How to get notification when a new message is received like Facebook - php

Question

I have a chatting room with maximum of 2 users, when one user send a message to another, the second user should be notified that new message is received just like Facebook
I have done it with Ajax request like
$(document).ready(
function() {
setInterval(function() {
$.ajax({
url: 'incs/check_new_msg.php' ,
cache: false,
success: function(data)
{
$('#message').html(data);
},
});
}, 1000);
});
<div id="message"></div>
In check_new_msg.php I use the following code:
$new_msg = mysql_query("select * from inbox where status = '0' ");
echo mysql_num_rows($new_msg);
The above code work good but the problem is that it check inbox and new message each second , but it seems harmful for processor as it run a MySQL query each second, please help me how to to execute checking query only when a new message is received.

Answer 1

i will give you a concept then you should try to implement it.
create an external text file when inserting something from another computer and at client side check same file each second rather than checking database. if file exists then check database else continue checking text file

Answer 2

So your only concern is it runs the query every second right?
Here's my solution:
$(document).ready(
function() {
function check_message()
{
$.ajax({
url: 'incs/check_new_msg.php' ,
cache: false,
success: function(data)
{
$('#message').html(data);
},
complete: function(data)
{
check_message();
},
});
}
check_message();
});
<div id="message"></div>
What this does is it will call the ajax recursively once the last ajax request is completed.

Answer 3

One of the ways of implementing the feature you discussed is long polling method. In this method you leave the connection open for certain time and if the changes occur within that time, the response is returned back to user. and another connection is opened and so on.
You should google about longpolling as there are lots of tutorials available. Best of luck

Answer 4

I found a good solution for this problem , for this purpose i use a notepad file in same directory where the script exists.
when inserting a new record from any computer you have to create notepad file with insertion.
$insert = mysql_query("insert into inbox .....");
if(insert)
{
if(!file_exists(notepad_file_path))
{
fopen(notepad_file_path);
}
}
Then I call ajax request request
$(document).ready(
function() {
function check_message()
{
$.ajax({
url: 'incs/check_new_msg.php' ,
cache: false,
success: function(data)
{
$('#message').html(data);
},
complete: function(data)
{
check_message();
},
});
}
check_message();
});
<div id="message"></div>
After that in external ajax file check existence of notepad file, if file exists then give access to database, in that way it will not be harmful for processor.
if(file_exists(notepad_file_path))
{
$new_msg = mysql_query("select * from inbox where status = '0' ");
echo mysql_num_rows($new_msg);
if(mysql_num_rows($new_msg) == 0)
{
unlink(notepad_file_path);
}
}