IIS Express is about to join the Express family of development tools and servers. It is easy to use and has been designed to make development easy.
At the moment if you want to test an ASP .NET web site you have the choice of either using the development server, aka Cassini, that comes with Visual Studio (including the Express Web developer) or a full IIS installation. It takes time and effort to set up a full IIS but the development server doesn't have the full range of options.
In a recent blog post, Scott Guthrie, Microsoft's Corporate Vice president of the .NET Developer platform, told the world that a beta of IIS Express would soon be available for download. No exact date was given or even hinted at.
The whole advantage of the development server is that it is lightweight in every respect. It needs no installation, doesn't listen on remote ports and can be run under a non-admin account - all of which makes it easy to use without raising security issues. IIS, on the other hand, is the opposite in terms of these characteristics - it does need to be installed and configured and it does need administrative rights.
Soon you could have the best of both worlds with IIS Express. This is a lightweight server with lots of the options found in the full IIS. It is promised to be around 10Mb and downloadable with a quick install. It can be run with a non-admin account from Visual Studio - effectively replacing the development server. To be clear, after installing a patch, IIS Express will automatically load and serve the web site you are trying to run under Visual Studio 2010 or Express Web Developer. It will also install a self signed certificate to make testing SSL web pages easier.
Unlike the development server it does suport a full range of web server options including - SSL, URL Rewrite, dynamic compression, logging, Media support, all IIS 7 modules and can be extended in the same way as IIS. It will not only serve ASP web sites but in principle handle anything that can be served by IIS 7.
Interestingly it is claimed to work on everything from and including Windows XP.
The beta isn't quite ready for download just yet but Microsoft has promised to follow though with patches for both Visual Studio 2010 and Express Web Developer. Future versions of both environments will ship with IIS Express as standard.
Microsoft releases new tools for Visual Studio 2010