(9.1+) Distributed Notification Servers

In order for two distributed copies of the Notification Server application to function cooperatively, the site.config file on each Notification Server must provide the following additional information:
  • a list of all nodes supporting the notification server application
  • a list of all other nodes supporting the notification server application (the first list with the current node removed)
The Notification Server uses a "global name" to receive messages from various instances in the solution set. This global name can only be claimed by one application at a time. As a result, only the Notification Server that claimed the name will receive update messages. Any others will wait for the first one to fail before again trying to claim the global name.As a distributed application, Notification Server runs with multiple nodes which work to ensure that exactly one (no more, no less) copy of the application is running. This one running copy of the application will claim the global name. Should the running copy of the distributed application fail (or the node on which it runs fails), the remaining nodes will negotiate a replacement which will claim the now-abandoned global name.Configuring Distributed Notification ServersGiven two servers, host a and host b, the configuration for host a would contain the following lists of nodes:
  • All participating Notification Servers
    • notification_receiver_node@hosta.example.com
    • notification_receiver_node@hostb.example.com
  • All other Notification Servers
    • notification_receiver_node@hostb.example.com
    • [{kernel,[{distributed,[{notification_receiver_impl,100,[{notification_receiver_node@hosta.example.com, notification_receiver_node@hostb.example.com}]}]},{sync_nodes_optional,[notification_receiver_node@hostb.example.com]},{sync_nodes_timeout,500}]},{lager...
The configuration of each server is basically a cut-and-paste copy of the other with only a slight difference. The snyc_nodes_optional entry on one node will always indicate the other node.
  1. Configure the site.config file on each of the two Notification Servers per the above example.
  2. Restart the two Notification Servers.