Pseudostates
Pseudostates are special types of states that represent specific behavior during transitions between regular states. Combined with basic transitions, pseudostates can represent complex state changes within a state machine.
Figure 8-17. A simplified SMTP protocol state machine
Table 8-1 shows the types of pseudostates and their symbols. Refer to Figure 8-1 for an example showing how these symbols are used.
Table 8-1. Types of pseudostates
|
Pseudostate name |
Symbol |
Description |
|---|---|---|
|
Initial pseudostate |
|
The starting point of a state machine. The transition from the initial pseudostate to the first full state may be labeled with the event that instantiates the object the state machine is modeling. |
|
Choice |
|
Allows the execution of a state machine to choose between several different states based on guard conditions on the transitions (see Figure 8-17). |
|
Deep history |
|
Used inside a state region, a transition to this pseudostate from outside the region indicates the state machine should resume the last substate it was in within the given region, no matter ... |
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