Java/AEM: How to trigger an EventListener (javax.jcr.observation.EventListener)?

[jayv25585659]

I'm trying to debug a existing code where it's supposed to trigger when "Event.PROPERTY_CHANGED+Event.PROPERTY_ADDED" events happened but I don't think it's triggering.

Any ideas on how to help debug the code? (I want my breakpoint inside "onEvent" function to stop the execution)

Some info/observations:

• My PDF is located in "/content/dam/files/careers/factsheets/Recruitment-Q-and-A-Factsheet.pdf"
• I inspected the PDF in CRX/DE and this path "/content/dam/files/careers/factsheets/Recruitment-Q-and-A-Factsheet.pdf/jcr:content" has this property "jcr:primaryType=dam:AssetContent".
• If I edit the metadata (example title), the parent path for the attributes/properties is located in "/content/dam/files/careers/factsheets/Recruitment-Q-and-A-Factsheet.pdf/jcr:content/metadata"
• I put a breakpoint in this line "session = commonService.getSession();" and execution stops here when my AEM instance is starting (either starting it up for the first time or restarting the instance). I didn't encounter any errors/exceptions inside "activate" function.
• To test my breakpoint inside the "onEvent" function, I changed the metadata of the PDF. I also tried publishing it. I also manually created 2 new nodes of types "nt:unstructed" and "nt:folder" inside "/content/dam/files/careers" folder (via CRX/DE). None of these actions triggered my breakpoint.
• This is my code

        protected void activate() {
            try {
                session = commonService.getSession(); //this is a custom service created by 3rd party
                
                observationManager = session.getWorkspace().getObservationManager();
                
                final String[] types = { "dam:Asset", "dam:AssetContent", "nt:unstructured", "nt:folder" };
                
                final String path = "/content/dam/files";
                
                final int events1 = Event.PROPERTY_CHANGED | Event.PROPERTY_ADDED | Event.NODE_ADDED;
                
                observationManager.addEventListener(this, events1, path, true, null, types, false);
            } catch(Exception e) {
                log.error("bad stuff happened",e);
            }
        }
        
        
        public void onEvent(EventIterator eventIterator) {
            while (eventIterator.hasNext()){
                Event event = eventIterator.nextEvent();
                
                //insert more code here
            }
        }

[Tanika02]

Hello @jayv25585659  - 

You can additionally try : 

• Adding loggers inside the onEvent method to check if it is being called.
• Additionally ensuring that the commonService.getSession() method returns a valid session. Check if the custom service (commonService) is properly implemented and injected into the component.

could you please also look for possible logging errors in error log?

[jayv25585659]

• Unsure if additional logging would help since I already have a breakpoint in the first line of the function. If the execution is not stopping in the breakpoint, I don't think extra logging will help. BUT I'll try it anyway.
• I clearly mentioned that I debugged "activate" function and no errors/exceptions there. (if session is null, i would get an NPE)

[aanchal-sikka]

Hello @jayv25585659 

Service is Active?

Can you please check, if the Service is Active and (immediate=true) is set on the Listener?

https://medium.com/@toimrank/aem-handler-and-listener-12b6c8b5a3d3

Also, the signature of the activate() is different. Don't know if it matters, as Event Listener is old way of doing things, haven't worked on it for a while.

User has necessary access?

Please check the access levels of the user. If in doubt, add the user to administrators group and try triggering the events

[Sady_Rifat · Accepted solution]

Hello @jayv25585659 ,

If I understand correctly the problem might be in your 

session = commonService.getSession();

The third-party session might not have enough user permission in your content path.

For better and fully proven code you can use a service-user and give that user permission[Read access] on the particular content node. The sample code will be like this,

@Reference 
private SlingRepository repository;

@Activate
protected void activate() {
    Session session = repository.loginService("your-service-user-name", null);
    // Write your logic
}


@Deactivate
protected void deactivate() throws RepositoryException {
    Session session = repository.loginService("your-service-user-name", null);
    try {
        if (observationManager != null)
            observationManager.removeEventListener(this);
    } finally {
        if (session != null) session.logout();
    }
}