Implementing the challenge handler in JavaScript (Cordova, Web) applications

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Overview

Prerequisite: Make sure to read the CredentialsValidationSecurityCheck’s challenge handler implementation tutorial.

The challenge handler will demonstrate a few additional features (APIs) such as the preemptive login, logout and obtainAccessToken.

Login

In this example, UserLogin expects key:values called username and password. Optionally, it also accepts a Boolean rememberMe key, which tells the security check to remember this user for a longer period. In the sample application, this is collected by a Boolean value from a checkbox in the login form.

userLoginChallengeHandler.submitChallengeAnswer({'username':username, 'password':password, rememberMe: rememberMeState});

You may also want to login a user without any challenge being received. For example, showing a login screen as the first screen of the application, or showing a login screen after a logout, or a login failure. We call those scenarios preemptive logins.

You cannot call the submitChallengeAnswer API if there is no challenge to answer. For those scenarios, the Mobile Foundation SDK includes the login API:

WLAuthorizationManager.login(securityCheckName,{'username':username, 'password':password, rememberMe: rememberMeState}).then(
    function () {
        WL.Logger.debug("login onSuccess");
    },
    function (response) {
        WL.Logger.debug("login onFailure: " + JSON.stringify(response));
    });

If the credentials are wrong, the security check sends back a challenge.

It is the developer’s responsibility to know when to use login, as opposed to submitChallengeAnswer, based on the application’s needs. One way to achieve this is to define a Boolean flag, for example isChallenged, and set it to true when handleChallenge is reached, or set it to false in any other cases (failure, success, initialization, etc).

When the user clicks the Login button, you can dynamically choose which API to use:

if (isChallenged){
    userLoginChallengeHandler.submitChallengeAnswer({'username':username, 'password':password, rememberMe: rememberMeState});
} else {
    WLAuthorizationManager.login(securityCheckName,{'username':username, 'password':password, rememberMe: rememberMeState}).then(
//...
    );
}

Note: The WLAuthorizationManager login() API has its own onSuccess and onFailure methods, the processSuccess or handleFailure methods of the relevant challenge handler are also called.

Obtaining an access token

Because this security check supports the RememberMe functionality (as therememberMe Boolean key), it would be useful to check whether the client is currently logged in when the application starts.

The Mobile Foundation SDK provides the obtainAccessToken API to ask the server for a valid token:

WLAuthorizationManager.obtainAccessToken(userLoginChallengeHandler.securityCheckName).then(
    function (accessToken) {
        WL.Logger.debug("obtainAccessToken onSuccess");
        showProtectedDiv();
    },
    function (response) {
        WL.Logger.debug("obtainAccessToken onFailure: " + JSON.stringify(response));
        showLoginDiv();
});

Note: The WLAuthorizationManager obtainAccessToken() API has its own onSuccess and onFailure methods, the handleSuccess or handleFailure methods of the relevant challenge handler are also called.

If the client is already logged-in or is in the remembered state, the API triggers a success. If the client is not logged in, the security check sends back a challenge.

The obtainAccessToken API takes in a scope. The scope can be the name of your security check.

Learn more about scopes in the Authorization concepts tutorial.

Retrieving the authenticated user

The challenge handler handleSuccess method receives data as a parameter. If the security check sets an AuthenticatedUser, this object contains the user’s properties. You can use handleSuccess to save the current user:

userLoginChallengeHandler.handleSuccess = function(data) {
    WL.Logger.debug("handleSuccess");
    isChallenged = false;
    document.getElementById ("rememberMe").checked = false;
    document.getElementById('username').value = "";
    document.getElementById('password').value = "";
    document.getElementById("helloUser").innerHTML = "Hello, " + data.user.displayName;
    showProtectedDiv();
}

Here, data has a key called user which itself contains a JSONObject representing the AuthenticatedUser:

{
  "user": {
    "id": "john",
    "displayName": "john",
    "authenticatedAt": 1455803338008,
    "authenticatedBy": "UserLogin"
  }
}

Logout

The Mobile Foundation SDK also provides a logout API to log out from a specific security check:

WLAuthorizationManager.logout(securityCheckName).then(
    function () {
        WL.Logger.debug("logout onSuccess");
        location.reload();
    },
    function (response) {
        WL.Logger.debug("logout onFailure: " + JSON.stringify(response));
    });

Sample applications

Two samples are associated with this tutorial:

  • PreemptiveLogin: An application that always starts with a login screen, using the preemptive login API.
  • RememberMe: An application with a Remember Me checkbox. The user can bypass the login screen the next time the application is opened.

Both samples use the same UserLogin security check from the SecurityCheckAdapters adapter Maven project.

Sample usage

Follow the sample’s README.md file for instructions. The username/password for the app must match, i.e. “john”/”john”.

sample application

Last modified on January 16, 2017