# Process - LifeCycle (Entity State) (Status)

In a process based model, every entity has a lifecycle (Status) that shows a finite number of distinct states.

The status shows the state of an entity ie:

$$State + Us = Status$$

This process may be implemented/visualized as a finite automata

Sequence:

State:

## Example

### Store Transaction

Non-deterministic Finite automata representing a transaction between a customer, a store and a bank

Every actor needs to make a transition (going from one state to another) when an action is executed. (An action is a label on a arc) (ie it is not possible for the system as a whole to die because the customer automaton has no response to an action)

where:

• loops on certain states are irrelevant action (ie actions that must be ignored - highlighted in yellow) (To save space the labels were combined onto one arc rather than showing several arcs with the same heads and tails but different labels)
• for the store: cancel (each of its seven states has a loop labeled cancel)
• for the bank: pay, ship
• for the customer: ship, redeem and transfer
• a customer initiates the following actions: pay, cancel
• a bank may: redeem, transfer
• a store may: ship

chapter 2.1.2 - page 55 from Hopcroft, Motwani, Ullman, Automata Theory, Languages, and Computation 3rd Edition. pdf

### Communication Protocol

communications protocols (such as protocols for secure exchange of information, …)

### Web Application

Every web application has a lifecycle. Common tasks, such as:

• handling incoming requests,
• decoding parameters,
• modifying and saving state,
• and rendering web pages to the browser,

are all performed during a web application lifecycle.

Some web application frameworks hide the details of the lifecycle from you, whereas others require you to manage them manually.