重用 MQMessage 对象

Question

我有这个永远监听消息的测试代码。如果它得到一个它打印出来。我想要做的是避免必须在每个 get() 之前构造一个 MQMessage 对象。我如何为多次调用 get() 重用 MQMessage？

using System;
using IBM.WMQ;

namespace WMQ {
    class Program {
        static void Main(string[] args) {
            string QueueManagerName = "A1PATA00";
            string channelName = "ECACHE";
            string connectionName = "A1PATA00.WORLDSPAN.COM(1414)";
            var queueManager = new MQQueueManager(QueueManagerName, channelName, connectionName);
            MQQueue get = queueManager.AccessQueue("SPLASH.ECAC.2", MQC.MQOO_INPUT_AS_Q_DEF | MQC.MQGMO_FAIL_IF_QUIESCING);
            var gmo = new MQGetMessageOptions();
            gmo.Options = MQC.MQGMO_FAIL_IF_QUIESCING | MQC.MQGMO_WAIT;
            gmo.WaitInterval = 10000000;// wait time
            // var queueMessage = new MQMessage();  <--- i want to do this new once!
            while (true) {
                var queueMessage = new MQMessage(); // <-- only works if I do this every time i do a get
                get.Get(queueMessage, gmo);
                var strReturn = queueMessage.ReadString(queueMessage.MessageLength);
                Console.WriteLine(strReturn);
            }
        }
    }
}

Answer 1

在 IBM MQ 知识中心页面“ClearMessage method”中，它记录了以下内容：

This method clears the data buffer portion of the MQMessage object. Any Message Data in the data buffer is lost, because MessageLength, DataLength, and DataOffset are all set to zero.

The Message Descriptor (MQMD) portion is unaffected; an application might need to modify some of the MQMD fields before reusing the MQMessage object. To set the MQMD fields back use New to replace the object with a new instance.

在 IBM MQ 知识中心页面“MQMessage .NET class”中，它记录了以下内容：

public byte[] MessageId {get; set;}

For an MQQueue.Get call, this field specifies the message identifier of the message to be retrieved. Normally, the queue manager returns the first message with a message identifier and correlation identifier that match the message descriptor fields. Allow any message identifier to match using the special value MQC.MQMI_NONE.

public byte[] CorrelationId {get; set;}

For an MQQueue.Get call, the correlation identifier of the message to be retrieved. The queue manager returns the first message with a message identifier and a correlation identifier that match the message descriptor fields. The default value, MQC.MQCI_NONE, helps any correlation identifier to match.

试试这个：

            var queueMessage = new MQMessage();  <--- i want to do this new once!
            while (true) {
                //var queueMessage = new MQMessage(); // <-- only works if I do this every time i do a get
                queueMessage.ClearMessage();
                queueMessage.MessageId = MQC.MQMI_NONE;
                queueMessage.CorrelationId = MQC.MQCI_NONE; 
                get.Get(queueMessage, gmo);

Answer 2

看到这样的问题，我摇摇头。你不了解 .NET VM（框架）中面向对象的概念，以及垃圾收集。
另外，你为什么不写纯 C# 代码？
最后，在安全非常重要的世界中，您的代码确实不支持 SSL/TLS and/or 用户名和密码验证。

(1) 请注意我在哪里定义 MQMessage 对象（非常重要）。

以下2个代码片段在内存使用或速度上基本没有区别：

(A)

MQMessage msg = null;
while (true)
{
   msg = new MQMessage();
   get.Get(msg, gmo);
   Console.WriteLine(msg.ReadString(msg.MessageLength));
}

(B)

MQMessage msg = new MQMessage();
while (true)
{
   get.Get(msg, gmo);
   Console.WriteLine(msg.ReadString(msg.MessageLength));
   msg.ClearMessage();
   msg.MessageId = MQC.MQMI_NONE;
   msg.CorrelationId = MQC.MQCI_NONE;
}

我更喜欢 (A)，因为它更清晰易读。

(2) 当您使用 'var' 时，您是在强制 .NET 框架猜测您在做什么。做纯面向对象的编程。即

MQMessage msg = new MQMessage();

(3)在MQQueueManager中显式设置通道名和连接名不允许设置MQ安全信息。另外，不要使用 MQEnvironment class，因为它不是线程安全的。最好将所有信息放在一个 Hashtable 中并将 Hashtable 传递给 MQQueueManager class。这是一个使用哈希表获取 MQ 连接信息的 MQ .NET managed-mode 示例：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using IBM.WMQ;

namespace MQTest02
{
   class MQTest02
   {
      private Hashtable inParms = null;
      private Hashtable qMgrProp = null;
      private System.String qManager;
      private System.String outputQName;

      /*
      * The constructor
      */
      public MQTest02()
         : base()
      {
      }

      /// <summary> Make sure the required parameters are present.</summary>
      /// <returns> true/false
      /// </returns>
      private bool allParamsPresent()
      {
         bool b = inParms.ContainsKey("-h") && inParms.ContainsKey("-p") &&
                  inParms.ContainsKey("-c") && inParms.ContainsKey("-m") &&
                  inParms.ContainsKey("-q");
         if (b)
         {
            try
            {
               System.Int32.Parse((System.String)inParms["-p"]);
            }
            catch (System.FormatException e)
            {
               b = false;
            }
         }

         return b;
      }

      /// <summary> Extract the command-line parameters and initialize the MQ variables.</summary>
      /// <param name="args">
      /// </param>
      /// <throws>  IllegalArgumentException </throws>
      private void init(System.String[] args)
      {
         inParms = Hashtable.Synchronized(new Hashtable());
         if (args.Length > 0 && (args.Length % 2) == 0)
         {
            for (int i = 0; i < args.Length; i += 2)
            {
               inParms[args[i]] = args[i + 1];
            }
         }
         else
         {
            throw new System.ArgumentException();
         }

         if (allParamsPresent())
         {
            qManager = ((System.String)inParms["-m"]);
            outputQName = ((System.String)inParms["-q"]);

            qMgrProp = new Hashtable();
            qMgrProp.Add(MQC.TRANSPORT_PROPERTY, MQC.TRANSPORT_MQSERIES_MANAGED);

            qMgrProp.Add(MQC.HOST_NAME_PROPERTY, ((System.String)inParms["-h"]));
            qMgrProp.Add(MQC.CHANNEL_PROPERTY, ((System.String)inParms["-c"]));

            try
            {
               qMgrProp.Add(MQC.PORT_PROPERTY, System.Int32.Parse((System.String)inParms["-p"]));
            }
            catch (System.FormatException e)
            {
               qMgrProp.Add(MQC.PORT_PROPERTY, 1414);
            }

            if (inParms.ContainsKey("-u"))
               qMgrProp.Add(MQC.USER_ID_PROPERTY, ((System.String)inParms["-u"]));

            if (inParms.ContainsKey("-x"))
               qMgrProp.Add(MQC.PASSWORD_PROPERTY, ((System.String)inParms["-x"]));

            if (inParms.ContainsKey("-s"))
               qMgrProp.Add(MQC.SECURITY_EXIT_PROPERTY, ((System.String)inParms["-s"]));

            System.Console.Out.WriteLine("MQTest02:");
            Console.WriteLine("  QMgrName ='{0}'", qManager);
            Console.WriteLine("  Output QName ='{0}'", outputQName);

            System.Console.Out.WriteLine("QMgr Property values:");
            foreach (DictionaryEntry de in qMgrProp)
            {
               Console.WriteLine("  {0} = '{1}'", de.Key, de.Value);
            }
         }
         else
         {
            throw new System.ArgumentException();
         }
      }

      /// <summary> Connect, open queue, read a message, close queue and disconnect.
      ///
      /// </summary>
      /// <throws>  MQException </throws>
      private void testReceive()
      {
         MQQueueManager qMgr = null;
         MQQueue queue = null;
         int openOptions = MQC.MQOO_INPUT_AS_Q_DEF + MQC.MQOO_FAIL_IF_QUIESCING;
         MQGetMessageOptions gmo = new MQGetMessageOptions();
         MQMessage receiveMsg = null;

         try
         {
            qMgr = new MQQueueManager(qManager, qMgrProp);
            System.Console.Out.WriteLine("MQTest02 successfully connected to " + qManager);

            queue = qMgr.AccessQueue(outputQName, openOptions, null, null, null); // no alternate user id
            System.Console.Out.WriteLine("MQTest02 successfully opened " + outputQName);

            receiveMsg = new MQMessage();

            queue.Get(receiveMsg, gmo);
            System.Console.Out.WriteLine("Message Data>>>" + receiveMsg.ReadString(receiveMsg.MessageLength));
         }
         catch (MQException mqex)
         {
            System.Console.Out.WriteLine("MQTest02 cc=" + mqex.CompletionCode + " : rc=" + mqex.ReasonCode);
         }
         catch (System.IO.IOException ioex)
         {
            System.Console.Out.WriteLine("MQTest02 ioex=" + ioex);
         }
         finally
         {
            try
            {
               queue.Close();
               System.Console.Out.WriteLine("MQTest02 closed: " + outputQName);
            }
            catch (MQException mqex)
            {
               System.Console.Out.WriteLine("MQTest02 cc=" + mqex.CompletionCode + " : rc=" + mqex.ReasonCode);
            }
            try
            {
               qMgr.Disconnect();
               System.Console.Out.WriteLine("MQTest02 disconnected from " + qManager);
            }
            catch (MQException mqex)
            {
               System.Console.Out.WriteLine("MQTest02 cc=" + mqex.CompletionCode + " : rc=" + mqex.ReasonCode);
            }
         }
      }

      /// <summary> main line</summary>
      /// <param name="args">
      /// </param>
      //        [STAThread]
      public static void Main(System.String[] args)
      {
         MQTest02 mqt = new MQTest02();

         try
         {
            mqt.init(args);
            mqt.testReceive();
         }
         catch (System.ArgumentException e)
         {
            System.Console.Out.WriteLine("Usage: MQTest02 -h host -p port -c channel -m QueueManagerName -q QueueName [-u userID] [-x passwd] [-s securityExit]");
            System.Environment.Exit(1);
         }
         catch (MQException e)
         {
            System.Console.Out.WriteLine(e);
            System.Environment.Exit(1);
         }

         System.Environment.Exit(0);
      }
   }
}

要运行 MQTest02 使用您的信息，它将是：

MQTest02.exe -h A1PATA00.WORLDSPAN.COM -p 1414 -m A1PATA00 -c ECACHE -q SPLASH.ECAC.2

重用 MQMessage 对象

Reuse MQMessage object

c#

ibm-mq