Date

Date

 

---

 

 

The Date header gives the date and time at which the message was created. This header is required in servers' responses because the time and date at which the server believes the message was created can be used by caches in evaluating the freshness of a response. For clients, this header is completely optional, although it's good form to include it.

Type

General header

Basic Syntax

Date: HTTP-date

Examples

Date: Tue, 3 Oct 1997 02:15:31 GMT

HTTP has a few specific date formats. This one is defined in RFC 822 and is the preferred format for HTTP/1.1 messages. However, in earlier specifications of HTTP, the date format was not spelled out as well, so server and client implementors have used other formats, which need to be supported for the sake of legacy. You will run into date formats like the one specified in RFC 850, as well as dates in the format produced by the asctime( ) system call. Here they are for the date represented above:

Date: Tuesday, 03-Oct-97 02:15:31 GMT RFC 850 format

Date: Tue Oct 3 02:15:31 1997 asctime( ) format

The asctime( ) format is looked down on because it is in local time and it does not specify its time zone (e.g., GMT). In general, the date header should be in GMT; however, robust applications should handle dates that either do not specify the time zone or include Date values in non-GMT time.