Instant Google App Engine

Getting up and running on the App Engine couldn’t be any easier, man — in fact, Google even provides an Eclipse plug-in that handles just about everything for you! In order to get started though, you do need an App Engine account (which is free, by the way). Once you’ve done that, you can download the Eclipse plug-in via Eclipse’s Software Update feature as shown below. In my case, since I’m using version 3.4, I used the following URL: <a href="https://dl.google.com/eclipse/plugin/3.4">https://dl.google.com/eclipse/plugin/3.4</a>.

Once that step is complete, you can then install the plug-in via the Install button and that’s it! The hardest part about the whole process was creating an account, don’t you think?

With the plug-in installed, you should notice a few new buttons (pictured above)– namely, a button to create a new web application project (that allows you to select if you’d like the project to be associated with Google’s GWT and/or the App Engine), another button to compile a GWT project (the Google Web Toolkit takes normal Java and converts it into JavaScript), and finally, a button to deploy an App Engine project.

Go ahead and create a project by hitting the New Web Application Project button that Google was so hip to provide — in the resulting dialog that is shown below below, for simplicity’s sake, unclick the “Use Google Web Toolkit” option as we don’t be needing it for now.

Call the project what ever you’d like and name the corresponding package in any manner that suites you — it really doesn’t matter to Google.

If you create a new App Engine project, the Google team was nice enough to include as a part of the project creation, everyone’s favorite “Hello World” example, but in this case, it’s in the form of a servlet (nicely packaged according to the package structure you instructed in the project creation step, no less). It’s helpful to explain a few things regarding how the Google App Engine deployment process works at a high level before writing any code — besides, there isn’t any need to write any code as Google’s already done that too!

First and foremost, App Engine deployments can be versioned — that is, you can assign a string pattern (which can signify a version if you’d like) to a deployment. This is, of course, helpful when you begin to have multiple releases — via URLs and Google’s dashboard, you can delineate which version is the “live” one and which ones aren’t (although any versioned deployment is accessible via a URL provided you don’t remove it first). For example, the image below shows a list of 4 different versions of an application deployed on Google’s infrastructure.

Accordingly, anytime you which to deploy a new version of your project to Google’s infrastructure, you must give that deployment a valid version (which in truth can be a string pattern without .’s — i.e. 1.1 doesn’t work, but 1-1 does). Versions can be assigned in the appengine-web.xml file found in the war/WEB-INF directory already generated for you when you created a new project. It’s easy to find as you can see in below!

To deploy your freshly minted project, you won’t initially have to deal with versions (yet) as Google was kind enough to specify an initial version of 1 in the generated appengine-web.xml file. All you have to do is hit the last of the newly created buttons on the right — the one that looks like a flying Engine.

Once you hit the Deploy App Engine Project button, you’ll be asked to specify your credentials (as shown above)– those being your email and password. These are the credentials you used when you created an App Engine account earlier. Lastly, you’ll have to associate your local project with a Application ID (pictured below)– again, this is something you created when you initially created an App Engine account — you can more than one Application IDs but you are limited to 10. Once you’ve specified all the required data you are free to deploy. So what are you waiting for? Deploy your web application, baby!

Once you hit the Deploy button, you’ll see a lot of text fly by on the Eclipse console — the plug-in is doing a lot behind the scenes including enhancing any required classes that which to leverage Google’s impressive data storage service (that’s a subject for another post, believe me). Once the noise settles down (and everything worked correctly) you should see a message along the lines of “Deployment completed successfully” (pictured below) and that’s your cue to go to your App Engine account page (at Google).

Find the “Versions” link on the Google dashboard — there you’ll see a list of your deployed versions and their corresponding URL. Click the URL, and then the generated link to the generated Servlet and view (probably for the 100th time in your career) the prosaic but oh so gratifying “Hello, world” printed in plain text Servlet 101-HTML 1.0-1998-Servlet’s are new and cool-style.