How to communicate between php and boost library IPC?

I have client and server in php communicating over shared memory, Now I would like to access this shred memory object using Boost.Interprocess how can I access it? server.php:

  function create_image($str){
  // Create a blank image and add some text
  $im = imagecreatetruecolor(300, 20);
  $text_color = imagecolorallocate($im, 233, 14, 91);
  $stringBanner=exec("date").$str;
  imagestring($im, 1, 5, 5,  $stringBanner , $text_color);

  ob_start();
   imagejpeg($im);
  $i = ob_get_contents();
  ob_get_clean(); 
  imagedestroy($im);
   return $i; 
  }  
  echo "\n".__FILE__."\n";
  $shm_key = ftok(__FILE__, 't');
  echo $shm_key."\n";


  $shm_id = shmop_open($shm_key, "a", 0, 0); 
 if ($shm_id) {
  //it is already created
  shmop_delete($shm_id);
  shmop_close($shm_id); 
 } 
 //you need to create it with shmop_open using "c" only
 echo "try to create\n";
 if(!$shm_id = shmop_open($shm_key, "c", 0777, 1024*4))exit(-1);


 echo "ID ".$shm_id."\n";
 $i=0;
 for(;;){
 sleep(1);
 $s="i=".$i++;
 $str=$i;
 $im=serialize(create_image($str));

 $data=serialize(strlen($im));
 $shm_bytes_written = shmop_write($shm_id, $data, 0);
 $shm_bytes_written = shmop_write($shm_id, $im, 32);
 echo $shm_bytes_written." bytes  is written: ".$s." ID = $shm_id\n";
}

client.php

<?php
$shm_key =1946222626;// ftok(__FILE__, 't');
$shm_id = shmop_open(
         $shm_key, "a", 
         0644,1024*4
         );


 $s=shmop_size($shm_id);
 $data = unserialize(
        shmop_read( $shm_id, 0, 
            31)
       );

 $im =  unserialize(
       shmop_read( $shm_id, 32, 
               $data)
       );
  // Set the content type header - in this case image/jpeg
 header('Content-Type: image/jpeg');
// Output the image
echo $im;

What kind of key I should provide to Boost to get this memory region?

boost_client.cpp

#include <boost/interprocess/shared_memory_object.hpp> 
#include <iostream> 
#in