[omniORB] transient exception handler and call timeout problem

[Wernke zur Borg]

Hi,

I guess you have overlooked the COMM_FAILURE_UnMarshalArguments in the
server trace. This often means that the IDL was changed and the code was
adapted on one side but not at the other. It can have other reasons, though.
So before further investigating the timeouts I would get rid of those. Also
make sure to have a last catch clause for the exceptions not caught by
specific handlers.

Wernke

> -----Original Message-----
> From: omniorb-list-bounces at omniorb-support.com 
> [mailto:omniorb-list-bounces at omniorb-support.com] On Behalf 
> Of Vladislav Vrtunski
> Sent: 20 April 2005 13:03
> To: omniorb-list at omniorb-support.com
> Subject: [omniORB] transient exception handler and call 
> timeout problem
> 
> Hi,
> 
>     We are trying to limit call duration to 2 seconds and if 
> the timeout 
> is reached we want to repeat the call, hoping that it won't last that 
> long the second time. This is part of an attempt to make a fault 
> tolerant system. In order to achieve that, we have set client call 
> timeout and installed both transient and comm_failure exception 
> handlers. Each of these handlers is written to allow ORB to retry the 
> operation once in case exception occurs.
>     Here is the problem. When the timeout is reached and 
> TRANSIENT_CallTimedout exception is thrown, our transient exception 
> handler is called and it returns 1 so that ORB repeats the call. 
> Immediately after that TRANSIENT_ConnectFailed is thrown 
> without server 
> side method being called, although we can see in omniORB 
> trace that the 
> server has accepted the second connection from client. Is this the 
> expected behavior? We would expect the second call to at 
> least reach the 
> server method.
> 
> Server side trace:
> 
> omniORB: Server accepted connection from giop:tcp:192.168.0.15:1695
> omniORB: AsyncInvoker: thread id = 3 has started. Total threads = 3
> omniORB: Accepted connection from giop:tcp:192.168.0.15:1695 
> because of 
> this rule: "* tcp"
> omniORB: Handling a GIOP LOCATE_REQUEST.
> omniORB: AsyncInvoker: thread id = 4 has started. Total threads = 4
> omniORB: throw giopStream::CommFailure from 
> giopStream.cc:831(0,NO,COMM_FAILURE_UnMarshalArguments)
> omniORB: Server accepted connection from giop:tcp:192.168.0.15:1696
> omniORB: Accepted connection from giop:tcp:192.168.0.15:1696 
> because of 
> this rule: "* tcp"
> omniORB: throw giopStream::CommFailure from 
> giopStream.cc:831(0,NO,COMM_FAILURE_UnMarshalArguments)
> omniORB: Server close connection from giop:tcp:192.168.0.15:1696
> omniORB: Server close connection from giop:tcp:192.168.0.15:1695
> omniORB: AsyncInvoker: thread id = 4 has exited. Total threads = 4
> omniORB: AsyncInvoker: thread id = 3 has exited. Total threads = 3
> 
> Client side trace:
> 
> omniORB: LocateRequest to remote: root<0>
> omniORB: Client opened connection to giop:tcp:192.168.0.16:1044
> omniORB: throw giopStream::CommFailure from 
> giopStream.cc:831(0,MAYBE,TRANSIENT_CallTimedout)
> omniORB: Client close connection to giop:tcp:192.168.0.16:1044
> Transient handler called. Retries = 0
> omniORB: throw giopStream::CommFailure from 
> giopStream.cc:1073(0,NO,TRANSIENT_ConnectFailed)
> Transient handler called. Retries = 1
> omniORB: throw TRANSIENT from omniObjRef.cc:759 
> (NO,TRANSIENT_ConnectFailed)
> TRANSIENT exception caught! Code = 1096024066
> 
> Client code fragment:
> 
> CORBA::Boolean TransientHandler(void* pCookie, CORBA::ULong nRetries, 
> const CORBA::TRANSIENT& ex)
> {
>    cerr << "Transient handler called. Retries = " << nRetries << endl;
>    return ((nRetries < 1) ? 1 : 0);
> }
> 
> //part of the main func
> {
>         ...
>         omniORB::installCommFailureExceptionHandler(NULL, 
> CommFailureHandler);
>         omniORB::installTransientExceptionHandler(NULL, 
> TransientHandler);
>         CORBA::ULong ct = 2000;
>         omniORB::setClientCallTimeout(ct);
>         try
>         {
>             nStatus = pServer->GetStatus();
>         }
>         catch (CORBA::TRANSIENT& ex)
>         {
>             tcout << _T("TRANSIENT exception caught! Code = ") << 
> ex.minor() << endl;
>         }
>         catch(CORBA::COMM_FAILURE&)
>         {
>             tcout << _T("Caught system exception COMM_FAILURE 
> -- unable 
> to contact the object!") << endl;
>         }
>         ...
> }
> 
> We are using omniORB-4.0.5 on Win2k machines and VC++6.0 compiler.
> 
> Regards,
> 
> -- 
> Vladislav Vrtunski
> DMS Group
> Serbia & Montenegro
> 
> 
> 
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