[Ace-users] [tao-users] How to set the NS multicast discovery timeout

[Steve Totten]

Hi Keith,

Douglas C. Schmidt wrote:
> Hi Keith,
> 
>> When using the multicast discovery feature for the naming service, a
>> client will wait 10 sec before giving up if the NS isn't found.  We'd
>> like the client to fail quicker (say, after waiting for 1 sec).  Is
>> there a command-line option to specify the discovery timeout?
> 
> I don't think so, but there's no reason that one couldn't be added.  If
> you folks would like to do the work and contribute this back to us that
> would be great!

The "service discovery timeout" is controlled by the following
macro definition in $TAO_ROOT/tao/orbconf.h:

// The default timeout receiving the location request to the TAO
// Naming, Trading and other servicesService.
#if !defined (TAO_DEFAULT_SERVICE_RESOLUTION_TIMEOUT)
#define TAO_DEFAULT_SERVICE_RESOLUTION_TIMEOUT 10
#endif /* TAO_DEFAULT_SERVICE_RESOLUTION_TIMEOUT */

So, you could #define TAO_DEFAULT_SERVICE_RESOLUTION_TIMEOUT to
your preferred value in ace/config.h file and recompile.
Obviously, that does not provide the same flexibility as a
run-time option would provide.

You can also override the value of the service resolution timeout
in code by passing it as the optional 2nd parameter to
CORBA::ORB::resolve_initial_references().  The 2nd parameter
defaults to zero (really, a null ACE_Time_Value), causing the ORB
to use the value specified by the above macro.  See
$TAO_ROOT/tao/ORB.h:

     /**
      * This method acts as a mini-bootstrapping Naming Service, 
which is
      * provided by the ORB for certain well-known object 
references.  TAO
      * supports the "NameService", "TradingService", "RootPOA",
      * "ImplRepo", and "POACurrent" via this method.  The @c timeout
      * value bounds the amount of time the ORB blocks waiting to
      * resolve the service.  This is most useful for bootstrapping
      * remote services, such as the "NameService" or 
"TradingService",
      * that are commonly resolved via multicast.  By default, the
      * value is 0, which means "use the @c
      * TAO_DEFAULT_SERVICE_RESOLUTION_TIMEOUT timeout period".
      *
      * @note By using a default value for the @c timeout parameter,
      *       TAO will remains compliant with the CORBA
      *       resolve_initial_references() specification.
      */
     CORBA::Object_ptr resolve_initial_references (
       const char *name,
       ACE_Time_Value *timeout = 0);

So, for a one-second timeout, you could just call:

CORBA::Object_var obj =
   orb->resolve_initial_references(
     "NameService", ACE_Time_Value(1));

You could easily turn the value into a command-line parameter to
your application (and it shouldn't be much harder to make it an
ORB initialization option).

The above call to resolve_initial_references() is, of course,
a TAO extension to the CORBA specification.

HTH,
Steve
-- 
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  Steve Totten, Principal Software Engineer and Partner
  Object Computing, Inc. (OCI), St. Louis, MO, USA
  http://www.ociweb.com/  http://www.theaceorb.com/
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