Have a Java servlet running using a Tomcat server. So when the servlet starts, I would like the client to connect to a RMI registry (Port 33996). The client is initialized during the init() of the servlet. However, for some reason, it is unable to connect to the server
Server code
@Override
public void startRMIRegistry(CentralServer server){
try {
AsyncLogger.log("Setting up RMI Registry.....");
Registry registry = LocateRegistry.createRegistry(
Integer.parseInt(ServerConfigUtils.getProperty(ServerConfigUtils.PORT)));
registry.rebind(ServerConfigUtils.getProperty(ServerConfigUtils.NAME), server);
} catch (RemoteException e) {
e.printStackTrace();
}
}
Client code
private ICentralServer getServerConnection() {
String serverHost = ServerConfigUtils.getProperty(ServerConfigUtils.HOST);
Integer serverPort = Integer.valueOf(ServerConfigUtils.getProperty(ServerConfigUtils.PORT));
String serverName = ServerConfigUtils.getProperty(ServerConfigUtils.NAME);
Integer failureCount = 0;
while (failureCount < SERVER_ACTION_ATTEMPTS) {
try {
return (ICentralServer)
LocateRegistry.getRegistry(serverHost, serverPort).lookup(serverName);
} catch (Exception e) {
failureCount++;
continue;
}
}
AsyncLogger.log("Failed to connect to central server, giving up");
throw new RuntimeException();
}
Servlet
@Override
public void init() throws ServletException {
try {
client = new LabClient();
} catch (Exception e) {
e.printStackTrace();
}
super.init();
}
Error
INFO: Starting ProtocolHandler ["http-nio-8080"]
sg.gov.moh.exceptions.CannotReachServerException: java.lang.NullPointerException
at sg.gov.moh.client.LabClient.<init>(LabClient.java:366)
at launcher.servlet.MainServlet.init(MainServlet.java:36)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1152)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1097)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:768)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:133)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:544)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:364)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:624)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:831)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1651)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
at sg.gov.moh.centralServer.CentralServer.pingOrPrune(CentralServer.java:318)
at sg.gov.moh.centralServer.CentralServer.registerLaboratory(CentralServer.java:297)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:357)
at sun.rmi.transport.Transport$1.run(Transport.java:200)
at sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:303)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:279)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:163)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:235)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:180)
at com.sun.proxy.$Proxy5.registerLaboratory(Unknown Source)
at sg.gov.moh.client.LabClient.registerCallback(LabClient.java:69)
at sg.gov.moh.client.LabClient.<init>(LabClient.java:364)
... 21 more
Had my peers tried this code, they were all able to connect successfully. Have tried toggling off firewall, setting inbound rules to the port but to no avail
