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KannanCh2
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February 13, 2024
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query in dispatcher cache

  • February 13, 2024
  • 1 reply
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Hi All

I have a query in dispatcher cache 

When the dispatcher receives a request, it performs a content check and comparison using the stat file mechanism. If the dispatcher detects outdated content, it retrieves the latest version from the publish env and serves it to the incoming request.

When a page is published, the latest change will be reflected in the Dispatcher as well in AEM as a cloud ?.

The latest content will be pushed from Author->Publish->Dispatcher. ?

 

How the cache works in background in AEM as a cloud ? I would greatly appreciate it if someone could kindly explain these details.

 

Thanks 

KannaCh2

 

 

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Best answer by AlbinIs1

When an author activates or publishes new or modified content, it is moved to the publishers. Simultaneously, a cache invalidation notification is sent to the dispatcher. We follow a multiple cache invalidation approach, which includes methods like .stat file-based and TTL-based invalidation. At this stage, if the newly activated content already exists, it is deleted from the Dispatcher cache.

The next time a user requests this page, the Dispatcher cache will technically not have a cached version of this specific page. Consequently, the Dispatcher will request the page from the publisher. If the publisher responds successfully, the Dispatcher will cache a local copy of the page before sending it to the user so that the next request will be directly served by dispatcher from cache. The behavior of what can be cached is controlled by various configurations.

Regards

Albin

https://www.albinsblog.com

Albin Issac – Medium

1 reply

Raja_Reddy
Raja_Reddy
New Participant
February 13, 2024

Hi @kannanch2 

  1. Author Environment: Content authors create and modify content in the author environment.

  2. Publish Environment: When content authors publish a page, the changes are replicated from the author environment to the publish environment. The publish environment serves as the source of truth for the published content.

  3. Dispatcher Cache: The dispatcher cache is a caching layer that sits in front of the publish environment. When a request is made to the dispatcher, it checks its cache for the requested content. If the content is not found or if it is outdated, the dispatcher retrieves the latest version from the publish environment and serves it to the request.

So, when a page is published, the latest changes are pushed from the author environment to the publish environment. The dispatcher cache, being in front of the publish environment, will also receive the latest content and serve it to subsequent requests.
https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/implementing/content-delivery/caching.html#:~:text=The%20AEM%20layer%20sets%20cache,cache%20headers%20are%20left%20untouched. 
https://experienceleague.adobe.com/docs/experience-cloud-kcs/kbarticles/KA-17461.html?lang=en 

    K
    KannanCh2Author
    New Participant
    February 13, 2024

    Hi @raja_reddy 

     

    Thanks for your reply ..I m aware of that "When a request is made to the dispatcher, it checks its cache for the requested content. If the content is not found or if it is outdated, the dispatcher retrieves the latest version from the publish environment and serves it to the request."

     

    But my doubt is  , might be my understanding is wrong, just want to clarify that ,

    When a page is published, the latest change will be reflected in the Dispatcher as well in AEM as a cloud ?.The latest content will be pushed from Author->Publish->Dispatcher. on the same time without made any request to dispatcher ?

      Raja_Reddy
      Raja_Reddy
      New Participant
      February 13, 2024

      Hi @kannanch2 

      Yes, you are correct. When a page is published in AEM, the latest changes will be reflected in both the Publish environment and the Dispatcher. The content is pushed from the Author environment to the Publish environment, and then it is replicated to the Dispatcher. This ensures that the latest version of the content is available to users without the need to make a request to the Dispatcher.

      regarding your question:

      When a page is published, the latest change will be reflected in the Dispatcher as well in AEM as a cloud? The latest content will be pushed from Author->Publish->Dispatcher. on the same time without made any request to dispatcher?

      The Dispatcher doesn't automatically receive content pushed from the author environment. Instead, it serves content from the publish environment. When content is published from the author environment to the publish environment, it becomes available for the Dispatcher to serve to end-users. The Dispatcher doesn't actively pull content from the author environment; it serves content from the publish environment when requests are made by end-users.

      So, to summarize, when content is published in AEM:

      1. The latest content becomes available in the publish environment.
      2. The Dispatcher serves this latest content to end-users upon request.
      3. There's no direct push of content from the author environment to the Dispatcher; content is served from the publish environment by the Dispatcher.
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