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AEM 6.4 upgrade @reference does not work in a workflow

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Level 10

All i have a workflow process step and it references class A that exposes a service, but when i check for the value of A in the process step, it appears to be null,

i am injecting this service A using the @Reference.

1 Accepted Solution

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Correct answer by
Level 10

So Scott, i finally have a response and after consultation and weeks of debugging assuming i was doing something wrong for something that is so simple,

i am asked (by adobe) to avoid using @reference in abstract classes , and this worked on 6.2 and is something that breaks in 6.4, , with bunch of scr annotation errors and components appear to be in satisfied state

Infact abstract keyword for a service at times sets the component to state "16", solution - remove abstract keyword

If you have nested inheritance and a class that is abstract and implement workflowprocess, keep it simple, take off  abstract keyword and avoid inheritance since if  a child class(extending parent class that implements workflow process) is invoked the annotations of the parent class is null, so just keep child class that implements workflowprocess and avoid inheritance where the parent class uses annotation and no abstract keyword.

https://forums.adobe.com/thread/2461255

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16 Replies

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Community Advisor

Hi,

Which annotation are you using Felix or Osgi?

How did you created your service? Are you able to see your service at http://localhost:4502/system/console/services

I created a Demo Process and shared with you which include Reference to my custom service HandleSession and I am able to get the Service reference inside workflow process.

Thanks

Arun



Arun Patidar

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Level 10

I used the OSGI, yes i see the service as well. Sent the code over, its a custom service and not OOTB so i am not sure if that affects anything.

I took off the @Reference annotation and just instantiated the class and it worked fine. i wonder why the annotation would not work within a workflow.

I do see errors as well, could this be related?

[com.adobe.granite.workflow.core.job.ExternalProcessPollingHandler(917)] : Could not get service from ref [com.adobe.granite.workflow.exec.WorkflowProcess]

15.06.2018 20:10:15.785 *WARN* [FelixStartLevel] com.adobe.granite.workflow.core bundle com.adobe.granite.workflow.core:2.0.168 (275)[com.adobe.granite.workflow.core.job.ExternalProcessPollingHandler(917)] : DependencyManager : invokeUnbindMethod : Service not available from service registry for ServiceReference [com.adobe.granite.workflow.exec.WorkflowProcess] for reference WorkflowProcess

15.06.2018 20:10:15.785 *ERROR* [FelixStartLevel] com.test.core bundle com.test.core:1.5.10.SNAPSHOT (1033)[com.test.core.workflows.BaseWorkflowProcess(3632)] :  Error during instantiation of the implementation object: null

15.06.2018 20:10:15.785 *ERROR* [FelixDispatchQueue] com.adobe.granite.workflow.core FrameworkEvent ERROR (org.osgi.framework.ServiceException: Service factory returned null. (Component: com.test.core.workflows.BaseWorkflowProcess (3632)))

org.osgi.framework.ServiceException: Service factory returned null. (Component: com.test.core.workflows.BaseWorkflowProcess (3632))

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Level 10

I also tried @Reference ResourceResolverFactory rrf; and it appears to be null as well, so curious if @reference throws null for some unknown reason>

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Community Advisor

Hi,

Check below article with same kind of issue, something may be wrong with service

Could not get service from ref [javax.servlet.Servlet, javax.servlet.ServletConfig, java.io.Serializ...

Could you please check the sample code to Create Service WorkflowProcess and invoked using @Reference inside Process Step

aem63app-repo/demo at master · arunpatidar02/aem63app-repo · GitHub

Thanks

Arun



Arun Patidar

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Level 10

Will be logging a ticket with Adobe,

Created classes as you've shared and weird issues were noted

1. With @reference annotation, custom workflow process  (java)step did not appear in the dropdown  for the workflow

2.Without @Reference annotation, the process step java class was visible.

Avatar

Level 10

What Annotations are you using - DS Annotations or Felix Src annotations.

Post some of your code - including your import statements - that will tell us exactly what you are trying to do. I do not believe using @Reference ins a custom workflow step has an issue.

Avatar

Level 10

Sure thanks i believe i used maven arch 13, but i am attaching the code here

package com.test.core.workflows.general;

public interface DemoWFService {

public String showMessage(String msg);

}

------------------------------------

package com.test.core.workflows.general;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class DemoWFServiceImpl implements DemoWFService {

protected final Logger log = LoggerFactory.getLogger(this.getClass());

String PrefixMessage = "Service Invoked by Workflow -- ";

@Override

public String showMessage(String msg) {

return PrefixMessage+msg;

}

}

------------------------

package com.test.core.workflows.general;

import org.osgi.framework.Constants;

import org.osgi.service.component.annotations.Component;

import org.osgi.service.component.annotations.Reference;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import com.adobe.granite.workflow.WorkflowException;

import com.adobe.granite.workflow.WorkflowSession;

import com.adobe.granite.workflow.exec.WorkItem;

import com.adobe.granite.workflow.exec.WorkflowProcess;

import com.adobe.granite.workflow.metadata.MetaDataMap;

@Component(immediate = false,service= WorkflowProcess.class, property={

        Constants.SERVICE_DESCRIPTION + "=Test.",

        Constants.SERVICE_VENDOR + "=Test",

        "process.label" + "=Test"

})

public class WFProcessStep implements WorkflowProcess {

@Reference

private DemoWFService ws;

    private static final Logger logger = LoggerFactory.getLogger(WFProcessStep.class);

@Override

public void execute(WorkItem arg0, WorkflowSession arg1, MetaDataMap arg2) throws WorkflowException {

    logger.info("********************* WF");

    logger.info("wfff"+ws.showMessage("text"));

}

}

Avatar

Community Advisor

Hi,

*you missed @Component annotation in your service implementation.

below is correct code:you can try with this


package com.test.core.workflows.general;
import org.osgi.service.component.annotations.Component;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@Component
public class DemoWFServiceImpl implements DemoWFService {
protected final Logger log = LoggerFactory.getLogger(this.getClass());

String PrefixMessage = "Service Invoked by Workflow -- ";

@Override
public String showMessage(String msg) {
  return PrefixMessage + msg;
}
}



Arun Patidar

Avatar

Level 10

Thanks Arun, i had that in my workflow, but missed adding it here ..

so here are the updates:

I got a custom workflow to work but the one i was trying didn't work and would not appear in the dropdown in the custom process step

reasons:

1. Class that implements workflow process is marked abstract

Yet to investigate, ..

This worked smooth on 6.2..

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Level 10

Please watch the video - i show all the code and shows it works in 6.4

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Level 10

Yes Scott, that helps, but with the keyword abstract there are issues , so looking into it

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Level 10

In my example - i did not use that. Simply used an interface and the implementation class that uses @Component.

Let me know if you find a solution when that keyword is used (which seems to be causing an issue). 

Avatar

Correct answer by
Level 10

So Scott, i finally have a response and after consultation and weeks of debugging assuming i was doing something wrong for something that is so simple,

i am asked (by adobe) to avoid using @reference in abstract classes , and this worked on 6.2 and is something that breaks in 6.4, , with bunch of scr annotation errors and components appear to be in satisfied state

Infact abstract keyword for a service at times sets the component to state "16", solution - remove abstract keyword

If you have nested inheritance and a class that is abstract and implement workflowprocess, keep it simple, take off  abstract keyword and avoid inheritance since if  a child class(extending parent class that implements workflow process) is invoked the annotations of the parent class is null, so just keep child class that implements workflowprocess and avoid inheritance where the parent class uses annotation and no abstract keyword.

https://forums.adobe.com/thread/2461255