From: http://lostechies.com/derekgreer/2012/05/29/rabbitmq-for-windows-headers-exchanges/

RabbitMQ for Windows: Headers Exchanges

Posted by Derek Greer on May 29, 2012

This is the eighth and final installment to the series: RabbitMQ for Windows.  In thelast installment, we walked through creating a topic exchange example.  As the last installment, we’ll walk through a headers exchange example.

Headers exchanges examine the message headers to determine which queues a message should be routed to.  As discussed earlier in this series, headers exchanges are similar to topic exchanges in that they allow you to specify multiple criteria, but offer a bit more flexibility in that the headers can be constructed using a wider range of data types (1).

To subscribe to receive messages from a headers exchange, a dictionary of headers is specified as part of the binding arguments.  In addition to the headers, a key of “x-match” is also included in the dictionary with a value of “all”, specifying that messages must be published with all the specified headers in order to match, or “any”, specifying that the message needs to only have one of the specified headers specified.

As our final example, we’ll create a Producer application which publishes the message “Hello, World!” using a headers exchange.  Here’s our Producer code:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
using System.Threading;
using RabbitMQ.Client;
using RabbitMQ.Client.Framing.v0_9_1; namespace Producer
{
  class Program
  {
    const string ExchangeName = "header-exchange-example";     static void Main(string[] args)
    {
      var connectionFactory = new ConnectionFactory();
      connectionFactory.HostName = "localhost";       IConnection connection = connectionFactory.CreateConnection();
      IModel channel = connection.CreateModel();
      channel.ExchangeDeclare(ExchangeName, ExchangeType.Headers, false, true, null);
      byte[] message = Encoding.UTF8.GetBytes("Hello, World!");       var properties = new BasicProperties();
      properties.Headers = new Dictionary<string, object>();
      properties.Headers.Add("key1", "12345");
     
      TimeSpan time = TimeSpan.FromSeconds(10);
      var stopwatch = new Stopwatch();
      Console.WriteLine("Running for {0} seconds", time.ToString("ss"));
      stopwatch.Start();
      var messageCount = 0;       while (stopwatch.Elapsed < time)
      {
        channel.BasicPublish(ExchangeName, "", properties, message);
        messageCount++;
        Console.Write("Time to complete: {0} seconds - Messages published: {1}\r", (time - stopwatch.Elapsed).ToString("ss"), messageCount);
        Thread.Sleep(1000);
      }       Console.Write(new string(' ', 70) + "\r");
      Console.WriteLine("Press any key to exit");
      Console.ReadKey();
      message = Encoding.UTF8.GetBytes("quit");
      channel.BasicPublish(ExchangeName, "", properties, message);
      connection.Close();
    }
  }
}

In the Producer, we’ve used a generic dictionary of type Dictionary<string, object> and added a single key “key1” with a value of “12345”.  As with our previous example, we’re using a stopwatch as a way to publish messages continually for 10 seconds.

For our Consumer application, we can use an “x-match” argument of “all” with the single key/value pair specified by the Producer, or we can use an “x-match” argument of “any” which includes the key/value pair specified by the Producer along with other potential matches.  We’ll use the latter for our example.   Here’s our Consumer code:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using RabbitMQ.Client;
using RabbitMQ.Client.Events; namespace Consumer
{
  class Program
  {
    const string QueueName = "header-exchange-example";
    const string ExchangeName = "header-exchange-example";     static void Main(string[] args)
    {
      var connectionFactory = new ConnectionFactory();
      connectionFactory.HostName = "localhost";       IConnection connection = connectionFactory.CreateConnection();
      IModel channel = connection.CreateModel();
      channel.ExchangeDeclare(ExchangeName, ExchangeType.Headers, false, true, null);
      channel.QueueDeclare(QueueName, false, false, true, null);       IDictionary specs = new Dictionary();
      specs.Add("x-match", "any");
      specs.Add("key1", "12345");
      specs.Add("key2", "123455");
      channel.QueueBind(QueueName, ExchangeName, string.Empty, specs);
// 注意,这个StartConsume是我们写的函数,其实他是在一个循环内反复调用CallBack函数。
      channel.StartConsume(QueueName, MessageHandler);
      connection.Close();
    }     public static void MessageHandler(IModel channel, DefaultBasicConsumer consumer, BasicDeliverEventArgs eventArgs)
    {
      string message = Encoding.UTF8.GetString(eventArgs.Body);
      Console.WriteLine("Message received: " + message);
      foreach (object headerKey in eventArgs.BasicProperties.Headers.Keys)
      {
        Console.WriteLine(headerKey + ": " + eventArgs.BasicProperties.Headers[headerKey]);
      }       if (message == "quit")
        channel.BasicCancel(consumer.ConsumerTag);
    }
  }
}

Rather than handling our messages inline as we’ve done in previous examples, this example uses an extension method named StartConsume() which accepts a callback to be invoked each time a message is received.  Here’s the extension method used by our example:

using System;
using System.IO;
using System.Threading;
using RabbitMQ.Client;
using RabbitMQ.Client.Events; namespace Consumer
{
  public static class ChannelExtensions
  {
    public static void StartConsume(this IModel channel, string queueName,  Action<IModel, DefaultBasicConsumer, BasicDeliverEventArgs> callback)
    {
      var consumer = new QueueingBasicConsumer(channel);
      channel.BasicConsume(queueName, true, consumer);       while (true)
      {
        try
        {
          var eventArgs = (BasicDeliverEventArgs)consumer.Queue.Dequeue();
          new Thread(() => callback(channel, consumer, eventArgs)).Start();
        }
        catch (EndOfStreamException)
        {
          // The consumer was cancelled, the model closed, or the connection went away.
          break;
        }
      }
    }
  }
}

Setting our solution to run both the Producer and Consumer applications upon startup, running our example produces output similar to the following:

Producer

Running for 10 seconds
Time to complete: 08 seconds - Messages published: 2

Consumer

Message received: Hello, World!
key1: 12345
Message received: Hello, World!
key1: 12345

That concludes our headers exchange example as well as the RabbitMQ for Windows series.  For more information on working with RabbitMQ, see the documentation athttp://www.rabbitmq.com or the purchase the book RabbitMQ in Action by Alvaro Videla and Jason Williams.  I hope you enjoyed the series.

Footnotes:

1 – See http://www.rabbitmq.com/amqp-0-9-1-errata.html#section_3 andhttp://hg.rabbitmq.com/rabbitmq-dotnet-client/diff/4def852523e2/projects/client/RabbitMQ.Client/src/client/impl/WireFormatting.csfor supported field types.

http://blog.csdn.net/puncha/article/details/8450302

RabbitMQ学习之:(九)Headers Exchange (转贴+我的评论)的更多相关文章

  1. rabbitmq学习(九) —— 关于消息队列的选型

    转自http://cmsblogs.com/?p=3846 在IM这种讲究高并发.高消息吞吐的互联网场景下,MQ消息中间件是个很重要的基础设施,它在IM系统的服务端架构中担当消息中转.消息削峰.消息交 ...

  2. (九)RabbitMQ消息队列-通过Headers模式分发消息

    原文:(九)RabbitMQ消息队列-通过Headers模式分发消息 Headers类型的exchange使用的比较少,以至于官方文档貌似都没提到,它是忽略routingKey的一种路由方式.是使用H ...

  3. RabbitMQ学习之:(六)Direct Exchange (转贴+我的评论)

    From: http://lostechies.com/derekgreer/2012/04/02/rabbitmq-for-windows-direct-exchanges/ RabbitMQ fo ...

  4. RabbitMQ入门教程(九):首部交换机Headers

    原文:RabbitMQ入门教程(九):首部交换机Headers 版权声明:本文为博主原创文章,遵循CC 4.0 BY-SA版权协议,转载请附上原文出处链接和本声明. 本文链接:https://blog ...

  5. RabbitMQ学习系列(四): 几种Exchange 模式

    上一篇,讲了RabbitMQ的具体用法,可以看看这篇文章:RabbitMQ学习系列(三): C# 如何使用 RabbitMQ.今天说些理论的东西,Exchange 的几种模式. AMQP协议中的核心思 ...

  6. RabbitMQ headers Exchange

    Headers Exchange headers也是一种交换机类型,但是在rabbitmq官网中的教程中并没有说到.资料也很少,但是找一找总会有的. headers与direct的模式不同,不是使用r ...

  7. RabbitMQ学习总结 第六篇:Topic类型的exchange

    目录 RabbitMQ学习总结 第一篇:理论篇 RabbitMQ学习总结 第二篇:快速入门HelloWorld RabbitMQ学习总结 第三篇:工作队列Work Queue RabbitMQ学习总结 ...

  8. (转)RabbitMQ学习之Headers交换类型(java)

    http://blog.csdn.net/zhu_tianwei/article/details/40923131 Headers类型的exchange使用的比较少,它也是忽略routingKey的一 ...

  9. RabbitMQ学习之:(七)Fanout Exchange (转贴+我的评论)

    From:http://lostechies.com/derekgreer/2012/05/16/rabbitmq-for-windows-fanout-exchanges/ PunCha: Ther ...

随机推荐

  1. mysql tinyint(1) 在java中被转化为boolean

    数据库表字段类型为:tinyint 长度为1 在java中对应的类型是boolean 查询时直接在页面展示成true或false 如果是2,3,4 这样的也是默认成true,非常不友好. 解决方案: ...

  2. c语言之一个简单的《学生教师管理系统》小结记录(二)

    本篇博文用来记录学生头/教师文件建立以及结构体链表创建及链表相关操作 首先是头文件的建立 头文件包含学生结构体以及链表结构 1.学生结构体建立 /****定义学生信息******/ typedef s ...

  3. asp.net 设计音乐网站

    第一步 收集资料 http://www.logoko.com.cn/    --设计logo网站 设计音乐文档  https://wenku.baidu.com/view/3d957617f18583 ...

  4. 使用pipenv管理你的python项目

    怎么使用pipenv管理你的python项目   原文链接:https://robots.thoughtbot.com/how-to-manage-your-python-projects-with- ...

  5. JPA规则

  6. linux系统编程--信号

    信号的概念 man 7 siganl  查看man手册 信号在我们的生活中随处可见, 如:古代战争中摔杯为号:现代战争中的信号弹:体育比赛中使用的信号枪......他们都有共性:1. 简单 2. 不能 ...

  7. locate/find

    locate 从数据库 (/var/lib/mlocate/mlocate.db) 查找命令,使用updatedb更新库. 类似于数据库的索引建立,在首次简历索引的时候,很耗费资源,在建立完成后,查询 ...

  8. 洛谷P4698 [CEOI2011]Hotel [贪心,二分,并查集]

    题目传送门 Hotel 题目描述 你经营着一家旅馆,这家旅馆有 n 个房间,每个房间有维护费用和容量.其中第 i 个房间的维护费用为 ci​,容量为 pi​ 人. 现在有 m 个订单,每个订单有两个参 ...

  9. a a[0] &a &a[0]的理解

    数组中几个关键符号(a a[0] &a &a[0])的理解(前提是 int a[10])(1)这4个符号搞清楚了,数组相关的很多问题都有答案了.理解这些符号的时候要和左值右值结合起来, ...

  10. 第一次使用Open Live Writer写博客

    写一下来试一试,感觉还是蛮有趣的.但是我并不知道写下来的文章是什么格式的,我刚才用VS Code打开看了一下好像都是二进制格式. 7.5正式入职,已经过去七天了.等培训结束就要去Base地了,新的生活 ...