Re: Byte ranges -- formal spec proposal

It has been suggested that byte ranges could be supported by either a new
HTTP method or by a new HTTP header.  The point of byteranges is to allow
HTML anchors to request a range of bytes from a document.  There
is no way to do this with either a new method or a new header unless
new syntax and semantics are added to HTML and all browsers are changed
to support this syntax.  Experience suggests this is (1) not a good thing
to propose and (2) that it is very unlikely to happen.

The byterange URL proposal has the advantage that no additions to HTML
are required and it works fine with all current browsers.  Indeed,
essentially this proposal has been implemented and is widely used in
both the GN and the WN servers (in the case of GN for over two years).
It works fine with all browsers.

Some other clarifications:

1) Once again, this is a proposal for HTT URLs, not for all URLs.

2) If a server chooses not to support byteranges for one document or
all documents and for whatever reasons, it is quite appropriate to
send a "document not found" status.   The server should not parse the
request and send the entire file when a range was requested.  The 
behavior of current servers which do not support byteranges would be
quite appropriate if they received a byterange request.

Two issues have been raised that I would like to hear more discussion

Should byteranges be 0 based or 1 based.  My initial view was that
it is important to be consistent and some other ranges like lines
(already implemented in some servers) really should be base 1. I am
not completely sure, however, just how important this consistency is.
It may be less confusing to have bytes be base 0 even if lines, say,
are base 1.  NOTE:  This proposal does not call for standardizing line
ranges or chapter ranges or whatever.  We merely want to leave open that
possibility and not do anything which could cause problems later.

The second issue is also about possible future extensions.  Dan Connoly
pointed out that an '&' for multiple parameters would have to be 
escaped in an anchor in an HTML document.  This is indeed a problem,
on the other hand it would be nice to have the same syntax as HTML form

John Franks

Received on Thursday, 18 May 1995 09:02:04 UTC