C#中關於ActiveMQ的應用詳解

ActiveMQ是個好東東，不必多說。ActiveMQ提供多種語言支援，如Java, C, C++, C#, Ruby, Perl, Python, PHP等。由於我在windows下開發GUI，比較關心C++和C#，其中C#的ActiveMQ很簡單，Apache提供NMS（.Net Messaging Service）支援.Net開發，只需如下幾個步驟即能建立簡單的實現。C++的應用相對麻煩些，稍後寫文章介紹。

1、去ActiveMQ官方網站下載最新版的ActiveMQ，我之前下的是5.3.1，5.3.2現在也已經出來了。

2、去ActiveMQ官方網站下載最新版的Apache.NMS，需要下載Apache.NMS和Apache.NMS.ActiveMQ兩個bin包，如果對源碼感興趣，也可下載src包。這裡要提醒一下，如果下載1.2.0版本的NMS.ActiveMQ，Apache.NMS.ActiveMQ.dll在實際使用中有個bug，即停止ActiveMQ應用時會拋WaitOne函數異常，查看src包中的源碼發現是由於Apache.NMS.ActiveMQ-1.2.0-src\src\main\csharp\Transport\InactivityMonitor.cs中的如下代碼造成的，修改一下源碼重新編譯即可。看了一下最新版1.3.0已經修複了這個bug，因此下載最新版即可。

private void StopMonitorThreads()           {               lock(monitor)               {                   if(monitorStarted.CompareAndSet(true, false))                   {                       AutoResetEvent shutdownEvent = new AutoResetEvent(false);                       // Attempt to wait for the Timers to shutdown, but don't wait                       // forever, if they don't shutdown after two seconds, just quit.                       this.readCheckTimer.Dispose(shutdownEvent);                       shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                       this.writeCheckTimer.Dispose(shutdownEvent);                       shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                                                       //WaitOne的定義：public virtual bool WaitOne(TimeSpan timeout,bool exitContext)                       this.asyncTasks.Shutdown();                       this.asyncTasks = null;                       this.asyncWriteTask = null;                       this.asyncErrorTask = null;                   }               }           }  　　　　 private void StopMonitorThreads()         {             lock(monitor)             {                 if(monitorStarted.CompareAndSet(true, false))                 {                     AutoResetEvent shutdownEvent = new AutoResetEvent(false);                    // Attempt to wait for the Timers to shutdown, but don't wait                     // forever, if they don't shutdown after two seconds, just quit.                     this.readCheckTimer.Dispose(shutdownEvent);                     shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                     this.writeCheckTimer.Dispose(shutdownEvent);                     shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                                                     //WaitOne的定義：public virtual bool WaitOne(TimeSpan timeout,bool exitContext)                     this.asyncTasks.Shutdown();                     this.asyncTasks = null;                     this.asyncWriteTask = null;                     this.asyncErrorTask = null;                 }             }         }

3、運行ActiveMQ，找到ActiveMQ解壓後的bin檔案夾：...\apache-activemq-5.3.1\bin，執行activemq.bat批次檔即可啟動ActiveMQ伺服器，預設連接埠為61616，這可在設定檔中修改。

4、寫C#程式實現ActiveMQ的簡單應用。建立C#工程（一個Producter項目和一個Consumer項目），WinForm或Console程式均可，這裡建的是Console工程，添加對Apache.NMS.dll和Apache.NMS.ActiveMQ.dll的引用，然後即可編寫實現代碼了，簡單的Producer和Consumer實現代碼如下：

producer：

using System;   using System.Collections.Generic;   using System.Text;   using Apache.NMS;   using Apache.NMS.ActiveMQ;   using System.IO;   using System.Xml.Serialization;   using System.Runtime.Serialization.Formatters.Binary;   namespace Publish   {       class Program       {           static void Main(string[] args)           {               try              {                   //Create the Connection Factory                   IConnectionFactory factory = new ConnectionFactory("tcp://localhost:61616/");                   using (IConnection connection = factory.CreateConnection())                   {                       //Create the Session                       using (ISession session = connection.CreateSession())                       {                           //Create the Producer for the topic/queue                           IMessageProducer prod = session.CreateProducer(                               new Apache.NMS.ActiveMQ.Commands.ActiveMQTopic("testing"));                           //Send Messages                           int i = 0;                           while (!Console.KeyAvailable)                           {                               ITextMessage msg = prod.CreateTextMessage();                               msg.Text = i.ToString();                               Console.WriteLine("Sending: " + i.ToString());                               prod.Send(msg, Apache.NMS.MsgDeliveryMode.NonPersistent, Apache.NMS.MsgPriority.Normal, TimeSpan.MinValue);                               System.Threading.Thread.Sleep(5000);                               i++;                           }                       }                   }                   Console.ReadLine();              }               catch (System.Exception e)               {                   Console.WriteLine("{0}",e.Message);                   Console.ReadLine();               }           }       }   }

consumer:

using System;   using System.Collections.Generic;   using System.Text;   using Apache.NMS;   using Apache.NMS.ActiveMQ;   using System.IO;   using System.Xml.Serialization;   using System.Runtime.Serialization.Formatters.Binary;   namespace Subscribe   {       class Program       {           static void Main(string[] args)           {               try              {                   //Create the Connection factory                   IConnectionFactory factory = new ConnectionFactory("tcp://localhost:61616/");                   //Create the connection                   using (IConnection connection = factory.CreateConnection())                   {                       connection.ClientId = "testing listener";                       connection.Start();                       //Create the Session                       using (ISession session = connection.CreateSession())                       {                           //Create the Consumer                           IMessageConsumer consumer = session.CreateDurableConsumer(new Apache.NMS.ActiveMQ.Commands.ActiveMQTopic("testing"), "testing listener", null, false);                           consumer.Listener += new MessageListener(consumer_Listener);                           Console.ReadLine();                       }                       connection.Stop();                       connection.Close();                   }               }               catch (System.Exception e)               {                   Console.WriteLine(e.Message);               }           }           static void consumer_Listener(IMessage message)           {               try              {                   ITextMessage msg = (ITextMessage)message;                   Console.WriteLine("Receive: " + msg.Text);              }               catch (System.Exception e)               {                   Console.WriteLine(e.Message);               }           }       }   }

程式實現的功能：生產者producer建立名為testing的主題，並每隔5秒向該主題發送訊息，消費者consumer訂閱了testing主題，因此只要生產者發送testing主題的訊息到ActiveMQ伺服器，伺服器就將該訊息發送給訂閱了testing主題的消費者。

編譯產生producer.exe和consumer.exe，並執行兩個exe，即可看到訊息的發送與接收了。

這個例子是建的主題（Topic），ActiveMQ還支援另一種方式：Queue，即P2P，兩者有什麼區別呢？區別在於，Topic是廣播，即如果某個Topic被多個消費者訂閱，那麼只要有訊息到達伺服器，伺服器就將該訊息發給全部的消費者；而Queue是點到點，即一個訊息只能發給一個消費者，如果某個Queue被多個消費者訂閱，沒有特殊情況的話訊息會一個一個地輪流發給不同的消費者，比如：

msg1-->consumer A

msg2-->consumer B

msg3-->consumer C

msg4-->consumer A

msg5-->consumer B

msg6-->consumer C

特殊情況是指：ActiveMQ支援過濾機制，即生產者可以設定訊息的屬性（Properties），該屬性與消費者端的Selector對應，只有消費者設定的selector與訊息的Properties匹配，訊息才會發給該消費者。Topic和Queue都支援Selector。

Properties和Selector該如何設定呢？請看如下代碼：

producer：

public void SetProperties(){ITextMessage msg = prod.CreateTextMessage();                               msg.Text = i.ToString();                               msg.Properties.SetString("myFilter", "test1");                               Console.WriteLine("Sending: " + i.ToString());                               prod.Send(msg, Apache.NMS.MsgDeliveryMode.NonPersistent, Apache.NMS.MsgPriority.Normal, TimeSpan.MinValue);  ITextMessage msg = prod.CreateTextMessage();                             msg.Text = i.ToString();                             msg.Properties.SetString("myFilter", "test1");                             Console.WriteLine("Sending: " + i.ToString());                             prod.Send(msg, Apache.NMS.MsgDeliveryMode.NonPersistent, Apache.NMS.MsgPriority.Normal, TimeSpan.MinValue);}

consumer：

public void SetSelector(){//產生consumer時通過參數設定Selector   IMessageConsumer consumer = session.CreateConsumer(new Apache.NMS.ActiveMQ.Commands.ActiveMQQueue("testing"), "myFilter='test1'");  //產生consumer時通過參數設定Selector IMessageConsumer consumer = session.CreateConsumer(new Apache.NMS.ActiveMQ.Commands.ActiveMQQueue("testing"), "myFilter='test1'");}