Each Sync Group needs a Leader player. This is the player in charge of broadcasting orders, while multiple Follower players listen and react to these broadcasts.
The process of determining the Leader player is automatic: administrators and digital schedulers do not need to identify which player is the Leader and which are the followers. In case of machine or network failures, the Leader/Follower configuration of the players will adjust itself to keep providing proper playback.
At start up, if a sync group is enabled, the player will go in standby mode for up to ten seconds. During that time, if it hears from a Leader Player on the same Sync Group, it’ll switch to Follower Mode and start playing. If ten seconds go by without hearing anything, the player assumes it is the first of that group to come online and becomes the Leader.
Every five seconds, the Leader broadcasts a heartbeat to signal its existence.
If a follower goes more than ten seconds without hearing from its Leader, it will switch to being a Leader itself and start broadcasting both orders and a heartbeat.
If two Leaders meet on the same Sync Group (for example, the network was down, both became Leaders, and now the network is back on), the Leaders will renegotiate for supremacy. Whenever a Player becomes a Leader, it is given a random ID. This ID is part of the heartbeat sent every five seconds. A leader that receives a heartbeat with an ID greater than its own will switch down to Follower mode.
An Example Using Three Players
Here is an example using three players to illustrate what happens in case of a network failure.
- Player One is currently Leader (with ID 1). Players Two and Three are followers to it.
- The network goes down. Two and Three get promoted to Leader, with ID 2 and 3 respectively.
- When the network is restored between One and Two: they clash. Player Two wins, so Player One becomes follower to Player Two.
- When the network is restored between this new group and isolated Player Three: Two and Three renegotiate. Three wins. Two becomes a follower to Three. One also begins following three.