[EMAIL PROTECTED] wrote,
> Manuel M. T. Chakravarty writes:
> > [EMAIL PROTECTED] wrote,
> >
> > > Manuel M. T. Chakravarty writes:
> > > > "Erik Meijer" <[EMAIL PROTECTED]> wrote,
> > > [...]
> > > > I understand that the fact that COM fixes the binary
> > > > interface makes it much easier to deal with.
> > >
> > > I don't understand this - perhaps you could explain.
> >
> > For Corba you usually have to select an ORB first and you
> > need a language mapping - simply fewer variables with COM
> > (you pay with loss of portability).
>
> I think you need a language mapping anyway - I don't see how you can use COM
> without defining how to map Haskell to it.
True, but with Corba all IDL compilers for a given
programming language should use the same mapping, COM
doesn't seem to require this (but I guess the COM experts
know this better than I). Therefore, you can just map it
somehow - but I should probably say that the H/Direct
designers being true believers ;-) in solidly specified
software provide a rather rigorous definition in the
H/Direct paper.
> As far as I can see, once you have selected an ORB, you
> mainly need to arrange argument marshalling and
> unmarshalling to and from the format desired by the
> ORB. Because of IIOP, the choice of ORB is not
> significant, unless you want to short-circuit calls for
> extreme speed ala ORBit. So it appears to me that, in this
> respect, COM is like CORBA restricted to only one brand of
> ORB.
This is probably a good comparison. However, I think in
practice your choice of ORB actually matters quite a lot in
CORBA - if you look at a list like
http://adams.patriot.net/%7etvalesky/freecorba.html
the features provided by different ORBs vary significantly.
To be honest, I am myself still undecided whether to prefer
CORBA's "everything goes and we fix only the framework"
approach or COM's "that's how it works, and you don't change
a bit" philosophy.
Manuel
