我在 .Net 上使用 RabbitMQ 已经有一段时间了,对此我没有太大的问题。现在我正在使用 node.js 迁移到 rabbit.js,但我对它不太熟悉。rabbit.js 的文档有限。我只知道基本的 PUSH/PULL 或 PUB/SUB。现在我想做 REQ/REP 但我不知道怎么做。任何人都可以分享一些片段。
非常感谢您的回复。
最好的,
这可能比您要求的要多,但我有一个片段(即使它很长)用于使用node-amqp而不是 REQ/RES 和 rabbit.js 进行 RPC。我所做的类似于您在RabbitMQ 教程中找到的关于 RPC的内容
目前,消息中的内容应该是一个对象(散列),它将被 amqp 模块转换为 json。
AmqpRpc 类在初始化时采用 amqp 连接,然后只需调用 makeRequest 并等待回调中的响应即可。响应具有function(err, response)的形式,其中 err 可能是超时错误
很抱歉,它不完全符合您的要求,但可能已经足够接近了。我还将代码作为要点发布在 github 上:https ://gist.github.com/2720846
编辑: 示例更改为支持多个未完成的请求。
amqprpc.js
var amqp = require('amqp')
, crypto = require('crypto')
var TIMEOUT=2000; //time to wait for response in ms
var CONTENT_TYPE='application/json';
exports = module.exports = AmqpRpc;
function AmqpRpc(connection){
var self = this;
this.connection = typeof(connection) != 'undefined' ? connection : amqp.createConnection();
this.requests = {}; //hash to store request in wait for response
this.response_queue = false; //plaseholder for the future queue
}
AmqpRpc.prototype.makeRequest = function(queue_name, content, callback){
var self = this;
//generate a unique correlation id for this call
var correlationId = crypto.randomBytes(16).toString('hex');
//create a timeout for what should happen if we don't get a response
var tId = setTimeout(function(corr_id){
//if this ever gets called we didn't get a response in a
//timely fashion
callback(new Error("timeout " + corr_id));
//delete the entry from hash
delete self.requests[corr_id];
}, TIMEOUT, correlationId);
//create a request entry to store in a hash
var entry = {
callback:callback,
timeout: tId //the id for the timeout so we can clear it
};
//put the entry in the hash so we can match the response later
self.requests[correlationId]=entry;
//make sure we have a response queue
self.setupResponseQueue(function(){
//put the request on a queue
self.connection.publish(queue_name, content, {
correlationId:correlationId,
contentType:CONTENT_TYPE,
replyTo:self.response_queue});
});
}
AmqpRpc.prototype.setupResponseQueue = function(next){
//don't mess around if we have a queue
if(this.response_queue) return next();
var self = this;
//create the queue
self.connection.queue('', {exclusive:true}, function(q){
//store the name
self.response_queue = q.name;
//subscribe to messages
q.subscribe(function(message, headers, deliveryInfo, m){
//get the correlationId
var correlationId = m.correlationId;
//is it a response to a pending request
if(correlationId in self.requests){
//retreive the request entry
var entry = self.requests[correlationId];
//make sure we don't timeout by clearing it
clearTimeout(entry.timeout);
//delete the entry from hash
delete self.requests[correlationId];
//callback, no err
entry.callback(null, message);
}
});
return next();
});
}
下面是一个关于如何使用它的小例子。保存两个代码部分,然后运行...
node client.js
如果您没有服务器来提供回复,则请求将超时。
客户端.js
//exmaple on how to use amqprpc
var amqp = require('amqp');
var connection = amqp.createConnection({host:'127.0.0.1'});
var rpc = new (require('./amqprpc'))(connection);
connection.on("ready", function(){
console.log("ready");
var outstanding=0; //counter of outstanding requests
//do a number of requests
for(var i=1; i<=10 ;i+=1){
//we are about to make a request, increase counter
outstanding += 1;
rpc.makeRequest('msg_queue', {foo:'bar', index:outstanding}, function response(err, response){
if(err)
console.error(err);
else
console.log("response", response);
//reduce for each timeout or response
outstanding-=1;
isAllDone();
});
}
function isAllDone() {
//if no more outstanding then close connection
if(outstanding === 0){
connection.end();
}
}
});
我什至会投入一个示例服务器以进行良好的衡量
服务器.js
//super simple rpc server example
var amqp = require('amqp')
, util = require('util');
var cnn = amqp.createConnection({host:'127.0.0.1'});
cnn.on('ready', function(){
console.log("listening on msg_queue");
cnn.queue('msg_queue', function(q){
q.subscribe(function(message, headers, deliveryInfo, m){
util.log(util.format( deliveryInfo.routingKey, message));
//return index sent
cnn.publish(m.replyTo, {response:"OK", index:message.index}, {
contentType:'application/json',
contentEncoding:'utf-8',
correlationId:m.correlationId
});
});
});
});
https://github.com/demchenkoe/node-amqp-rpc
我发现这对于在 rabbitMQ 上使用 node 执行 rpc 非常有用。强烈推荐。