How can i know that servers are up and running?

Question

hello everyone...
i have a distributed application which does the following.. a client submits a job which is passed from one server to another and after some processing on each server the job is returned back to the client.. the thing is that i want to make the whole application more reliable... how can i found out if the next server that i am going to submit the job is up and running?
the client has decided the order of the servers that should be followed but when a server processes the job another one may "die..." and i am telling you that because i cannot check if the cast of the objectReference fails when i make the list on the client...
is there any function that i can call to the orb and find that out ?
thxxxxx
ps. i am using java and corba orb

Answer 1

hmm... when i reproduce the situation i get the following
15 ─ίΆ 2006 2:39:47 ΉΉ com.sun.corba.se.impl.transport.SocketOrChannelConnection
Impl <init>
WARNING: "IOP00410201: (COMM_FAILURE) Connection failure: socketType: IIOP_CLEAR
_TEXT; hostname: 10.34.153.11; port: 2945"
org.omg.CORBA.COMM_FAILURE:   vmcid: SUN  minor code: 201  completed: No
        at com.sun.corba.se.impl.logging.ORBUtilSystemException.connectFailure(U
nknown Source)
        at com.sun.corba.se.impl.logging.ORBUtilSystemException.connectFailure(U
nknown Source)
        at com.sun.corba.se.impl.transport.SocketOrChannelConnectionImpl.<init>(
Unknown Source)
        at com.sun.corba.se.impl.transport.SocketOrChannelConnectionImpl.<init>(
Unknown Source)
        at com.sun.corba.se.impl.transport.SocketOrChannelContactInfoImpl.create
Connection(Unknown Source)
        at com.sun.corba.se.impl.protocol.CorbaClientRequestDispatcherImpl.begin
Request(Unknown Source)
        at com.sun.corba.se.impl.protocol.CorbaClientDelegateImpl.request(Unknow
n Source)
        at org.omg.CORBA.portable.ObjectImpl._request(Unknown Source)
        at WorkflowFramework._ServiceStub.translationService(_ServiceStub.java:1
8)
        at wF.ServantEnglishToGreek.translationService(ServantEnglishToGreek.jav
a:294)
        at WorkflowFramework._ServiceImplBase._invoke(_ServiceImplBase.java:41)
        at com.sun.corba.se.impl.protocol.CorbaServerRequestDispatcherImpl.dispa
tchToServant(Unknown Source)
        at com.sun.corba.se.impl.protocol.CorbaServerRequestDispatcherImpl.dispa
tch(Unknown Source)
        at com.sun.corba.se.impl.protocol.CorbaMessageMediatorImpl.handleRequest
Request(Unknown Source)
        at com.sun.corba.se.impl.protocol.CorbaMessageMediatorImpl.handleRequest
(Unknown Source)
        at com.sun.corba.se.impl.protocol.CorbaMessageMediatorImpl.handleInput(U
nknown Source)
        at com.sun.corba.se.impl.protocol.giopmsgheaders.RequestMessage_1_2.call
back(Unknown Source)
        at com.sun.corba.se.impl.protocol.CorbaMessageMediatorImpl.handleRequest
(Unknown Source)
        at com.sun.corba.se.impl.transport.SocketOrChannelConnectionImpl.dispatc
h(Unknown Source)
        at com.sun.corba.se.impl.transport.SocketOrChannelConnectionImpl.doWork(
Unknown Source)
        at com.sun.corba.se.impl.orbutil.threadpool.ThreadPoolImpl$WorkerThread.
run(Unknown Source)
Caused by: java.net.ConnectException: Connection refused: connect
        at sun.nio.ch.Net.connect(Native Method)
        at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
        at java.nio.channels.SocketChannel.open(Unknown Source)
        at com.sun.corba.se.impl.transport.DefaultSocketFactoryImpl.createSocket
(Unknown Source)
        ... 19 more
NEXT SERVER IS DOWN! org.omg.CORBA.COMM_FAILURE:   vmcid: SUN  minor code: 201
completed: Noi added to my code the following catch
try{
//call next server
nextServerRef.translationService(objRef, buffer);
catch(org.omg.CORBA.COMM_FAILURE o){
System.out.println("NEXT SERVER IS DOWN! "+o);
}it is obvious that i haven't worked with exceptions a lot rather than some standard things.. which are the exact exceptions that i should catch and how??
thx again!!
Message was edited by:
panosjava