+
+ /**
+ * Transaction has been open and is being actively worked on.
+ */
+ private static final State OPEN = new State("OPEN");
+
+ /**
+ * Transaction has been sealed by the user, but it has not completed flushing to the backed, yet. This is
+ * a transition state, as we are waiting for the user to initiate commit procedures.
+ *
+ * <p>
+ * Since the reconnect mechanics relies on state replay for transactions, this state needs to be flushed into the
+ * queue to re-create state in successor transaction (which may be based on different messages as locality may have
+ * changed). Hence the transition to {@link #FLUSHED} state needs to be handled in a thread-safe manner.
+ */
+ private static final State SEALED = new State("SEALED");
+
+ /**
+ * Transaction state has been flushed into the queue, i.e. it is visible by the successor and potentially
+ * the backend. At this point the transaction does not hold any state besides successful requests, all other state
+ * is held either in the connection's queue or the successor object.
+ *
+ * <p>
+ * Transition to this state indicates we have all input from the user we need to initiate the correct commit
+ * protocol.
+ */
+ private static final State FLUSHED = new State("FLUSHED");
+
+ /**
+ * Transaction state has been completely resolved, we have received confirmation of the transaction fate from
+ * the backend. The only remaining task left to do is finishing up the state cleanup, which is done via purge
+ * request. We need to hang on to the transaction until that is done, as we have to make sure backend completes
+ * purging its state -- otherwise we could have a leak on the backend.
+ */
+ private static final State DONE = new State("DONE");