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Re: Dynamic invocation vs. late/dynamic binding

From: Mark Baker <distobj@acm.org>
Date: Tue, 7 Jan 2003 15:30:16 -0500
To: Sanjiva Weerawarana <sanjiva@watson.ibm.com>
Cc: www-ws-arch@w3.org
Message-ID: <20030107153016.B29146@www.markbaker.ca>

On Wed, Jan 08, 2003 at 01:21:22AM +0600, Sanjiva Weerawarana wrote:
> > Late/dynamic binding means being able to manipulate squares and circles
> > with the Shape interface.  Dynamic invocation means being able to
> > construct, for example, a "displaySquare" message without compile-time
> > knowledge of the full Square interface.
> That's fine - WSIF can handle that using something called JROM we
> created (see alphaWorks again) to represent arbitrary schema typed
> values. 
> Clearly, in the absence of magic the information about the interface
> (namely the data type defs) is needed at runtime at least (possibly
> using xsi:type), so once that's available you're on easy street.

That seems to be something very different than what I'm talking about.
Sorry, I don't see how it relates.

> > The former enables a client written to access Shape objects, to later
> > access triangles, ovals, hexagons, you name it.  The latter doesn't.
> I guess we're back to the REST vs. WS debate; your program cannot
> manipulate those shapes in a meaningful way without an understanding
> of what an oval is vs. a square.

Of course you can!  All you need in order to create an abstraction
is commonality.  Can't you "meaningfully" treat brown cows and black
cows as cows?

Where's the disconnect here?  Surely you've used polymorphism before?
(which, in case you were wondering, the Shape example isn't trying to
demonstrate .. exactly)

Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Web architecture consulting, technical reports, evaluation & analysis
Received on Tuesday, 7 January 2003 15:29:48 UTC

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