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varshsr
varshsr
Level 5
January 6, 2017

Multi site/domain dispatcher docroot vs common docroot

  • January 6, 2017
  • 1 reply
  • 6768 views

Hi,

We tried setting up an multi site - multi domain (using single dispatcher/apache) using multiple virtualhost and farm entries as in docs and have a separate farm entry for dispatcher flush -https://docs.adobe.com/docs/en/dispatcher/disp-domains.html

the docroot is of each site in httpd - virtual host and dispatcher farm is /usr/lib/apache/httpd-2.4.3/htdocs/sitea ,/usr/lib/apache/httpd-2.4.3/htdocs/siteb

dispatcher starts with these configs

farms[farm_sitea].cache.docroot = /usr/lib/apache/httpd-2.4.3/htdocs/sitea

farms[farm_siteb].cache.docroot = /usr/lib/apache/httpd-2.4.3/htdocs/siteb

farms[farm_flush].cache.docroot = /usr/lib/apache/httpd-2.4.3/htdocs

and we see these getting cached under the respective sites docroot 

sitea - /sitea/content/sitea , /sitea/content/dam,/sitea/etc

siteb- /siteb/content/siteb , /siteb/content/dam, /siteb/etc

As an observation these are my questions and all the sites are using MSM and site branding is the same

1) How can we prevent repeated cache of /conten/dam and /etc repeating under each site docroot avoiding (large IO space)  being used?

2) What will be pro and cons of keeping the common docroot as parent level folder instead of specific site level folders

3) What is advantage of keeping site specific docroot as in https://docs.adobe.com/docs/en/dispatcher/disp-domains.html

We tried (2) to have a common docroot in httpd - virtual host and dispatcher farm refer to parent folder - /usr/lib/apache/httpd-2.4.3/htdocs/ 

and the dispatcher starts with these configs

farms[farm_sitea].cache.docroot = /usr/lib/apache/httpd-2.4.3/htdocs

farms[farm_siteb].cache.docroot = /usr/lib/apache/httpd-2.4.3/htdocs

farms[farm_flush].cache.docroot = /usr/lib/apache/httpd-2.4.3/htdocs

We tried (2) and it is caching the /content/sitea and /content/siteb and /etc and /content/dam are not repeated as dispatcher  cache mirrors the content structure of the publish content

Is there any problem with (2) using same parent docroot for all the sites . We also plan to enable higher statsfilelevel so that cache invalidation happens to respective sites

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1 reply

joerghoh
Adobe Employee
joerghohAdobe Employee
Adobe Employee
January 6, 2017

Hi,

To 1) Having /etc for each site shouldn't be a huge overhead, isn't it? I would rather think that /content/dam has larger files and is driving disk space consumption. Do you have shared DAM content which is used on both SiteA and SiteB? I would rather think, that the invalidation topic is harder to solve (ok, if you use a custom invalidation script you can implement all the logic easily).

To the other questions: I don't get what you mean with "common docroot as parent level folder" and "common docroot" (as mentioned in question 2 and 3). Can you give an example for it?

In the multi-site setup you have to pay special attention to the aspect of dispatcher cache invalidation, as in the simplest approach the invalidation doesn't work.

Jörg

varshsr
varshsrAuthor
Level 5
January 6, 2017

Hi Jörg,

AEM is multi tenant for site content (SiteA and SiteB) and DAM  (SiteA and SiteB) . we have node separation as here

  • /content/SiteA
  • /content/dam/SiteA

 

  • /content/SiteB
  • /content/dam/SiteB

We have a dispatcher flush farm as in the aem docs

for (2) and (3) as mentioned in my above post we have a common docroot as /usr/lib/apache/httpd-2.4.3/htdocs for both SiteA and SiteA instead of seperate /usr/lib/apache/httpd-2.4.3/htdocs/SiteA and /usr/lib/apache/httpd-2.4.3/htdocs/SiteB docroot 

and hope to control the invalidation via a decent higher statsfilelevel

a) Given the above what is advantage to have separate SiteA and SiteB docroot  ?

b) What is the issue if there no separate SiteA and SiteB docroot  and only have common docroot /usr/lib/apache/httpd-2.4.3/htdocs ?

joerghoh
Adobe Employee
joerghohAdobe Employee
Adobe Employee
January 6, 2017

Hi,

if you don't use shortened URLs (siteA.com/home.html), but "long" URLS (siteA.com/content/siteA/pages/home.html), then a single docroot is OK, because the dispatcher cache directory structure can directly mimic the structure in the Sling resource tree.

But when you have shortened your URLs, the topic gets more complicated, I talked once about in a "Ask the exports" session [1]. If you visualize the sites and the resources and try to map it to a filesystem structure, it's not identical to the Sling resource tree anymore. And if it's not identical, the default dispatcher invalidation mechanics do not work anymore. Then you have to fix this by writing custom invalidation scripts, which know about your content structure and can do the invalidation based on these.

So to answer your questions:

a) it allows you to make each site cacheable on dispatcher side (and each site having shortened URLs)

b) you either don't use shortened URLs or http://siteA.com/home.html might return the same file as http://siteB.com/home.html

HTH,

Jörg

 

[1] https://communities.adobeconnect.com/p8h87dumxgv/

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