Developing an Extensible TCP Server with Sockets in PHP - Defining the createSocketServer() function and the SocketServer class
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Since I already showed you how to use a procedural script for creating a multi-request TCP server, I'll now list different versions of the same application, just in case you want to work with a reusable function or, specifically in the object-based area, with a PHP class. Here are the respective definitions for both approaches:
/*
/**************************************************************
/ 'createSocketServer()' function
/**************************************************************
*/
function createSocketServer($host='127.0.0.1',$port=12345){
set_time_limit(0);
// create low level socket
if(!$socket=socket_create(AF_INET,SOCK_STREAM,0)){
trigger_error('Error creating new socket',E_USER_ERROR);
}
// tie up socket to TCP port
if(!socket_bind($socket,$host,$port)){
trigger_error('Error binding socket to TCP
port',E_USER_ERROR);
}
// begin listening connections
if(!socket_listen($socket)){
trigger_error('Error listening socket
connections',E_USER_ERROR);
}
// create communication socket
if(!$comSocket=socket_accept($socket)){
trigger_error('Error creating communication
socket',E_USER_ERROR);
}
$message='This is a simple TCP/IP server created with PHP
sockets!'."rn";
socket_write($comSocket,$message,strlen($message));
// start a loop and continue reading user input
do{
// delay loop execution
sleep(10);
// read socket input
$socketInput=socket_read($comSocket,1024);
if(trim($socketInput)!=''){
// if user did not entered the 'STOP" command
continue reading data
if(trim($socketInput)!='STOP'){
// convert to uppercase socket input
$socketOutput='The string you entered was
'.$socketInput."rn";
// write data back to socket server
socket_write($comSocket,$socketOutput,strlen
($socketOutput));
echo 'The string you entered is '.$socketOutput;
}
else{
// if 'STOP' command was entered close
communication socket & terminate all the connections
socket_close($comSocket);
break;
}
}
}
while(true);
// close global socket
socket_close($socket);
}
/*
/*************************************************************
/ 'SocketServer()' class
/*************************************************************
*/
class SocketServer{
var $host;
var $port;
var $delay=10;
var $message="This is a simple TCP/IP server created with PHP
sockets!rn";
function SocketServer($host='127.0.0.1',$port=12345){
if(!is_int($port)||$port<1||$port>65535){
trigger_error('Invalid port number',E_USER_ERROR);
}
$this->host=$host;
$this->port=$port;
$this->connect();
}
function connect(){
set_time_limit(0);
// create low level socket
if(!$socket=socket_create(AF_INET,SOCK_STREAM,0)){
trigger_error('Error creating new
socket',E_USER_ERROR);
}
// tie up socket to TCP port
if(!socket_bind($socket,$this->host,$this->port)){
trigger_error('Error binding socket to TCP
port',E_USER_ERROR);
}
// begin listening connections
if(!socket_listen($socket)){
trigger_error('Error listening socket
connections',E_USER_ERROR);
}
// create communication socket
if(!$comSocket=socket_accept($socket)){
trigger_error('Error creating communication
socket',E_USER_ERROR);
}
socket_write($comSocket,$this->message,strlen($this-
>message));
// start a loop and continue reading user input
do{
// delay loop execution
sleep($this->delay);
// read socket input
$socketInput=socket_read($comSocket,1024);
if(trim($socketInput)!=''){
// if user did not entered the 'STOP" command
continue reading data
if(trim($socketInput)!='STOP'){
$socketOutput='The string you entered was
'.$socketInput."rn";
// write data back to socket server
socket_write($comSocket,$socketOutput,strlen
($socketOutput));
echo 'The string you entered is
'.$socketOutput;
}
else{
// if 'STOP' command was entered close
communication socket & terminate all the connections
socket_close($comSocket);
break;
}
}
}
while(true);
// close global socket
socket_close($socket);
}
}
In the first case, if you're going to use the "createSocketServer()" function, this one can be used like this:
// call 'createSocketServer()" function
createSocketServer();
Or, in case you prefer to work with an object-oriented approach, the "SocketServer" class can be utilized as follows:
// instantiate 'SocketServer' object
$sock=&new SocketServer();
To wrap up
That's all for the moment. In this second part of the series, I've shown you how to build an extensible TCP server that handles multiple incoming requests, using the PHP socket-related functions that you learned in the first tutorial. But, do you think that's all? Nope; in the last article, I'll demonstrate how to implement a Web server on your own machine, by utilizing a few low-level sockets. You don't have any excuses to miss it!
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