Null app

Progressing the channel outcome via unanimous consensus allows some of the more advanced features of Nitro protocol, such as topping-up the funds in a ledger channel.

An elegant approach to reaching consensus is to exploit the abilitiy for participants to support a state by countersigning it.

One can imagine a ficticious "null" app.

function validTransition(s1, s2) {
return false

This is only ficticious because, in the current implementation of ForceMove.sol, this is equivalent to using appDefinition = address(0) (or any address that has no rules). So no contract need actually be deployed.

If outcome o1 is supported, and Alice wants to propose outcome o2, then she can simply sign a state with that outcome and broadcast it.

  • If everyone signs it, we've reached consensus.
  • If someone doesn't sign it, then forceMove(s1) closes the channel with s1, since there are no valid transitions.

This is more scalable than an explicit consensus app: In a channel with n participants, ForceMove guarantees that any participant can close an app with valid transitions in O(n) time. Since there are no valid moves in the null app, anyone can close the null app in O(1) time.

Last updated on by George C. Knee