需要了解如何在我的应用程序中管理角色（ASP.NET MVC3）

I'm developing some website which is a kind of online workplace, there will be some users and some ongoing computer programming projects, and each user can have multiple roles, for example one particular user can be a project manager for an project and a developer for another project. naturally the project manager has more authority than the developer in the project. my question is how to manage this in my code neatly? I was going to use my custom Role Provider and use the Authorize attribute with this, but it's not sufficient , since I'd need the project Id plus the user Id to find the role of user in an specific project. I'm developing some website which is a kind of