[www-vrml] X3D EXTERNPROTO [was: VRML still the most ...]

[Leonard Daly <daly@realism.com>]

The spec team had a lot of discussion of EXTERNPROTO. As a content
developer capability, there is no change from VRML97. The change does
come about for browser writers. In X3D you cannot use the EXTERNPROTO
mechanism to provide an interface for new nodes. New nodes are built into
the browser and should not use an EXTERNPROTO interface.

So if the browser builder BTC decides to add a node that supports a 6DoF
joystick, they could add a node (e.g., BTC_Joystick) for this purpose.
There would be no EXTERNPROTO that content developers would reference.
Content developers would access this new node in the 'Component'
statement (e.g., 'Component BTC:1').

This new node would be only available in the BTC browser. Support for it
would not be required (and may actually be prohibited) in other
browsers.


If you are a content developer creating EXTERNPROTO, then you can use any
node available to you (for the Profile and Component that you declare).
If you do choose to refer to a node like BTC_Joystick, then it needs to
be declared in the EXTERNPROTO and in the top level X3D file.

        

Leonard
Daly



At 07:24 AM 9/3/04, George Birbilis wrote:
> > >   X3D is just
> integration plus more features.
> >
> >
> <http://www.web3d.org/x3d/faq/index.html#technical-2>
> >
> > The abandonment of EXTERNPROTO as a browser extension mechanism
> should
> > not be trivialized. The text in the above link says that, "The
> way to
> > provide browser-specific extensions is through custom
> components." But
> > how do you refer to one of these "custom components" over
> the network?
>
> Hi Braden,
> I believe the idea is that once the browser sees a component it doesn't
> know
> mentioned in the header of a X3D file, tries to contact the browser
> vendor's
> host (or some local network repository folder set in browser options)
> and
> check for a plugin/update to add support for that component (say one
> had
> installed the browser with minimum components for quick download) and if
> it
> doesn't find such it shows message to the user...
>
> ...probably also playing it nice and showing some dialog to the user
> with
> the other X3D browsers found in the system to chose one to use (can do
> that
> on Windows using the registry), showing only those browsers that have
> marked
> in the registry that they support that component (supposing W3D
> group
> defines the format for such info in the registry and what's the min
> required
> info to have there for an X3D browser)
>
> cheers,
> George
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> George Birbilis <birbilis@kagi.com> [Microsoft MVP J#]
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + QuickTime VCL and ActiveX controls (for PowerPoint/VB/Delphi 
> etc.)
> + Plugs VCL and ActiveX controls (InterProcess/Internet
> communication)
> + TransFormations, VB6 forms to ASP.net WebForms convertion
> http://www.kagi.com/birbilis
> + Robotics
> http://www.mech.upatras.gr/~robgroup
> ........................................................................
>
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+--------
| Leonard Daly <daly@realism.com>
| Internet Development http://realism.com/
| e3D News Technical Editor http://e3dNews.com/
| SIGGRAPH 2002&2003 X3D Course Organizer
| Member, Web3D Board of Directors
+------------------------------