Action compositions are invoked by means of a helper conductor action. Results of completed action compositions, execution traces, and intermediate states of live action compositions are stored in a Redis instance. A Node.js manager library provides an interface to the Redis instance. One execution of an action composition is a session.
The conductor action schedules the execution of the composed actions, manages the session state, and executes inline functions.
A complete trace of execution starts and ends with a conductor activation and alternates conductor activations with activations of the composed actions. For instance, assuming no error, an invocation of the composition composer.sequence('action1', 'action2', 'action3') eventually produces the trace:
conductoraction1conductoraction2conductoraction3conductorOne execution of an action composition is a session. The session is identified by a session id. The session id is equal to the activation id for the first invocation of the conductor action in the execution trace for the session.
The manager library makes it possible to retrieve session results and execution traces, kill live compositions, and purge sessions from Redis.