For quite some time I have been thinking about trying out that ‘Cloud-thing‘ and see what all the fuzz is about. Because at first I was very skeptic, ‘how is this any different then a normal hosting service’ or ‘how does this any different than a grid’. Because depending on the used definition, or cloud provider, those difference are subtle.

Then Google came along and launched their Java version of their Cloud environment(Google App
Engine). Since this one seemed to be easy and free to try, I decided to give it a try with the tutorial. ( App Engine the java platform , so not only the java language is supported, but languages like groovy and jruby also work, but I stayed with ‘just’ Java)  

Within a time span of 5 to 10 minutes I had registered my cloud application and was ready to get started. The registration is not much different than for a Gmail account. Then I decided to install the eclipse plugins, this also worked as a charm.
Next, I generated a GWT App engine project with hello-world example code and pressed deploy and my ‘hello world’ was running in the cloud.

The total time taken for this test run was less than 15 minutes and additional applications would be deployed even faster because the environment is all ready installed.

The benefits of this over a normal hosting provider for me are ease of use (the java hosting providers i am used to take a lot more time for installing a build), and scalability (the app engine requires you to work in way no local file access to enable distributed computing which enables them to scale your application).

And just as an exercise I decided to port a normal small java project of mine into my cloud project. Not much had to be changed, the local property file access was replaced by a classpath resource, and I had to hack my way into GWT which i never had used before. And that last part cost me the most time.

For the few interested in my IMDB profile compare tool see: http://film-freak.appspot.com/ It’s supposed to help film freaks compare which films they both saw and which the other didn’t saw. (If you have an imdb vote history you need to make it public first before you can use your profile number, and some large profiles are not handled right but the feature this service uses is not yet supported by IMDB)

Is the app engine flawless? yeah, well even though app engine comes with a local environment that resembles the real app engine, I had a bug that occurred in the real one but not the local one. The bug was related to the character parsing of the app engine (the bug is still in my application btw)

Also this application didn’t use the datastore, but I heard quite some troubles with the use of frameworks and standards (JPA) on the appengine. To summarize this; the appengine has a special datastore, BigTable, which is fast but not a RDBMS, and to use JPA or JDO plugins for frameworks have to be created and the quality of those plugins define what part of JPA and JDO is available and at this moment this seem to be quite limited. Maybe later this year I’ll take some time to play around with this datastore.

Also see:
http://www.theserverside.com/news/thread.tss?thread_id=54919

http://groups.google.com/group/google-appengine-java/web/will-it-play-in-app-engine

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