New Feature in asp.net 4: Using Browser Capabilities Providers

In ASP.NET version 3.5 Service Pack 1, you can define the capabilities that a browser has in the following ways:

· At the machine level, you create or update a .browser XML file in the following folder:

\Windows\Microsoft.NET\Framework\v2.0.50727\CONFIG\Browsers

After you define the browser capability, you run the following command from the Visual Studio Command Prompt in order to rebuild the browser capabilities assembly and add it to the GAC:

aspnet_regbrowsers.exe –I c

· For an individual application, you create a .browser file in the application’s App_Browsers folder.

These approaches require you to change XML files, and for machine-level changes, you must restart the application after you run the aspnet_regbrowsers.exe process.

ASP.NET 4 includes a feature referred to as browser capabilities providers. As the name suggests, this lets you build a provider that in turn lets you use your own code to determine browser capabilities.

In practice, developers often do not define custom browser capabilities. Browser files are hard to update, the process for updating them is fairly complicated, and the XML syntax for .browser files can be complex to use and define. What would make this process much easier is if there were a common browser definition syntax, or a database that contained up-to-date browser definitions, or even a Web service for such a database. The new browser capabilities providers feature makes these scenarios possible and practical for third-party developers.

There are two main approaches for using the new ASP.NET 4 browser capabilities provider feature: extending the ASP.NET browser capabilities definition functionality, or totally replacing it. The following sections describe first how to replace the functionality, and then how to extend it.