Date sent: Thu, 20 Jul 2000 19:43:21 -0400 From: "Aaron E. Walsh" Organization: Mantis Development Corp. To: Universal Media Working Group , "Content Review List (Universal Media)" Copies to: Content Working Group , Martin Reddy , Don Brutzman , GeoVRML Working Group Subject: [media] Netscape vs. URNs? (Transparent encoding URNs in URLs) Send reply to: "Aaron E. Walsh" I wonder if anyone using Contact 4.3 has had the following problems trying to run Universal Media demos under Netscape Navigator? In all cases for me (Win95, 98 and NT4) Netscape pops up a dialog box upon loading a UMedia world to alert me to the fact that URNs are not internally supported (this is a Netscape dialog, not Contact). An alert appears for each and every URN in a world, each of which must be "OKed" before you can get to the world. For example, if I try to run the various Dragon demos at: http://www.web3dmedia.com/UniversalMedia/demos/ six (6!) instances of the following alert dialog appear (one after another, for each URN used) in Netscape that prevents the user from navigating the world until each is dismissed: __________________________________________________________ "URN's not internally supported, use an HTTP proxy server: urn:web3d:media:textures/panoramas/desert_1_bottom.jpg" __________________________________________________________ Worlds that have even more textures (some have more than 20 or 30 UMedia textures) are practically impossible to get to (after clicking on the alter "OK" button, only to see another appear for what seem like for ever I usually bail and fire up IE). As a result I always use Internet Explorer. Do others have the same problem? I ask because this is one of the reasons that I suggest we consider transparently encoding URNs into URLs (see "Transparent URN Encoding in URLs" post and replies for details -- original posted below for convenience). Our Siggraph UMEdia Working Group meeting is scheduled for Friday from 9-10am, during which we can talk about the best way to deal with this problem and similar alters from VRML browsers such as WorldView (granted it's an old browser, but many users have it pre-installed with IE under the name "VRML 2.0 Browser"). Anyone interested in Universal Media is welcome to drop by for our Friday morning meeting (Friday July 28th Room: 285, Ernest N. Morial Convention Center from 9 to 10 am) to discuss the current and future state of Universal Media. Aaron ----- Subject: Transparent URN Encoding in URLs (concept and chat excerpt) From: "Aaron E. Walsh" 7/2/00 7:31 PM To: Don Brutzman , Martin Reddy , Universal Media Working Group , GeoVRML Working Group Hello Don and everyone, as it turns out I'm going to be burnt for time most of this week so I probably won't have a chance to complete the "Transparent URN Encoding in URLs" as mentioned in my reply to Don's original message regarding local host URLs. I will probably complete it over the next weekend so that we have something that everyone can comment on before Siggraph, and also in hopes of nailing down the local mapping issues that have resurfaces (I think the gap if finally closing on local URLs, it's just a matter of drilling into them for a while longer). Instead I hope that the below excerpt from our Web3D.about.com chat helps. The concept is simple: embed URNs directly into URLs for transparent support of URNs by software that doesn't understand them already (Web browsers, for example). By mapping such a URL to a local location similar to the idea Don suggested we should be able to develop a single resource naming solution that travels well from web to all local platform (assuming we also establish local installation default locations, which shouldn't be a problem -- vendors simply place a folder on the root level of the startup drive having the same domain name as the URLs itself. For example, consider the following URL (notice the URN encoded in it): http://www.web3dmedia.com/urn:web3d:media:/textures/nature/grass_1.jpg The above would map to the local file location on Windows systems: C:\www.web3dmedia.com\urn\web3d\media\textures\nature\grass_1.jpg Colons are mapped to local (platform specific) directory separators (backward slashes, in the case of Windows above). NOTE THAT THIS IS NOT HOSTED ON web3d.org at the moment because I was experimenting with it quite a bit and pushing it live didn't make sense (instead I worked on it at the above media site), although we'd do it via web3d.org officially if we agree it's a good idea (to avoid multiple local installations of the same textures, sounds, etc.). If we can come to some agreement on this I have no problem updating our Universal Media URN proposal to reflect 1) Transparent URN encoding guidelines and recommendations, 2) Local mapping guidelines and recommendations, 3) A *new* default installation location for our system based on the above. Please consider the following chat we had before diving in, as we covered some preliminary ground that might answer questions in advance. Regards, Aaron -------------------------------------------------------- NOTE: BELOW EXCERPT TAKEN FROM WEB3D.ABOUT.COM CHAT LOG: http://web3d.about.com/compute/web3d/library/chatlogs/2000/blcl032200a.htm SUBSTANTIALLY EDITED FOR CLARITY (REORGANIZED) -------------------------------------------------------- ...... Log on 031500 started at Wed Mar 15 18:30:11 PST 2000 ...... AaronWalsh said: Anybody seen one of these: http://www.web3dmedia.com/urn:web3d:media:/textures/nature/grass_1.jpg ? It's a URN encoded in the body of a valid URL -- best of both worlds. Here's the hook -- 1 identifier that acts like a URL and an URN at once... Braden: I'd have to check RFC1738, but I'm not entirely sure that's kosher with the definition of the http scheme. AaronWalsh: Last week I ran it by Leslie Dangle (URN chair at IETF). It may fly. Braden: What was the reaction? JEM: What does it accomplish? AaronWalsh: Universal Media in standard Web browsers! Web browsers don't support multiple URLs, soooo....we give them 1, only 1, that has a URN and URL. If it's UMedia savvy it grabs the resource locally, otherwise it fetches it off the net without a problem. It also resolves ALL OF THE NASTY dialog boxes that some browsers toss up with they encounter a URL (URN) that they can't handle (Worldview, for example). It also allows us to migrate into single URL environments where we aren't already... Guy: that's a great solution to the single line urn/url web3dADM: would this turn out to be a new method for caching? AaronWalshL: Sandy (vweb3dADM) -- yes!!!! Braden: I'm still not clear on the problem this is solving. Web browsers don't know about multiple URIs, but VRML browsers do. Why can't they check the URN (if they understand it) and then hand off a URL (subsequent in the list) if that doesn't work out? AaronWalsh: UMedia is all about global caching, one that ALL programs has access to. JEM: You know, it's possible for 3rd parties to write protocol handlers (such as URN:) for Internet Explorer. I bet it could be done pretty easily. Mozilla probably has a similar capability.. AaronWalsh: Braden, how would you hand a URN to a Web browser via HTML today? Braden: Aaron, Why would I need to? AaronWalsh: Braden, suppose that you wanted to use a UMedia texture for the background image of your Web page (HTML). Or as a IMG image.By handing it a URL/URN combo we could support future-ready browsers without breaking the millions of browsers already out there. Future browsers can pick out the URN and resolve locally, while others fetch from the fully specified URL. Seamless backwards compatibillity with HTML. web3dADM: right it's UMEL as applied to any Web media application AaronWalsh: Yes, waaaay beyond Web3D years from now. web3dADM: I could see UMEL flash content Guy: sure. the content is very useful for many tools and apps web3dADM: with the main benfit I think, of increased reliability and backward compatability for old browsers AaronWalsh: We're building media building blocks and a global, shared cache that's valuable to any application that needs images, sounds, or 3D objects. Braden: And how do current browsers resolve the URL-URN hybrid? What conventional URL would your hybrid map to? AaronWalsh: Hold on....let me get one: http://www.web3dmedia.com/urn:web3d:media:/textures/nature/grass_1.jpg Load that into your Web browser now... does it resolve? Laurent: it even works AaronWalsh: yep! Braden: Sho' 'nuff. web3dADM: hey it worked! keithv: Cool! Guy: well pinch my toes and call me a jelly donut. It works..! AaronWalsh: If you were a savvy tool, like Spazz3D or Contact, you'd see this substring: urn:web3d:media:/textures/nature/grass_1.jpg and grab it from the hard drive instead. 2 in one: URL for backwards compatiblity, URN for the future... web3dADM: why does it work? AaronWalsh: It's a URL! AaronWalsh: What you get when you load this into your Web browser is a real, honest to God URL. Guy: it's a URN..! AaronWalsh: No, it's a URL with a URN in it! Cool, huh? Guy it's two.. two.. two links in ONE web3dADM: yeah way cool AaronWalsh: Yes, so if we do this instead of making our URNs separate, we handle everything without breaking current standards. -------------------------------------------------------- NOTE: ABOVE EXCERPT TAKEN FROM WEB3D.ABOUT.COM CHAT LOG: http://web3d.about.com/compute/web3d/library/chatlogs/2000/blcl032200a.htm SUBSTANTIALLY EDITED FOR CLARITY (REORGANIZED) -------------------------------------------------------- Regards, Aaron -- --------------------------------------------------------------------- Aaron E. Walsh http://www.mantiscorp.com/people/aew/ 617.350.7119 ---------------------------------------------------------------------