Dispatcher is not forwarding Last-Modified header when caching is disabled | Community
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schwabix
schwabix
New Participant
Nov 22, 2017 9:29 AM UTC
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Dispatcher is not forwarding Last-Modified header when caching is disabled

In our setup Dispatcher is not used for caching - this is done by Varnish that sits in front of Dispatcher.

For cache invalidation we need the Last-Modified header that is returned by AEM Publisher, but Dispatcher is removing the header line.

Is there a way to instruct Dispatcher to just forward the Last-Modifed header that is returned by AEM Publisher?

thx Michael

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    joerghoh
    joerghohAccepted solution
    Employee
    Nov 23, 2017 7:52 AM UTC

    When the file is deliverd out of the dispatcher cache without the header-caching being active, the last-modification time is taken from the mtime of the cache file.

    To get the mtime of the AEM publish instance, enable dispatcher header caching; yesterday there was a AEM Gems session on dispatcher where it was mentioned. I hope that Dispatcher - New features and best practices  will be updated today.

    Jörg

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    5 replies

    15473203
    15473203
    Level 2
    Feb 17, 2018 6:32 AM UTC

    I'm having a similar issue. I'm using Dispatcher 4.2.3 and caching the response headers, but when a cached dam asset is returned, the cached header value is not used, the last modified time of the actual cached file is still used. Any ideas? /clientheaders allows all headers.

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    schwabix
    schwabixAuthor
    New Participant
    Nov 23, 2017 3:46 PM UTC

    Thank you for your answers, but our issue was with uncached urls, so activating header caching was not feasible.

    This was actually a known issue with Dispatcher 4.2.2 - Daycare support just send me info on this.

    DISP-676 - Dispatcher removes Last-Modified header for uncached requests

    They also provided a pre-release version of Dispatcher 4.2.3 that solves our issue.

    Thx again for warm welcome on this forum

    Best regards

    Michael

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      joerghoh
      joerghohAccepted solution
      Employee
      Nov 23, 2017 7:52 AM UTC

      When the file is deliverd out of the dispatcher cache without the header-caching being active, the last-modification time is taken from the mtime of the cache file.

      To get the mtime of the AEM publish instance, enable dispatcher header caching; yesterday there was a AEM Gems session on dispatcher where it was mentioned. I hope that Dispatcher - New features and best practices  will be updated today.

      Jörg

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      kautuk_sahni
      kautuk_sahni
      Employee
      Nov 23, 2017 7:48 AM UTC

      Jörg Hoh​ Can you please look at this one?

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      Kautuk Sahni
      smacdonald2008
      smacdonald2008
      Level 10
      Nov 23, 2017 12:08 AM UTC

      Make sure that Last-Modified header is allowed by the /clientheaders section of the dispatcher farm.

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