RabbitMq初探——用队列实现RPC

rabbitmq构造rpc

前言

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rpc——remote procedure call 远程调用。在我接触的使用过http协议、thrift框架来实现远程调用。其实消息队列rabbitmq也可以实现。

原理

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我们称调用远程服务者为Client，远程服务提供者为Server。

Client充当生产者，将请求发送到rabbitmq队列中，Server作为消费者，处理Client请求产生结果数据result，此刻Server作为生产者，将result

通过rabbitmq队列传递到Client，Client作为结果数据的消费者，得到result。

代码

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rpc_client.php

<?php
/**
 * Created by PhpStorm.
 * User: 王大西
 * Date: 2017/10/23
 * Time: 16:36
 */
require_once __DIR__ . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Message\AMQPMessage;

class RpcClient
{
    private $connection = null;
    private $channel = null;
    private $callbackQueue = null;
    private $response = null;
    private $corrId = null;

    public function __construct()
    {
        $this->connection = new AMQPStreamConnection('127.0.0.1', 5672, 'guest', 'guest');
        $this->channel = $this->connection->channel();

        list($this->callbackQueue, ,) = $this->channel->queue_declare("", false, false, true, false);
        $this->channel->basic_consume($this->callbackQueue, '', false, false, false, false, array($this, 'onResponse'));
    }

    public function onResponse($rep)
    {
        if ($rep->get('correlation_id') == $this->corrId) {
            $this->response = $rep->body;
        }
    }

    public function call($n)
    {
        $this->response = null;
        $this->corrId = uniqid();

        $msg = new AMQPMessage((string) $n, array(
            'correlation_id' => $this->corrId,
            'reply_to' => $this->callbackQueue
        ));

        $this->channel->basic_publish($msg, '', 'rpc_queue1');
        while (!$this->response) {
            $this->channel->wait();
        }
        return intval($this->response);
    }

}

$number = isset($argv[1]) ? $argv[1] : 30;
$objRpcClient = new RpcClient();
$response = $objRpcClient->call($number);

echo " RPC result $response\n";

rpc_server.php

<?php
/**
 * rpc server
 * Created by PhpStorm.
 * User: 王大西
 * Date: 2017/10/23
 * Time: 16:36
 */
require_once __DIR__ . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Message\AMQPMessage;

$connection = new AMQPStreamConnection('127.0.0.1', 5672, 'guest', 'guest');
$channel = $connection->channel();

$channel->queue_declare('rpc_queue1', false, false, false, false);

function fib($n){
    if ($n == 0) {
        return 0;
    }
    if ($n == 1) {
        return 1;
    }
    return fib($n-1) + fib($n-2);
}

echo " [x] Awaiting RPC requests\n";
$callback = function($req){
    $n = intval($req->body);
    //todo $n empty return
    echo " [.] fib(", $n, ")\n";

    $msg = new AMQPMessage((string) fib($n), array('correlation_id' => $req->get("correlation_id")) );
    $req->delivery_info['channel']->basic_publish($msg, '', $req->get('reply_to'));

    $req->delivery_info['channel']->basic_ack($req->delivery_info['delivery_tag']);
};

$channel->basic_qos(null, 1, null);
$channel->basic_consume('rpc_queue1', '', false, false, false, false, $callback);

while(count($channel->callbacks)) {
    $channel->wait();
}

$channel->close();
$connection->close();

测试

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server

client