Re: [hybi] [Uri-review] ws: and wss: schemes
John Kemp <john@jkemp.net> Wed, 19 August 2009 17:57 UTC
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Date: Wed, 19 Aug 2009 13:50:52 -0400
From: John Kemp <john@jkemp.net>
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To: Jamie Lokier <jamie@shareable.org>
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Cc: hybi@ietf.org, uri-request@w3.org, Kristof Zelechovski <giecrilj@stegny.2a.pl>, uri@w3.org, uri-review@ietf.org, noah_mendelsohn@us.ibm.com, 'David Booth' <david@dbooth.org>
Subject: Re: [hybi] [Uri-review] ws: and wss: schemes
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Jamie Lokier wrote: > noah_mendelsohn@us.ibm.com wrote: >> Jamie Lokier writes: ... > Given a URI, you > cannot tell from Content-Type whether that URI supports WebDAV, However, the WebDAV specification does specifically offer some level of compatibility with existing non-WebDAV-aware clients - http://tools.ietf.org/html/rfc4918#appendix-B Without a WebDAV-aware client, I can still perform some non-WebDAV HTTP requests. With a WebDAV-aware client, I can perform WebDAV HTTP requests which the server may or may not support, but the server can tell me, according to HTTP specification that a "method is not supported". > and > you cannot tell whether that URI accepts POSTs to submit new blog > entries - just to pick two widely used examples. A client able to submit a POST can try, but might fail. > > That requires another level of descriptive metadata, which > Content-Type does not provide and is not always available in any other > form. But, just like people can enter a "blog posting" URI into their > mobile phone, there will be reasons why people enter WebSockets URIs > into applications, with no way for the application to verify the > protocol except by trying it. The question is perhaps really about whether you want to provide _some_ compatibility with existing non-websock-aware clients. > >> So, this is a desirable characteristic for Web resources, and it's >> one of the things that HTTP gives you. Indeed, the whole Web is >> designed so that you can start with RFC 3986, the specification for >> URIs, and using the references to which it (recursively) delegates, >> discover how to correctly interact with and interpret responses from >> any resource on the Web. Under the auspices of the W3C TAG, I >> prepared a "finding" [1] that goes into more detail on these issues >> and their implications. > > In other words, I disagree with the above. You can't find which > particular protocols are overlaid on top of HTTP at every findable URI > by the existing mechanisms, and it's unlikely that will ever be > possible. It is possible for those designing Web protocols to consider compatibility with existing Web client software, and to provide ways of allowing new and existing clients to determine the capabilities of HTTP-identified resources. The TAG finding that Noah mentions describes ways in which (some) others have allowed for clients to "follow their noses" and discover how to operate with servers regarding particular resources. There are other ways to do it, but the point is that it depends on protocol designers making the decision to offer such facilities. Using HTTP URIs to identify resources is a good way to begin that process. Regards, - johnk [1] http://www.w3.org/2001/tag/doc/selfDescribingDocuments.html
- [hybi] ws: and wss: schemes Ian Hickson
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Greg Wilkins
- Re: [hybi] [Uri-review] ws: and wss: schemes Ian Hickson
- Re: [hybi] [Uri-review] ws: and wss: schemes Maciej Stachowiak
- Re: [hybi] [Uri-review] ws: and wss: schemes Chris Anderson
- Re: [hybi] [Uri-review] ws: and wss: schemes Mark Nottingham
- Re: [hybi] [Uri-review] ws: and wss: schemes Pieter Hintjens
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Greg Wilkins
- Re: [hybi] [Uri-review] ws: and wss: schemes Maciej Stachowiak
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Maciej Stachowiak
- Re: [hybi] [Uri-review] ws: and wss: schemes Maciej Stachowiak
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes David Orchard
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Ian Hickson
- Re: [hybi] [Uri-review] ws: and wss: schemes Roy T. Fielding
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Ian Hickson
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes noah_mendelsohn
- Re: [hybi] [Uri-review] ws: and wss: schemes Toby Inkster
- Re: [hybi] [Uri-review] ws: and wss: schemes Křištof Želechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Erik Wilde
- Re: [hybi] [Uri-review] ws: and wss: schemes noah_mendelsohn
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes John Kemp
- Re: [hybi] [Uri-review] ws: and wss: schemes noah_mendelsohn
- Re: [hybi] [Uri-review] ws: and wss: schemes Mark Nottingham
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Erik Wilde
- Re: [hybi] [Uri-review] ws: and wss: schemes noah_mendelsohn
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes noah_mendelsohn
- Re: [hybi] ws: and wss: schemes Ian Hickson
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] ws: and wss: schemes Ian Hickson
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] ws: and wss: schemes Ian Hickson
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] ws: and wss: schemes Ian Hickson
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Toby Inkster
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] ws: and wss: schemes Martin J. Dürst
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes Toby Inkster
- Re: [hybi] [Uri-review] ws: and wss: schemes David Booth
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Martin J. Dürst
- Re: [hybi] [Uri-review] ws: and wss: schemes Křištof Želechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Křištof Želechovski
- Re: [hybi] [Uri-review] ws: and wss: schemes Jamie Lokier
- Re: [hybi] [Uri-review] ws: and wss: schemes Joseph A Holsten
- Re: [hybi] [Uri-review] ws: and wss: schemes Joseph A Holsten
- Re: [hybi] [Uri-review] ws: and wss: schemes Joseph A Holsten
- Re: [hybi] [Uri-review] ws: and wss: schemes Daniel R. Tobias
- Re: [hybi] [Uri-review] ws: and wss: schemes Daniel R. Tobias
- Re: [hybi] [Uri-review] ws: and wss: schemes Daniel R. Tobias
- Re: [hybi] [Uri-review] ws: and wss: schemes Lisa Dusseault
- Re: [hybi] [Uri-review] ws: and wss: schemes Infinity Linden
- Re: [hybi] [Uri-review] ws: and wss: schemes Lloyd Wood
- Re: [hybi] [Uri-review] ws: and wss: schemes Kristof Zelechovski
- Re: [hybi] ws: and wss: schemes Ian Hickson
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] ws: and wss: schemes Ian Hickson
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] ws: and wss: schemes Roy T. Fielding
- Re: [hybi] ws: and wss: schemes Julian Reschke
- Re: [hybi] [Uri-review] ws: and wss: schemes Martin J. Dürst
- Re: [hybi] ws: and wss: schemes Ian Hickson