De video presentaties van deze sessie zijn nu beschikbaar.

Innovatie, Services en Open Source
Rene van Hees, Technical Authority Software bij Thales

http://www.youtube.com/watch?v=2NlzXw37okM

OSGi en Dynamische Services
Marcel Offermans, lid van de Apache Software Foundation

http://www.youtube.com/watch?v=bfEOKva1xhc

Apache Celix en Apache Foundation
Alexander Broekhuis, Software Engineer Luminis, committer Apache Celix

http://www.youtube.com/watch?v=FG04jERMznU

A conference like no other

Apache probably is the strongest brand in the open source space, but the conference itself focusses strongly on content. Here you will see no sponsored talks by commercial vendors, no sales people trying to sell you anything, it’s all about the code, the community and collaborating with each other. In that sense it’s quite different from most other conferences and if you like meeting and discussing fellow developers, this is a great place to visit. Many events facilitate discussion, and power and internet connectivity are available everywhere.

What open source is all about

Brian Behlendorf summarized the three main cultural elements of Apache quite well:

• write good code and debate it to the bone
• be humble
• collaborate

In essence, Apache is a meritocracy, of which only individuals can become a member. It’s sometimes also described as a do-ocracy as projects are driven by contributions: if you want something done, just do it. Another important aspect is that everything that is done on the Apache projects is discussed and archived on the mailing list. All discussions, code diffs and decisions must be recorded there.

Presenting Apache ACE

Tuesday evenings “birds of a feather” session featured a discussion about Apache ACE, where questions mostly centered around the use cases for ACE and possible integrations with other OSGi components. One of the conclusions is that there are probably three different phases of deployment:

1. Using Apache Felix File Installer, which allows you to drop components in a local folder to have them installed.
2. Using Apache Felix Karaf’s provisioning components, which allow you to define features which basically group components and allow you to define dependencies on other features.
3. Using Apache ACE, which allows you to group components and automatically deploy them to many remote systems.

Friday’s OSGi track started with an introduction to OSGi and moved into more advanced topics during the day. The Apache ACE talk was received well, with several people expressing an interest in wanting to use it and contribute to it.

Final thoughts

Summarizing the week, Floris and I had a great time talking to many interesting people and learning about various projects. ApacheCon is a great conference, and I’m already looking forward to the next one.

Google Web Toolkit is cool, and so is OSGi. However, when building a web UI for Apache ACE, I found out that creating a web application that can use OSGi services is not that easy. By the end of this tutorial, you will have created a GWT project that delivers a usable jar. If you’re impatient, skip to the end for the downloadable Eclipse project.

Step 1: Create a GWT project

Create a regular GWT project using the regular webAppCreator; this will give you a project that includes an Ant buildfile, we will need that later on.

angelos:workspace angelos$ ./gwt-mac-1.6.4/webAppCreator -out GwtDemo net.luminis.gwt.gwtdemo
Created directory GwtDemo/src
Created directory GwtDemo/war
Created directory GwtDemo/war/WEB-INF
Created directory GwtDemo/war/WEB-INF/lib
Created directory GwtDemo/src/net/luminis/gwt
Created directory GwtDemo/src/net/luminis/gwt/client
Created directory GwtDemo/src/net/luminis/gwt/server
Created file GwtDemo/src/net/luminis/gwt/gwtdemo.gwt.xml
Created file GwtDemo/war/gwtdemo.html
Created file GwtDemo/war/gwtdemo.css
Created file GwtDemo/war/WEB-INF/web.xml
Created file GwtDemo/src/net/luminis/gwt/client/gwtdemo.java
Created file GwtDemo/src/net/luminis/gwt/client/GreetingService.java
Created file GwtDemo/src/net/luminis/gwt/client/GreetingServiceAsync.java
Created file GwtDemo/src/net/luminis/gwt/server/GreetingServiceImpl.java
Created file GwtDemo/build.xml
Created file GwtDemo/README.txt
Created file GwtDemo/.project
Created file GwtDemo/.classpath
Created file GwtDemo/gwtdemo.launch
Created file GwtDemo/war/WEB-INF/lib/gwt-servlet.jar

If you want to, you can import this project directly into your Eclipse. If you check the mark “use Google Web Toolkit” in the project properties, you can use all the same goodies that creating the project in Eclipse would have given you. Remember to replace the buildpath entries for gwt-user.jar and gwt-dev-*.jar by a Library import for GWT.

Step 2: Include the necessary OSGi references

Create an ‘ext’ directory, and add org.osgi.core.jar to that. In Eclipse, add this jar to your build path.

Step 3: Use OSGi services from your web applicaiton

We will first add a simple Activator on the server side.

package net.luminis.gwt.server;
 
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
 
public class Activator implements BundleActivator {
    private static BundleContext m_context;
 
    public static BundleContext getContext() {
        return m_context;
    }
 
    public void start(BundleContext context) throws Exception {
        m_context = context;
    }
 
    public void stop(BundleContext context) throws Exception {
    }
}

Then, we up the GreetingServiceImpl to actually use this BundleContext (note that we use it directly here, but you could use it to get other services, create a ServiceTracker, etc.)

public String greetServer(String input) {
  String serverInfo = getServletContext().getServerInfo();
  String userAgent = getThreadLocalRequest().getHeader("User-Agent");
  return "Hello, " + input + "!
 
I am running " + serverInfo
    + ".
 
It looks like you are using:" + userAgent +
    "The framework we run from has " + Activator.getContext().getBundles().length + " bundles in it.";
}

Step 4: Add OSGi dependencies for the compiler

Add our OSGi dependencies to the classpath, so the compiler can find all of it.

    <!-- Add any additional non-server libs (such as JUnit) -->

Right, let’s give it a try!

angelos:GwtDemo angelos$ ant war
Buildfile: build.xml
 
...some output removed...
 
war:
[zip] Building zip: /Users/angelos/workspace/workspace/GwtDemo/gwtdemo.war
 
BUILD SUCCESSFUL
Total time: 36 seconds

You will find a war in your project directory now. There still is one ingredient we need. We need to make this into a proper bundle. We can use bnd to help us with that.

Step 5: use bnd to create a proper war

Download bnd, and put into a lib directory, and add it to your buildfile.

We create a new target that transforms our war into a jar.

<target name="jar">
    <copy file="gwtdemo.war" tofile="gwtdemo.jar"/>
    <echo file="gwtdemo.bnd">Import-Package: junit.framework;resolution:=optional, com.google.gwt.*;resolution:=optional, org.w3c.*;resolution:=optional, sun.misc;resolution:=optional, javax.imageio;resolution:=optional, javax.servlet.*;resolution:=optional, *
Bundle-Name: GWT Demo
Bundle-ClassPath: WEB-INF/classes, WEB-INF/lib/gwt-servlet.jar
Bundle-SymbolicName: net.luminis.gwt.gwtdemo
Webapp-Context: gwtdemo
Bundle-Activator: net.luminis.gwt.server.Activator
    </echo>
    <bndwrap jars="gwtdemo.jar" output="gwtdemo.jar"/>
    <jar file="gwtdemo.jar" update="true">
    <manifest>
        <attribute name="Bundle-ClassPath" value="WEB-INF/classes, WEB-INF/lib/gwt-servlet.jar, ."/>
     </manifest>
    </jar>
    <delete file="gwtdemo.bnd"/>
</target>

What’s happening here?

• we copy our war to the same file, but with a jar extension,
• we create a file for bnd to use, stating that we
  • want optional imports for junit and the gwt benchmarks, and non-optional imports for everything else (that what the * is for),
  • have some classes that we want bnd to scan for finding dependencies,
  • want to use a given Webapp-Context (this is a Pax war extender specific entry),
• let bnd do its magic,
• update our manifest: we put the . back on the classpath. This is important for the web application to find all resources, but if we would tell bnd to do it like this, it would treat . as the root of the classpath.
• Finally, we delete that temporary bnd file.

What does that give us?

angelos:GwtDemo angelos$ ant jar
Buildfile: build.xml
 
...some output removed...
 
jar:
[copy] Copying 1 file to /Users/angelos/workspace/workspace/GwtDemo
[bndwrap] gwtdemo 41 910305
[bndwrap] Warnings
[bndwrap] Superfluous export-package instructions: [WEB-INF.classes.net, gwtdemo.gwt.standard.images, WEB-INF, gwtdemo, WEB-INF.classes.net.luminis.gwt, gwtdemo.gwt.standard, WEB-INF.classes.net.luminis, WEB-INF.lib, WEB-INF.classes, gwtdemo.gwt.standard.images.ie6, WEB-INF.classes.net.luminis.gwt.client, WEB-INF.classes.net.luminis.gwt.server, gwtdemo.gwt]
[jar] Updating jar: /Users/angelos/workspace/workspace/GwtDemo/gwtdemo.jar
[delete] Deleting: /Users/angelos/workspace/workspace/GwtDemo/gwtdemo.bnd
 
BUILD SUCCESSFUL
Total time: 23 seconds

That’s it! You can now deploy this jar into a framework that uses the pax web tools. Right, let’s give that a try.

Download pax-runner, and unzip that somewhere. Copy in your new jar, an try the following command

angelos:pax-runner angelos$ sh bin/pax-run.sh --profiles=war,compendium gwtdemo.jar

Now visit http://localhost:8080/gwtdemo:

Summary

So, what did we need?

• A fairly regular GWT project, create with an Ant file,
• some code that tries to use OSGi services,
• some bnd magic to make the war into a jar,
• Pax tools to get it all running quickly.

If you don’t want to use pax runner, you can need to deploy pax-web-extender-war(jar, snapshot 23 June) and an http server, preferably pax-web-service(jar), into your framework.

You can download the gwtdemo Eclipse project to play around with it. I have not provided the GWT runtime in this download; you should edit line 4 of the build.xml to point to your installation of GWT.

We are pleased to announce the launch of EZdroid, the world’s first open-source, collaborative platform for the safe deployment of component-based software applications and content across Android, and other Linux-based mobile devices.
EZdroid was founded by two of Europe’s leading companies in the field of OSS technology; the platform consists of Android, Apache Felix and a number of their own enhancements (e.g. software license-, device- and integrated software-management). EZdroid supports the secure deployment of software applications and content (known as Provisioning) to Android phones and in the future, other Linux-based operating systems. It is available to any organization or individual wishing to make software and content available to Android users world-wide. Further information and a demonstration of the platform is now available and downloadable to Android phones at: http://www.ezdroid.com.

EZdroid’s founders: Luminis BV (www.luminis.nl/en) of The Netherlands and Akquinet GmbH (www.akquinet.com/en) of Germany are now inviting partners and collaborators to become part of the EZdroid community – whether these are developers, wishing to show-case their applications, business partners interested in co-development or an OEM relationship, or organizations which are interested in owning and controlling their own application repository/App Store.

The launch of EZdroid is very significant; it is the world’s first platform, built from open source components, which will allow the mass deployment of applications without proprietary licensing issues. The founders intend to supplement the platform with a validation and quality assurance system – to ensure that applications are safe and do not interfere with Android’s normal operations.