In working with the DotNetNuke, nGallery and .Text source here at dbvt.com I'm finding that caching is killing me, making it difficult to provide individual customization on a user-by-user basis. Elements are cached on the server so extensively that those on the respective ASP.NET Forums who often ask “How do I turn off caching for [enter any of the three apps here]?” find there are no easy solutions. I shouldn't use the term “solution“ because caching is a good thing. Its just that caching causes problems in serving up unique, dynamically generated pages on a user-by-user basis.
For example, yesterday during a Saturday morning head-banging session (not the good kind), I wanted to display a user's DotNetNuke userID next to a post as phase one testing in adding Comment Notification. (A shared AnonymousUserID is used if not dnn-logged, with this value coming from a cookie. The user needs a unique userID via registration/logging in to enable comment notification.) I use two machines to test the display behavior of posts. On the first machine, the user's ID is obtained and displayed with the post. A user from another machine--with a different userID--loads the page, but the ID of the first user is displayed because the post is served from cache. Logging in and logging out from two machines and not being able to break through the Cache barrier was not the high-point of the day. Hey, 4 vs.net projects in .Text alone, caching everywhere. Not a quick fix. Then you turn off caching behavior for a component to test, but the old component is still in memory.
This is the same reason why the nGallery area of DBVT.COM does not yet support role-based access to albums and photos, since they too are publicly cached on the server. The same components are loaded for all users with no option for dynamic display based on the user's roles.
One thing for sure, time to dig into caching.