Breaking out of the Google App Engine Python lock-in? [closed]

Question

Are there any guidelines to writing Google App Engine Python code that would work without Google's infrastructure on other platforms?

Is there any known attempt to create an open source framework which can run applications designed for Google App Engine on other platforms?

Edit:

To clarify, the question really is:

If I develop an application on Google App Engine now, will I be able to migrate to another platform later, or is it a lock in?

Answer 1

There's a number of components required to make an app fully portable:

• The runtime environment itself. This can be ported relatively simply, by setting up a CGI or FastCGI server that emulates the App Engine environment (which itself is basically slightly-enhanced CGI). Most of the code to do this is already in the SDK. Unfortunately, there's no easy pre-packaged toolkit for this yet.
• The datastore. By far the most complicated API to port. There are a number of efforts underway: AppScale runs on EC2/Eucalyptus/Xen and uses a HyperTable or HBase backend; it's still very much beta quality and they don't distribute the data connector separately (it's the beginnings of a complete run-your-app-on-your-own-cloud solution). Jens is/was writing an SQLite backend, and there's my own project, BDBDatastore, which uses BDB-JE as the backend, and is fully functional (though beta quality). AppDrop, which others have mentioned, simply uses the development server as a backend, and hence isn't suitable for production use.
• The users API needs replacing with something else, such as an OpenID based API. Again, fairly simple, but no premade solutions yet.
• The Memcache API needs a backend that uses standard C memcache backends.
• The other APIs have perfectly functional backends as part of the SDK, so don't really need porting.
• Cron support would also need implementing, as would background processing, XMPP, etc, when they become available.

As you can see, there's a lot of work to be done, but no fundamental barriers to making your App Engine app run outside Google's environment. In fact, if you're interested, you're more than welcome to participate - I and others have plans to combine the solutions for the various pieces into a single 'OpenEngine' solution for hosting your own apps.