This document discusses a proposed "Web Application Service" that allows for modular web applications based on OSGi. The service would parse a web.xml file to register servlets, filters, and other configuration for a web application across OSGi bundles. It aims to simplify deployment of existing web applications to OSGi. Currently taglib support, listeners, and security are missing but under development. The service follows the extender pattern and API to integrate with OSGi bundles and web containers. A demo is shown of deploying Tomcat examples as OSGi bundles using this approach.

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Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license
Modular web applications based on OSGi
Jochen Hiller
March,18th 2008

2. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license2
The OSGi HttpService …
• is lightweight
• is restricted to Servlet Spec 2.1
 no filters, no listeners, no welcome-files
 no JSP support
• requires registration at HttpService
 servlets / resources
 programmatically
 via extension point if using Equinox
• Equinox provides techniques to add missing functionality
 see org.eclipse.equinox.http.helper classes from Simon Kaegi
 but: complex, additional effort required

3. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license3
A solution: “Web Application Service”
• The web.xml provides all configuration information
• Parse web.xml to …
 register all servlets and filters from contributing bundle
 support specified welcome-files
 add JSP support by default
 add all mime-types, support default mime-types
• Map web application to a context (alias in HttpService terms)
• Resource lookup from contributing bundle
• Binds to all OSGi HttpServices
• The technique: register wrapper servlets
• See https://bugs.eclipse.org/bugs/show_bug.cgi?id=162132

4. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license4
Web Application Service: The Service API
package org.eclipse.equinox.webapp.service;
public interface WebAppService {
public Object registerWebApp(
String alias,
Bundle bundle,
String bundleResourcePath,
String webXml,
Dictionary options)
throws WebContextException;
public void unregisterWebApp(Object handle);
}

5. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license5
Web Application Service: As Extension point
<!– web application service as extension point -->
<extension
id="webapp"
name="DemoWebApp“
point="org.eclipse.equinox.webapp.registry.webapp">
<webapp
alias="/"
path="/WebContent">
</webapp>
</extension>

6. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license6
Web Application Service: As Extender pattern
• Follows Extender Pattern as proposed by OSGi
• Bundle Listener observes all bundles coming / leaving
the platform
• Trigger file is /WEB-INF/web.xml
• Context to register is bundle symbolic name
 May be configured through /WEB-INF/osgi-web.xml

7. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license7
What are the benefits?
• Easy development of JavaEE based web applications
based on OSGi
• Simplified deployment of existing web applications
(WAR) to OSGi
• OSGi can act as a lightweight web container
• Implementation is not dependent on OSGi runtime
implementation

8. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license8
Demo: Deploy Tomcat examples
• Tomcat 5.5.x example applications
 servlet-examples
 jsp-examples
• Changes required:
 Create /META-INF/MANIFEST.MF
 Added /WEB-INF/classes and /WEB-INF/lib/*.jar to
bundle classpath
 May be automated using bnd tool from Peter Kriens

9. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license9
Limitations, Plans
• And what is missing?
 Taglib support is missing
 Listeners not yet supported
 Declarative security not supported
 Implementation under development, API may change
 Documentation, Tutorials
 More testing (e.g. compatibility with servlet bridge, other
OSGi implementations)
• Further ideas:
 Equinox specific framework extension to directly support
loading WAR files
 Align with Enterprise OSGi and RFC 66 activities

10. Modular web applications based on OSGi | March 18th 2008 | Short Talk #244
© Copyright 2008 Jochen Hiller; Source code in this presentation is made available under the EPL v1.0, remainder of the presentation is licensed
under Creative Commons Att. Nc Nd 2.5 license10
Questions?
• Contact me:
 jo.hiller@googlemail.com
• Incubator project at:
 http://sourceforge.net/projects/sse-examples
 CVS, webapp-incubator