This example demonstrates the following features of omniORB and CORBA:

  o  use of call-backs
  o  use of threads for asynchronous processing
  o  use of IDL modules
  o  orderly shutdown of a server, cleaning up resources


It consists of three programs:

  o  cb_server     -  a server application
  o  cb_client     -  you'll never guess ...
  o  cb_shutdown   -  initiates shutdown of the server


To run the server:

  $ ./cb_server
  'IOR:3456098456.......345604598'


To run a client, cut and paste the IOR from the server:

  $ ./cb_client 'IOR:3456098456.......345604598'
  cb_client: server->one_time(call_back, "Hello!")
  cb_client: call_back("Hello!")
  cb_client: Returned.

In this example the server invokes the call-back object in the client
before returning.  You observe the CORBA calls as they occur in the ORB
by passing the -ORBtraceInvocations flag to your applications:

  $ ./cb_client 'IOR:3456098456.......345604598' -ORBtraceInvocations
  cb_client: server->one_time(call_back, "Hello!")
  omniORB: Invoke 'one_time' on remote: root<0>
  omniORB: Dispatching remote call 'call_back' to: root<0>
  cb_client: call_back("Hello!")
  cb_client: Returned.


In a second mode of operation, the client registers the call-back with
the server, and waits for the server to make asynchronous call-backs.
The server spawns a new thread to serve the client.  This server thread
exits when the client goes away, or the server is shut down.  Note that
this is not a very efficient way of serving many clients!

The two additional arguments passed to the client are the pause in seconds
between call-backs, and a time in seconds after which the client will
exit:

  $ ./cb_client 'IOR:3456098456.......345604598' 1 4
  cb_client: server->register(call_back, "Hello!", 1)
  cb_client: Returned.
  cb_client: call_back("Hello!")
  cb_client: call_back("Hello!")
  cb_client: call_back("Hello!")
  cb_client: Finished.


Finally, the server may be asked to shut itself down cleanly.  This is
done as follows:

  $ ./cb_shutdown 'IOR:3456098456.......345604598'

Notice that the instance of server_i registered with the ORB is properly
cleaned up.