CORBA

[Mark Pollack <markp@bnl.gov>]

Dear GC'ers,

During the past few days I have been fooling around with the
free version of CORBA that I mentioned on the rhic mailing
lists (Omnibroker www.ooc.com)  and ORBIX.  
I though I would mention what my experience has been.

The omnibroker orb compiled easily on both solaris/intel 
and NT 4.0. I tested co-located client/server communication 
on both these platforms and also with the server on NT and the 
client on solaris.  These tests went well and everything worked 
as expected.

I also then put the corba client inside of STAF on solaris/intel
(just inside a PAM, not replacing the whole corba guts of STAF) 
and was able to get information from a co-located server.  
So there were  no apparent conflicts  using omnibroker inside of STAF.

I then went through in detail the "grid" example that comes with
ORBIX and implemented this inside of omnibroker.  The differences
the user would see in the two implementations of corba seem to be 
small.  ORBIX (on sun/solaris) uses nested classes and type definition
scopes whereas omnibroker generates unnested definitions using the 
same names but :: is turned into _
ie CORBA::Short   goes to CORBA_Short
There is also a difference in how the IDL compilers handle a method
with the same name as its class. 
 
Another difference might be in the exception handling, at the surface it 
does not look like there is a difference but I did not test it yet.  I also did
not look into the differences when using the TIE approach to implementation.

As it turned out, the "grid" example in ORBIX also was not 100% corba
compliant in its initialization, however the ORBIX manual notes this and
supports the corba compliant initalization.  So I was very pleased to see that
at this level there were many similarities in using the two products.


The documentation that comes with ORBIX is extremely good where as that
for omnibroker is rather poor.  However, it does come with the code
used in the book "CORBA - Fundamentals and Programming from 
Siegel/OMG" and that code exercises many aspects of corba. 

I also had an ORBIX client (on sun/solaris) talk via IIOP to 
the omnibroker server on my NT machine. I would expect that 
other configurations of client/server/os  would work, but 
I did not test that yet.

At the end of it all I got the impression that for "lightweight" use of CORBA,
where we don't need many corba services or special database adapters,
omnibroker is a solid product.  Also, since it can talk through IIOP to ORBIX
we might be able to use ORBIX on the server to do things which omnibroker
is not capable of performing and have an omnibroker client get the results.


- Mark