Re: SPEC ADDITIONS (_please_)

Mitra ([email protected])
Thu, 25 May 1995 09:11:29 -0700


At 11:19 PM 5/23/95, Nathan J. Strange wrote:
>> >I will point out again that this is why we need a mechanism for
>> >distributing and/or caching common items -- spaces are a *lot* faster
>> >to download if you've already got some of the building blocks locally.
>> >We still haven't addressed this point in any sort of coherent way, and
>> >really ought to by, at the latest, the time of rollout for 2.0...
>>
>> Am I right in thinking that you can specify a "file" URL in a document that
>> is not itself a "file"? IOW could http://www.mystuff.com/home.wrl include
>> a WWWAnchor with the URL "file:///c:/vrml/objlib/chair.wrl"?

Doing this is really dangerous, since you dont know that the receiver of
this doc has that file - there are two orthogonal solutions,
1) Build a set at a well known server e.g. http://vrml.org/objlib/chair.wrl
then either hope your HTTP Proxy has the file already - or at least will
cache it for you - or build caching into the client - or even retrieve the
file using a clever HTTP client like Netscape.
2) Use URN's when/if they become available, then URN:VRMLLIB/chair.wrl becomes
a known, replicable, and cachable object, but unless you implement caching
then having a URN doesnt gain you much.

>How about adding a Library node, that will basically be just like
>the WWWInline node, but the browser will know that it's gonna get called
>often...
>
>WWWInline lets you use another file to hold primitives, but the browser
>dosn't know to download it once and keep it handy for calls from other
>.wrl files, with a Library node the browser can download the .wrl file
>put it somewhere handy and referance it whenever it is needed.

Bad one! Creating another node which is essentially identical to the
WWWInline just increases the work required, I'd suggest that if something
like this is wanted that we add a field like "hints", so that we can say
something like.

WWWInline {
URL "http://foo.com/objlib/chair.wrl"
hint CACHE
}

This would allow suggestions to be made that clever browsers could use or
not depending on how clever they are. I've seen this used very well as part
of the GUI in OS's like GeoWorks.

- Mitra

=======================================================================
Mitra [email protected]
Internet Consulting (415)826-2499
<http://earth.path.net/mitra> fax (415)826-4423