Determining App or Session Context

I'd like to be able to use some of the same methods whether or not I'm using an app auth token or a user auth token, and need a test to determine which context I'm in. Something like the following:

    publi开发者_Python百科c FacebookClient GetFacebookClient() {
        return IsUserRequest() ? GetFacebookWebClient() : GetFacebookAppClient();
    }
    public dynamic GetUser(long fbId) {
        var fbClient = GetFacebookClient();
        return fbClient.Query(String.Format(@"SELECT uid,name FROM user WHERE uid = ({0})", fbId);
   }

However, I can't seem to find a good test to implement IsUserRequest(). Any ideas?

I was using a singleton for my Facebook utilities class, and so I just allowed for two: a web context singleton, and an app context singleton.

public class FbUtil {
    private static readonly FbUtil webInstance = new FbUtil(false);
    private static readonly FbUtil appInstance = new FbUtil(true);
    static FbUtil() {}
    private FbUtil(bool isAppInstance) {
        IsAppInstance = isAppInstance;
    }
    private readonly bool IsAppInstance;
    public static FbUtil WebInstance {
        get { return webInstance; }
    }
    public static FbUtil AppInstance {
        get { return appInstance; }
    }
    public FacebookClient GetFacebookAppClient() {
        var oauth = new FacebookOAuthClient { AppId=Config.FacebookConfig.AppId, AppSecret=Config.FacebookConfig.AppSecret };
        dynamic tokenRes = oauth.GetApplicationAccessToken();
        return new FacebookClient(tokenRes.access_token);           
    }
    public FacebookClient GetFacebookWebClient() {
        return new FacebookWebClient();         
    }
    public FacebookClient GetFacebookClient() {
        return IsAppInstance ? GetFacebookAppClient() : GetFacebookWebClient();
    }
    public FbUser GetUser(long facebookId) {        
        var client = GetFacebookClient();
        dynamic result = client.Get(facebookId);
        return new FbUser(result);
    }
    ... etc. other FB utility methods
}

and I simply call it like so from my business objects:

  var fbUser = FbUtil.WebInstance.GetUser("12345");

or

  var fbUser = FbUtil.AppInstance.GetUser("12345");    

This keeps the interface clean, and I don't have any redundant methods. If a method is not availlable in the app context, I throw an exception, which isn't ideal, but it suits my purposes for now. prabir, how do you feel about this approach?