Miscellaneous CORBA info

I'm not sure where some of this information belongs, but I don't want to forget it.

TAO idiosyncrasies:

Multicast functionality will crash a DEC Alpha running DU 4.0.
Difficult to augment Makefiles so that IDL-related source files reside in another directory.
Pure clients not possible. Server-related object files must be linked with clients to support co-location optimizations.
No eviction policy provided with TAO CosEvent_Service -- clients that fail to disconnect persist indefinitely.
POAManager not fully implemented -- it shouldn't be possible for servants to receive requests from a non-activated POAManager, but currently, they can.

Linux Cluster Issues:

The ORB method, object_to_string(), stringifies a CORBA object into an Interoperable Object Reference (IOR). Enough information must be stored in an IOR to allow one object to access the object identified by the IOR via a particular protocol. The most common protocol is IIOP, or Internet Inter-Object Protocol. IIOP requires a hostname and a port, among other things, so that a TCP/IP connection may be established between the two objects.

Clients external to the Linux cluster connect to a virtual hostname, i.e. hydra.mobsec.com. This is troublesome for CORBA objects because their IOR's will contain the name of the actual machine within the cluster on which they're running, i.e. services00.hydra.mobsec.com. External clients are unable to resolve this name into an actual IP address.

Also, TAO services seem to only listen on one network interface. If a machine has two cards, as a cluster gateway might, it could be that only internal or external clients can connect, but not both.

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Jim Crossley

Last modified: Sat Mar 20 16:28:35 EST 1999