COM/CORBA/DCOP (was: Hello people. I have some questions)

Alex Martelli aleax at aleax.it
Mon Sep 3 12:11:07 CEST 2001


"Duncan Grisby" <dgrisby at uk.research.att.com> wrote in message
news:9mu5si$9gg$1 at pea.uk.research.att.com...
    ...
> I don't know why people would consider CORBA too heavyweight for
> connecting desktop apps -- the few performance comparisons between COM
> and CORBA I have seen show CORBA to be as fast or faster than COM.

For *in-process* interaction?!  There's something askew here... I
did the measurements myself back around 1994/1995, under Windows/NT,
using COM (in-process and out-of-process) and Iona's Orbix, which
Iona claimed was the fastest ORB for NT, and the difference in
terms of performance overhead was *at least* an order of magnitude
in favour of COM (using C to program "toy"-level servers and
clients, instrumented for measuring communication overhead, and
striving to simulate the kinds of loads our own applications would
place on a componentization infrastructure).  Have things changed
so drastically since then?

Now, depending on the kind of interoperation those "desktop apps"
do in fact use, a slow-down by a factor of 10 or 20 in the
communication overhead itself may be irrelevant (or else you
wouldn't see any *Automation* usage on top of COM -- the mostly
interpretive nature of Automation dispatching does impose at
least that much extra overhead when compared to down-to-the-
metal COM on binary interfaces).  But "Corba faster than COM"
(except any _remoting_ scenario -- I'm *NOT* saying DCOM is a
match for IIOP, mind you!-) is really news to me.


Alex






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