dependency> <groupId>de.odysseus.juel</groupId> <artifactId>juel-spi</artifactId> <version>2.2.7</version> </dependency> <dependency> <groupId>de.odysseus.juel</groupId> <artifactId>juel-impl</artifactId> <version>2.2.7</version> </dependency>
3. Configure a service loader in src/main/resources/META-INF/services/javax.el.ExpressionFactory with de.odysseus.el.ExpressionFactoryImpl
This ticket was migrated to github: https://github.com/camunda/camunda-bpm-platform/issues/2610. Please use this link for any future references and continue any discussion there.
We are heavily reliant on method expressions, so upvoting this for future inclusion.