Class JMS

java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.JMS
All Implemented Interfaces:
javax.jms.MessageListener

public class JMS extends Protocol implements javax.jms.MessageListener
Implementation of the transport protocol using the Java Message Service (JMS). This implementation depends on the JMS server that will distribute messages published to the specific topic to all topic subscribers.

Protocol parameters are:

  • topicName - (required), full JNDI name of the topic to be used for message publishing;
  • cf - (optional), full JNDI name of the topic connection factory that will create topic connection, default value is "ConnectionFactory";
  • jndiCtx - (optional), value of the javax.naming.Context.INITIAL_CONTEXT_FACTORY property; you can specify it as the JVM system property -Djava.naming.factory.initial=factory.class.Name;
  • providerURL - (optional), value of the javax.naming.Context.PROVIDER_URL property; you can specify it as the JVM system property -Djava.naming.provider.url=some_url
  • ttl - (required), time to live in milliseconds. Default value is 0, that means that messages will never expire and will be accumulated by a JMS server.

Note, when you are using the JMS protocol, try to avoid using protocols that open server socket connections, like FD_SOCK. I belive that FD is more appropriate failure detector for JMS case.

Author:
Roman Rokytskyy (rrokytskyy@acm.org)
  • Field Details

  • Constructor Details

    • JMS

      public JMS()
      Empty constructor.
  • Method Details

    • getName

      public String getName()
      Get the name of the protocol.
      Specified by:
      getName in class Protocol
      Returns:
      always returns the "JMS" string.
    • toString

      public String toString()
      Get the string representation of the protocol.
      Overrides:
      toString in class Object
      Returns:
      string representation of the protocol (not very useful though).
    • setProperties

      public boolean setProperties(Properties props)
      Set protocol properties. Properties are:
      • topicName - (required), full JNDI name of the topic to be used for message publishing;
      • cf - (optional), full JNDI name of the topic connection factory that will create topic connection, default value is "ConnectionFactory";
      • jndiCtx - (optional), value of the javax.naming.Context.INITIAL_CONTEXT_FACTORY property; you can specify it as the JVM system property -Djava.naming.factory.initial=factory.class.Name;
      • providerURL - (optional), value of the javax.naming.Context.PROVIDER_URL property; you can specify it as the JVM system property -Djava.naming.provider.url=some_url
      Overrides:
      setProperties in class Protocol
    • onMessage

      public void onMessage(javax.jms.Message jmsMessage)
      Implementation of the javax.jms.MessageListener interface. This method receives the JMS message, checks the destination group name. If the group name is the same as the group name of this channel, it checks the destination address. If destination address is either multicast or is the same as local address then message is unwrapped and passed up the protocol stack. Otherwise it is ignored.
      Specified by:
      onMessage in interface javax.jms.MessageListener
      Parameters:
      jmsMessage - instance of javax.jms.Message.
    • handleDownEvent

      protected Object handleDownEvent(Event evt)
      Handle down event, if it is not a Event.MSG type.
      Parameters:
      evt - event to handle.
    • down

      public Object down(Event evt)
      Called by the protocol above this. We check the event type, and if it is message, we publish it in the topic, otherwise we let the handleDownEvent(Event) take care of it.
      Overrides:
      down in class Protocol
      Parameters:
      evt - event to process.
    • sendMessage

      protected void sendMessage(Message msg)
      Publish message in the JMS topic. We set the message source and destination addresses if they were null.
      Parameters:
      msg - message to publish.
    • start

      public void start() throws Exception
      Start the JMS protocol. This method instantiates the JNDI initial context and looks up the topic connection factory and topic itself. If this step is successful, it creates a connection to JMS server, opens a session and obtains publisher and subscriber instances.
      Overrides:
      start in class Protocol
      Throws:
      javax.jms.JMSException - if something goes wrong with JMS.
      NamingException - if something goes wrong with JNDI.
      IllegalArgumentException - if the connection factory or topic cannot be found under specified names.
      Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so Channel.connect(String) will throw an exception
    • stop

      public void stop()
      Stops the work of the JMS protocol. This method closes JMS session and connection and deregisters itself from the message notification.
      Overrides:
      stop in class Protocol
    • generateLocalAddress

      protected String generateLocalAddress() throws UnknownHostException
      Generate random local address. This method takes host name and appends it with randomly generated integer.
      Returns:
      randomly generated local address.
      Throws:
      UnknownHostException