Re: Do you understand this?

[Robert J. Chassell]

Thanks to Andreas, Jason, and Nic I think I now understand the rfc2616
HTTP specification a great deal better than before.

Perhaps we should add the following to

    emacs/man/url.texi

after the text saying:

    @node HTTP language/coding
    @subsection Language and Encoding Preferences

    HTTP allows clients to express preferences for the language and
    encoding of documents which servers may honour.

Is this now an accurate description?


An @samp{Accept:} or @samp{Accept-Charset} statement or @samp{headers}
allows you to specify the priority or weighing of the type of
statement you would like to accept.

In contrast to their precedence in English text, commas separate
@emph{bigger} groupings than semi-colons, which are used to prefix
weightings or priority values.  Priority values go from 0.0 to 1.0,
with 1.0 being highest.  When a priority or weighting value is not
listed the value is presumed to be 1.0.  Moreover, an @samp{Accept:}
or @samp{Accept-Charset} list need not be in priority or precedence
order.

@need 800
@noindent
Thus, an accept statement such as

@smallexample
Accept: text/plain;
        q=0.5, text/html, text/x-dvi;
        q=0.8, text/x-c
@end smallexample

@need 1000
@noindent
could be reformatted as

@smallexample
Accept: text/plain; q=0.5,
        text/x-dvi; q=0.8,
        text/html ; q=1.0,
        text/x-c  ; q=1.0
@end smallexample

@noindent 
This latter expression shows the list in order from lower to higher
priority.  Both @samp{text/html} and @samp{text/x-c} are of equal
(and highest) priority.

When sent in an HTTP request for a resource, the above @samp{Accept:}
statement tells the server that the user prefers to either an HTML or
text/x-c document.  If neither of those reprsentations is available,
then DVI is next preference.  If none of those three are available,
then plain text should be sent.  If neither plain text, DVI, HTML nor
x-c are available, then the server's response should indicate that it
is failing to find a representation that satisfies the request.

-- 
    Robert J. Chassell                         
    address@hidden                         GnuPG Key ID: 004B4AC8
    http://www.rattlesnake.com                  http://www.teak.cc