Hi Timothy,
You can use also PHP or Java Shindig. Just a few file you need to customize and it would work with your application. there are some good opensource examples to help you in that (
http://code.google.com/p/esprit and
http://code.google.com/p/zing)
If you want to use GAE-OpenSocial then it is also possible. Your container will have shindig URL pointing to GAE-OpenSocial and GAE-OpenSocial will be talking to your APIs to create/update data in your database. But for this your applications should provide all the APIs for which you need shindig to work like people, activities and application data.
In all the cases you need to customize few files either in GAE-opensocial or PHP or Java Shindig. These files are basically intended to interact with your database or APIs for persistent data.
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Ram Sharma
Impetus Infotech (India) Pvt Ltd