Subject: 'Age' for web pages

From: Merin Tresa Willy <[email-masked]>
Date: Fri, 11 Jun 2010 16:55:34 +0000

Is a third dimension - 'age' necessary for webpages? Will its inclusion help
search engines and the like, to retrieve pages containing up-to-date data?
Or is there already any mechanism for retrieving the age of the contents of
dynamic web pages?

- Merin

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From: Nathan <[email-masked]>
Date: Fri, 11 Jun 2010 22:04:48 +0100

> Or is there already any mechanism for retrieving the age of the contents of

Last-Modified ?

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From: Merin Tresa Willy <[email-masked]>
Date: Sat, 12 Jun 2010 05:21:03 +0000

Doesn't the 'last-modified' detail actually work only for the static
pages? For dynamic pages, it gives the then current time, right? So it
might not prove useful when working with pages containing dynamic
content?

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From: Thomas Broyer <[email-masked]>
Date: Sat, 12 Jun 2010 15:22:21 +0200

> might not prove useful when working with pages containing dynamic

It really depends how the pages are generated. It is expected (i.e.
developers should do it, or at least try to, because there are clear
advantages with no drawback at all) that the Last-Modified be based on
the timestamp of data, templates, and "code" that participated in
generating the page (or to make it simpler, it could be only the
data).
There's little chance that a developer not providing a Last-Modified
value along those lines would do it for another response header.

-- 
Thomas Broyer
/tɔ.ma.bʁwa.je/

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From: Nathan <[email-masked]>
Date: Sat, 12 Jun 2010 14:39:12 +0100

> might not prove useful when working with pages containing dynamic

AFAICT that issue is entirely orthogonal to HTTP, more of a design 
choice in how you choose to build applications, and indeed whether you 
create them in an HTTP friendly way.

For instance, you could create applications which produce 'static' 
files, and every time something changes on a page (a new comment is 
added, an edit is made, etc) the application regenerates the page and 
saves it back to a static file - to everybody looking at the system the 
pages are 'dynamic' - there are really no disadvantages to doing it this 
way, you can handle much more traffic, the application has less work to 
do, it's http friendly, your web server (typically) handles all the 
cache control and setting of headers and so forth. Even if the page 
updates every 10 seconds on a high traffic site, it's still a huge benefit.

I suppose a flip on the question may help, if you (or your system) knows 
that the content of a page hasn't changed since X, why would you want to 
keep generating the same content over and over for every request you 
receive?

Best,

Nathan