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Re: HTTP HEAD requests for Last-Modified info

From: Brandon Long <blong@uiuc.edu>
Date: Wed, 19 Jun 1996 17:25:32 -0500 (CDT)
Message-Id: <199606192225.RAA07422@fiction.isdn.uiuc.edu>
To: mcmanus@nysernet.org
Cc: steve@wco.com, www-talk@w3.org
Last time, Patrick McManus uttered the following other thing:
> 
> 
> In a previous episode...Stephen Zagerman said:
> -> 
> -> Awhile ago, I posted a question re: HTTP requests to obtain Last-Modified
> -> info for web pages. I got answers that indicated the way to get header info
> -> for a theoretical "www.site.com/page.html" would be to open a connection to
> -> www.site.com and issue the following request:
> -> 
> -> HEAD /page.html HTTP/1.0 <CRLF><CRLF>
> -> 
> -> This is good in that it does elicit a set of info, but it's bad in that it
> -> does not ALWAYS return Last-Modified info... which is what I really need.
> -> 
> -> Does anyone know if there is something additional I need to add to the
> -> request to ALWAYS get the Last-Modified info? I've read the spec, but am
> -> not clear on what I need to do.
> -> 
> 
> Last-Modified is an Entity Header.. here's what http/1.0 has to say
> about entity headers:
> 
> Entity-Header fields define optional metainformation about the
> Entity-Body or, if no body is present, about the resource identified
> by the request.
> 
> In short they are optional.. if the server doesn't supply them you
> pretty much have to assume last-modified = currentdate.

In addition, there is not always a Last-Modified header, because
certain documents served are modified each time they are sent,
either because they are parsed by the server or because they are
generated by an external CGI script.

Brandon
-- 
 Brandon Long         "I think, therefore, I am confused." -- RAW
 HTTPd/SDG/NCSA	  I violated the Communications Decency Act ... or will.
 ECE/UIUC	    blong@uiuc.edu   http://www.uiuc.edu/ph/www/blong
 N9WUC		Don't worry, these aren't even my views.
Received on Wednesday, 19 June 1996 18:23:48 GMT

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