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In the event a controller boots up and connects, the SimpleFT module will insert a list of its switches and their roles to the store. And upon controller disconnection events, the module gets the disconnected node's switch list from store and set all the disconnected controller's switches as MASTER.
More Information
One can follow FT Q&A threads (such as this one) in the floodlight-dev@openflowhub.org email list.
One might also find Tulio's initial dev thread useful.
Lastly, the Write to our email list.
The source code is located on GitHub here.