Dispatcher Configurations for AEM Screens

Dispatcher is Adobe Experience Manager’s caching and/or load balancing tool.

The following page provides the guidelines for configuring dispatcher for an AEM Screens project.

Before you configure dispatcher for an AEM Screens project, you must have prior knowledge of Dispatcher.
Refer to Configuring Dispatcher for more details.

Configuring Dispatcher for Manifest Version v2

AEM Screens players or devices use authenticated session to access the resources in the publish instances as well. So, when you have multiple publish instances, the requests should always go to the same publish instance so that the authenticated session is valid for all the requests coming from the AEM Screens players/devices.

Follow the steps below to configure dispatcher for an AEM Screens project.

Enabling Sticky Sessions

If you want to use multiple publish instances fronted by single dispatcher, you will have to update the dispatcher.any file to enable stickiness

/stickyConnections {
  /paths
  {
    "/"
  }
 }

If you have one publish instance fronted by one dispatcher, enabling the stickiness at the dispatcher will not help as the load balancer may send each request to dispatcher. In this case, click on Enable in Stickiness field to enable it at your load balancer level, as shown in the figure below:

For example, if you are using AWS ALB, refer to Target groups for your Application Load Balancers for enabling stickiness at the ALB level. Enable the stickiness for 1 day.

Step 1: Configuring Client Headers

Add the following to /clientheaderssection:

X-Requested-With

X-SET-HEARTBEAT

X-REQUEST-COMMAND

Step 2: Configuring Screens Filters

To configure Screens filters, add the following to /filter.

## AEM Screens Filters
## # Login, Ping and Device Configurations
/0200 { /type "allow" /method "POST" /url "/libs/granite/core/content/login.validate/j_security_check" }
/0201 { /type "allow" /method "GET" /url "/libs/granite/csrf/token.json" }
/0202 { /type "allow" /method "GET" /url "/content/screens/svc.json" }
/0203 { /type "allow" /method "GET" /url "/content/screens/svc.ping.json" }
/0204 { /type "allow" /method "GET" /url "/content/screens/svc.config.json" }
## # Device Dashboard Configurations
/0210 { /type "allow" /method '(GET|POST)' /url "/home/users/screens/*/devices/*/profile_screens.preferences.json" }
/0211 { /type "allow" /method "POST" /url "/home/users/screens/*/devices/*/profile_screens.logs.json" }
/0212 { /type "allow" /method "POST" /url "/home/users/screens/*/devices/*/profile_screens.statusinfo.json" }
/0213 { /type "allow" /method "POST" /url "/home/users/screens/*/devices/*/profile_screens.screenshot.json" }
## # Content Configurations
/0220 { /type "allow" /method '(GET|HEAD)' /url "/content/screens/*" }
/0221 { /type "allow" /method '(GET|HEAD)' /url "/content/screens/*/jcr:content/*/offline-config_*.zip" }
/0222 { /type "allow" /method '(GET|HEAD)' /url '/var/contentsync/content/screens/.+/jcr:content/.+/offline-config_.*\.[0-9]+\.zip' }

Step 3: Disabling Dispatcher Cache

Disable dispatcher caching for /content/screens path.

Screens players uses authenticated session, so the dispatcher does not cache any of the screens players requests for channels/assets.

To enable the cache for the assets so that the assets are served from dispatcher cache, you must:

• Add /allowAuthorization 1 in /cache section
• Add the below rules to /rules section of /cache

/0000
    {
        /glob "*"
        /type "allow"
    }

/0001
    {
        # Disable Dispatcher Cache for Screens channels
        /glob "/content/screens/*.html"
        /type "deny"
    }

/0002
    {
    # Disable Dispatcher Cache for Screens offline manifests
    /glob "/content/screens/*.json"
    /type "deny"
    }

/0003
    { # Disable Dispatcher Cache for Screens devices json
    /glob "/home/users/screens/*.json"
    /type "deny"
    }

Configuring Dispatcher for Manifest Version v3

Please make sure to allow these filters and cache rules in dispatchers fronting the publish instances for functioning of Screens.

Pre-requisites for Manifest Version v3

Please ensure that you follow these two prerequisites before configuring Dispatcher (manifest version v3) for AEM Screens:

• Make sure that you are using v3 manifests. Navigate to https://<server:port>/system/console/configMgr/com.adobe.cq.screens.offlinecontent.impl.ContentSyncCacheFeatureFlag and ensure that Enable ContentSync Cache is unchecked.

• Make sure dispatcher flush agent is configured at /etc/replication/agents.publish/dispatcher1useast1Agent in publish instance.

  

  

Filters

## AEM Screens Filters
## # Login, Ping and Device Configurations
/0200 { /type "allow" /method "POST" /url "/libs/granite/core/content/login.validate/j_security_check" }
/0201 { /type "allow" /method "GET" /url "/libs/granite/csrf/token.json" }
/0202 { /type "allow" /method "GET" /url "/content/screens/svc.json" }
/0203 { /type "allow" /method "GET" /url "/content/screens/svc.ping.json" }
/0204 { /type "allow" /method "GET" /url "/content/screens/svc.config.json" }

## # Device Dashboard Configurations
/0210 { /type "allow" /method '(GET|POST)' /url "/home/users/screens/*/devices/*/profile_screens.preferences.json" }
/0211 { /type "allow" /method "POST" /url "/home/users/screens/*/devices/*/profile_screens.logs.json" }
/0212 { /type "allow" /method "POST" /url "/home/users/screens/*/devices/*/profile_screens.statusinfo.json" }
/0213 { /type "allow" /method "POST" /url "/home/users/screens/*/devices/*/profile_screens.screenshot.json" }

## # Content Configurations
/0220 { /type "allow" /method '(GET|HEAD)' /url "/content/screens/*" }
#/0221 { /type "allow" /method '(GET|HEAD)' /url "/content/experience-fragments/*" } ## uncomment this, if you're using experience-fragments
/0222 { /type "allow" /extension '(css|eot|gif|ico|jpeg|jpg|js|gif|pdf|png|svg|swf|ttf|woff|woff2|html|mp4|mov|m4v)' /path "/content/dam/*" } ## add any other formats required for your project here

## # Enable clientlibs proxy servlet
/0230 { /type "allow" /method "GET" /url "/etc.clientlibs/*" }

Cache Rules

• Add /allowAuthorized "1" to /cache section in publish_farm.any.

• All the Screens players will use authenticated session to connect to AEM (author/publish). Out-of-the-box Dispatcher does not cache these urls, so we should enable those.

• Add statfileslevel "10" to /cache section in publish_farm.any
  This will support caching up to 10 levels from the cache docroot and invalidate accordingly when content is published rather than invalidating everything. Feel free to change this level based on how deep your content structure is

• Add the following to /invalidate section in publish_farm.any

  /0003 {
      /glob "*.json"
      /type "allow"
  }
  

• Add the following rules to /rules section in /cache in publish_farm.any or in a file that is included from publish_farm.any:

  ## Don't cache CSRF login tokens
  /0001
      {
      /glob "/libs/granite/csrf/token.json"
      /type "deny"
      }
  ## Allow Dispatcher Cache for Screens channels
  /0002
      {
          /glob "/content/screens/*.html"
          /type "allow"
      }
  ## Allow Dispatcher Cache for Screens offline manifests
  /0003
      {
      /glob "/content/screens/*.manifest.json"
      /type "allow"
      }
  ## Allow Dispatcher Cache for Assets
  /0004
      {
  
      /glob "/content/dam/*"
      /type "allow"
      }
  ## Disable Dispatcher Cache for Screens devices json
  /0005
      {
      /glob "/home/users/screens/*.json"
      /type "deny"
      }
  ## Disable Dispatcher Cache for Screens svc json
  /0006
      {
      /glob "/content/screens/svc.json"
      /type "deny"
      }
  

Add invalidation rule for segments.js

If you are using targeted campaigns with AEM Screens, then the segments.js file served by the dispatcher needs to be invalidated, as you add and publish new segments on AEM. Without this invalidation rule, new targeted campaigns will not work on the Screens player (it will show the default content instead).

• Add an invalidation rule to /etc/httpd/conf.dispatcher.d/available_farms/999_ams_publish_farm.any. Here is the rule to add:

    /invalidate {
                        .
                        .
                        /0004 {
                               /glob "conf/<project-name>/settings/wcm/.js"
                               /type "allow"
                        }
                }

• This rule ensures the segments.js file is invalidated and latest is fetched when modified.

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