OSGi Text Scrambling Service

Here's most of the code from the peaberry example I mentioned in my previous post - as you can see, peaberry lets you import and export OSGi services from your Guice enabled application, without introducing a dependency on the OSGi API. In fact you can even plug your own service frameworks into peaberry.

EXPORTING BUNDLE

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package examples.scrambler.impl;

import static org.ops4j.peaberry.Peaberry.registration;
import static org.ops4j.peaberry.util.TypeLiterals.export;

import com.google.inject.AbstractModule;
import com.google.inject.Key;

import examples.scrambler.Scramble;

// here's where we bind the exported service...
public class ExportModule extends AbstractModule {

  @Override
  protected void configure() {
    // note: the service is exported at injection time
    bind(export(Scramble.class)).toProvider(
        registration(Key.get(ScrambleImpl.class)).export());
  }
}

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package examples.scrambler.impl;

import static com.google.inject.Guice.createInjector;
import static org.ops4j.peaberry.Peaberry.osgiModule;

import org.ops4j.peaberry.Export;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;

import com.google.inject.Inject;

import examples.scrambler.Scramble;

@SuppressWarnings("unused")
public class Activator implements BundleActivator {

  @Inject
  final Export<Scramble> handle = null;

  public void start(final BundleContext ctx) throws Exception {

    // apply the exported service binding
    createInjector(osgiModule(ctx), new ExportModule()).injectMembers(this);
  }

  public void stop(final BundleContext ctx) throws Exception {

    if (null != handle) {
      handle.remove();
    }
  }
}

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IMPORTING BUNDLE

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package examples.scrambler.test;

import static org.ops4j.peaberry.Peaberry.service;

import com.google.inject.AbstractModule;

import examples.scrambler.Scramble;

// here's where we bind the imported service...
public class ImportModule extends AbstractModule {

  @Override
  protected void configure() {
    bind(Scramble.class).toProvider(service(Scramble.class).single());
  }
}

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package examples.scrambler.test;

import static com.google.inject.Guice.createInjector;
import static org.ops4j.peaberry.Peaberry.osgiModule;

import org.ops4j.peaberry.ServiceUnavailableException;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;

import com.google.inject.Inject;

import examples.scrambler.Scramble;

@SuppressWarnings("unused")
public class Activator implements BundleActivator {

  // plain text to be scrambled...
  final static String TEXT = "This is a simple test of peaberry.";

  @Inject
  final Scramble service = null; // Guice can actually inject final fields!

  Thread tester;

  public void start(final BundleContext ctx) throws Exception {

    // apply the imported service binding
    createInjector(osgiModule(ctx), new ImportModule()).injectMembers(this);

    // quick'n'dirty test thread
    tester = new Thread(new Runnable() {
      public void run() {
        // support cooperative cancellation
        while (Thread.currentThread() == tester) {
          try {
            System.out.println('[' + service.process(TEXT) + ']');
          } catch (final ServiceUnavailableException e) {
            System.err.println("No scrambler service!");
          }
          try {
            Thread.sleep(2000);
          } catch (final InterruptedException e) {
            // wake-up
          }
        }
      }
    });

    tester.start();
  }

  public void stop(final BundleContext ctx) throws Exception {

    // cooperatively stop the thread
    final Thread zombie = tester;
    tester = null;
    zombie.join();
  }
}

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