[omniORB] Synchronization between omniNames service & Services

[Philip Tait]

I had the same issue. Here's my updated version of
'examples/echo/example_echo_nsclt.py' that tolerates stop and restart of
'examples/echo/example_echo_srv.py'

Comments and suggestions for improvement are welcome.

Philip J. Tait
http://subarutelescope.org

------------------------------------------------------

#!/usr/bin/env python

import sys
# Import the CORBA module
from omniORB import CORBA
# Import the stubs for the CosNaming and Example modules
import CosNaming, Example

def bindContext(name):
    try:
        obj = rootContext.resolve(name)
    except CosNaming.NamingContext.NotFound, ex:
        print "Name not found"
        sys.exit(1)
    # Narrow the object to an Example::Echo
    eo = obj._narrow(Example.Echo)
    if eo is None:
        print "Object reference is not an Example::Echo"
        sys.exit(1)
    return eo

# Initialise the ORB
orb = CORBA.ORB_init(sys.argv, CORBA.ORB_ID)

# Obtain a reference to the root naming context
obj         = orb.resolve_initial_references("NameService")
rootContext = obj._narrow(CosNaming.NamingContext)

if rootContext is None:
    print "Failed to narrow the root naming context"
    sys.exit(1)

# Resolve the name "test.my_context/ExampleEcho.Object"
name = [CosNaming.NameComponent("test", "my_context"),
        CosNaming.NameComponent("ExampleEcho", "Object")]

eo = bindContext(name)

import time
import traceback

# Invoke the echoString operation
message = "Hello from Python"

while True:
    while True:
        try:
            result  = eo.echoString(message)
            break
        except (CORBA.COMM_FAILURE, CORBA.TRANSIENT):
            traceback.print_exc()
            eo = bindContext(name)
            time.sleep(1)
    print "I said '%s'. The object said '%s'." % (message,result)
    time.sleep(10)
--------------------------------------------------------------------------

On Tue, 2008-08-05 at 15:12 +0100, Nigel Rantor wrote:
> sorry, meant to reply to list, not just to OP
> 
> R. P. Janaka wrote:
> > The second one is the scenario..
> > 
> > As you think I am also guess, the problem is trying to contact the 
> > original object reference that was registered with the Nameservice 
> > rather than the new one.
> 
> Yes. That does look to be your problem.
> 
> To make this work you will have to make the client smart enough to
> look-up the object reference again if it finds that it fails like this.
> 
>    n
> 
> > 
> > On Tue, Aug 5, 2008 at 3:09 PM, Nigel Rantor <wiggly at wiggly.org 
> > <mailto:wiggly at wiggly.org>> wrote:
> > 
> >     R. P. Janaka wrote:
> > 
> >         No.. still did not get a solution.
> > 
> >         As I found with new experiments, this problem is not a specific
> >         for this Master/Slave case. If we just consider only about the
> >         Master, Problem still remains. I found these result with debugging.
> > 
> >         I just repeat the same procedure with only a single server.
> > 
> >            * Start the server and get registered with the name service
> >            * Manually kill the server
> >            * Start the server and get registered with the name service
> >         *again *.
> > 
> > 
> >         Then the registration also get success. But when the client try
> >         to call server's functions, it gives this exception.
> > 
> >         the exception is *"SystemException: TRANSIENT_ConnectFailed"*
> > 
> >         The reason for this problem may be the sudden break down of the
> >         server with out informing it to the name service.
> > 
> >         Do we have any solution for this....?
> > 
> > 
> >     You're going to have to be more explicit about this.
> > 
> >     Which of the following is the order things are happening in?
> > 
> >     A
> >     --------------------------------------------------------------
> >     - Start server
> >     - Server registers with Nameservice as "server"
> >     - Kill server
> >     - Start server again
> >     - Server registers with Nameservice as "server"
> >     - Start client
> >     - Client looks up "server" with Nameservice
> >     - Client invokes an operation on the reference from the Nameservice
> >     - Client gets "SystemException: TRANSIENT_ConnectFailed"
> >     --------------------------------------------------------------
> > 
> >     B
> >     --------------------------------------------------------------
> >     - Start server
> >     - Server registers with Nameservice as "server"
> >     - Client looks up "server" with Nameservice
> >     - Kill server
> >     - Start server again
> >     - Server registers with Nameservice as "server"
> >     - Start client
> >     - Client invokes an operation on the reference from the Nameservice
> >     - Client gets "SystemException: TRANSIENT_ConnectFailed"
> >     --------------------------------------------------------------
> > 
> >     My question is, has the client got the most recently bound name from
> >     the nameservice or not?
> > 
> >     It appears from you description that it is trying to contact the
> >     original object reference that was registered with the Nameservice
> >     rather than the new one.
> > 
> >      n
> > 
> > 
> > 
> > 
> > -- 
> > Regards,
> > R. P. Janaka
> 
> 
> 
> _______________________________________________
> omniORB-list mailing list
> omniORB-list at omniorb-support.com
> http://www.omniorb-support.com/mailman/listinfo/omniorb-list