Long-Lived IIOP.NET Objects...

I have been working with IIOP.NET, a CORBA toolkit for .NET, a bit more than with Using Multiple Vendor's ORBs with Name Services. While my test application was working great, my actual application was not, however.

The server component started up, instantiated a CORBA object, and saved the IOR into the registry. Then my client component would start up and take the IOR from the registry, send a message to the CORBA server, do some data processing for about 15-30 minutes, and send another message to the CORBA server. This issue I ran into is that usually the first message made it to the server, but the second one rarely did, with the error message:

• CORBA system exception : omg.org.CORBA.OBJECT_NOT_EXIST, completed: Completed_No minor: 0 omg.org.CORBA.OBJECT_NOT_EXIST: CORBA system exception : omg.org.CORBA.OBJECT_NOT_EXIST, completed: Completed_No minor: 0
• Server stack trace:
• Exception rethrown at [0]:
•   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
•   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
•   ...

At this level of detail, it would appear that something goes wonky on the client side, since the first message usually gets to the server, however, I also failed to mention that I usually started the server and client at the same time. When I did not start the server at the same time of the client, I would get the exception above.

In light of this detail, it became very obvious that I had an object lifetime issue on the server. Coming from more of a Java CORBA experience, I had assumed that the lifetime of the object would by-default be long-lived, however, it appears that this is not the case. To make your IIOP.NET objects long-lived (or to control the default behaviour), your objects that derive from System.MarshalByRefObject must override the method InitializeLifetimeService(). The follow makes the object live forever:

1. public class TimeImpl : System.MarshalByRefObject, TimeTools.Time {
2. // ...
3.   public override object InitializeLifetimeService() {
4.     return null;
5.   }
6. // ...
7. }

Since my objects are all long-lived, the above fixed my problem. The documentation for InitializeLifetimeService() does, however, have some other examples in the event that you need more fine-grained control.

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