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From "Claus Ibsen (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ARIES-1010) BlueprintContainer - reload() - no way to know when the reload is fully done
Date Tue, 29 Jan 2013 11:15:12 GMT
Claus Ibsen created ARIES-1010:
----------------------------------

             Summary: BlueprintContainer - reload() - no way to know when the reload is fully
done
                 Key: ARIES-1010
                 URL: https://issues.apache.org/jira/browse/ARIES-1010
             Project: Aries
          Issue Type: Improvement
          Components: Blueprint
    Affects Versions: 1.0
            Reporter: Claus Ibsen
            Priority: Critical


If you have a blueprint application deploy in felix / karaf. Then you can restart the bundle
from karaf shell using
{code}
osgi:restart 123
{code}

Where 123 is the bundle id. This works fine, as it does a fully restart.

If you want to be notified about the starting|stopping in your blueprint application, you
can use the org.osgi.framework.ServiceListener and listen for changes, and wait for the BlueprintContainer
itself to be created/unregistered. For example we use this in Camel to know when we can start
Camel after all the osgi blueprint has been fully started:

We have an init method in a POJO that we ensure blueprint invokes. This allows us to register
our service listener. 
{code}
    public void init() throws Exception {
        LOG.trace("init {}", this);
        // add service listener so we can be notified when blueprint container is done
        // and we would be ready to start CamelContext
        bundleContext.addServiceListener(this);
    }
{code}


Where we listen for the blueprint container to be created, and invoke the maybeStart method
which will start Camel.
{code}
    @Override
    public void serviceChanged(ServiceEvent event) {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Service {} changed to {}", event, event.getType());
        }

        // look for blueprint container to be registered, and then we can start the CamelContext
        if (event.getType() == ServiceEvent.REGISTERED && event.getServiceReference().isAssignableTo(bundleContext.getBundle(),
                "org.osgi.service.blueprint.container.BlueprintContainer")) {
            try {
                maybeStart();
            } catch (Exception e) {
                LOG.error("Error occurred during starting Camel: " + this + " due " + e.getMessage(),
e);
            }
        }
    }
{code}



However if you use the API on ExtendedBlueprintContainer, which is the {{reload()}} method
then it does *not* work the same as the reload command above.

The issue is in particular that we do not get any service listener callbacks. So we cannot
know when the blueprint container has been fully restarted.

On the ExtendedBlueprintContainer there is no API either to get the state, eg a getState method.
If we had that we could potentially "work around" this by having to wait for the state to
be changed to CREATED.

I am not sure if a reload should trigger the BlueprintContainer service to be unregistered/registered
again. Which will fix this for all people. As then a reload works just as stop|start a bundle.

An alternative is that we get some API in blueprint so we can know when the reload is done.
And it would also be nice to have the getState method on the ExtendedBlueprintContainer.


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