Active Directory Authentication Library (ADAL) in an MVVM Phone 8.1 App - mvvm

Question

I am currently trying to convert the phone sample app from the official ADAL github repo to a caliburn.micro MVVM app. But there are so many moving parts backed into the code-behind to get along with WebAuthenticationBroker that I don't now how to push that into viewmodels and handle navigation correctly when the app is activated again after the broker did the sign-on. Since I am totally clueless at the moment there is no code to share yet.

Answer 1

I've been using MvvmLight along with ADAL in my Windows Phone 8.1 App. What you need to do is as soon as you get a token, you need to send the message using the Messenger pattern. All of those view models which require the token and have already subscribed to it will receive it. Here is something I've done in my app using MvvmLight. Remember that you need to have a ContinuationManager class and IWebContinuable interface to make the app work.
private async void Login()
{
AuthenticationResult result = null;
context = AuthenticationContext.CreateAsync("https://login.windows.net/<tenant-id>").GetResults();
try
{
//try to check if you can get the token without showing pop-up
result = await context.AcquireTokenSilentAsync("https://management.core.windows.net/", "<clientid>");
if(result.Status==AuthenticationStatus.ClientError)
{
bool exists = CheckInVault();
if(exists)
{
PasswordVault vault = new PasswordVault();
var tokenvault = vault.FindAllByResource("Token");
string RefreshToken = tokenvault[0].Password;
var refresh=await context.AcquireTokenByRefreshTokenAsync(RefreshToken, clientid);
vault.Remove(tokenvault[0]);
StoreToken(refresh);
}
else
{
context.AcquireTokenAndContinue("https://management.core.windows.net/", clientid, WebAuthenticationBroker.GetCurrentApplicationCallbackUri(), StoreToken);
}
}
else if(result != null && result.Status == AuthenticationStatus.Success)
{
// A token was successfully retrieved. Post the new To Do item
bool exists = CheckInVault();
if (exists)
{
PasswordVault vault = new PasswordVault();
var tokenvault = vault.FindAllByResource("Token");
vault.Remove(tokenvault[0]);
}
StoreToken(result);
}
//this method will be called when app is opened first time and pop-up appears
result=await context.AcquireTokenSilentAsync("https://management.core.windows.net/", "<client-id>");
}
catch(Exception e)
{
MessageDialog dialog = new MessageDialog("Error");
}
}
What I am doing here is - after acquiring the access token and reference token when the user signs up first, I store the refresh token in the PasswordVault, so as to get it in the future to enable single sign-on. ADAL actually does using its caching feature, but sometimes the single sign-on failed for me, hence using the PasswordVault to store the refresh token. After the authentication completes, I have a delegate to StoreToken function, where I actually store the new refresh token and send the access token to all the subscribers using the Messenger class in MvvmLight.
private void StoreToken(AuthenticationResult result)
{
try
{
var token = result.AccessToken;
Messenger.Default.Send<string>(token); //send the access token.
PasswordVault vault = new PasswordVault();
PasswordCredential credential = new PasswordCredential();
credential.UserName = result.AccessToken;
credential.Password = result.RefreshToken;
credential.Resource = "Token";
vault.Add(credential);
}
catch(Exception e)
{
}
}
I would recommend handling the navigation in the view models. Define a helper class like NavigationService:
public class NavigationService:INavigationService
{
private Frame _frame;
public Frame Frame
{
get
{
return _frame;
}
set
{
_frame = value;
_frame.Navigated+= OnFrameNavigated;
}
}
public void NavigateTo(string type)
{
Frame.Navigate(Type.GetType(type));
}
public void GoForward()
{
if (Frame.CanGoForward)
Frame.GoForward();
}
public void GoBack()
{
if (Frame.CanGoBack)
Frame.GoBack();
}
}
To navigate to a page from the view models, you use the NavigateTo(string) method as
NavigateTo("<fully qualified class name of the page you want to navigate to>,<assembly name>")
I would also suggest using a IoC container (MvvmLight gives you a ViewModelLocator class) so that you can maintain singleton instances of your view models and helpers like NavigationService. I haven't used the CaliburnMicro framework but I would assume there would be similar features for Messaging and Dependency Injection.