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[www-vrml] Incremental Downloads [was: VRML still the most ...]

George,

There is nothing in the specification that requires browsers to support incremental downloads of their capabilities. This was specifically decided not to require this because:

1) It is a browser-specific marketing position
2) Immersive browser foot-print is pretty small (~1MB)
3) Not all browsers may be connected to the Internet at the time of use
4) Define plugin APIs is out of scope for this specification


For Windows target systems, you can specify the browser to use (if it's a plugin in IE) using CLASSID tag. This does not work for other OS or browsers. If you want cross-browser, cross-OS compatibility, then use only spec defined nodes at the standard profiles, and depend on the MIME-Type information to cause the web browser to load the correct X3D browser.

This still leaves open the question of ensuring that a sufficiently capable browser will handle your content. If a user has installed an Interchange-only browser, they will not be able to view Interactive or Immersive content. This was discussed extensively about 16 months ago. The decision was made to not identify the profile (or component) in the MIME-Type. There is no way to automatically pre-determine if the browser can support the content prior to starting the browser.

It conclusion was that all important browsers for general web use would support Immersive. Interchange is primarily for use by applications. Interchange is an in-between state that may generate sufficient interest; however, the current level of interest did not justify forcing a specification solution at this time. The Full Profile includes so much that it would not be practical as a general-purpose web browser.

        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
+------------------------------