using old exp date to refresh cache?

Discussion in 'HTML' started by Developwebsites, Sep 14, 2004.

  1. Just got into an argument with one of them masters of synergism.

    http://www.shorelinewebdesign.com

    from source code:
    <meta http-equiv="Expires" content="Mon, 06 Jan 1990 00:00:01 GMT">
    <meta name="generator" content="Allaire HomeSite 4.0">

    his explanation:
    "The expired tag predated as it is, assures that a new page is sourced from the
    server at each read request rather than from the users local cache."

    what the hell is he talking about?
    He uses the same tag in all of his sites in his portfolio.
    Developwebsites, Sep 14, 2004
    #1
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  2. Developwebsites

    Black Rose Guest

    In fact, he want the user's web browser not cache the page.

    On 14 Sep 2004 02:30:44 GMT, ATSPAM
    (Developwebsites) wrote:

    >Just got into an argument with one of them masters of synergism.
    >
    >http://www.shorelinewebdesign.com
    >
    >from source code:
    ><meta http-equiv="Expires" content="Mon, 06 Jan 1990 00:00:01 GMT">
    ><meta name="generator" content="Allaire HomeSite 4.0">
    >
    >his explanation:
    >"The expired tag predated as it is, assures that a new page is sourced from the
    >server at each read request rather than from the users local cache."
    >
    >what the hell is he talking about?
    >He uses the same tag in all of his sites in his portfolio.
    Black Rose, Sep 14, 2004
    #2
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  3. ATSPAM (Developwebsites) wrote:

    > from source code:
    > <meta http-equiv="Expires" content="Mon, 06 Jan 1990 00:00:01 GMT">


    It is an imitation of an HTTP header.

    > <meta name="generator" content="Allaire HomeSite 4.0">


    Irrelevant. I wouldn't condemn a dog on <meta> tag extracts; HomeSite may
    or may not be guilty of spitting out the header, but the author of the
    page has the ultimate responsibility,

    > his explanation:
    > "The expired tag predated as it is, assures that a new page is
    > sourced from the server at each read request rather than from the
    > users local cache."
    >
    > what the hell is he talking about?


    It's common cargo cult nonsense. Actually somewhat worse than nonsense,
    since the tag sometimes actually prevents caching, thereby causing
    unnecessary network load. But it mainly harms the author's purposes only,
    when visitors leave after realizing they have entered a World Wide Wait
    area of the Web.

    If _you_ want to know what's going on (he obviously doesn't), please
    consult the oft-recommended caching tutorial
    http://www.mnot.net/cache_docs/

    --
    Yucca, http://www.cs.tut.fi/~jkorpela/
    Pages about Web authoring: http://www.cs.tut.fi/~jkorpela/www.html
    Jukka K. Korpela, Sep 14, 2004
    #3
  4. Developwebsites, Sep 14, 2004
    #4
  5. Developwebsites

    Chris Morris Guest

    ATSPAM (Developwebsites) writes:
    > >If _you_ want to know what's going on (he obviously doesn't), please
    > >consult the oft-recommended caching tutorial
    > >http://www.mnot.net/cache_docs/

    >
    > he provided the following as references:
    > www.webdeveloper.com/html/html_metatags_part2.html


    "As of the release of MSIE 4.01..."

    Not that it was good advice when that page was written, but it's even
    worse advice now.

    > http://www.i18nguy.com/markup/metatags.html


    "Note: It may be better to specify cache commands in HTTP than in META
    statements, where they can influence more than the browser, but
    proxies and other intermediaries that may cache information."

    If one was to substitute 'may' for 'almost certainly, unless you are
    attempting something very strange' then that would be about right.

    Since lots of the caching on the web goes on in proxies, that's as
    good a reason as any not to use meta for it, along with the fact that
    anything in meta will get overridden by the real headers which most
    servers send by default anyway.

    Caching on the web generally doesn't last longer than a few days (as
    caches have limited disk space and browsers recheck anyway after a
    while) so it's not a problem for most pages. Rapidly updated pages can
    benefit from setting *caching headers through HTTP* but far less (if
    at all) from <meta>.

    Imagine the likely situation:
    Your server <------> ISP Caching Proxy <------> Browser

    The browser notices that the page is expired according to its <meta>
    information (assuming it's buggy enough to use that in preference to
    the real HTTP headers) and asks for it again to see if it's updated.

    The proxy notices it has one in its cache, and *it* only knows about
    the HTTP headers. So since it's still up-to-date, it sends it back to
    the browser.

    There are ways around this with real HTTP headers for pages that
    *actually* need cache avoidance, of course, but the vast majority of
    pages don't.

    --
    Chris
    Chris Morris, Sep 14, 2004
    #5
  6. Developwebsites

    Barefoot Kid Guest

    Barefoot Kid, Sep 14, 2004
    #6
  7. >that sux
    >--
    >Hung Diep


    what does?

    PS: are you really hung?
    Developwebsites, Sep 15, 2004
    #7
  8. Developwebsites

    WebcastMaker Guest

    WebcastMaker, Sep 15, 2004
    #8
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