ActiveMQ发布订阅模式
ActiveMQ的另一种模式就SUB/HUB即发布订阅模式,是SUB/hub就是一拖N的USB分线器的意思。意思就是一个来源分到N个出口。还是上节的例子,当一个订单产生后,后台N个系统需要联动,但有一个前提是都需要收到订单信息,那么我们就需要将一个生产者的消息发布到N个消费者。
生产者:
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(); }
假设生产者每5秒发送一次消息:
消费者:
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 listener1"; 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 listener1", 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); } }
启动一个消费者:
我们发现他是从15开始的,而不是像上节一样从头开始,再启动另一个消费者:
我们发现就是从启动时开始接受消息的,之前的消息就丢失了。
整体状态如下:
我们观察管理界面:
产生了一个testing的Topics,而订阅方有2个都订阅的是testing:
这样只需要在需要获取消息的地方订阅即可及时获得。