- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Fri, 08 May 2009 20:06:01 +0200
- To: Brian Smith <brian@briansmith.org>
- CC: 'Geoffrey Sneddon' <foolistbar@googlemail.com>, 'HTTP Working Group' <ietf-http-wg@w3.org>
Brian Smith wrote: > Julian Reschke wrote: >> 3.2. Date/Time Formats >> The first format is preferred as an Internet standard and >> represents a fixed-length subset of that defined by >> [RFC1123]. > > I still think it is misleading to refer to RFC1123 here when HTTP doesn't > use the syntax or the semantics of RFC1123. Besides, the specification > doesn't have to justify why the that syntax is preferred. The next paragraph > already states that implementations MUST use it. I'd just delete that > paragraph. I think it's useful to understand why HTTP/1.1 happens to use this format. > I don't get why s-Mon, s-Jan, l-Mon, etc. are named productions (instead of > unnamed alternatives like in RFC 5023), but that is not new to this change. For readability; our version is case-sensitive, so we can't use string constants in the ABNF. > The semantics of the obsolete date formats are not defined. How is a server > supposed to interpret a 2-digit year? Good question. Do you have an answer? Can we mandate the rules in <http://tools.ietf.org/html/rfc5322#section-4.3>? >> asctime-date = day-name SP date3 SP time-of-day SP 4DIGIT >> date2 = 2DIGIT "-" month "-" 2DIGIT >> ; day-month-year (e.g., 02-Jun-82) > > Might as well use "day" and "year": We can re-use "day", but not "year" (because it's 4DIGIT). > asctime-date = day-name SP date3 SP time-of-day SP year > date2 = day "-" month "-" 2DIGIT > ; day-month-year (e.g., 02-Jun-82) > >> Note: HTTP requirements for the date/time stamp format apply only to >> their usage within the protocol stream. Clients and servers are not >> required to use these formats for user presentation, request logging, >> etc. > > Might as well delete this while you are at it. It is strange to single out > that this one part of the HTTP syntax doesn't have to be used outside of the > protocol, when that is generally true for all parts of the syntax. I think I agree, but I'd like to avoid taking out stuff without more review. >> While at it, we probably should also drop the surplus subsection 3.2.1 >> and move all of this into 3.2 (this is a left-over from partitioning >> RFC 2616). > > +1. Will do that when the patch gets applied. In the meantime I have re-arranged stuff a bit more so that it's more clear what belongs to which format, and which ones are preferred/obsolete; and also moved the other note to the end of the paragraph. See <http://trac.tools.ietf.org/wg/httpbis/trac/attachment/ticket/163/163.diff> and full text below: -- snip -- 3.2. Date/Time Formats 3.2.1. Full Date HTTP applications have historically allowed three different formats for the representation of date/time stamps: Sun, 06 Nov 1994 08:49:37 GMT ; RFC 1123 Sunday, 06-Nov-94 08:49:37 GMT ; obsolete RFC 850 format Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() format The first format is preferred as an Internet standard and represents a fixed-length subset of that defined by [RFC1123]. The other formats are described here only for compatibility with obsolete implementations. HTTP/1.1 clients and servers that parse the date value MUST accept all three formats (for compatibility with HTTP/1.0), though they MUST only generate the RFC 1123 format for representing HTTP-date values in header fields. See Appendix A for further information. All HTTP date/time stamps MUST be represented in Greenwich Mean Time (GMT), without exception. For the purposes of HTTP, GMT is exactly equal to UTC (Coordinated Universal Time). This is indicated in the first two formats by the inclusion of "GMT" as the three-letter abbreviation for time zone, and MUST be assumed when reading the asctime format. HTTP-date is case sensitive and MUST NOT include additional whitespace beyond that specifically included as SP in the grammar. HTTP-date = rfc1123-date / obs-date Preferred format: rfc1123-date = day-name "," SP date1 SP time-of-day SP GMT day-name = s-Mon / s-Tue / s-Wed / s-Thu / s-Fri / s-Sat / s-Sun s-Mon = %x4D.6F.6E ; "Mon", case-sensitive s-Tue = %x54.75.65 ; "Tue", case-sensitive s-Wed = %x57.65.64 ; "Wed", case-sensitive s-Thu = %x54.68.75 ; "Thu", case-sensitive s-Fri = %x46.72.69 ; "Fri", case-sensitive s-Sat = %x53.61.74 ; "Sat", case-sensitive s-Sun = %x53.75.6E ; "Sun", case-sensitive date1 = day SP month SP year ; e.g., 02 Jun 1982 day = 2DIGIT month = s-Jan / s-Feb / s-Mar / s-Apr / s-May / s-Jun / s-Jul / s-Aug / s-Sep / s-Oct / s-Nov / s-Dec year = 4DIGIT s-Jan = %x4A.61.6E ; "Jan", case-sensitive s-Feb = %x46.65.62 ; "Feb", case-sensitive s-Mar = %x4D.61.72 ; "Mar", case-sensitive s-Apr = %x41.70.72 ; "Apr", case-sensitive s-May = %x4D.61.79 ; "May", case-sensitive s-Jun = %x4A.75.6E ; "Jun", case-sensitive s-Jul = %x4A.75.6C ; "Jul", case-sensitive s-Aug = %x41.75.67 ; "Aug", case-sensitive s-Sep = %x53.65.70 ; "Sep", case-sensitive s-Oct = %x4F.63.74 ; "Oct", case-sensitive s-Nov = %x4E.6F.76 ; "Nov", case-sensitive s-Dec = %x44.65.63 ; "Dec", case-sensitive GMT = %x47.4D.54 ; "GMT", case-sensitive time-of-day = hour ":" minute ":" second ; 00:00:00 - 23:59:59 hour = 2DIGIT minute = 2DIGIT second = 2DIGIT The semantics of day-name, day, month, year, and time-of-day are the same as those defined in the RFC 5322 constructs with the corresponding name ([RFC5322], Section 3.3). Obsolete formats: obs-date = rfc850-date / asctime-date rfc850-date = day-name-l "," SP date2 SP time-of-day SP GMT date2 = day "-" month "-" 2DIGIT ; day-month-year (e.g., 02-Jun-82) day-name-l = l-Mon / l-Tue / l-Wed / l-Thu / l-Fri / l-Sat / l-Sun l-Mon = %x4D.6F.6E.64.61.79 ; "Monday", case-sensitive l-Tue = %x54.75.65.73.64.61.79 ; "Tuesday", case-sensitive l-Wed = %x57.65.64.6E.65.73.64.61.79 ; "Wednesday", case-sensitive l-Thu = %x54.68.75.72.73.64.61.79 ; "Thursday", case-sensitive l-Fri = %x46.72.69.64.61.79 ; "Friday", case-sensitive l-Sat = %x53.61.74.75.72.64.61.79 ; "Saturday", case-sensitive l-Sun = %x53.75.6E.64.61.79 ; "Sunday", case-sensitive asctime-date = day-name SP date3 SP time-of-day SP year date3 = month SP ( 2DIGIT / ( SP 1DIGIT )) ; month day (e.g., Jun 2) Note: Recipients of date values are encouraged to be robust in accepting date values that may have been sent by non-HTTP applications, as is sometimes the case when retrieving or posting messages via proxies/gateways to SMTP or NNTP. Note: HTTP requirements for the date/time stamp format apply only to their usage within the protocol stream. Clients and servers are not required to use these formats for user presentation, request logging, etc. -- snip -- Best regards, Julian
Received on Friday, 8 May 2009 18:06:47 UTC