How to specify Expiration DATE and TIME to cache of a document

hai
i am using CGI.pm and DBI for my perl CGI Programs. I have one problem with my navigation in previous and next link.
When i press back button of browser it says "Data Missing" . I want to specify an expiry date and Time for my html Document.
How can i do?
thanks in advance

vijay

Send the Expires header:
print $query->header(-expires=>'Thu, 01 Dec 1994 16:00:00 GMT');

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Good luck,
Bas

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E-mail me at: b.vandermeijden@pecoma.nl

hai,

The date we specified is which system date!
whether i have to specify my server date or client side date?

How i have to specify HTTP Date ...
I know that there is one RFC is there?
Can u please help me in finding that?

vijay

The RFC 2616 is the spec for HTTP 1.1. There is info on the HTTP date, but also on all HTTP headers (including the expires).

FROM RFC 2616:

14.18 Date
The Date general-header field represents the date and time at which the message was originated, having the same
semantics as orig-date in RFC 822. The field value is an HTTP-date, as described in section 3.3.1; it MUST
be sent in RFC 1123 [8]-date format.
Date = "Date" ":" HTTP-date
An example is
Date: Tue, 15 Nov 1994 08:12:31 GMT
Origin servers MUST include a Date header field in all responses, except in these cases:
1. If the response status code is 100 (Continue) or 101 (Switching Protocols), the response MAY include a
Date header field, at the server’s option.
2. If the response status code conveys a server error, e.g. 500 (Internal Server Error) or 503 (Service
Unavailable), and it is inconvenient or impossible to generate a valid Date.
3. If the server does not have a clock that can provide a reasonable approximation of the current time, its
responses MUST NOT include a Date header field. In this case, the rules in section 14.18.1 MUST be
followed.
A received message that does not have a Date header field MUST be assigned one by the recipient if the message
will be cached by that recipient or gatewayed via a protocol which requires a Date. An HTTP implementation
without a clock MUST NOT cache responses without revalidating them on every use. An HTTP cache, especially a
shared cache, SHOULD use a mechanism, such as NTP [28], to synchronize its clock with a reliable external
standard.
Clients SHOULD only send a Date header field in messages that include an entity-body, as in the case of the PUT
and POST requests, and even then it is optional. A client without a clock MUST NOT send a Date header field in a
request.
The HTTP-date sent in a Date header SHOULD NOT represent a date and time subsequent to the generation of the
message. It SHOULD represent the best available approximation of the date and time of message generation, unless
the implementation has no means of generating a reasonably accurate date and time. In theory, the date ought to
represent the moment just before the entity is generated. In practice, the date can be generated at any time during the
message origination without affecting its semantic value.

14.18.1 Clockless Origin Server Operation
Some origin server implementations might not have a clock available. An origin server without a clock MUST NOT
assign Expires or Last-Modified values to a response, unless these values were associated with the resource
by a system or user with a reliable clock. It MAY assign an Expires value that is known, at or before server
configuration time, to be in the past (this allows “pre-expiration” of responses without storing separate Expires
values for each resource).

For all RFC's go to http://www.rfc-editor.org/


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Good luck,
Bas

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E-mail me at: b.vandermeijden@pecoma.nl

[This message has been edited by MeijdenB (edited October 09, 2000).]