Ajax Timed Refresh / PHP / MySQL - php

Question

It seems there are some very good resources on my question - at least the basics. But there are still a few dark areas for myself.
First - What I am trying to do.
I am having users "wait" at an intermediary page while I check to see if they have submitted the correct information from another resource (ie. SMS or email) to confirm their subscription to my service. The page should asynchronously check ever couple of seconds to see if they have completed the required steps and their status has been set to '1' or 'active' in the database.
Completing the ajax request seems pretty straightforward - the timing however, I am a little thick about.
Also, what is it that I am trying to do with the information I am retrieving - great, so the user has been set to 'active' and I can retrieve that value - but then what do I use to redirect them to the final or 'thank you' page? Is it a javascript variable that should hold the value then redirect?
Sorry if this seems a little discombobulated, but this is my first try at Ajax & timed refreshes/responses.

Answer 1

I'd do a predefined number of intervals on the ajax call - after 3 attempts, fail with a message:
var attempts = 0;
var validation_attempt = setInterval(function(){
if(attempts > 3)
{
clearInterval(validation_attempt);
$('#my_div').html('No activity, try again later');
return false;
}
$.ajax({
url: '/my_file.php',
/* other params */
success:function(data){
if(data == 'ok')
{
clearInterval(validation_attempt);
$('#my_div').html('Your account has been approved');
}
else
{
attempts++;
}
}
});
},3000); // 3 seconds
This should essentially let the user wait for 9 seconds at the most before seeing a "No activity, try again later" message.

Answer 2

Your "waiting" page can poll with ajax for completion. It might poll every 15-20 seconds initially, back up to once a minute after a little while and then stop polling all together after awhile. In all cases, make sure you don't keep polling forever as this will be bad for your backend if the user never completes their end of the subscription process.
If the ajax polling gets a successful answer, I would think you would then redirect the user to one of two places:
1) A page that just indicates "Success - you are now subscribed" and tells them what to do next.
or
2) The opening web page for actually using the service. This may be a login page or perhaps you can already log them in automatically so you take them to the open page for the service.
You can do this redirect either in client-side javascript (e.g. it already knows where to redirect the user in all scenarios) or you can include the redirection URL in that actual ajax response so the flow of pages can be controlled server-side. You can do it either way.

Answer 3

I was coding this in response to your question. I think I'll post it in case it is useful:
var active = false, i, t;
// check 'active' for truthyness, if so kill timers
function checkActive() {
if(active) {
clearInterval(i);
clearTimeout(t);
window.location.href = "success.html";
}
return false;
}
// recursively call URL to check 'active' status
function checkStatus() {
$.post("checkStatus.php", { some: "variable" }, function(resp) {
if(resp !== "1") {
t = setTimeout(checkStatus, 2000);
} else {
active = true;
}
});
}
$(document).ready(function() {
checkStatus();
i = setInterval(checkActive, 2000);
});

Answer 4

You can try using a server push (comet) rather than ajax for this solution.