.net - 如何在.Net客户端接收时删除WebSphere MQ分组消息中的消息头信息

Question

我正在尝试使用 .Net 客户端使用 native api [amqmdnet - WebSphere MQ Classes for .NET] 从远程 MQ 接收逻辑分组的消息，该消息是由 java 客户端使用 native api 放置的。

当我们获取逻辑分组的消息时，我们会在该组中的所有消息中看到一些标题信息，这些信息在每个编辑器([notepad++、editplus 等])中显示不同。

下面指定的 header 信息附加在该组中的每个逻辑消息中，例如“MDE”

我们正在使用getmessageoptions、openoptions，如下所示，

mintMQQueueOpenOptions = IBM.WMQ.MQC.MQOO_INPUT_SHARED + IBM.WMQ.MQC.MQOO_FAIL_IF_QUIESCING
mobjMQGetMessageOptions = New MQGetMessageOptions
mobjMQGetMessageOptions.Options = IBM.WMQ.MQC.MQGMO_NO_SYNCPOINT +  IBM.WMQ.MQC.MQGMO_FAIL_IF_QUIESCING
'mobjMQGetMessageOptions.Options = mobjMQGetMessageOptions.Options + MQC.MQGMO_LOGICAL_ORDER  'Or MQC.MQGMO_ALL_MSGS_AVAILABLE

用于读取该组中所有逻辑消息的代码片段，

            '=================================
            ' INTANTIATE THE MQ MESSAGE OBJECT
            objMQMessage = New MQMessage
            objMQMessage.Format = MQC.MQFMT_STRING
            '=================================
            ' CLEAR THE MESSAGE VARIABLE
            strMQMessage = ""

            Do
                '============================
                ' GET THE MESSAGE FROM THE MQ
                mobjMQQueue.Get(objMQMessage, mobjMQGetMessageOptions)

                '============================
                ' READ THROUGH THE MESSAGE
                strMQMessage += objMQMessage.ReadString(objMQMessage.MessageLength)

                '============================
                ' SET GMO.MATCHOPTIONS TO GROUP ID, INITIALLY IT WAS SET TO "MQC.MQMO_NONE"                            
                mobjMQGetMessageOptions.MatchOptions = MQC.MQMO_MATCH_GROUP_ID

                '============================
                ' DO UNTIL - MESSAGE IS THE LAST IN THE GROUP OR THE GROUP CONSISTS OF ONLY ONE MESSAGE.
            Loop While (mobjMQGetMessageOptions.GroupStatus <> MQC.MQGS_LAST_MSG_IN_GROUP)

            '====================================
            ' COLLECT THE MESSAGE IN AN ARRAYLIST
            If Not String.IsNullOrEmpty(strMQMessage) Then objMQMessageList.Add(strMQMessage)

            '============================
            ' COMMIT THE FETCH OPERATION
            mobjMQQueueManager.Commit()

我们如何从每封邮件中删除此 header 信息？

Answer 1

MQMDE 包含存在于版本 2 MQMD 中但不存在于版本 1 MQMD 中的 MQMD 字段。信息中心主题 Overview for MQMD描述 MQMD 版本如何影响 GET 调用的行为:

On the MQGET call, if the application provides a version-1 MQMD, the queue manager prefixes the message returned with an MQMDE, but only if one or more of the fields in the MQMDE has a non-default value. The Format field in MQMD will have the value MQFMT_MD_EXTENSION to indicate that an MQMDE is present.

基于此，我建议提供版本 2 MQMD。也许这可以解决问题:

            '=================================
            ' INTANTIATE THE MQ MESSAGE OBJECT
            objMQMessage = New MQMessage
            objMQMessage.Version = 2
            objMQMessage.Format  = MQC.MQFMT_STRING
            '=================================

由于 objMQMessage 会在连续调用中重复使用，因此您可能需要在每次 GET 之前设置版本。

IBM MQ 知识中心页面“MQMDE - Message descriptor extension > Overview for MQMDE”也提供了有关该主题的一些有用信息:

Usage: Applications that use a version-2 MQMD will not encounter an MQMDE structure. However, specialized applications, and applications that continue to use a version-1 MQMD, might encounter an MQMDE in some situations. The MQMDE structure can occur in the following circumstances:

• Specified on the MQPUT and MQPUT1 calls
• Returned by the MQGET call
• In messages on transmission queues