基于php的json rpc原理及应用

json rpc 是一种以json为消息格式的远程调用服务，它是一套允许运行在不同操作系统、不同环境的程序实现基于Internet过程调用的规范和一系列的实现。这种远程过程调用可以使用http作为传输协议，也可以使用其它传输协议，传输的内容是json消息体。

下面我们code一套基于php的rpc框架，此框架中包含rpc的服务端server，和应用端client；

（一）PHP服务端RPCserver jsonRPCServer.php

class jsonRPCServer {
    /**
     *处理一个request类，这个类中绑定了一些请求参数
     * @param object $object
     * @return boolean
     */
    public static function handle($object) {
       // 判断是否是一个rpc json请求
        if ($_SERVER['REQUEST_METHOD'] != 'POST' || empty($_SERVER['CONTENT_TYPE'])
            ||$_SERVER['CONTENT_TYPE'] != 'application/json') {
            return false;
        }
        // reads the input data
        $request = json_decode(file_get_contents('php://input'),true);
        // 执行请求类中的接口
        try {
            if ($result = @call_user_func_array(array($object,$request['method']),$request['params'])) {
                $response = array ( 'id'=> $request['id'],'result'=> $result,'error'=> NULL );
            } else {
                $response = array ( 'id'=> $request['id'], 'result'=> NULL,
                                        'error' => 'unknown method or incorrect parameters' );}
        } catch (Exception $e) {
            $response = array ('id' => $request['id'],'result' => NULL, 'error' =>$e->getMessage());
        }
       // json 格式输出
        if (!empty($request['id'])) { // notifications don't want response
            header('content-type: text/javascript');
            echo json_encode($response);
        }
        return true;
    }
}

(二)Rpc客户端，jsonRPCClient.php

<?php
/*
 */
class jsonRPCClient {

    private $debug;
    private $url;
    // 请求id
    private $id;
    private $notification = false;
    /**
     * @param $url
     * @param bool $debug
     */
    public function __construct($url,$debug = false) {
        // server URL
        $this->url = $url;
        // proxy
        empty($proxy) ? $this->proxy = '' : $this->proxy = $proxy;
        // debug state
        empty($debug) ? $this->debug = false : $this->debug = true;
        // message id
        $this->id = 1;
    }

    /**
     *
     * @param boolean $notification
     */
    public function setRPCNotification($notification) {
        empty($notification) ? $this->notification = false  : $this->notification = true;
    }

    /**
     * @param $method
     * @param $params
     * @return bool
     * @throws Exception
     */
    public function __call($method,$params) {
        // 检验request信息
        if (!is_scalar($method)) {
            throw new Exception('Method name has no scalar value');
        }
        if (is_array($params)) {
            $params = array_values($params);
        } else {
            throw new Exception('Params must be given as array');
        }

        if ($this->notification) {
            $currentId = NULL;
        } else {
            $currentId = $this->id;
        }

       // 拼装成一个request请求
        $request = array(  'method' => $method,  'params' => $params,'id' => $currentId);
        $request = json_encode($request);
        $this->debug && $this->debug.='***** Request *****'."\n".$request."\n".'***** End Of request *****'."\n\n";
        $opts = array ('http' => array (
                                    'method'  => 'POST',
                                    'header'  => 'Content-type: application/json',
                                    'content' => $request
        ));
        //  关键几部
        $context  = stream_context_create($opts);
		if ( $result = file_get_contents($this->url, false, $context)) {
            $response = json_decode($result,true);
		} else {
			throw new Exception('Unable to connect to '.$this->url);
		}
        // 输出调试信息
        if ($this->debug) {
            echo nl2br(($this->debug));
        }
        // 检验response信息
        if (!$this->notification) {
            // check
            if ($response['id'] != $currentId) {
                throw new Exception('Incorrect response id (request id: '.$currentId.', response id: '.$response['id'].')');
            }
            if (!is_null($response['error'])) {
                throw new Exception('Request error: '.$response['error']);
            }
            return $response['result'];

        } else {
            return true;
        }
    }
}
?>

(三) 应用实例

（1）服务端 server.php

<?php
<span style="white-space:pre">	</span>require_once 'jsonRPCServer.php';

// member 为测试类
<span style="white-space:pre">	</span>require 'member.php';
<span style="white-space:pre">	</span>// 服务端调用
<span style="white-space:pre">	</span>$myExample = new member();
<span style="white-space:pre">	</span>// 注入实例
<span style="white-space:pre">	</span>jsonRPCServer::handle($myExample)
	or print 'no request';
?>

（2）测试类文件，member.php

class member{
    public function getName(){
        return 'hello word ' ;  // 返回字符串
    }
}

（3）客户端 client.php

require_once 'jsonRPCClient.php';

$url = 'http://localhost/rpc/server.php';
$myExample = new jsonRPCClient($url);

// 客户端调用
try {
	$name = $myExample->getName();
    echo $name ;
} catch (Exception $e) {
	echo nl2br($e->getMessage()).'<br />'."\n";
}