Why Google App Engine Matters
I was incredibly excited to see the announcement of Google App Engine (GAE) recently. I can run web applications on Google’s grid, and have access to their authentication and back-end data store? Sign me right up!
Since it was announced, GAE has taken a lot of heat from pundits. For the most part, they are right, once you cut past the hyperbole. It is exceptionally limited: you cannot run spun-off processes on the server, there are no cron jobs, and the data store, BigTable, is not a relational database. It does threaten to lock in your application: if you use Google authentication, good luck migrating your users, and moving from BigTable to a relational database elsewhere would possibly be tough.
However, limitations can provoke creativity, and enhance applications built for that space. There are a lot of applications you can build without background processes, and if the end-game for your application is not to be bought, having Google’s authentication in place could vastly increase your user registration rate, as most users will not have to sign up for a new account. If you want to make a web application that does an interesting, simple task, GAE may be the best platform around once it gets out of beta.
From a development perspective, the fact that GAE only runs the Python programming language is definitely limiting. It is obvious why it was chosen: Guido van Rossum, the inventor of Python, works at Google, and they needed to limit the Python virtual machine to disable writing to the filesystem or other machine-specific tasks. Google’s announcement that they plan to support other languages, however, excites me. One of Google’s main languages is Java. The Java virtual machine (JVM) is a great piece of software; many languages have been ported to it including Ruby, our favorite here at Viget, and new languages have been written for it, such as Scala, one of my personal favorites. It is fairly trivial to use the JVM to sandbox these languages and limit their abilities to manipulate the machine as Google has done with Python. I expect to see JRuby supported soon, and a flood of languages thereafter. What this means for Rubyists is Google putting resources into developing JRuby, or even Rubinius, if they choose that route for a sandboxed Ruby.
The other exciting part about GAE to me is that they have a software development kit (SDK) to run GAE apps locally. This has already been ported to Amazon’s EC2, allowing you to run GAE apps there. BigTable, Google’s data store, is an interesting concept, and the development community has expressed interest lately in document databases, like CouchDB. With this SDK, we have been given a specification for the interface for BigTable. This is interesting: we may well see competing implementations of this non-relational database come out, allowing GAE apps to use any of them on non-Google machines. This can only result in innovation in database design, something which I have not seen a lot of in the last few years.