Application Reuse Through Portal Frameworks

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Application Reuse Through Portal Frameworks

• Mark Baker and Rahim Lakhoo

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Outline

• Introduction.
• Motivation.
• Technologies
• JSR-223,
• PHP-JavaBridge,
• PortletBridge-Portlet,
• Other Bridging Technologies.
• System Architecture.
• Demonstration Applications.
• Issue.
• Conclusions.

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Introduction

• Portsmouth and Readings role in the Sakai VRE
  project is to develop and deploy a number of
  portlet-based tools and services.
• In particular we are looking at
• Collaborative tools based on NaradaBrokering,
• Semantic Web tools based on RDF,
• Bridging technologies to enable legacy
  applications,
• Peer-to-Peer technologies.
• We will make these tools available, either via a
  native JSR-168 capability, or via the WSRP
  consumer developed within the Sakai project.
• In this talk we will recount our experiences
  investigating, deploying and testing a range of
  emerging portal bridging technologies.

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Legacy Applications

• Motivation
• Investigate whether script-based Web
  applications, such as PHP can be reused in
  Java-based environment,
• Investigate if PHP applications can be reused as
  a portlets,
• Test by deploying a number of PHP applications as
  portlets,
• Add useful tools/utilities to the Sakai
  Demonstrator.

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Bridging Technologies

• JSR-223
• Reference implementation available,
• Allows Java to communicate objects with
  script-based languages and vice versa,
• To be included with the next release of Sun JDK
  Mustang (JDK 1.6).
• PHP-JavaBridge
• Described as an XML-based network protocol,
• Allows communications between Java and PHP,
• Provides a suitable environment to execute PHP
  scripts under Apache Tomcat.
• PortletBridge-Portlet
• Renders Web pages into a JSR-168 portlet,
• Proxies links and other external resources
  contained in a Web page,
• Can load multiple instances, with different
  configurations.

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Bridges - JSR-223 (1)

• JSR-223 specification is lead by Zend
  Technologies and Sun, amongst others.
• Allows script-based languages to be used in Java
  server-side applications and vice versa.
• Defines a new API, javax.script..
• New API includes scripting-engines for different
  languages.
• Reference implementation includes support for
  Rhino, PHP and Groovy.

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Bridges - JSR-223 (2)

• Reference Implementation

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Bridges - JSR-223 (3)

• Reference implementation of JSR-223 includes a
  pre-compiled skeleton installation of PHP5.
• JSR-223 API includes some scripting engines for
  PHP, Groovy and Rhino.
• Also includes a script to invoke Java classes,
  which contain script-based calls, from the
  command-line.
• Samples scripts/programs are available for PHP,
  Groovy amongst others
• Command-line and Web capabilities.

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Bridges - PHP-JavaBridge (1)

• Described as an XML-based network protocol.
• Designed to communicate with native scripting
  engines, which have a Java or ECMA 335 virtual
  machine.
• Provides a suitable environment for PHP
  applications to run under Apache Tomcat.
• Allows Java and PHP to share sessions, in a J2EE
  environment.
• Has a number of configurations for installation
  and connections to existing Web servers.

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Bridges - PHP-JavaBridge (2)
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Bridges - PHP-JavaBridge (3)

• Includes PHP5-CGI binaries and configurations
  files.
• Although the PHP-JavaBridge is not limited to the
  included CGI environment, it can use the PHP
  environment of the hosting server.
• The PHP-JavaBridge can connect to an existing
  Apache Web Server, executing PHP applications.
• Has a number of different modes
• Request - Created/destroyed on every
  request/response,
• Dynamic - Starts/stops synchronously with a HTTP
  server,
• System - Installed from a RPM as a system
  service,
• J2EE - Installed into a J2EE server, such as
  Apache Tomcat.
• If the PHP instance crashes with the
  PHP-JavaBridge the backend Java server/servlet is
  unaffected.

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Bridges - PortletBridge-Portlet (1)

• Generic method of rendering Web sites into a
  JSR-168 portlet, developed by Jamie McCrindle.
• Tested in various portlet containers, including
  GridSphere, JetSpeed and JBoss.
• Proxies a Web sites content, so that a user may
  use the application from within a portlet.
• Uses XSLT to rewrite downstream content from Web
  sites.
• Includes remote proxy server settings for complex
  network set-ups.
• Allows for multiple instances with different
  configurations.

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Bridges - PortletBridge-Portlet (2)
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Bridges - PortletBridge-Portlet (3)

• PorltetBridge-portlet, uses Apaches httpclient
  to GET/POST from/to Web pages.
• Uses the CyberNeko HTML Parser.
• Web pages are transformed using XSLT, which
  rewrites links and other content, such as
• CSS,
• JavaScript,
• Images,
• Forms,
• Headers,
• etc
• Uses Regex for defining the proxy scope.
• PortletBridge defines a Memento for storing users
  state, such as cookies.

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Bridges - Others

• Apache Portals Bridges project aims to use common
  Web frameworks via portlets.
• Currently support is being developed for
• Struts,
• JSF,
• Perl CGI Scripts,
• PHP,
• Velocity Templates.
• GridSphere 2.1.x portal includes the Struts
  Portals Bridge.

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System Architecture (1)

• The PHP-JavaBridge provides the runtime
  environment for the PHP application.
• A PHP application is packaged and configured as a
  Web archive (WAR).
• Included in the WAR is a configured CGI
  environment, complete with PHP configuration
  files and extensions, per application.
• The PHP application can communicate with Java if
  extra functionality or a hybrid application is
  desired.

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System Architecture (2)
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System Architecture (3)

• The PortletBridge-Portlet is installed as a
  JSR-168 portlet under GridSphere.
• PortletBridge-Portlet instances are created and
  configured for each PHP application installed
  under the PHP-JavaBridge.
• If desired, XSL Style Sheets can be configured
  per PHP application.
• Once configured, the PHP applications are
  presented as individual portlets, which can be
  subscribed to by users.

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Demonstration Applications

• Using a combination of the PHP-JavaBridge and the
  PortletBridge-Portlet, we configured some PHP
  applications as portlets.
• These are the applications configured
• BibAdmin - Bibtex database,
• YW Guest Book - PHP guest book application,
• FhImage - A simple image gallery.
• Deployment procedure
• Applications are first deployed as WARs under
  Tomcat.
• Then an instance of the PortletBridge-Portlet is
  created and configured for each PHP application.

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BibAdmin Portlet
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Guest Book Portlet
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Guest Book Admin Portlet
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Image Gallery Portlet
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Demonstrated Applications

• The PHP applications tested with this technique
  have no real difference in terms of functionality
  when compared to native installations.
• Some PHP applications are easier to port to a
  portlet than others.
• Other PHP applications have a poor
  implementation/design, which can lead to issues
  within a portal environment.

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Issues

• Login mechanisms can cause problems simple PHP
  and PHP with JS logins were tested successfully
• However, it is also feasible to disable logins of
  PHP applications in favor of utilising the
  portals security framework.
• Some applications need to have pre-defined PHP
  variables changed to reflect the J2EE
  environment, i.e. port number.
• PHP applications which load new windows have
  issues with the constraints imposed by a portal.
• Frames are not supported by the
  PortletBridge-Portlet.
• XHTML or mixed XHTML/HTML documents currently
  cause the proxy facility of the
  PortletBridge-Portlet to fail
• The developers are working on this.
• There are some CSS leaks into the portal,
  currently this issue has been seen with
  GridSphere
• Also, background colours cannot always be seen in
  the portlet versions.

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Conclusions

• Although this technique is not without issues, it
  does present a viable solution for reusing
  existing PHP applications.
• The PortletBridge-Portlet is still a young
  project, which is being actively developed.
• Other bridging technologies, such as the Apache
  Portals Bridges project will be of interest, as
  they are starting to be included in portals, such
  as GridSphere.
• JSR-223 should see an increase in developers
  using the new API, as the release of Sun JDK 1.6
  approaches.
• Bridging technologies should be an interesting
  alternative/addition for developing portlets and
  could be useful when combined with WSRP.

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References

• http//portals.rdg.ac.uk
• http//www.jcp.org/aboutJava/communityprocess/edr/
  jsr223/index.html
• http//PHP-Java-Bridge.sourceforge.net
• http//www.portletbridge.org
• http//www.gridpshere.org
• http//portals.apache.org/bridges/

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• Questions?

http//dsg.port.ac.uk http//acet.rdg.ac.uk
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