C#/Java portability [closed]

Question

What mainstream frameworks, patterns, and tools would you choose to develop two projects in parallel, one in C#, one in Java, in order to minimize the total effort. (Disregard the obvious cases of interchangeable or equivalent tools, like SCC, Unit Testing, etc. Also assume generic broad RDBMS support.)

"Mainstream" means the market in general won't disregard the result because it uses something untested they've never heard of, or arcane skills are required to implement and support it.

Assume a broadly applicable tactical business appication.

Answer 1

db4o uses an in house tool called sharpen to maintain one source repository (Java I think) and convert it automatically to C#.

As they say in thier blog post:

Before you start dreaming: sharpen is not a "magic wand". Don't expect to feed it an arbitrary Java app and receive a running .NET version at the push of a button. The translation process will require some design compromises on the Java side, and parts of the .NET code still have to be hand crafted and integrated into the converted sources.

However it is still quite a cool project. Also, I think it would work best for a new project. Released under the GPL but you have to register with developer.db4o.com to download it.

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Edit: Here is an example blog post too.