Alternative to using setTimeout with AJAX?

Question

Hey guys, is there a more efficient way to do this?

setInterval('getAllWords()', 2000);

function getAllWords() {
    $.ajax({
        type: "GET",
        url: "queries.php",
        data: "action=all",
        success: function(data){
            dataArray = data.split('|');
            $('#words').html('');
            for (var i = 0; i < dataArray.length; i++) {
                if ((dataArray[i]).length > 1) {
                    $('ul').append('<li>' + dataArray[i] + '</li>');
                }
            }
        }
    });
}

ELABORATION (?)
This basically connect every 2 seconds to the database and checks for updated words, is there an easy way to implement a push request or something to minimise the database activity?

MORE INFO:
My hosting doesn't support installing of AJAX Push servers and they won't install one for me

:(

Answer 1

听起来像您要服务器推送

Answer 2

If you can't install a push server, consider this hack:

Run an infinite loop that only sends an answer to your ajax request once there's something new (while(true) { check for updated words}).

In your ajax code you can then simply start a request and as soon as it's finished start a new one (eg. readyState == 4 --> start new request)

Answer 3

If you don't need internet explorer support, you could use webSockets

Otherwise there are several standard ways of implementing server push

Here is a way to implement long polling using php - use google to find more :)

Answer 4

If query caching is enabled on your db server, then this shouldn't be a cause for worry. The query cacher will not load the db until the words field is updated.

On other note,

I prefer using setTimeout than using setInterval. What if response from server takes more than 2 secs to return? setInterval will issue request again even if previous request is not complete.

So, I'd use this

function getAllWords() {

    $.ajax({
        type: "GET",
        url: "queries.php",
        data: "action=all",
        success: function(data){
            dataArray = data.split('|');
            $('#words').html('');
            for (var i = 0; i < dataArray.length; i++) {
                if ((dataArray[i]).length > 1) {
                    $('ul').append('<li>' + dataArray[i] + '</li>');
                }
            }

            setTimeout(getAllWords,2000);
        }
    });
}

getAllWords();

Answer 5

to minize the db activity, you could:

• use a record to save whether something changed in your keywords instead of checking directly in the keywords'table.

OR

• use Application scope variable : which do not exist natively in PHP. But if you have a APC installed on your server, you can use an APC variable.

Answer 6

you can use setInterval() function, however efficiency of the method depend upon your requirement.

Please let me know your requirement.