Is Mono ready for prime time?
Has anyone used Mono, the open source .NET implementation on a large or medium sized project? I'm wondering if it's ready for real world, production environments. Is it stable, fast, compatible, ... enough to use? Does it take a lot of effort to port projects to the Mono runtime, or is it really, really compatible enough to just take of and run already written code for Microsoft's runtime?
Answer
There are a couple of scenarios to consider: (a) if you are porting an existing application and wondering if Mono is good enough for this task; (b) you are starting to write some new code, and you want to know if Mono is mature enough.
For the first case, you can use the Mono Migration Analyzer tool (Moma) to evaluate how far your application is from running on Mono. If the evaluation comes back with flying colors, you should start on your testing and QA and get ready to ship.
If your evaluation comes back with a report highlighting features that are missing or differ significantly in their semantics in Mono you will have to evaluate whether the code can be adapted, rewritten or in the worst case whether your application can work with reduced functionality.
According to our Moma statistics based on user submissions (this is from memory) about 50% of the applications work out of the box, about 25% require about a week worth of work (refactoring, adapting) another 15% require a serious commitment to redo chunks of your code, and the rest is just not worth bothering porting since they are so incredibly tied to Win32. At that point, either you start from zero, or a business decision will drive the effort to make your code portable, but we are talking months worth of work (at least from the reports we have).
If you are starting from scratch, the situation is a lot simpler, because you will only be using the APIs that are present in Mono. As long as you stay with the supported stack (which is pretty much .NET 2.0, plus all the core upgrades in 3.5 including LINQ and System.Core, plus any of the Mono cross-platform APIs) you will be fine.
Every once in a while you might run into bugs in Mono or limitations, and you might have to work around them, but that is not different than any other system.
As for portability: ASP.NET applications are the easier ones to port, as those have little to no dependencies on Win32 and you can even use SQL server or other popular databases (there are plenty of bundled database providers with Mono).
Windows.Forms porting is sometimes trickier because developers like to escape the .NET sandbox and P/Invoke their brains out to configure things as useful as the changing the cursor blinking rate expressed as two bezier points encoded in BCD form in a wParam. Or some junk like that.