<?php
 //serverSoap.php
 $soap = new SoapServer(null,array('uri'=>"http://127.0.0.1/"));//This uri is your SERVER ip.
 $soap->addFunction('minus_func');                                                 //Register the function
 $soap->addFunction(SOAP_FUNCTIONS_ALL);
 $soap->handle();
 function minus_func($i, $j){
     $res = $i - $j;
     return $res;
 }
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 <html>
  <head>
   <title> callServer.php </title>
   <meta charset="UTF-8">
   <meta name="Author" content="">
   <meta name="Keywords" content="">
   <meta name="Description" content="">
  </head> <body>
  <form method="post" action="">
  a:<input type="text" name="numa"><br>
  b:<input type="text" name="numb"><br>
  <input type="submit">
  </form>
  <hr><?php
 //client端 clientSoap.php
 $a=(isset($_POST["numa"]))?$_POST["numa"]:100;
 $b=(isset($_POST["numb"]))?$_POST["numb"]:90;
 try {
     $client = new SoapClient(null,
         array('location' =>"http://127.0.0.1/myphp/serverSoap.php",'uri' => "http://127.0.0.1/")
     );
     echo $client->minus_func($a,$b);
 } catch (SoapFault $fault){
     echo "Error: ",$fault->faultcode,", string: ",$fault->faultstring;
 }
 ?>
  </body>
 </html>