The document discusses storing a sequence of events instead of state in a system. It proposes an "event store" approach where commands are logged as events and the current state can be reconstructed by replaying the sequence of events from the beginning. This allows an audit log to be maintained and for multiple "read models" to be generated from the event stream to serve different queries or views of the data.
24. Store the sequence of events that led up to the
current state, instead of the current state.
25. Command State
Put up a new card
“Reset Password”
Card
“Reset Password”
“Todo”
Move card to doing
Card
“Reset Password”
“Doing”
… …
26. Command Event State
Put up a new card
“Reset Password”
Card put up
“Reset Password”
“Todo”
Card
“Reset Password”
“Todo”
Move card to doing
Moved card to section
“Doing”
Card
“Reset Password”
“Doing”
… … …