Re: ORBit mail 3 - Vtable layouts

[Phil Dawes <philipd parallax co uk>]

Lauri Alanko wrote:
> 
> [reply-to directed to orbit-list@cuc.edu, that's where this belongs..]
> 
> On Mon, 15 Jun 1998, Phil Dawes wrote:
> > Agreed. Unfortunately the whole point of inproc components is that they
> > are not distributed. Areas where this could be of use are e.g. plugins
> > for applications (e.g. gimp etc..), and in a component architecture.
> > Witness how COM is used on OLE in windows for example.
> 
> "Not distributed"? You mean an object that cannot be invoked outside its
> process context? If you want something like that, why use CORBA?
> 

Because you might have objects written in different languages.
I didn't mean that the object *couldn't* be invoked outside their
address space. I just meant that the most likely use-case for such a
component is to execute in the same address space as its client.


> > Unfortunately the corba spec is not designed to be used with inproc
> > objects (it doesn't define a binary standard), so I was hoping that we
> > could develop one around the C-language POA mapping. Unfortunately it
> > looks like this requires using casting macros which aggregate to a
> > 'queryinterface' style function which as you mention goes against the
> > corba spec.
> 
> Frankly, I don't understand all this fuss about optimizing in-process
> calls at any costs. If you have objects that are going to communicate
> in-process, and you want it fast, you have no reason to use CORBA anyway.
> You can have the implementation code call other objects' implementation
> code directly and forget all this reference/object adapter fuss.
> 

Yes, but you might wan't to be able to use different languages within
the same address space - that's somewhere that a mapping like CORBA
makes things simpler

Basically I'd like to have something along the lines of COM for gnome,
and CORBA seems like a fairly good fit.

> You can't bypass all marshalling with in-process CORBA objects, at least
> if they use vanilla POA. Calls can be forwarded, a POA could change state
> and all that.. You can't just bypass the POA, at least if you want
> conforming code.
> 

That's a shame. I've had a short read through the spec and I couldn't
find any reason why you can't. I'll do some more reading tonight.

> Of course, you can have an extension, or custom OA, that is optimized for
> in-process communication, but to me at least that seems rather
> secondary at this stage..
> 
> As I said, if you want in-process performance, you don't want to use CORBA
> anyway..
> 

But I do want different languages in the same address space. There
aren't many other choices AFAIK (com or ilu).

Cheers,

Phil.
-- 
_______________________________________________________________________
 Phil Dawes                               |   My opinions are my own
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