HA-JNDI multicast reply not reaching client ------------------------------------------- Key: JBAS-772 URL: http://jira.jboss.com/jira/browse/JBAS-772 Project: JBoss Application Server Issue Type: Bug Security Level: Public(Everyone can see) Components: Clustering Affects Versions: JBossAS-3.2.6 Final Reporter: SourceForge User Assigned To: Jerry Gauthier Fix For: JBossAS-5.0.0.CR1 Attachments: DeviceManager.jsp, DeviceModule.java, TelematicsJNDI.java SourceForge Submitter: rmontag . I just made some expiriences with the HA-JNDI multicast and running multiple instances on a single machine. I encountered some problems... My setup: - JBoss 3.2.2 - JDK 1.4.2 - Two instances running on a single W2K-PC, alternatively I 'm using two instances running on a single SUN solaris. instance 1 using 1200 as HA-JNDI port, instance 2 using 1300. - "JBoss Clustering" documentation, 4. edition - Standalone testclient (JUnit) on PC or SUN, configured for Multicast (url-property not set) The problem: Case A: Testclient and server instances on PC Case B: Testclient on PC, server instances on SUN When starting my testclient and making a lookup via multicast, both instances receive the GET_ADDRESS datagram. Then each server send a datagram packet back NOT using a multcast. Since the testclient opens a MulticastSocket on the Multigroup port 1102, each server sends a response datagramm back to <client-ip>:1102. I encountered two problems with this approach: 1) If client and server are one the same instance like in case A, they have the same ip-address. In my environment one server instance always "catches" all the answers, so the client timed-out with no answers (Note: On W2K, I set "loopback" to true, on SUN to false as described in the cluster document). 2) Same problem if two clients on one instance make a concurrent multicast call (servers on other machine): Both waiting for responses, only one client catches all the responses. The second client ever lose. Two possible solutions come to my mind: 1) Currently the NamingContext opens a MulticastSocket on the multicast group port. If the client would use a different dedicated port, he can send his call with the multicast group address and the server could reply to <client-ip>:<dedicated client-port> with his answer. No one else (another client or server) would "catch" the server response if using different port numbers (Disadvantage: One additional HA-JNDI JNP property like "jnp.multicastPort"). 2) HANamingService currently sends a response datagram back to a dedicated IP:port address (Unicast). Why doesn't the server also sends a multicast call using the well-known multicast group address to propagate his answer ? A multicast answer seems to be a clean solution because: a) All clients waiting for an answer will receive them and b) other server(s) receiving the answer will ignore them as they already do now. Solution 2 simply means exchanging one line in HANamingService.java: Instead of DatagramPacket p = new DatagramPacket (ipAddress, ipAddress.length, packet.getAddress(), packet.getPort()); do this one: DatagramPacket p = new DatagramPacket(ipAddress, ipAddress.length, group, adGroupPort); Solution 1, as stated above would need one additinal config property for the client port.