title Healthy Replication 

participant Client1 
participant Instance1
participant Instance2
participant Client2

state over Client1, Client2, Instance1, Instance2: W0
state over Client1 : W0 -> W1
Client1 -> +Instance1: Push W1
Instance1 -> Client1: Ack W1
state over Instance1 : W0 -> W1
Instance1->-Instance2: Replicate W1
state over Instance2, Client1, Instance1: W0 -> W1

state over Instance1 : Crash

state over Client2 : W0 -> W2
Client2 -> +Instance2: Push W2
Instance2 -> Client2: Missing W1
Client2 -> Instance2: Pull W1
state over Client2 : W0 -> W1 -> W2
Client2 -> Instance2: Push W2

state over Instance2 : W0 -> W1 -> W2

state over Instance1:  Restart

Instance2->Instance1: Replicate W2

state over Instance2, Client2, Instance1: W0 -> W1 -> W2