Event-related constructs are described below.

Event

Events are raised and handled by state machines in the collaborative state machine and are matched based on their name.

Events fall into three categories: internal, external, and global.

Internal events are exclusively handled by the state machine that raised them and not seen by other state machines. External events are received by state machines that have subscribed to the events raised by other state machines. This linkage introduces decentralization, allowing state machines to dynamically subscribe to events of interest raised by other state machines. Global events are not tied to any specific source state machine and are universally seen by every state machine. This universal handling establishes a global communication channel within the application.

A raised event may contain data transmitted to the receiver; an expression is used to gather the data to include with the event.

When a state machine processes the received event and takes a transition, the event data is assigned to the current state's local data using the name and value of each provided context variable.

This overrides existing variables or creates new variables if they don't exist within the dynamic extent.

new Event {
    name = "e1"
    channel = "global"
    data = new Data{...}
}

The following keywords can/must be provided:

name

The name keyword specifies the event name. Events are matched according to their name. Event names may be re-used.

channel

The channel keyword specifies the event channel of the raised event.

The event channel is a string enumeration and must be one of the following:

• internal
• external
• global

data

The data keyword specifies the event data contained within the event.

Event data will be assigned to the local data of the state machine's current state which processes the event and takes a transition.

Event data can be accessed inside expressions by their variable names, with event data variables prefixed by a $ to indicate their special status compared to context variables. The lifetime of event data is bound to the transition following the event and any subsequently executed actions.