Historically, the web development choice between the Microsoft platform and open source has been a fork in the road with many consequences. Choose Microsoft, and you generally use Visual Studio, Internet Information Server, ASP.NET, C# or Visual Basic, and SQL Server for the database manager. Choose open source, and you most likely target LAMP in one of its guises, the most common being Linux, Apache, MySQL and PHP, and work in Eclipse or almost anything other than Visual Studio.

Recently the boundaries have been blurring a little. Apache actually runs nicely on Windows, and I've used it happily to host a Subversion repository, while on the other side Microsoft has been making an effort to support PHP in IIS 7.0. But what about running ASP.NET on Linux, is that a silly idea?

I've been following the efforts of the Mono project in this area for some time, though it's been a while since I've tried it out. Mono was originally focused more on desktop than web applications, and I've used it mostly in that context. When laterooms.com tried Mono in early 2006 it quickly gave up, citing problems with Mono's Boehm garbage collector; see the developer's comments to my blog post at the time.

Still, that was three years ago. I had another look a couple of weeks ago, and I've been impressed. In particular, the ability to develop in Visual Studio and deploy to Linux is interesting. I'm working on a small project, and getting this working is remarkably simple. I used Visual Studio 2008, but set the project to target .NET Framework 2.0, as Mono lags behind Microsoft in implementing the latest .NET APIs, and using MySQL rather than SQL Server, since this is available on my Linux web server. Using MySQL with .NET is straightforward thanks to the official ADO.Net provider, which specifically supports Mono as well as Microsoft .NET.

On the web server, running Debian 5.0 Linux (Lenny), I installed the libapache2-mod-mono and mono-apache-server2 packages using Aptitude. Next, I configured Apache to use Mono on a particular web site, with a few lines of manual configuration, as explained here, and imported the MySQL database from the Windows development machine to the Linux web server.

Back in Visual Studio, I compiled the web site, uploaded it, and it worked first try. Performance is good as well.

I realise that a number of caveats apply. It's worth reading this page, the current Mono todo list, which notes some of the important areas where Mono is lacking and includes the comment:

Mono is known to be not as performant as the .NET Framework.

Note that Mono still uses the Boehm garbage collector, though an alternative is in development. Further, Mono does not implement the entire .NET Framework. Mono is a brave choice; Windows and IIS the sensible option for .NET applications.

It still seems to me significant that you can easily deploy to Linux and Apache using Mono. Not all applications are mission-critical, and not all applications need to scale as well as Laterooms.com. Mono has a number of attractions. First, it is open source, so in the event of problems you can always obtain and amend the source code. Second, running on Apache and Linux is a considerable saving in license costs. Third, you can get official developer support from Novell.

Why would you use C# and ASP.NET rather than PHP or Java? The main reason would be because you know and like the language, the platform, and/or the Visual Studio IDE. In an interesting report on the state of the computer book market, O'Reilly notes that C# is now the largest programming language for all book sales. Thanks to Mono, you can use C# but still deploy to an open source platform.

It also seems to me that Microsoft's official support for Moonlight, the Mono implementation of Silverlight, is important. Microsoft now needs Mono, in order to tick the cross-platform box and compete with Flash, giving more assurance to its long-term future.

Mono's growth over nearly a decade has been slow but steady. Perhaps now is the moment that it creeps into the mainstream.

Are you using Mono, for web or desktop development? I'd be interested in your comments.