Working with configs using pure OSGi interfaces with ManagedService - osgi

Question

i am working on OSGI bundle. I have implemented a BundleActivator and here is my code.
public class Activator implements BundleActivator {
private static final String CONFIG_PID = "ConfigApp";
private ServiceRegistration serviceReg;
public VfsDAO app;
#Override
public void start(BundleContext context) throws Exception {
System.out.println("Hello................ bundle started");
Hashtable<String, Object> properties = new Hashtable<String, Object>();
properties.put(Constants.SERVICE_PID, CONFIG_PID);
serviceReg = context.registerService(ManagedService.class.getName(), new ConfigUpdater() , properties);
}
#Override
public void stop(BundleContext context) throws Exception {
serviceReg.unregister();
}
/**
* Updates the configuration in the application. Of course your class can also directly implement ManagedService but this
* way you can work with pojos
*/
private final class ConfigUpdater implements ManagedService {
#SuppressWarnings("rawtypes")
#Override
public void updated(Dictionary config) throws ConfigurationException {
if (config == null) {
return;
}
if (app == null) {
app = new VfsDAO();
}
app.setAllowed((String)config.get("title"));
System.out.println("FROM................ bundle ACTIVATOR");
app.refresh();
}
}
}
Now if i make a object of VfsDAO() in any other class setAllowed is not called and so the String allowed is not initialized.How can i get the value when i make a new VfsDAO() object in any other class? or how can i call (String)config.get("title") in VfsDAO class to that when i make a new object of VfsDAO() in any other class string allowed is initiled.

Answer 1

For your VfsDAO to be notified by OSGi on a configuration change it has to be managed in some way by the OSGi runtime. The code you have above accomplishes this by acting as an OSGi managed service wrapper around your VfsDAO. If you're using new VfsDAO() in some places in your code and you aren't wrapping that lifecycle management as you are in the example above (or have some other lifecycle tie-in to OSGi) there will be no way for OSGi to know that your code created a VfsDAO.
If you need multiple VfsDAO instances perhaps configured with different allowed attributes, I'd recommend using the OSGi ManagedServiceFactory. Using the managed service factory you would instead create multiple VfsDAO instances each with their own PID and configuration by way of the ConfigAdmin.