摘要：可以在主進(jìn)程中拋出一個(gè)子進(jìn)程，子進(jìn)程中實(shí)現(xiàn)的自動發(fā)現(xiàn)，子進(jìn)程偵察到節(jié)點(diǎn)數(shù)據(jù)變化時(shí)，主動通知主進(jìn)程。架構(gòu)的整體思路是子進(jìn)程實(shí)現(xiàn)的自動發(fā)現(xiàn)，主進(jìn)程維護(hù)一個(gè)節(jié)點(diǎn)數(shù)據(jù)的共享變量，其他服務(wù)要想使用節(jié)點(diǎn)數(shù)據(jù)時(shí)，從主進(jìn)程中獲取。

php是當(dāng)下最流行的web服務(wù)器端語言，zookeeper是大型分布式協(xié)同工具，本文在這里介紹一種架構(gòu)實(shí)現(xiàn)php服務(wù)器對于zookeeper數(shù)據(jù)變化的自動監(jiān)聽

一.問題背景
php可以CLI模式模式連接zookeeper（下面簡稱zk），并實(shí)現(xiàn)zk節(jié)點(diǎn)數(shù)據(jù)的自動發(fā)現(xiàn)，這里不做過多敘述。但web服務(wù)器中，php只能主動連接zk以獲得節(jié)點(diǎn)數(shù)據(jù)，做不到zk數(shù)據(jù)的自動發(fā)現(xiàn)。其次，php web服務(wù)，也難以和php CLI模式下的服務(wù)共享數(shù)據(jù)變量(cli模式下zk數(shù)據(jù)做成共享變量)。這就導(dǎo)致如果并發(fā)量大的話，每一個(gè)http請求php都會去連接zk，zk集群的壓力會很大，其次，每一個(gè)請求都會連接zk，請求結(jié)束又釋放zk連接，zk的連接與釋放過于頻繁。

二.解決思路
nodeJs多進(jìn)程間可以通信，可以解決php服務(wù)難以實(shí)現(xiàn)共享變量的問題。nodeJs可以在主進(jìn)程中拋出一個(gè)子進(jìn)程，子進(jìn)程中實(shí)現(xiàn)zk的自動發(fā)現(xiàn)，子進(jìn)程偵察到zk節(jié)點(diǎn)數(shù)據(jù)變化時(shí)，主動通知主進(jìn)程。node主進(jìn)程寫一個(gè)服務(wù)，像外界提供zk的數(shù)據(jù)。php web服務(wù)需要zk節(jié)點(diǎn)數(shù)據(jù)時(shí)，通過RPC協(xié)議(這里使用thrift協(xié)議)，訪問本地node主進(jìn)程服務(wù),來獲取zk節(jié)點(diǎn)數(shù)據(jù)。這樣做有三點(diǎn)好處：1.實(shí)現(xiàn)zk節(jié)點(diǎn)變化的自動發(fā)現(xiàn);

     2.php和node通信在同一臺服務(wù)器上，不走網(wǎng)管，速度快，穩(wěn)定性可靠
     3.thrift協(xié)議直接操作套接字傳輸數(shù)據(jù)，比http服務(wù)要快，可以近似看作php調(diào)用自己的方法

三.具體實(shí)現(xiàn)

1.搭建zookeeper服務(wù)，這里我搭了一個(gè)5臺zk服務(wù)的偽集群(zk服務(wù)的搭建這里不做過多介紹)，測試zk服務(wù)是否能正常寫入與讀取節(jié)點(diǎn)數(shù)據(jù)
分別啟動五臺zk服務(wù)器./server001/bin/zkServer.sh start
./server002/bin/zkServer.sh start
./server003/bin/zkServer.sh start
./server004/bin/zkServer.sh start
./server005/bin/zkServer.sh start
![zookeeper集群啟動][1]

啟動成功后，測試節(jié)點(diǎn)是否能夠正常寫入讀取(這里提前創(chuàng)建了一個(gè)/zk_test節(jié)點(diǎn))
啟動zk客戶端./bin/zkCli.sh
/zk_test測試寫入123：set /zk_test 123 發(fā)現(xiàn)可以正常寫入與讀取
![zk寫入與讀取][2]



2.創(chuàng)建node服務(wù)
定義thrift提供的服務(wù)，新建thrift文件，定義返回zk數(shù)據(jù)的服務(wù):zkDataService，服務(wù)中有一個(gè)方法zkData返回節(jié)點(diǎn)數(shù)據(jù)
namespace php tutorial
service zkDataService {
     string zkData()
}
根據(jù)thrift協(xié)議生成服務(wù)端可客戶端的中間代碼(生成中間代碼我放在windows上完成)，C:Users77388AppData	hrift-0.10.0.exe -r --gen js:node zkData.thrift
此時(shí)會在文件夾中生成中間代碼，在gen-nodejs文件夾中
![生成node端中間代碼][3]
node安裝zookeeper模塊：cnpm install node-zookeeper-client，編寫子進(jìn)程support.js，自動發(fā)現(xiàn)zk節(jié)點(diǎn)數(shù)據(jù)變更

console.log("pid in worker:", process.pid);

process.on("message", function(msg) {
  console.log("3:", msg);
});

var i=0;

var zookeeper = require("node-zookeeper-client");
var client = zookeeper.createClient("localhost:2181");
var path = "/zk_test";//節(jié)點(diǎn)名稱
 


function getData(client, path) {
    client.getData(
        path,
        function (event) {
            console.log("Got event: %s", event);
            getData(client, path);
        },
        function (error, data, stat) {
            if (error) {
                console.log("Error occurred when getting data: %s.", error);
                return;
            }
            process.send("zookeeper節(jié)點(diǎn)數(shù)據(jù)"+data.toString("utf8"));//通知主進(jìn)程zk節(jié)點(diǎn)數(shù)據(jù)
        }
    );
}


 
client.once("connected", function () {
    console.log("Connected to ZooKeeper.");
    getData(client, path);
});
 
client.connect();

process.emit("message", "======");

編寫主進(jìn)程server.js，實(shí)現(xiàn)thrift定義的服務(wù)，并在主進(jìn)程中啟動子進(jìn)程

var childprocess = require("child_process");
var worker = childprocess.fork("./support.js");

console.log("pid in master:", process.pid);
var childMessage="";
//監(jiān)聽子進(jìn)程事件
worker.on("message", function(msg) {
  childMessage=msg;
  console.log("1:", msg);//監(jiān)聽子進(jìn)程zk數(shù)據(jù)，并將zk節(jié)點(diǎn)數(shù)據(jù)打印
})
process.on("message", function(msg) {
  console.log("2:", msg);
})

worker.send("主進(jìn)程給子進(jìn)程傳遞的數(shù)據(jù)");

//觸發(fā)事件 message
process.emit("message", "------");



var thrift = require("thrift");
var zkDataService = require("./gen-nodejs/zkDataService");
var ttypes = require("./gen-nodejs/tutorial_types");

var data = {};

var server = thrift.createServer(zkDataService, {
  zkData: function(result) {
    result(null, childMessage);//將zk節(jié)點(diǎn)數(shù)據(jù)返回
  }
});

server.listen(9090);

啟動nodeJs主進(jìn)程:node server.js

3.創(chuàng)建php服務(wù)，在php服務(wù)中也要生成thrift中間件程序，與node端類似，php端調(diào)用node主進(jìn)程server.js的zkData方法，獲取zk節(jié)點(diǎn)數(shù)據(jù)

registerNamespace("Thrift", __DIR__ . "/lib");
$loader->registerDefinition("shared", $GEN_DIR);
$loader->registerDefinition("tutorial", $GEN_DIR);
$loader->register();

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

use ThriftProtocolTBinaryProtocol;
use ThriftTransportTSocket;
use ThriftTransportTHttpClient;
use ThriftTransportTBufferedTransport;
use ThriftExceptionTException;

try {
  if (array_search("--http", $argv)) {
    $socket = new THttpClient("localhost", 8080, "/php/PhpServer.php");
  } else {
    $socket = new TSocket("192.168.0.105", 9090);
  }
  $transport = new TBufferedTransport($socket, 1024, 1024);
  $protocol = new TBinaryProtocol($transport);
  $client = new 	utorialzkDataServiceClient($protocol);

  $transport->open();

  $result= $client->zkData();
  print "$result";//打印zk節(jié)點(diǎn)數(shù)據(jù)

  $transport->close();

} catch (TException $tx) {
  print "TException: ".$tx->getMessage()."
";
}

?>

啟動php服務(wù)，發(fā)現(xiàn)正常獲取zk數(shù)據(jù)

修改zookeeper數(shù)據(jù)，在啟動php服務(wù)，發(fā)現(xiàn)可以自動發(fā)現(xiàn)

總結(jié):自此，php和nodeJS相協(xié)作，完成php服務(wù)對zk數(shù)據(jù)的自動發(fā)現(xiàn)就完成了。架構(gòu)的整體思路是node子進(jìn)程實(shí)現(xiàn)zk的自動發(fā)現(xiàn)，node主進(jìn)程維護(hù)一個(gè)zk節(jié)點(diǎn)數(shù)據(jù)的共享變量，其他服務(wù)要想使用zk節(jié)點(diǎn)數(shù)據(jù)時(shí)，從node主進(jìn)程中獲取。