[omniORB] client call timeout

[Luke Deller]

Hi Peter,

On Mon, 2005-12-19 at 17:06 +0100, Peter Honeder wrote:
> I have the following problem with omniorb. Imagine the IOR of some 
> object I know and now I would like to find out if the object is still 
> alive. So I call the method isAlive of this object (which is available 
> for this object).

There's no need to define your own method for this purpose; you can call
_non_existent() on any object reference.  See section 4.3.5 of the CORBA
spec for details.

> The problem now arises if the ior of the object contains an ip address 
> which is not within my subnet and some router in between filters the 
> packet and does not drop my connection by sending a close back. The 
> problem which arises then is that it takes a tcp timeout of about 3 
> minutes until the check finishes.
> 
> I can workaround the problem by using the clientCallTimeOutPeriod 
> setting but this would also mean that a client call can only take that 
> long. This imposes further problems to the situation as some calls could 
> take about 5-10 seconds but the isAlive check should only take 0,5-1 
> seconds maximum.
> 
> Is there some kind of option to check if only the connection 
> establishment took a certain period of time. Something like 
> clientCallConnectionEstablishmentTimeOutPeriod which could be set to 500 
> ms while still keeping the clientCallTimeOutPeriod blocking with value 0?
> 
> Alternatively do you know a better way to check if an object is still 
> alive? In my case small numbers of false negatives would be not much of 
> a problem (e.g. if the network is unresponsive once in a while).

As well as the global clientCallTimeOutPeriod setting which you have
found, omniORB also allows the timeout to be set per-thread or
per-object-reference.  Details are in section 8.3.1 of the omniORB
manual:
  http://omniorb.sourceforge.net/omni40/omniORB/omniORB008.html#htoc93

So you can check if an object is still alive by temporarily setting a
low timeout for your thread, and then calling the _non_existent method.

Regards,
Luke.


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