Re: Format of RTSP URLs

Roy T. Fielding (
Tue, 15 Jul 1997 11:03:09 -0700

To: Rob Lanphier <>
Subject: Re: Format of RTSP URLs 
In-reply-to: Your message of "Tue, 15 Jul 1997 09:50:28 PDT."
Date: Tue, 15 Jul 1997 11:03:09 -0700
From: "Roy T. Fielding" <>
Message-ID:  <>

>I think this may be acceptable, but there's one other possible requirement
>I'd like to mention.  It would be nice to have the ability to have relative
>URLs, so that, for example, the following scenario can play out (using ":"
>as a server side fragment identifier for the time being)
>C->S  DESCRIBE rtsp://foo/db/moviebase?movie=twister RTSP/1.0 1
>S->C  RTSP/1.0 200 1 OK
>      Content-length: 178
>      Content-type: application/sdp
>      s= sample rtsp presentation
>      r = rtsp://foo/db/moviebase?movie=twister   /* aggregate URL*/
>      m= audio 0 RTP/AVP 0
>      r = :track=audio1                           /* URL to control audio*/
>      m=video 0 RTP?AVP 26
>      r = :track=video1                           /* URL to control video*/
>At this point, the client can easily discern that the audio track and the
>video track are indeed merely fragments of the same object on the server,
>and not separately controlled entities.  I'm not sure how this would work
>with ";" parameters, since the relative behavior defined in 1808 is
>different than what I'd expect above (which is more akin to "#").

Those relative URLs would resolve to


which is obviously not what you would want.  Query info and relative
references do not mix in practice.  In any case, using query info to
select a resource, as opposed to redirecting to the real resource URL,
is poor namespace management.