queue - 如何将 MQ Server 回复消息与正确的请求相匹配

Question

我正在连接到 IBM Websphere MQ。我希望能够将回复消息与正确的请求消息相匹配。我翻阅了数百页才找到这个，但没有成功。

我有一个类 - MQHandler - 它将消息发送到一个定义的队列，并从另一个队列读取请求。这工作得很好，但是，如果多个用户同时使用该应用程序，消息就会混淆。

我似乎无法在接收器上找到一种方法来指示要匹配的 CorrelationID。类似...

consumer.receive(选择器);

您可以检查以下方法以确保我正确执行此操作吗？

/**
 * When the class is called, this initialisation is done first.
 * 
 * @throws JMSException
 */
public void init() throws JMSException
{
    // Create a connection factory
    JmsFactoryFactory ff;
    try
    {
        ff = JmsFactoryFactory.getInstance( WMQConstants.WMQ_PROVIDER );
        cf = ff.createConnectionFactory();

        // Set the properties
        cf.setStringProperty( WMQConstants.WMQ_HOST_NAME, hostServer );
        cf.setIntProperty( WMQConstants.WMQ_PORT, 1414 );
        cf.setStringProperty( WMQConstants.WMQ_CHANNEL, channel );
        cf.setIntProperty( WMQConstants.WMQ_CONNECTION_MODE, WMQConstants.WMQ_CM_CLIENT );
        cf.setStringProperty( WMQConstants.WMQ_QUEUE_MANAGER, qManager );

        connection = cf.createConnection();

        session = connection.createSession( false, Session.AUTO_ACKNOWLEDGE );
    }
    catch( JMSException e )
    {
        throw e;
    }

} // end of init



/**
 * @param request
 * @return
 * @throws JMSException
 */
private String sendRequest( String request ) throws JMSException
{

    // Create JMS objects
    Destination destination = session.createQueue( "queue:///" + writeQueueName );

    // Enable write of MQMD fields. See documentation for further
    // details.
    ((JmsDestination) destination).setBooleanProperty( WMQConstants.WMQ_MQMD_WRITE_ENABLED, true );

    // Set message context, if needed. See comment at the top.

    // Create a producer
    MessageProducer producer = session.createProducer( destination );

    // Create a message
    TextMessage message = session.createTextMessage( request );

    // Generate a custom message id
    message.setJMSCorrelationID( generateRandomID() );

    // Start the connection
    connection.start();

    // And, send the message
    producer.send( message );
    System.out.println(message);

    return message.getJMSCorrelationID();
}


/**
 * @param customMessageId
 * @return
 * @throws JMSException
 */
private String recvResponse( String customMessageId ) throws JMSException
{
    Destination destination = session.createQueue( "queue:///" + readQueueName );

    // Enable read of MQMD fields.
    ((JmsDestination) destination).setBooleanProperty( WMQConstants.WMQ_MQMD_READ_ENABLED, true );
    ((JmsDestination) destination).setObjectProperty( WMQConstants.JMS_IBM_MQMD_CORRELID, customMessageId );

    // Create a consumer
    MessageConsumer consumer = session.createConsumer( destination );

    // Start the connection
    connection.start();

    // And, receive a message from the queue
    TextMessage receivedMessage = (TextMessage)consumer.receive( 15000 );

    connection.close();
    session.close();

    return receivedMessage.getText();
}

这是主要方法的片段...

    try
    {
        String customMessageId;
        init();
        customMessageId = sendRequest( request );
        return recvResponse( customMessageId );
    }
    catch( Exception ex )
    {
        System.out.println( "Error on MQ." );
        throw new Exception( "\n\n*** An error occurred ***\n\n" + ex.getLocalizedMessage()
                             + "\n\n**********************************" );
    }

Answer 1

QueueReceiver queueReceiver = 
    session.createReceiver(destination, "JMSCorrelationID='customMessageId'");

TextMessage receivedMessage = (TextMessage)queueReceiver.receive( 15000 );

在我的示例中，customMessageId 应包含您之前设置的实际值。

此外，我见过很多情况，人们生成关联 ID 并将其设置在出站消息中，希望能够根据该值选择响应。执行此操作的教科书方法是服务提供商应用程序在响应时将消息 ID 复制到相关 ID。请求者仍将指定 JMSCorrelationID 作为选择器，但将使用原始 JMSMessageID 作为值。由于即使在 QMgrs 中，JMSMessageID 也能保证是唯一的，因此您在该值上发生冲突的可能性要小得多。您需要确保您的客户端在将值复制到相关 ID 方面与服务提供商的行为相匹配。