I have looked at a lot of versions of xmlroleproviders and this one is the easiest so far. I just pasted all the code so you can see the entire thing. Some things to note is that there are self healing "roles" that get added to the role provider regardless what the end users want. It also creates the file and adds the default roles if the file does not exist. That is a safeguard for the developer. We are using this on BE 1.2 and it seems to be going well. At first I was just going to add a "readonly" approach but saw the light and viola. Let me know if you have any questions.
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f060ff32-efc7-471a-810d-a4ddfe6e2dbd|2|4.5
xmlroleprovider, simple