Simple PHP REST / JSON Server with example.php by Jake Sankey (http://jakesankey.com/blog/2012/09/php-simple-rest-server/)

example.php

<?php

  // example request: http://path/to/resource/Example?method=sayHello&name=World

  require_once "RestServer.php";

  $rest = new RestServer(Hello);
  $rest->handle();

  class Hello
  {
     public static function sayHello($name)
     {
  	return "Hello, " . $name;
     }
  }

?>

RestServer.php

<?php

  class RestServer
	{
		public $serviceClass;
	
		public function __construct($serviceClass)
		{
			$this->serviceClass = $serviceClass;
		}
	
		public function handle()
		{
			if (array_key_exists("method", array_change_key_case($_REQUEST, CASE_LOWER)))
			{
				$rArray = array_change_key_case($_REQUEST, CASE_LOWER);
				$method = $rArray["method"];
	
				if (method_exists($this->serviceClass, $method))
				{
					$ref = new ReflectionMethod($this->serviceClass, $method);
					$params = $ref->getParameters();
					$pCount = count($params);
					$pArray = array();
					$paramStr = "";
					
					$i = 0;
					
					foreach ($params as $param)
					{
						$pArray[strtolower($param->getName())] = null;
						$paramStr .= $param->getName();
						if ($i != $pCount-1) 
						{
							$paramStr .= ", ";
						}
						
						$i++;
					}

					foreach ($pArray as $key => $val)
					{
						$pArray[strtolower($key)] = $rArray[strtolower($key)];
					}
	
					if (count($pArray) == $pCount && !in_array(null, $pArray))
					{
						echo call_user_func_array(array($this->serviceClass, $method), $pArray);
					}
					else
					{
						echo json_encode(array('error' => "Required parameter(s) for ". $method .": ". $paramStr));
					}
				}
				else
				{
					echo json_encode(array('error' => "The method " . $method . " does not exist."));
				}
			}
			else
			{
				echo json_encode(array('error' => 'No method was requested.'));
			}
		}
	}

?>