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Activiti + osgi

bhj2

Does anybody already use activiti with OSGI? Was it a good experience?

Best regards!

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Comments

schikkal

We are using activiti engine (not the web tooling) in servicemix/fuse osgi container along with activiti eclipse plugins (for authoring bpmn processes). There may be some corner issues, but for most of our needs for now, it works well. We had to add some glue code around it for spring and deployment configurations, but that is simple. We also added apache karaf (part of servicemix/fuse) shell commands to manage the deployed bpmn defintions and instances (if there is enough interest, we can contribute the karaf commands code to community).

Regards,
-Srinivasan

bhj2

It tried to do it, the JavaDelegate classes I need are found by the classloader but I have the following exception when trying to start a process:

1 sept. 2011 08:46:00 org.activiti.engine.impl.interceptor.CommandContext close<br>GRAVE: Error while closing command context<br>org.activiti.engine.ActivitiException: test.activiti.FormEnginePrepareTaskBean doesn't implement org.activiti.engine.delegate.JavaDelegate nor org.activiti.engine.impl.pvm.delegate.ActivityBehavior<br> at org.activiti.engine.impl.bpmn.helper.ClassDelegate.getActivityBehaviorInstance(ClassDelegate.java:136)<br> at org.activiti.engine.impl.bpmn.helper.ClassDelegate.execute(ClassDelegate.java:110)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationActivityExecute.execute(AtomicOperationActivityExecute.java:40)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationTransitionNotifyListenerStart.eventNotificationsCompleted(AtomicOperationTransitionNotifyListenerStart.java:48)<br> at org.activiti.engine.impl.pvm.runtime.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:52)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:45)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationTransitionCreateScope.execute(AtomicOperationTransitionCreateScope.java:44)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationTransitionNotifyListenerTake.execute(AtomicOperationTransitionNotifyListenerTake.java:61)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationTransitionDestroyScope.execute(AtomicOperationTransitionDestroyScope.java:111)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationTransitionNotifyListenerEnd.eventNotificationsCompleted(AtomicOperationTransitionNotifyListenerEnd.java:36)<br> at org.activiti.engine.impl.pvm.runtime.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:52)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.take(ExecutionEntity.java:326)<br> at org.activiti.engine.impl.bpmn.behavior.BpmnActivityBehavior.performOutgoingBehavior(BpmnActivityBehavior.java:92)<br> at org.activiti.engine.impl.bpmn.behavior.BpmnActivityBehavior.performDefaultOutgoingBehavior(BpmnActivityBehavior.java:49)<br> at org.activiti.engine.impl.bpmn.behavior.FlowNodeActivityBehavior.leave(FlowNodeActivityBehavior.java:44)<br> at org.activiti.engine.impl.bpmn.behavior.FlowNodeActivityBehavior.execute(FlowNodeActivityBehavior.java:36)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationActivityExecute.execute(AtomicOperationActivityExecute.java:40)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationProcessStartInitial.eventNotificationsCompleted(AtomicOperationProcessStartInitial.java:44)<br> at org.activiti.engine.impl.pvm.runtime.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:52)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.pvm.runtime.AtomicOperationProcessStart.eventNotificationsCompleted(AtomicOperationProcessStart.java:44)<br> at org.activiti.engine.impl.pvm.runtime.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:52)<br> at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:481)<br> at org.activiti.engine.impl.persistence.entity.ExecutionEntity.start(ExecutionEntity.java:280)<br> at org.activiti.engine.impl.cmd.SubmitStartFormCmd.execute(SubmitStartFormCmd.java:80)<br> at org.activiti.engine.impl.cmd.SubmitStartFormCmd.execute(SubmitStartFormCmd.java:35)<br> at org.activiti.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)<br> at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)<br> at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:33)<br> at org.activiti.engine.impl.FormServiceImpl.submitStartFormData(FormServiceImpl.java:64)<br> at egovrunnerserver.Activator.start(Activator.java:51)<br> at org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:783)<br> at java.security.AccessController.doPrivileged(Native Method)<br> at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:774)<br> at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:755)<br> at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:370)<br> at org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:374)<br> at org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:1067)<br> at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:561)<br> at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:546)<br> at org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:459)<br> at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:243)<br> at org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:440)<br> at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:227)<br> at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:337)<br>

trademak

Hi,

The exception says it all doesn't it. The FormEnginePrepareTaskBean needs to implement JavaDelegate or ActivityBehavior.

Best regards,

bhj2

Hi,

The exception says it all doesn't it. The FormEnginePrepareTaskBean needs to implement JavaDelegate or ActivityBehavior.

Best regards,

Yes but what is strange is that my class FormEnginePrepareTaskBean implements JavaDelegate.

public class FormEnginePrepareTaskBean implements JavaDelegate {<br><br> private Expression formEngine;<br><br> @Override<br> public void execute(DelegateExecution execution) {<br>&nbsp;&nbsp; execution.setVariable("formEngine",<br>&nbsp;&nbsp;&nbsp;&nbsp; formEngine.getValue(execution));<br> }<br>}

trademak

Ok good to know. I think this may have something to do with the OSGi wrapper.
Can you explain a bit more about your setup. Are you using Apache Karaf for example?
Can you post your example project?

Thanks,

bhj2

I'm using eclipse equinox as osgi container and not Apache Karaf.

I'll post my exemple project this afternoon.
Thank you for your help!

bhj2

Here are my two bundles and my test process. In the bundles you will have to add the necessary libraries(mybatis-3.0.4, activiti-engine-5.7 & h2-1.2.132). Sorry for my test i did'nt do a maven project

Is the project in the form you needed it?

<?xml version="1.0" encoding="UTF-8"?><br><definitions xmlns="<a href="http://www.omg.org/spec/BPMN/20100524/MODEL" rel="nofollow noopener noreferrer">http://www.omg.org/spec/BPMN/20100524/MODEL</a>"<br> xmlns:activiti="<a href="http://activiti.org/bpmn" rel="nofollow noopener noreferrer">http://activiti.org/bpmn</a>" targetNamespace="EGovRunnerProcesses"><br><br> <process id="MyTestProcess" name="MyTest Process"><br>&nbsp; <startEvent id="theStart" activiti:initiator="initiator"><br>&nbsp;&nbsp; <extensionElements><br>&nbsp;&nbsp;&nbsp; <activiti:formProperty id="person" type="string" /><br>&nbsp;&nbsp;&nbsp; <activiti:formProperty id="reason" type="string" /><br>&nbsp;&nbsp; </extensionElements><br>&nbsp; </startEvent><br><br>&nbsp; <sequenceFlow id='flow1' sourceRef='theStart'<br>&nbsp;&nbsp; targetRef='task1' /><br><br>&nbsp; <serviceTask id="task1" name="first task"<br>&nbsp;&nbsp; activiti:class="test.FormEnginePrepareTaskBean"><br>&nbsp; </serviceTask><br><br>&nbsp; <sequenceFlow id='flow2' sourceRef='task1'<br>&nbsp;&nbsp; targetRef='theEnd' /><br><br>&nbsp; <endEvent id="theEnd" /><br> </process><br><br></definitions>

Activiti_OSGI.zip

trademak

Hi,

I made some first steps in testing this. So the projects you uploaded are fine for me to test.
However I need some more time to investigate this. I'll come back to this in a couple of days.

Best regards,

thay

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jupi

I use Felix and activiti version 5.7.
I couldn't use groovy scripts in osgi environment.

Caused by: org.activiti.engine.ActivitiException: Can't find scripting engine for 'groovy'
        at org.activiti.engine.impl.scripting.ScriptingEngines.evaluate(ScriptingEngines.java:66)
        at org.activiti.engine.impl.bpmn.behavior.ScriptTaskActivityBehavior.execute(ScriptTaskActivityBehavior.java:43)
        at org.activiti.engine.impl.pvm.runtime.AtomicOperationActivityExecute.execute(AtomicOperationActivityExecute.java:40)

So i had to fall back to use javascript for scripting of ScriptTasks, although the groovy bundle was started. This was only a minor issue.

More important is that the classes of my bundle or classes from other bundles could not be reached by scripts of my processes.
I wonder if I could somehow specify the class loader of the scripting environment.

Is anybody there who could solve these issues?

trademak

Hi,

I'll be working with the OSGi implementation for the Activiti in Action book in the next days.
Note however that the Activiti OSGi module is mainly tested with Apache Karaf.
And that's what I'll be using for Activiti in Action.
But of course it should also be possible to get it running on Felix.

Best regards,

bhj2

Hi,

I made some first steps in testing this. So the projects you uploaded are fine for me to test.
However I need some more time to investigate this. I'll come back to this in a couple of days.

Best regards,

And do you have the same exceptions?! Any progress?

jupi

More important is that the classes of my bundle or classes from other bundles could not be reached by scripts of my processes.
I wonder if I could somehow specify the class loader of the scripting environment.

I managed to get around this problem by passing an object (actually a service locator) as a variable to the process.

bhj2

Hi,

I'll be working with the OSGi implementation for the Activiti in Action book in the next days.
Note however that the Activiti OSGi module is mainly tested with Apache Karaf.
And that's what I'll be using for Activiti in Action.
But of course it should also be possible to get it running on Felix.

Best regards,

Other question, what about the Activiti in Action book and this OSGI part? When is it going to be published? What will be the content? Will you write about the possibility to add the JavaDelegate classes in OSGI bundles at runtime?

Best regards

trademak

Hi,

I've not been able to work on this as much as I would have liked, but I've made some progress.
I still have to do some work on separating the JavaDelegate classes in separate bundles, so I didn't run into problems yet.

In the Activiti in Action book we'll discuss how to implement Activiti in Apache Karaf and that you can separate the process XML from the Java classes by using different bundles. This will also show hot deployment of a new version of the Java class bundle. The Activiti in Action book is already available in MEAP (which means that chapters will become available during writing). I've made quite some progress in the last weeks and we've 11/15 chapters written already. So I expect that the chapters should be ready in 1,5 month or so. Then the production process @ Manning will start, which also takes around 2 months.

Best regards,

trademak

Hi,

I've an OSGi example working on Apache Karaf. There are a number of pitfalls that I encountered while implementing the examples.
But you find the source code at the Activiti in Action google code repository: http://code.google.com/p/activitiinaction/ in the book-osgi-app project.

Best regards,

bhj2

Hi,

I've an OSGi example working on Apache Karaf. There are a number of pitfalls that I encountered while implementing the examples.
But you find the source code at the Activiti in Action google code repository: http://code.google.com/p/activitiinaction/ in the book-osgi-app project.

Best regards,

Thank a lot. I didn't look at the code yet but it sounds very interesting!

About the Activiti in action book, we only found the 7 first chapters in MEAP. Arn't the chapters 8-11 available yet?

Best regards!

trademak

Hi,

There's a big update coming up for the Activiti in Action MEAP, which includes a rewrite of all chapters to Activiti 5.7 and the addition of chapter 11 + 12 (ESB and Rules).
We are working very hard on the remaining chapters, so you can expect new chapters arriving very soon.

Best regards,

kaech

More important is that the classes of my bundle or classes from other bundles could not be reached by scripts of my processes.
I wonder if I could somehow specify the class loader of the scripting environment.

I have the same problem using the OSGi-Activiti bundle from the Activiti in action book. Activiti is running a simple process including a ScriptTask. The ScriptTask does:

def customer = new org.mytypes.Customer();

At runtime GroovyScriptEngineImpl.eval it complains that the Customer class can not be found.

Using a ServiceLocator might be an option to solve the problem, although it would be nicer if Activiti could resolve and create the types without such an intermediary.

Another option would be a dynamic import on the Groovy-OSGI-bundle, but this doesn't seem to be a good idea cause it weakens the strict class loading mechanism in OSGi.

What would be the best way to provide the custom types to Activiti?
Suggestions would be welcome.

trademak

Hi,

In my example I show how you can invoke Java service tasks deployed in a seperate bundle from your process definition.
You're absolutely right that the Script task is not working. This has to do with the script task implementation and the OSGi classloading.
So for now you can use the Java service task approach with OSGi.

Best regards,

kaech

Thanks for the quick response!

kaech

Tijs,

using ServiceTasks basically works.
But I have problems with custom data types which are required in our enterprise scenario.

This is my process:

<process id='businessProcess' name='Business process'>
    <startEvent id='start' />
    <sequenceFlow id='flow1' sourceRef='start' targetRef='serviceTask1'/>
    <serviceTask id='serviceTask1' activiti:delegateExpression='${taskBean1}'/>
    <sequenceFlow id='flow2' sourceRef='serviceTask1' targetRef='serviceTask2'/>
    <serviceTask id='serviceTask2' activiti:delegateExpression='${taskBean2}'/>
    <sequenceFlow id='flow3' sourceRef='serviceTask2' targetRef='end'/>
    <endEvent id='end'/>
</process>

In taskbean1 I create a custom object like this:

public void execute(ActivityExecution execution) throws Exception {
Customer customer = new Customer();
customer.setName("Max");
execution.setVariable("customer", customer);
}

In taskbean 2 I try to read the custom object like this:

public void execute(ActivityExecution execution) throws Exception {
Customer customer = (Customer) execution.getVariable("customer");
System.out.println("Customer name is " + customer.getName());
}

The taskbeans reside in a task bundle as shown in your Example.
When I run this process I get an exception from Activiti saying that the Customer object is unknown.

org.activiti.engine.ActivitiException: couldn't find type for org.mytypes.Customer@c6d2a0
at org.activiti.engine.impl.variable.DefaultVariableTypes.findVariableType(DefaultVariableTypes.java:62)
at org.activiti.engine.impl.persistence.entity.VariableScopeImpl.createVariableLocal(VariableScopeImpl.java:212)
at org.activiti.engine.impl.persistence.entity.VariableScopeImpl.setVariable(VariableScopeImpl.java:164)
at net.pleus.sbp.process.code.JavaTask.execute(JavaTask.java:14)

Actually that is what I expected, cause the Customer type is only visible in the bundle containing the tasks not in the Activiti bundle.

A solution would be to use only standard types (int, string, etc.). But this would be a great limitation as typical enterprise applications need to use custom complex datatypes.
Another option might be to add a dynamic import to the Activiti-OSGi-bundle.
What do you think? What would be the best way to go?

trademak

Hi,

Right that's not very elegant.
I'll have a look into this and how we can improve it in the Activiti OSGi module.

Best regards,

kaech

There is another issue.
I slightly modified the example from above and used plain strings as variables like this:

taskbean1:

public void execute(ActivityExecution execution) throws Exception {
execution.setVariable("customer", "Max");
for(String name: execution.getVariableNames()){
System.out.println("TaskBean1-Variable=" + name);
}
execution.takeAll(execution.getActivity().getOutgoingTransitions(),Collections.singletonList(execution));
}

taskbean2:

public void execute(ActivityExecution execution) throws Exception {
for(String name: execution.getVariableNames()){
System.out.println("TaskBean2-Variable=" + name);
}
String customer = (Customer) execution.getVariable("customer");
System.out.println("TaskBean2-Customer name is " + customer);
execution.takeAll(execution.getActivity().getOutgoingTransitions(),Collections.singletonList(execution));
}

When I execute the process the following is dumped on the console:

TaskBean1-Variable=Max
TaskBean2-Customer name is null

It seems that variable customer is properly written in TaskBean1 but not available in TaskBean2.
How can that be? Do you have any suggestions what could be wrong here?

trademak

Hi,

I've committed updates to the activiti-osgi and activiti-engine modules to make a deployment on Apache Karaf work out-of-the-box without additional coding.
The OSGi example of Activiti in Action is changed accordingly.
You now can run script tasks on the Apache Karaf container and you can add JavaBean variables like Customer.
You don't have to implement the ActivityBehavior interface no longer, you can now use the easier JavaDelegate approach.

Best regards,

kaech

I updated everything according to the current book example and built Activiti 5.8-SNAPSHOT to get the latest version.
Now the customer string variable is passed from taskBean1 to taskBean2.

But I still can't use our custom Customer type neither in the Groovy script nor in the JavaDelegate classes.
The Customer class can not be found.
Am I missing something? What did you change to make the complex types work?

trademak

Hi,

But my example includes a Customer object, did you check that?
Does your object implements Serializable?

Best regards,

kaech

Now it works. I can create Customers in Groovy and JavaDelegates and consume them in other JavaDelegates later in the process.

But when I update the bundle containing the Customer type I get an exception in the JavaDelegate at the following line

Customer customer = (Customer) execution.getVariable("customer");
Error executing command: org.mytypes.Customer cannot be cast to org.mytypes.Customer.
The customer variable was created in a ScriptTask using Groovy.
When I create the Customer object in a JavaDelegate it works.

Any ideas?

Another question. I have subscribed to Activitiinaction MEAP. Where can I find the information about Activiti + OSGi?

trademak

Hi,

Did you uninstall the previous bundle and install the new version? Or did you just install the new version bundle?
The Activiti + OSGi chapter will become available over the next weeks. I'm currently finishing writing it.

Best regards,

kaech

I tried different options:

update
stop / start
uninstall / install
none of them works.

Only when I shutdown and restart Karaf it works.