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Purpose

<aside> 💡 To describe and analyze the different possible states of an entity within a system, how that entity changes from one state to another, and what can happen to the entity when it is in each state.

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<aside> 🗨️ A state model is sometimes called a state transition model

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Description

<aside> ❓ An entity is an object or concept within a system

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<aside> 💡 About entities

• They may be used in several processes
• The life cycle of every entity has a beginning and an end </aside>

<aside> ❓ A state in a state model is a formal representation of a status

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<aside> 💡 A state helps to get a precise and consistent understanding of an entity that has complex behavior and complex rules about that behavior

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<aside> 💡 What a state model describes

• A set of possible states for an entity
• The sequence of states that the entity can be in
• How an entity changes from one state to another
• The events and conditions that cause the entity to change states
• The actions that can or must be performed by the entity in each state as it moves through its life cycle </aside>

<aside> 💡 A state model shows what happens to one entity across all the processes that affect it or use it

While a process model can show all of the entities that are used in or affected by that process, a state model shows a complementary view: what happens to one entity across all the processes that affect it or use it.

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Elements

State

<aside> 💡 An entity has a finite number of states during its life cycle

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<aside> 💡 An entity can be in more than one state at a time

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<aside> 💡 Each state is described with a name and the activities that could be performed while in that state

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<aside> 💡 There may be rules about which activities must or can be performed and which events it can respond to or trigger

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<aside> 💡 A complex state can be decomposed into sub-states

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State Transition