Tuesday, May 11, 2010

Using Vaadin with Google App Engine

Under the current situation of misalignment between Google and Vaadin in creating a project in Eclipse, to develop Vaadin applications that would work with Google Plugin for Eclipse, a few minor hurdles need to be jumped over. This tutorial outlines the simple steps that need to be taken to create a Vaadin project in Eclipse that runs on Google App Engine development environment.

Presuming the Google Plugin for Eclipse is already installed, follow the instructions found in http://vaadin.com/eclipse to install the Vaadin Plugin for Eclipse using [Help - Install new software] in Eclipse.

Have you ever wondered why [Install new software] item is found under [Help] menu in Eclipse? The help item is not instructions on how to install new software but actually installing new software. What are the nerds at Eclipse/IBM up to with this deliberate choice of menu structure? Difference between a nerd and a geek: a geek insists on being meticulously precise, whereas a nerd insists on being meticulously imprecise.

After restarting Eclipse (Do you really need to restart Eclipse? Could we just apply changes?), create a new Vaadin project.  You will find Vaadin section listed under the [New] menu item. If it is not within the first page of menu items, you would have to find it under [Other ...].
  • Give the project a name. Let's say you called it Zebra.
  • Set [Vaadin:Deployment configuration] to Google App Engine Servlet.
  • Choose the Vaadin version, or click download to download the latest one. This step may not be necessary because it is one of the causes of the project needing repair - but we have to fill in something no matter how erroneous, to be allowed to complete defining the project.
  • Then complete the rest as best as you can, before clicking [Finish].

Repairing the Vaadin project to use Google App Engine as development server
With a Vaadin project called Zebra,
  • Right-click on project Zebra for [Properties] item.
  • At [Java Build Path - Libraries tab], delete WebApps (under which is found the vaadin jar).
  • At [Google - App Engine] enable [Use Google App Engine] check box and fill the rest the best you could.

And again, voila Viola!

If you don't make these changes, you would encounter ClassNotFoundException when you try to launch the Vaadin Application. The reason being, there is disagreement of some sort between Vaadin and Google plugins on how plugins should build and dispense library references. Vaadin believes we should stick to the Eclipse standard and apparently Google has no vested interest in doing so.


You might also wish to allow OOPHM (browser plug-in debugging code server) to be used with debugging the project:
  • Delete the library references to vaadin downloaded gwt-user.jar and gwt-dev.jar files.
  • Create a new library reference for the vaadin.version.jar found in the WEB-INF/lib folder. If the jar is not found there, place a copy of the jar file there before making the library reference.
  • At [Google - Web Toolkit] enable [Use Google Web Toolkit] check box and fill the rest the best you could.
You should now be able to create a new Vaadin Application in the project from the context menu.

Do you have trouble correlating the term Out of Process Hosted Mode (OOPHM) with anything meaningful? Out of  what process? I think it is JVM-Based Browser Plug-in Hosting the Client-Side Debugging Co-Operand (of the Server-Side Debugger), which would be JVMBBPHtCSCO(oSSD). That's a mouthful. Hence, regardless being less precise, it is easier to say with a punch "Oophm!" Like someone had just punched you at the tummy.



15 comments:

  1. when I run the step: "Repairing the Vaadin project to use the Google App Engine development server" comes the following error:

    "java.lang.NoClassDefFoundError: com / google / appengine / tools / enhancer / Enhance
    Caused by: java.lang.ClassNotFoundException: com.google.appengine.tools.enhancer.Enhance
    at java.net.URLClassLoader $ 1.run (Unknown Source)
    at java.security.AccessController.doPrivileged (Native Method)
    at java.net.URLClassLoader.findClass (Unknown Source)
    at java.lang.ClassLoader.loadClass (Unknown Source)
    at sun.misc.Launcher $ AppClassLoader.loadClass (Unknown Source)
    at java.lang.ClassLoader.loadClass (Unknown Source)
    Exception in thread "main" "

    Any ideas?

    ReplyDelete
  2. Hi, Great.. Tutorial is just awesome..It is really helpful for a newbie like me.. I am a regular follower of your blog. Really very informative post you shared here. Kindly keep blogging. If anyone wants to become a Java developer learn from Java Training in Chennai. or learn thru Java Online Training India . Nowadays Java has tons of job opportunities on various vertical industry.

    ReplyDelete
  3. Michael Kors Outlet Online was a huge success there and became very well known. The designer Kors then branched out into accessories including Michael Kors Handbags Clearance. He never lost focus on his American chic styling. Some of his most notable collections include the Michael Kors Totes, Michael Kors satchel and the Designer MK Outlet and Michael Kors Outlet Online Store.

    No one has to know that they are cheap Ray Ban Sale UK and no one will know unless you tell them. Each of the cheap designer Ray Ban Sunglasses Sale UK carries the signature brand on the lens to let you know that you do have authentic designer Cheap Ray Ban Sunglasses UK.

    tags: Cheap Oakley Sunglasses UK,MK Outlet

    ReplyDelete
  4. Ce sac cartable Michael Kors est si universel qu'il pourrait plaire à tout le monde. Dans cet article, je vais essayer de passer en revue les caractéristiques principales et les éléments qui distinguent ce sac à main des autres.

    tags:Bolsos Michael Kors Rebajas,Bolsos Michael Kors Baratos,Bolsos Michael Kors El Corte Ingles

    L’extérieur de ce fourre-tout Michael Kors est un cuir métallisé de laiton froncé et froncé. Si vous connaissez les sacs à main Michael Kors, vous savez que ce cuir sera doux et souple. Les deux grandes poignées supérieures sont attachées au sac avec quelques centimètres de chaînes dorées, puis les moitiés supérieures des bretelles présentent le même cuir couleur laiton.

    tags:Bolsos Michael Kors Baratos,Michael Kors Örhängen

    La diversité des couleurs et la taille utilisable de ce sac le rendent parfait pour un usage quotidien. Les poches intérieures ne manquent pas pour aider à garder les choses en ordre. Il y a des endroits parfaits pour votre téléphone ou votre Blackberry. Le zip top empêche les malfaiteurs de saisir votre sac dans un bar et aide également à contenir tout ce qui se trouve à l'intérieur lorsque vous courez pour créer ce train.

    tags:Windguru Longchamps,Longchamp Soldes Destockage,Pronote College Longchamp

    ReplyDelete