设置JMS连接的理想方式,以便自动重新连接

Question

我正在为持久订阅编程一个信使服务(它可能最终不耐用,我们仍在讨论这个问题)我正在寻找一些关于如何处理我们的服务器由于某种原因而暂时停机的情况的建议我们需要自动重新订阅该主题.以下是它如何连接的示例代码:

public void DurableChatter(String broker, String username, String password)
{
    javax.jms.MessageProducer publisher = null;
    javax.jms.MessageConsumer subscriber = null;
    javax.jms.Topic topic = null;

    //Create a connection:
    try{
        javax.jms.ConnectionFactory factory;
        factory = (new progress.message.jclient.ConnectionFactory (broker));
        connection = factory.createConnection (username, password);

        //Durable Subscriptions are indexed by username, clientID and subscription name
        //It is a good proactice to set the clientID:
        connection.setClientID(CLIENT_ID);
        pubSession = connection.createSession(false,javax.jms.Session.AUTO_ACKNOWLEDGE);
        subSession = connection.createSession(false,javax.jms.Session.AUTO_ACKNOWLEDGE);
    }
    catch (javax.jms.JMSException jmse){
        System.err.println ("Error: Cannot connect to Broker - " + broker);
        jmse.printStackTrace();
        System.exit(1);
    }

    //Create Publisher and Durable Subscriber:
    try{

        topic = pubSession.createTopic(APP_TOPIC);
        subscriber = subSession.createDurableSubscriber(topic, "SampleSubscription");
        subscriber.setMessageListener(this);
        publisher = pubSession.createProducer(topic);
        connection.start();
    }
    catch (javax.jms.JMSException jmse){
        System.out.println("Error: connection not started.");
        jmse.printStackTrace();
        System.exit(1);
    }

    //Wait for user input

    try
    {
        System.out.println("Enter text to send as message and press enter.");
        java.io.BufferedReader stdin =
            new java.io.BufferedReader(new java.io.InputStreamReader(System.in));
        while (true)
        {
            String s = stdin.readLine();

            if(s == null){
                exit();
            }
            else if (s.length()>0)
            {
                try
                {
                    javax.jms.TextMessage msg = pubSession.createTextMessage();
                    msg.setText(username + ": " + s);
                    //Publish the message persistantly:
                    publisher.send(
                        msg,                               //message
                        javax.jms.DeliveryMode.PERSISTENT, //publish persistantly
                        javax.jms.Message.DEFAULT_PRIORITY,//priority
                        MESSAGE_LIFESPAN);                 //Time to Live
                }
                catch (javax.jms.JMSException jmse){
                    System.err.println("Error publishing message:" + jmse.getMessage());
                }
            }
        }
    }
    catch (java.io.IOException ioe)
    {
        ioe.printStackTrace();
    }
}

Answer 1

您需要多快的故障检测速度？设置您的协议，以保证每个客户端至少每分钟发送一次消息（您需要向您的通信协议添加一些新的“绒毛”保活消息） - 任何未收到保活消息的客户端都可以安全地假设服务器已关闭并开始重新连接。

理想情况下，这种事情最好使用 UDP 广播而不是 JMS（用于开销）来完成，但我假设如果您有 UDP 广播作为选项，您将使用 jgroups 为您进行集群检测/故障转移/重新加入。