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  From: Alan Kennington <akenning@dog.topology.org>
  To  : ob1@senet.com.au
  Date: Mon, 13 Sep 1999 06:01:32 +0930

Re: IIOP

On the subject of CORBA again....


I've just seen a post in Linux World about Corba.
Some sort of a course.
It seems to be a CORBA course for linux users.

Even though I know little about this area, I tend to think that
CORBA is more likley to survive longer and be more useful
in serious industrial applications than the corresponding Java thing.
That's just a guess on my part.
Anyway, here's the linux world CORBA course, part 1:

http://www.linuxworld.com/linuxworld/lw-1999-09/lw-09-corba_1.html

It has reference to KDE. The Koffice stuff is at

http://koffice.kde.org/

and this uses CORBA throughout. I guess this is for communicating between
the different office tools. I can imagine that some
sort of application-level IPC could be useful for such thing,
rather than packet level or byte level IPC as is provided
in TCP, UDP, Unix sockets, win32 messaging etc.

Maybe some generous expert in CORBA will put on a linux
SA talk on this topic some day!

Cheerio,
Alan Kennington.

=====================================================================
PS. British english: Programme. US english: program.
But both use "programming". And all the world uses "program" in
the programming context anyway.
But a TV or radio or concert programme is stilled as in the
original British in Britain and Australia, except by people
who learn their spelling from US cultural contexts.

PPS. My own meagre corba links are at
http://topology.org/corba.html

PPPS. I had a look at the public domain corba implementation MICO
on the web yesterday and today. MICO CORBA supports C++ interfaces only,
and is used with KDE in SuSE 6.2 linux.
It seems that ORBix is the implementation of CORBA used in GNOME
and RedHat 6.0, and it supports C, Python, and some other languages.
I.e. you have to choose whether you will write your code to use
one CORBA implementation or another, although they will
all interwork in the sense of communicating with each other
via ORBs.

PPPPS. I think I might be able to define corba's functionality 
category now:
My guess is that it is "a set of application-layer inter-process
protocols which are [in principle] programming-language independent,
architecture-independent, and transport-protocol-indpendent."
There's also some sort of addressing scheme which uses distributed
address servers (a bit like DNS, I think).

PPPPPS. Since CORBA skills are much sought after (if you
believe what employers write in job specs in the newspaper),
it seems to me that the free linux implementations are an
excellent way to improve one's CV. Especially since linux
is more likely to still be around in 5 years than
some other OSs.

PPPPPPS. According to the `linux world' tutorial mentioned above,
both the KDE and GNOME environments already use CORBA.
I.e. if you you're using them, then you're using CORBA.
This makes it sound less exotic, if I'm using it already.
The article is really excellent.
It makes it clear that CORBA has a substantial OSI layer 6
functionality. The only other layer-6 definition I know of is ASN.1,
which is used in SNMP (Simple Network Management Protocol).
(ASN.1 is also used in the [thankfully] obsolete OSI protocols
like FTAM - a sort of FTP.)
The IDL Interface Definition Language is just a meta-header-file
language. A header file written in IDL is translated as required
into header files in any particular programming language.

Now I've just tried this. A single line in IDL turns into a
big mob of C++ software, including templates (!!) and
virtual base classes (!!!). Awesome!
The MICO manual (111pages) looks good and clear too.

-- 
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