Jamie Honan <[EMAIL PROTECTED]> wrote:
>
> Robert,
I hope Robert doesn't mind if I stick my oar in here
>
> some questions if I might?
>
> Are there any references about CORBA (books, URLS) you could
> recommend?
The CORBA bible is "Advanced CORBA Programming with C++" by Vinoski
and Henning (Michi Henning is an Aussie too). Highly recommended.
Warning: there are a lot of really crap CORBA books around.
If you are interested in getting into CORBA then I suggest that you
that you follow the comp.object.corba newsgroup. Vinoski, Henning and
most of the CORBA gurus and ORB implementors hang out there.
>
> Do you know the differences between MICO and Orbit? I was interested
> in a Music application that needed MICO. It took forever to compile.
This is one of the main complaints about MICO. It relies heavily on
templates and can be a bitch to compile. It was designed as a teaching
aid rather than for efficiency and performance was a bit of a problem
too. I have heard that improvements have been made to the performance
recently. I believe that MICO has been adopted by KDE for desktop
interprocess comms (ala OLE/ActiveX/COM).
Orbit was instigated largely to correct these issues. It is meant to
be lean-and-mean. It is primarily intended for use with the C binding
(which is a bit ugly if you are used to C++), although there has been
some work done on a C++ binding - don't know how mature it is. Lots of
stuff is still missing from Orbit, but it should be fine for core
CORBA stuff. Orbit is the desktop ORB for Gnome.
The other two big ORBs in the public domain are OmniORB (this was an
Olivetti/AT&T product which was opensourced a few years ago) and
TAO. TAO is probably the most widely used public-domain ORB in
industrial-strength work. It is supported on lots of platforms and
was designed to be easily portable (it uses the ACE networking
abstractions). It has also been tuned for realtime stuff. TAO is
also a bit nasty to build, but you can download precompiled binaries
for the common platforms.
There are some free Java ORBs around too but this is outside my field.
>
> What are the differences between simple 'marshalling' and rpc methods
> are CORBA?
You can think about CORBA as "Object-Oriented RPCs". The interface to
a remote object is defined by IDL (Interface Definition Language), which
consists of type definitions, interfaces (~= classes) and operations
(~= methods). The IDL file forms a contract. For a client process to
interact with the server process all it needs is the IDL and a reference
to the object in the server.
There are lots of common CORBA services as well, several of which are
usually bundled with the ORB itself (naming and events being the most
common).
>
> What are your opinions about CORBA? Is this a technology in search
> of a purpose?
CORBA is pretty much mature now (over five years in the market). In
lots of fields it is really big. We are using it here (NEC) to replace
the old network management protocols (CMIP and SNMP). We also use it as
the glue between the processes in our system.
> I was interested in a particular RFP, the "OMG General Ledger
> Facility" - the heart of a financial control system.
> ( http://www.compassgl.org ). It looks very well thought out, but
> I am wondering about CORBA being overkill.
I am not familiar with this RFP, but RFPs often float around for 1
to 2 years before anyone delivers a useful implementation.
The overkill thing is one of the big hurdles I have come across. Getting
your head around the basic principles of CORBA is a bit of a learning
curve. Maybe two to four days for an experienced C++ programmer. Once
you have got a grip on CORBA though you will never mess about with
sockets again. It really does simplify the whole interprocess comms
stuff enormously.
You also get excellent re-use results from designs that incorporate
CORBA from the start. This is because it is much easier to plug in a
server process with a well-documented interface than to reuse at the
code level.
Information on all the ORBs I have mentioned here can be found at the
Free CORBA Page: http://adams.patriot.net/~tvalesky/freecorba.html
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goblin
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