Entry point

An entry point is an element of a state machine. An entry point pseudostate is an entry point of a composite state. The entry point changes the "enter-exit-do" sequence.

An entry point is used to join an external transition terminating on the entry point to an internal transition emanating from the entry point.

An entry point belongs to a composite state (not to a region).

Symbol

The symbol of an entry point is an empty circle.

The symbol of an entry point is placed on the border of the containing composite state.

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Symbol in context

Example 1

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The "enter-exit-do" sequence is the following without the entry points:

  1. Transition 'T0'

    1. Transition 'T0' is executed.

    2. State 'Simple state 1' is entered and executed.

  2. Transition 'T1'

    1. State 'Simple state 1' is exited.

    2. Transition 'T1' is executed.

    3. Composite states 'Composite state 1', 'Composite state 2' and 'Composite state 3' are entered.

    1. 'Simple state 2' is entered and executed.

Example 2

The "enter-exit-do" sequence is the following with the entry points:

  1. Transition 'T0'

    1. Transition 'T0' is executed.

    2. State 'Simple state 1' is entered and executed.

  2. Compound transition 'T1', 'T2', 'T3'

    1. Transition 'T1' is executed.

    2. 'Composite state 1' and 'Composite state 2' are entered.

    3. Transition 'T2' is executed.

    4. 'Composite state 3' is entered.

    5. Transition 'T3' is executed.

    6. Simple state 'Simple state 2' is entered and executed.

Characteristics

  • Composite states can contain multiple entry points.

  • An entry point can have multiple incoming and outgoing transitions.

  • When the entry point is contained by an orthogonal composite state, then it is handled as a fork. If it belongs to a non-orthogonal composite state (a composite state with just one region), it is handled as a junction.

  • An entry point can be the source of a transition if it is local or internal, but not external.

  • Entering a composite state via an entry point implies that the entry behavior of the composite state is executed before the action of the transition emanating from the entry point.