A computer-implemented method, comprising: replicating states of a state machine in a plurality of state machines over a computer network to create a plurality of replicated state machines; associating the plurality of replicated state machines with a plurality of processes and with a first globally ordered set of agreements that is visible to and maintains a consistency of all replicated state machines; changing the plurality of processes associated with the plurality of replicated state machines at an arbitrary point in the first globally ordered set of agreements by changing a role of at least one of the plurality of processes to one of proposal proposer, proposal acceptor and proposal learner, wherein: a proposal proposer is a process associated with a state machine that is configured to make a proposal for coordinated execution by all the state machines; a proposal acceptor is a process associated with a state machine that is responsive to the proposal made by the proposal proposer, each proposal acceptor being configured to vote on whether the proposal should be agreed by the membership; and a proposal learner is a process associated with a state machine that learns of agreements to proposals that have been agreed by proposal acceptors; and changing states, by at least some of the plurality of processes associated with the plurality of replicated state machines, while the change to the plurality of processes is being made. replicating states of a state machine in a plurality of state machines over a computer network to create a plurality of replicated state machines; associating the plurality of replicated state machines with a plurality of processes and with a first globally ordered set of agreements that is visible to and maintains a consistency of all replicated state machines; changing the plurality of processes associated with the plurality of replicated state machines at an arbitrary point in the first globally ordered set of agreements by changing a role of at least one of the plurality of processes to one of proposal proposer, proposal acceptor and proposal learner, wherein: a proposal proposer is a process associated with a state machine that is configured to make a proposal for coordinated execution by all the state machines; a proposal acceptor is a process associated with a state machine that is responsive to the proposal made by the proposal proposer, each proposal acceptor being configured to vote on whether the proposal should be agreed by the membership; and a proposal learner is a process associated with a state machine that learns of agreements to proposals that have been agreed by proposal acceptors; and a proposal proposer is a process associated with a state machine that is configured to make a proposal for coordinated execution by all the state machines; a proposal acceptor is a process associated with a state machine that is responsive to the proposal made by the proposal proposer, each proposal acceptor being configured to vote on whether the proposal should be agreed by the membership; and a proposal learner is a process associated with a state machine that learns of agreements to proposals that have been agreed by proposal acceptors; and changing states, by at least some of the plurality of processes associated with the plurality of replicated state machines, while the change to the plurality of processes is being made.