1.
Dynamic modular Web applications
with Equinox and Vaadin
Kai Tödter
Siemens Corporate Technology

2.
Who am I?
 Software Architect/Engineer at Siemens
Corporate Technology
 Eclipse RCP expert and OSGi enthusiast
 Open Source advocate
 Committer at e4 and Platform UI
 E-mail: kai.toedter@siemens.com
 Twitter: twitter.com/kaitoedter
 Blog: toedter.com/blog
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 2

3.
Outline
 Demo
 Server-side OSGi
 Vaadin
 Whiteboard Pattern
 OSGi Declarative Services (DS)
 Code deep dive
 Discussion
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 3

4.
Demo
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 4

5.
Download & Blog
 You can download the demo projects (6,8 MB,
including the target platform) at
http://www.toedter.com/download/vaadin/os
gi-vaadin-demo.zip
 See also my blog “Dynamic modular Web
Applications with Vaadin and OSGi”
http://www.toedter.com/blog/?p=412
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 5

6.
Server-side OSGi
Picture from
http://www.sxc.hu/photo/1043923
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 6

7.
Server-side OSGi
 For this demo I use Equinox as OSGi container
 To run server-side Equinox there’s 2 choices:
 Embed Equinox in a servlet container
 Embed a HTTP server in Equinox
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 7

8.
Embed Equinox in a Servlet Container
 Needed bundles:
 org.eclipse.equinox.servletbridge
 org.eclipse.equinox.servletbridge.http
 org.eclipse.equinox.http.servlet
 [optional] org.eclipse.equinox.http.registry
 See http://www.eclipse.org/equinox/server/
http_in_container.php
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 8

9.
Embed Jetty in Equinox
 Needed bundles:
 org.eclipse.equinox.http.jetty
 org.eclipse.equinox.http.servlet
 org.mortbay.jetty
 org.apache.commons.logging
 javax.servlet
 [optional] org.eclipse.equinox.http.registry
 See http://www.eclipse.org/equinox/server/
http_in_equinox.php
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 9

10.
Hello, JAX! OSGi Servlet Demo
Picture by Office Online, iStockPhoto
http://office.microsoft.com/en-us/images/results.aspx?qu=world#ai:MP900444203|
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 10

11.
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 11

12.
What is Vaadin?
 Server-based RIA Framework
 Uses Google Web Toolkit (GWT) as rendering
engine
 Pure Java, no JavaScript, no configuration
 Rich widget set
 Out of the box OSGi support
 Only one JAR file, already an OSGi bundle
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 12

13.
Demo
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 13

14.
The Whiteboard Pattern
 Problem: Often a service provides an
implementation of the publisher/subscriber
design pattern and provides methods to
register listeners for notifications
 The OSGi service model provides a service
registry with these notification mechanisms
already!
 So:
 Don’t get a service and register as listener
 Be a service yourself and register with the OSGi
service registry!
14

15.
Example: The Listener Pattern
 Clients use ApplicationService to register view and
action contributions
 Client is responsible for handling dynamic behavior
15

16.
Example: The Whiteboard Pattern
 Clients register view and action contributions as services
 Application manager is responsible for handling dynamic
behavior
16

17.
Whiteboard Pattern in Vaadin Demo
 The Action and View contribution managers
are NOT services
 Instead, they are wrapped in a OSGi Declarative
Services (DS) component
 All action and view contributions are OSGi
services and implement
 IActionContribution
 IViewContribution
17

18.
OSGi Declarative Services
Active Bundle Active Bundle
Component Component
Service
Component Component
Instance reference Instance
provide
Component Component
Description Description
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 18

19.
Life Cycle
DS-powered Bundle Service Component
Runtime (SCR)
Component
Component
Component create
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 19

20.
Declaring a Component
 Specify component description(s) via
Service-Component manifest header
Service-Component: OSGI-INF/treeView.xml
 Specify the implementation class
<component xmlns="http://www.osgi.org/xmlns/scr/v1.1.0">
<implementation class="...TreeView"/>
</component>
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 20

21.
Providing a Service
 Specify each service interface
 By default components providing a service are
created on demand (lazy)
<service>
<provide interface="...IViewContribution"/>
<provide interface="...IActionContribution"/>
</service>
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 21

22.
Referencing Services
 Specify the service interface
 Specify bind and unbind methods
 Specify the cardinality
<reference interface="...IPersonManager"
bind="setPersonManager"
unbind="removePersonManager"
cardinality="1..1"/>
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 22

23.
Further Reading
 Chris Brind:
 In Bed with Vaadin and OSGi
 http://www.perplentropy.com/2010/02/in-bed-with-
vaadin-and-osgi.html
 I use Chris’ bundles in this demo
 Neil Bartlett:
 Vaadin OSGi bridge at GitHub
 https://github.com/njbartlett/VaadinOSGi
 Petter Holmström:
 Creating a Modular Vaadin Application with OSGi
 http://vaadin.com/wiki/-
/wiki/Main/Creating%20a%20Modular%20Vaadin%20
Application%20with%20OSGi
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 23

24.
Putting it all together…
 Main demo application is a DS component
 factory='vaadin.app' => used Chris Brind’s
implementation
 0..n service references to
 IViewContribution
 IActionContribution
 Source code will be shown soon… 
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 24

25.
Resources, Images and Themes
 Resources (e.g. images) have to be put in a
fragment with the com.vaadin bundle as host
 See project
com.siemens.ct.osgi.vaadin.pm.theme
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 25

26.
Code Deep Dive
Picture from
http://www.sxc.hu/photo/1159613
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 26

27.
Picture from
http://www.sxc.hu/photo/922004
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 27

28.
License
 This work is licensed under the Creative Commons
Attribution-Noncommercial-No Derivative Works 3.0
Germany License
 See http://creativecommons.org/licenses/by-nc-
nd/3.0/de/deed.en_US
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 28

29.
Picture Index
Many thanks to the authors of the following pictures:
 Slide „Server-side OSGi“: http://www.sxc.hu/photo/1043923
 Slide „Hello JAX!“: http://office.microsoft.com/en-
us/images/results.aspx?qu=world#ai:MP900444203|
 Slide „Reindeer“ Animation:
http://www.sxc.hu/photo/1138596
 Slide „Code Browsing“: http://www.sxc.hu/photo/1159613
 Slide “Discussion”: http://www.sxc.hu/photo/922004
5/9/2011 © Kai Tödter and others, Licensed under Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. 29