Hello readers today we discuss about "HTTP Long Polling".
World-wide-web application coders can put into action an approach called HTTP extended polling, in which the client polls the server looking for brand new data. The particular server keeps the demand open right up until brand new information is not found. Ones the new information is found, the server reacts in addition to transmits the modern data to client. Once the client is receives the modern data he will again send the request and send the same modern data to server to make one more demand and server will follow the same process.
This specific successfully emulates a server force characteristic.
Look into the code for more details
Create a new php page like data.php and put the below code into it.
<?php
if(rand(1,3) == 1){
/* Fake an error */
header("HTTP/1.0 404 Not Found");
die();
}
/* Send a string after a random number of seconds (2-10) */
sleep(rand(2,10));
echo("Hello Have a random number: " . rand(1,10));
?>
Create a long_poller.html page and put the below code into it:
<html>
<head>
<title>Long Polling</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js" type="text/javascript" charset="utf-8"></script>
<style type="text/css" media="screen">
body{ background:#000;color:#fff;font-size:.9em; }
.msg{ background:#aaa;padding:.2em; border-bottom:1px #000 solid}
.old{ background-color:#246499;}
.new{ background-color:#3B9957;}
.error{ background-color:#992E36;}
</style>
<script type="text/javascript" charset="utf-8">
function addmsg(type, msg){
/* Simple helper to add a div.
type is the name of a CSS class (old/new/error).
msg is the contents of the div */
$("#messages").append(
"<div class='msg "+ type +"'>"+ msg +"</div>"
);
}
function waitForMsg(){
/* This requests the url "msgsrv.php"
When it complete (or errors)*/
$.ajax({
type: "GET",
url: "data.php",
async: true, /* If set to non-async, browser shows page as "Loading.."*/
cache: false,
timeout:5000, /* Timeout in ms */
success: function(data){ /* called when request to barge.php completes */
addmsg("new", data); /* Add response to a .msg div (with the "new" class)*/
setTimeout(
waitForMsg, /* Request next message */
100 /* ..after 1 seconds */
);
},
error: function(XMLHttpRequest, textStatus, errorThrown){
addmsg("error", textStatus + " (" + errorThrown + ")");
setTimeout(
waitForMsg, /* Try again after.. */
15000); /* milliseconds (15seconds) */
}
});
};
$(document).ready(function(){
waitForMsg(); /* Start the inital request */
});
</script>
</head>
<body>
<div id="messages">
<div class="msg old">
Long Polling here.
</div>
</div>
</body>
</html>
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