NOTICE: I replaced my polling system with
websockets
but I still want to know the answer to my questions above.
I'm trying to reduce an AJAX request of a traditional-polling message system, but I don't know how to get it:
$chatbox = $("#chatbox");
setInterval(function(){
// I send the sha1 of the chatbox html content to verify changes.
$.post("post.php", {checksum: hex_sha1($chatbox.html())}, function (data, status) {
switch (status) {
case "success":
// If version of "post.php" checksum is different than mine (there are changes) data isn't empty; I assign data as the new content of the chatbox.
if(data){
$chatbox.html(data);
$chatbox.scrollTop($chatbox[0].scrollHeight);
}
break;
default:
$chatbox.html('Connection error...');
break;
}
});
}, 1000);
Well, As you see I use an setInterval()
with 1000
miliseconds as parameter and thanks to the SHA1
checksum system I can reduce the size of all AJAX response to 343 B
(except when "post.php" returns some new message, obviously)
Why all my AJAX requests have ever the same size (343 B)
even though I change the SHA1 (20 B
) hash to MD5 (16 B
)?
My checksum variable (SHA1) occuppies 20 B
: Where do the remaining 323 B
?
Could I reduce more the AJAX request size? How?
NOTE:
hex_sha1()
is a implementation of SHA1 algorithm for Javascript: http://pajhome.org.uk/crypt/md5/sha1.html
NOTE 2:
Unfortunately I can't use an Server-Push Technique like
node.js
. I can only use Javascript (client-side) and PHP.
Why not use the plain javascript AJAX Request? Maybe your AJAX data is too long, that's why it has a large size: and the only thing you can do for it is to make the AJAX data have a few data.
What do you want? like Facebook AJAX Polling? Do it like this on the server PHP:
$chat_data = "(this is the chat data variable if there is no chat data it will idle)";
while (!$chat_data) {
// when there's no chat data let's idle the request without disconnecting
// the client from the AJAX request.
sleep(1);
}
exit(json_encode($chat_data));
On JavaScript Client Side:
function repoll () {
chat_poll = new XMLHttpRequest();
// the chat_req variable is for sending POST data to the server.
chat_req = new FormData();
chat_req.append("do", "chatpoll");
chat_poll.open("POST", "post.php");
chat_poll.send(chat_req);
chat_poll.onload = function () {
// do something here with the chat data
// repoll the server
repoll();
}
repoll();
By doing this, your implementing the Facebook like server polling.
For the websocket
example in JavaScript client side:
web_socket = new WebSocket("ws://[thesocket]:[theport]");
web_socket.onmessage = function (w) {
// do something here. this will fire if messages is received from the websocket.
// you will get the message from w.data variable.
alert("Data Received: " + w.data);
}
// to send data to the web socket do this:
web_socket.send("the data you want. I prefer JSON for sending configuration and chat data or XML if you want");