1  # Alice and Bob: batch data sync
 2  msc {
 3    hscale="2", wordwraparcs=on;
 4  
 5    alice [label="Alice"],
 6    bob [label="Bob"];
 7  
 8    --- [label="batch data sync"];
 9    alice => alice [label="add messages to payload state"];
10    alice >> bob [label="send payload with messages"];
11  
12    bob => bob [label="add acks to payload state"];
13    bob >> alice [label="send payload with acks"];
14  }