Portal integration and code reuse in portlets'

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Portal integration and code reuse in portlets.
Matthew Grove ltm.grove_at_rdg.ac.ukgtPortal
Developers Workshop, February 2008
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Outline

• This talk describes our experiences with two
  approaches to integrating web applications.
• Skinning (themes).
• Embedding inside portals.
• The message is we dont want re-write or fork
  code and you dont have to.
• The VRE II VERA project is used as an example
  throughout the talk.

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What do we mean by integration?

• There are a huge number of well maintained web
  applications which have had a lot of time and
  money invested in them.
• You probably already use some of these
  applications (including portal containers) in
  your projects.
• By integration we mean assembling a system from
  several existing web applications and making the
  whole system look / behave the same from a users
  perspective.
• We don't want to re-write everything or fork
  established projects if possible. If we fork
  things, who is going to maintain them? Do we have
  the money to maintain them?

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Two approaches to integration

• If you want to use a portal container you could
  integrate the portal into your existing system
  (make a skin for the portal).
• You could embed an existing application inside a
  portal without re-writing the application (using
  bridges and scrapers).
• In the VERA project we have tried both skinning a
  portal to integrate it with an existing system
  and embedding web applications inside a portal.

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Web application skinning

• VERA has a web presence which is also the
  platform for our research environment.
• We used off the shelf web applications to provide
  the wiki and the blog.
• We had to skin the wiki and the blog to provide a
  consistent user experience (integration).
• The skins consisted of CSS and a bit of
  JavaScript. Not a lot needed writing from scratch
  because we already had CSS and JavaScript from
  the web site design itself.

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The VERA website
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Skinning pros

• Can be almost trivial to do if you have strong
  CSS-fu.
• No forking code - we can use mainstream packages
  supported and maintained by our Linux
  distribution's package management system, so
  security updates are essentially automatic for us
  and we don't have to maintain any code.
• This approach is language agnostic, web
  applications could be written in Java, PHP,
  Python etc.

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Skinning cons

• No single-sign on built in. However, we have
  added this before in other projects like the
  acet.rdg.ac.uk site, where we made all of the web
  applications single sign-on.
• It relies on the web applications you choose
  supporting skinning.

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Skinning a portal container

• Remember you will be skinning a portal container
  not a portlet.
• This can be just like skinning a web application
  like Wordpress or Drupal.
• We did this for Gridsphere 3 (GS).

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Skinned Gridsphere
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GS skinning experiences

• GS does support themes (skins).
• GS lets you include JavaScript for a portlet but
  not for the whole portal (this makes our little
  up arrow at the top of the web site break). We
  fixed this by hacking the GS code (forced to
  break our own rule - we don't want to fork the
  code!).
• JavaScript is going to be more common with Web
  2.0, supporting only CSS is not sufficient for
  skins any more.
• We couldn't make some page elements do what we
  wanted because of the structure of the XHTML but
  we got the rest of the page looking identical to
  the rest of the VERA site.
• Changing the URL for the container broke
  everything for GS we have heard that this is
  fixed now. We could have got round this by using
  something like Apache rewrite. The URL is another
  aspect of providing a consistent user experience.
  

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Skinning summary

• If you have existing applications or want to use
  some complex web applications that are maintained
  by the community, maybe you should look at
  skinning for your integration.
• What it boils down to is how much effort is
  required to port everything to a portlet compared
  to writing some skins.
• We could adapt the authentication system we used
  with the acet.rdg.ac.uk site to provide single
  sign-on to integrate web apps outside of portals.

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Embedding apps inside portals

• This is almost the opposite approach the web
  application goes inside a portlet.
• The tricky bit is how to get a web application to
  look like a normal portlet to the user without
  rewriting the whole thing!
• There are existing tools such as the Portlet
  Bridge (now un-maintained) which let you embed
  some web applications inside portlets by using
  web scraping techniques.

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When web scraping fails...

• VERA is committed to getting an application
  called the IADB inside a standards compliant
  container.
• The IADB is 15 thousand lines of PHP and
  JavaScript, we are not going to re-write it.
• We have worked with the web scraping tools during
  VRE I, and we know that the existing web scraping
  tools can't cope with a site like the IADB.
  Mainly because of the nested iframes and complex
  JavaScript that the IADB uses.
• In this kind of scenario other people have tried
  using iframes but you can end up with an
  application which does not integrate well into
  the portal from a users perspective. The main
  issue is the lack of single sign-on (you log into
  the portal then have to log into the embedded
  application again).

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Vanilla IADB
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Single sign-on for embedded apps

• The elegant part of our solution is to use the
  client (web browser) to link the authentication
  information between the portal and the embedded
  application being consumed.
• We wrote a portlet called the Recycle Bridge
  which sets a cookie containing the
  username of the user logged into the portal.

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Recycle Bridge cont.

• The Recycle Bridge uses an iframe to display the
  embedded application inside the portal.
• You have to write an authentication plugin or
  patch for the application that is embedded to use
  the cookie (and suppress the applications log in
  screen).
• From the users perspective the application looks
  like part of the portal.
• There are settings for the Recycle Bridge to
  alter the appearance of the iframe to try and
  make the integration seamless from the users
  perspective.

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Wordpress in the Recycle Bridge
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Security for the cookie

• Essentially the web application needs to have a
  way to trust the cookie contains authentic user
  information.
• The Recycle Bridge shares a secret security token
  (salt) with any web application you want to
  embed. When you set things up you must provide a
  unique salt in the configuration files.
• The Recycle Bridge includes an MD5 hash with the
  cookie based on the salt and username to provide
  a way for the authentication plugin to check that
  the cookie has not been tampered with.

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Writing the authentication plugins

• This plugin approach is language agnostic - we
  can support any language that can read a cookie.
• We have split the process into two steps
• We have a generic library which provides the
  functions to read the cookie and check it is
  valid.
• You will need a plugin or patch for the specific
  application you want to embed.

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Plugins cont.

• We have written the authentication library for
  PHP.
• And plugins for
• MediaWiki (runs Wikipedia).
• Wordpress which is a very popular blogging app.
• We also wrote a patch for IADB, we have check in
  access to the IADB source repo.

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We want your code!

• We want more plugins and libraries.
• The Recycle Bridge SVN repo is set up to make it
  very easy for us to accept code from you.
• Even if you write a plugin for some obscure
  application, if you split the cookie functions
  out into a separate file (library) you will be
  helping anyone who wants to embed an application
  written in that language.
• We are happy to help you write your plugin,
  especially if it uses a language we don't yet
  have the library for.

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We want your portals!

• The Recycle Bridge is a JSR-168 portlet.
• As we all know, unfortunately portal containers
  do not have standard XML files for portlet
  deployment.
• We want help testing Recycle Bridge in your
  container, we don't have the manpower to install
  and test every container.
• If you tweak anything to get the Recycle Bridge
  to work in a portal, we want your changes!

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Summary

• We have tried two ways of using portals to
  re-reuse existing web applications.
• In the first we treat the portal like just
  another web application and integrate it into our
  website along side other complicated web
  applications using CSS and JavaScript skins.
• The second approach uses the Recycle Bridge to
  embed existing web applications into a portal.

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Future work

• We hope the Recycle Bridge will be useful for
  other people who are heavily invested in
  applications they don't want to / can't afford to
  re-write as portlets or who want to use web
  applications which are maintained by the
  community (like MediaWiki).
• We would like your help writing adding support
  for more applications to the Recycle Bridge.

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Links

• http//vera.rdg.ac.uk/software/ - Recycle Bridge
  homepage (with code).
• http//acet.rdg.ac.uk/mjeg/blog.php - Blog
  aggregating all of my research activities.
• http//www.portletbridge.org/ - Portlet Bridge
  (best of the web scrapers).