Javascript 当数据值发生变化时，如何将 redis PUBLISH/SUBSCRIBE 与 nodejs 结合使用来通知客户端？
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How to use redis PUBLISH/SUBSCRIBE with nodejs to notify clients when data values change?
提问by u443966
I'm writing an event-driven publish/subscribe application with NodeJS and Redis. I need an example of how to notify web clients when the data values in Redis change.
我正在使用 NodeJS 和 Redis 编写一个事件驱动的发布/订阅应用程序。我需要一个示例，说明如何在 Redis 中的数据值更改时通知 Web 客户端。
回答by Alfred
OLD only use a reference
OLD 仅使用参考
Dependencies
依赖关系
uses express, socket.io, node_redisand last but not least the sample codefrom media fire.
使用express、socket.io、node_redis以及最后但并非最不重要的来自 media fire的示例代码。
Install node.js+npm(as non root)
安装 node.js+npm（作为非 root）
First you should(if you have not done this yet) install node.js+npm in 30 seconds(the right way because you should NOTrun npm as root):
首先，你应该（如果你还没有这样做还）安装的node.js + NPM在30秒（以正确的方式，因为你应该不运行NPM作为根）：
echo 'export PATH=$HOME/local/bin:$PATH' >> ~/.bashrc
. ~/.bashrc
mkdir ~/local
mkdir ~/node-latest-install
cd ~/node-latest-install
curl http://nodejs.org/dist/node-latest.tar.gz | tar xz --strip-components=1
./configure --prefix=~/local
make install # ok, fine, this step probably takes more than 30 seconds...
curl http://npmjs.org/install.sh | sh
Install dependencies
安装依赖
After you installed node+npm you should install dependencies by issuing:
安装 node+npm 后，您应该通过发出以下命令来安装依赖项：
npm install express
npm install socket.io
npm install hiredis redis # hiredis to use c binding for redis => FAST :)
Download sample
下载样本
You can download complete sample from mediafire.
您可以从mediafire下载完整的示例。
Unzip package
解压包
unzip pbsb.zip # can also do via graphical interface if you prefer.
What's inside zip
拉链里面是什么
./app.js
./app.js
const PORT = 3000;
const HOST = 'localhost';
var express = require('express');
var app = module.exports = express.createServer();
app.use(express.staticProvider(__dirname + '/public'));
const redis = require('redis');
const client = redis.createClient();
const io = require('socket.io');
if (!module.parent) {
app.listen(PORT, HOST);
console.log("Express server listening on port %d", app.address().port)
const socket = io.listen(app);
socket.on('connection', function(client) {
const subscribe = redis.createClient();
subscribe.subscribe('pubsub'); // listen to messages from channel pubsub
subscribe.on("message", function(channel, message) {
client.send(message);
});
client.on('message', function(msg) {
});
client.on('disconnect', function() {
subscribe.quit();
});
});
}
./public/index.html
./public/index.html
<html>
<head>
<title>PubSub</title>
<script src="/socket.io/socket.io.js"></script>
<script src="/javascripts/jquery-1.4.3.min.js"></script>
</head>
<body>
<div id="content"></div>
<script>
$(document).ready(function() {
var socket = new io.Socket('localhost', {port: 3000, rememberTransport: false/*, transports: ['xhr-polling']*/});
var content = $('#content');
socket.on('connect', function() {
});
socket.on('message', function(message){
content.prepend(message + '<br />');
}) ;
socket.on('disconnect', function() {
console.log('disconnected');
content.html("<b>Disconnected!</b>");
});
socket.connect();
});
</script>
</body>
</html>
Start server
启动服务器
cd pbsb
node app.js
Start browser
启动浏览器
Best if you start google chrome(because of websockets support, but not necessary). Visit http://localhost:3000to see sample(in the beginning you don't see anything but PubSubas title).
如果您启动 google chrome 最好（因为 websockets 支持，但不是必需的）。访问http://localhost:3000以查看示例（一开始你什么也看不到，但PubSub作为标题）。
But on publishto channel pubsubyou should see a message. Below we publish "Hello world!"to the browser.
但是在publish频道上，pubsub您应该会看到一条消息。下面我们发布"Hello world!"到浏览器。
From ./redis-cli
来自 ./redis-cli
publish pubsub "Hello world!"
回答by nak
here's a simplified example without as many dependencies.
You do still need to npm install hiredis redis
这是一个没有那么多依赖项的简化示例。你仍然需要npm install hiredis redis
The node JavaScript:
节点 JavaScript：
var redis = require("redis"),
client = redis.createClient();
client.subscribe("pubsub");
client.on("message", function(channel, message){
console.log(channel + ": " + message);
});
...put that in a pubsub.js file and run node pubsub.js
...把它放在一个 pubsub.js 文件中并运行 node pubsub.js
in redis-cli:
在 redis-cli 中：
redis> publish pubsub "Hello Wonky!"
(integer) 1
which should display: pubsub: Hello Wonky!in the terminal running node!
Congrats!
应该显示：pubsub: Hello Wonky!在终端运行节点！恭喜！
Additional 4/23/2013:I also want to make note that when a client subscribes to a pub/sub channel it goes into subscriber mode and is limited to subscriber commands. You'll just need to create additional instances of redis clients. client1 = redis.createClient(), client2 = redis.createClient()so one can be in subscriber mode and the other can issue regular DB commands.
2013 年 4 月 23 日附加：我还想说明，当客户端订阅发布/订阅频道时，它会进入订阅者模式并且仅限于订阅者命令。您只需要创建额外的 redis 客户端实例。client1 = redis.createClient(), client2 = redis.createClient()所以一个可以处于订阅者模式，另一个可以发出常规的 DB 命令。
回答by nelsonic
CompleteRedis Pub/Sub Example (Real-time Chatusing Hapi.js & Socket.io)
完整的Redis Pub/Sub 示例（使用 Hapi.js 和 Socket.io进行实时聊天）
We were trying to understand Redis Publish/Subscribe ("Pub/Sub") and all the existing examples were either outdated, too simple or had no tests. So we wrote a CompleteReal-time Chat using Hapi.js + Socket.io + Redis Pub/Sub Example with End-to-End Tests!
我们试图理解Redis的发布/订阅（“发布/订阅”）和所有现有的例子要么过时，过于简单或没有测试。所以我们使用 Hapi.js + Socket.io + Redis Pub/Sub 示例编写了一个完整的实时聊天和端到端测试！
The Pub/Sub component is only a few lines of node.js code: https://github.com/dwyl/hapi-socketio-redis-chat-example/blob/master/lib/chat.js#L33-L40
Pub/Sub 组件只有几行 node.js 代码：https: //github.com/dwyl/hapi-socketio-redis-chat-example/blob/master/lib/chat.js#L33-L40
Rather than pasting it here (without any context) we encourageyou to checkout/try the example.
我们鼓励您查看/尝试示例，而不是将其粘贴到此处（没有任何上下文）。
We built it using Hapi.jsbut the chat.jsfile is de-coupledfrom Hapi and can easilybe used with a basicnode.js http serveror express(etc.)
我们使用Hapi.js构建它，但该chat.js文件与Hapi 分离，可以轻松地与基本的node.js http 服务器或express（等）一起使用
回答by Awemo
Handle redis errors to stop nodejs from exiting. You can do this by writing;
处理 redis 错误以阻止 nodejs 退出。你可以通过写作来做到这一点；
subcribe.on("error", function(){
//Deal with error
})
I think you get the exception because you are using the same client which is subscribed to publish messages. Create a separate client for publishing messages and that could solve your problem.
我认为您会遇到异常，因为您使用的是订阅发布消息的相同客户端。创建一个单独的客户端来发布消息，这可以解决您的问题。
回答by ma11hew28
Check out acani-node on GitHub, especially the file acani-node-server.js. If these links are broken, look for acani-chat-server among acani's GitHub public repositories.
在 GitHub 上查看acani-node，尤其是文件acani-node-server.js。如果这些链接失效，请在acani 的 GitHub 公共存储库中查找 acani-chat-server 。
回答by dirkk0
If you want to get this working with socket.io 0.7 ANDan external webserver you need to change (besides the staticProvider -> static issue):
如果你想让它与 socket.io 0.7和外部网络服务器一起工作，你需要改变（除了 staticProvider -> 静态问题）：
a) provide the domain nameinstead of localhost (i.e. var socket = io.connect('http://my.domain.com:3000'); ) in the index.html
a)在 index.html 中提供域名而不是 localhost（即 var socket = io.connect('http://my.domain.com:3000'); ）
b) change HOST in app.js (i.e. const HOST = 'my.domain.com'; )
b) 更改 app.js 中的 HOST（即 const HOST = 'my.domain.com'; ）
c) and add socketsin line 37 of app.js (i.e. 'socket.sockets.on('connection', function(client) { …' )
c) 并在 app.js 的第 37 行添加套接字（即 'socket.sockets.on('connection', function(client) { ...' ）
回答by Alex Mikhalev
回答by hbinduni
according to @alexsolution. if you have an error like this one as per @tylermention:
根据@alex解决方案。如果根据@tyler提到的类似错误：
node.js:134
throw e; // process.nextTick error, or 'error'
event on first tick ^ Error: Redis connection to 127.0.0.1:6379 failed - ECONNREFUSED, Connection refused at Socket.
then you need to install Redisfirst. check this out:
那么你需要先安装Redis。看一下这个：
