Web Notifications in a Load Balanced Environment

Cache invalidation in a load balanced environment has to be configured accordingly based on the hosting environment.

When hosting with Azure web apps, the invalidation across multiple instances is handled automatically. One web notification URL needs to be configured for the web app, and the web app handles forwarding the web notification request to all other web app instances. A portal bus cache invalidation feature detects that the code is executing in an Azure web app, and upon one of the web apps receiving the web notification request from the Dynamics 365 web notification functionality, the receiving website write files to the file system in the App_Data folder to propagate cache invalidation messages to other instances. The other instances of the web app detect file changes to the App_Data folder and invalidate their local cache.

When hosting in non Azure web app environments, a web notification URL needs to be configured for each web server via its own URL that the CRM server can connect to. The portal does not have any ability to forward the web notification requests to the other instances. Although such functionality used to exist in Adxstudio Portals v7, it was removed by Microsoft in this version. In a DMZ scenario, the web notification URL of each website does not have to be externally accessible, however each website URL must be accessible within the internal network by the CRM server.