How to prevent a user from having multiple instanc

Question

I'm wondering if it is possible to determine if a user already has a web browser open to the web application I'm working on. It seems that they can open several instances of the same web app and click on buttons to read information that they have used before to enter into an input screen that they're currently working on.

What happens though is that it seems to screw up Session variables and then the user will update their previous work with their new work. Or they will delete their previous work all together or who knows...

EDIT I have seen this done before with online banking web applications. If you are already logged in, the new window will kindly tell you that you already have the app open. In my case, the user does not need to log in.

Is there a simple way to determine if they already have a browser window open to the web application and if so, just close the browser or display a different page to let them know they can only have 1 open at a time?

Thanks

Answer 1

We have implemented a solution to this problem on the slicethepie.com. Users (or "scouts") are only allowed to have one browser window open at a time to ensure they listen to the music they are being paid to review.

When a scout requests the first track to review in their scouting session we set a new Guid on their account and return this "key" along with the details of the track they're being given to review. It happens that the recipient of this key is a flash movie, but it doesn't have to be. The key is re-submitted along with the scout's review, and we check to see if it matches the saved key. If it doesn't they've started a new scouting session in a new window.

I'm not implying this method is foolproof, but it could be adapted to your needs quite easily.

Answer 2

You could assign a 'mini-session' ID to each instance of the input form, then use AJAX to ping the server with that ID. If the user tries to request the same form when there's an active ID, it should display an error message. If the server doesn't hear the ping for a certain amount of time, expire the mini-session. (This is basically a very simple locking strategy)

Answer 3

You can stop the page functionality when user opened another tab or another window or even another browser

  $(window).blur(function(){

// code to stop functioning or close the page  

});

Answer 4

If someone copy the website url and paste it in a new window or tab, the browser history for that window/tab will be empty... so you can use javascript and check the history..

if (history.length == 1) {  //0 for IE, 1 for Firefox
    // This is a new window or a new tab.
}

Now you can prompt the user to close the tab, or disable that page (by making all elements disabled for example).

Answer 5

You can do this by window.name. In java script window.name has blank value on each new tab. Set window.name value on login page and save in session.

window.name = Math.random() + "_YourApplication"

Now check this window.name on master page/Layout page. Log out user if it contain multiple tab.

 if (!window.name || window.name != '@Session["WindowName"]') {
    //Log Off code
 }

Answer 6

Is there a simple way to determine if they already have a browser window open to the web application and if so, just close the browser or display a different page to let them know they can only have 1 open at a time?

In short, No.
Without writing some kind of activeX control, there is no code you could write that could stop the user from opening a (seperate instance of) IE/FF etc and having one instance detect the other.