Is It Possible To Trigger File Download To A User's Browser?

Is it possible to force file download to user's browser (with the standard dialog prompt of course)? To be triggered by the server. Basically I'm thinking of pushing a file to the

Solution 1:

Use an ajax json script that polls the server every 5 seconds or 10 seconds, when the server has a file ready responds with a positive answer "I have a file" have an iframe move to that url where the file is, and then it's handled as a normal download.

I have provided a little example of how I should think that it should work, so you have something to work from. I haven't checked it for bugs though, it's more a proof of concept thing.

jQuery example(without json):

$.ajax('/myserverscript.php?fileready=needtoknow').done(function(data) 
    {
    if(data.indexOf("I have a file") != -1)
        {
        xdata = data.split('\n');
        data = xdata[1];
        document.getElementById('myiframe').location.href = data;
        }
    });

PHP code

$x = filecheckingfunction();// returns false if none, returns url if there is a file
if($x !== false)
    {
    echo 'I have a file\n';
    echo $x;
    }

Solution 2:

It's definitely possible. Assuming you want this to be triggered by the server, you would simply send them this header:

Location: http://www.foo.com/path/to/file

Where foo.com is your domain and it contains the path to the file. This would send the user over to your file link and have them auto-download as a result.

Now, to get around the issue where your browser views the content, you would need server-side code to issue Content header information like so (using PHP as an example):

<?php
    header("Content-Type: application/octet-stream");
    header("Content-Length: " . filesize($file));   
    header('Content-Disposition: attachment; filename=' . $file); 
    readfile($file);
?>

Hopefully this works well enough as pseudo-code to get you started. Good luck!

Solution 3:

Since you are aware that you must prompt the user, try using a plain hyperlink with type="application/octet-stream".

You can also use: "content-disposition: attachment" in the header.