Alternatives of Google App Engine + Java

If I develop my web application on GAE using Java, in future would I have easy migration opportunities, or will I stuck to GAE?

Wh开发者_C百科at can be other alternatives of Google App Engine + Java?

Not:

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An GAE you are pretty much developing inside a Google managed Container - against restricted Java and other APIs. This is the PaaS - Platform As A Service approach to cloud computing. This would be similar to the Salesforce, Facebook etc approach.

However for most flexibility you should look at IaaS - Infrastructure As A Service Cloud platforms (like Amazon/Rackspace/etc..) where you have most flexibility.

We currently use both Rackspace and Amazon and have machines as our elastic containers on top of which we can deploy anything we want (custom Ubuntu image etc..)

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With some care, you can write a Java app such that it will work both on and off App Engine. A better option, though, would be to use AppScale if you choose to leave App Engine. AppScale provides an App Engine compatible environment on your own hardware.

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right now most viable competitor of GAE is Windows Azure. You can easily build a site/application in Azure without getting dependent on Azure framework. There is /very/ little from Azure APIs that you have to deal with(mostly for diagnostics). If you decide to use other Azure services, like table storage services, you'll want to get real good at abstracting yourself away from the table storage to make your code portable. Dealing with SQL Azure (at least from utilization perspective) is no different then using SQL Server and you would need to make a simple abstraction from actual rdbms implementation (most data access libraries do that anyway) to later utilize MySQL or Oracle, etc.

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You will probably be stuck to GAE (or a very similar platform you could replicate on your own).

Alternatives: Amazon EC2? Windows Azure?

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Using GAE requires you to design the app around their system so migration could require a rewrite. Certainly their NoSQL db at the least. Some people are saying Amazon EC2 is a better bet, but I haven't tried it yet. Also I prefer python-based stuff like Django, rather than Java stuff. Try the pyjamas client-side toolkit also.