CODEWITHSUNDEEP
serviceosgibundleapache-karafosgi-bundle
Ledivin
Ledivin

Reputation: 637

karaf osgi getServiceReference returns null

Does anyone have any experience with getServiceReference returning null for what seems like no reason?

The following bundle registers the service, and then proceeds to confirm that it's registered (whether or not this is even a valid test from the same package, idk).

package db.connector;
...
public class Activator implements BundleActivator {
    private static ServiceRegistration registration;
    ...
    public void start(BundleContext _context) throws Exception {
        DatabaseConnector dbc = new DatabaseConnectorImpl();
        registration = context.registerService(
                DatabaseConnector.class.getName(),
                dbc, null);

        checkServiceRegistered();
    }
    ...
    public void checkServiceRegistered() {
        System.out.println("Printing all entries:");
        ServiceReference sr = context.getServiceReference(DatabaseConnector.class.getName());
        DatabaseConnector dbc = (DatabaseConnector) context.getService(sr);
        List<Protocol> result = dbc.getAllProtocols();
        for(int i=0; i<result.size(); i++) {
            Protocol p = result.get(i);
            System.out.println("\t" + p.getId()+": "+p.getName()+"("+p.getOwner()+")");
        }
    }
}

The output runs successfully, everything seems OK. Checking in the karaf webconsole, the service seems to be registered correctly:

267 [db.connector.DatabaseConnector]    database-connector (144)

The code to get the registered service is as follows:

import db.connector.DatabaseConnector;
    ...
    public List<Protocol> printAllEntries() {
        ServiceReference sr = Activator.getContext().getServiceReference(DatabaseConnector.class.getName());
        DatabaseConnector dbc = (DatabaseConnector) Activator.getContext().getService(sr);
        return dbc.getAllProtocols();
    }
    ...

The DatabaseConnector bundle exports the correct package, and the one using the service imports the same.

What could possibly be going wrong here? I'm at a complete loss.

Upvotes: 1

Views: 2290

Answers (2)

Ledivin
Ledivin

Reputation: 637

Turns out, it was just that I didn't refresh the OSGi bundles. My servlet was pointing to a now-obsolete bundle ID, so of course the service find was failing.

Upvotes: 0

Frank Lee
Frank Lee

Reputation: 2748

It looks alright.

What comes to mind: Is the ordering ok? Are you sure the registration is done before checking the reference? The way you check in printAllEntries you check if the service is there on just that moment. As OSGi bundles can come and go, this isn't a reliable way to check. You should use either a ServiceTracker, or better still something like Declarative Services or Blueprint.

You could add a ServiceListener to the BundleContext, then you can print out what's happening in what order.

Hope this helps.

Upvotes: 1

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