HTTP Module and Cookies in Sharepoint 2007

Question

I have some proof concept code for a HTTP module. The code checks to see if a cookie exists, if so it retrieves a value, if the cookie does not exist it creates it and sets the value.

Once this is done I write to the screen to see what action has been taken (all nice and simple). So on the first request the cookie is created; subsequent requests retrieve the value from the cookie.

When I test this in a normal asp.net web site everything works correctly – yay! However as soon as I transfer it to SharePoint something weird happens, the cookie is never saved - that is the code always branches into creating the cookie and never takes the branch to retrieve the value - regardless of page refreshes or secondary requests.

Heres the code...

public class SwithcMasterPage : IHttpModule
{       

    public void Dispose()
    {
        throw new NotImplementedException();
    }

    public void Init(HttpApplication context)
    {
        // register handler
        context.PreRequestHandlerExecute += new EventHandler(PreRequestHandlerExecute);
    }

    void PreRequestHandlerExecute(object sender, EventArgs e)
    {
        string outputText = string.Empty;

        HttpCookie cookie = null;
        string cookieName = "MPSetting";

        cookie = HttpContext.Current.Request.Cookies[cookieName];
        if (cookie == null)
        {
            // cookie doesn't exist, create
            HttpCookie ck = new HttpCookie(cookieName);
            ck.Value = GetCorrectMasterPage();
            ck.Expires = DateTime.Now.AddMinutes(5);
            HttpContext.Current.Response.Cookies.Add(ck);

            outputText = "storing master page setting in cookie.";
        }
        else
        {
            // get the master page from cookie
            outputText = "retrieving master page setting from cookie.";
        }

        HttpContext.Current.Response.Write(outputText + "<br/>");
    }

    private string GetCorrectMasterPage()
    {
        // logic goes here to get the correct master page
        return "/_catalogs/masterpage/BlackBand.master";

    }

Answer 1

You can use Fiddler or FireBug (on FireFox) to inspect response to see if your cookie is being sent. If not then perhaps you can try your logic in PostRequestHandlerExecute. This is assuming that Sharepoint or some other piece of code is tinkering with response cookies. This way, you can be the last one adding the cookie.

Answer 2

This turned out to be the authentication of the web app. To work correctly you must use a FQDM that has been configured for Forms Authentication.