I think by now, most ASP.NET developers have come across some of the different provider models in ASP.NET 2.0. Most likely the Membership, Roles and SiteMap provider but also the custom provider model that you can use to create your own providers.

Still, I often come across custom authentication and authorization mechanisms instead of using the Membership and Roles provider model. Typically, a business object called User has a Logon method that does the authentication and returns a Boolean back to the login page, which sets a cookie and maybe session variable and then redirects the user to the password protected area of the website.

Then there’s usual also some custom authorization mechanism that prevents certain logged in users from certain areas such as admin pages. The menu is custom designed to hide and show only the pages available to the current user and the individual pages also makes the checks.

That is a common scenario and I see it very often. If you have such a scenario on your web application, then consider converting your existing logic to use the provider model. By creating a custom implementation of the Membership, Roles and SiteMap provider, you get all this for free and it is very simple to do so. You can keep your existing code and then build the providers on top of that.

The benefit is that these three providers work together so that the SiteMap automatically shows only the pages a user has permissions to see based on her role. You also get the cookie management for free. But the best part is that you can easily switch to a new provider when needed without changing your existing code. I did that today when I installed BlogEngine.NET on our intranet at ZYB. It had to use the Active Directory Membership provider so that we could log on using our network credentials. It took me 5 minutes to make the transition from my custom XML Membership provider to the Active Directory one. There’s a good guide at MSDN for using the Active Directory provider.

That flexibility comes free of charge with ASP.NET 2.0 and makes the lives of all .NET web developers much easier, more flexible and powerful. I have published my XML Membership provider and will wrap up the XML Roles provider soon and publish it as well.

When you first try the provider model, I promise that you’ll never go back.