CH6 systems

Actor

- An external entity with a specific role. In a use case model, these are used to model interaction with the system. -Example: would represent a customer in a simple use case diagram for a credit card transaction in a sales system. Other examples of this would be the post office in a use case diagram for changing a customer's mailing address, or patient making a medical appointment.

Attribute

- characteristics that describe the object. -Examples: a person has these such as hair color, eye color, and skin color.

Method

- defines specific tasks that an object can perform. Just as objects are similar to nouns and attributes are similar to adjectives, these resemble verbs that describe what and how an object does something. -Example: your computer performs a method called CREATE SPACE when you press the space bar, it can TYPE IN ALL CAPS when you press the caps lock button and type, and lastly BACK UP A SPACE when pressing the backspace key.

Object-Oriented analysis

-It is a popular approach that views the system in terms of objects that combine data and processes. The end product is an object model, which represents the information system -Advantages: Integrates easily with object-oriented programming languages. Code is modular and reusable, which can reduce cost. Easy to maintain and expand.

Object

-a representation of a real person, place, event, or transaction. -Examples: when a patient makes an appointment to see a doctor, it is the patient, the doctor, and the appointment itself

Encapsulation

-means that all data and methods are self-contained. By limiting access to internal processes, an object prevents its internal code from being altered by another object or process. -With the help of this, objects can be recreated while the code or processes can be reused.

Polymorphism

-the concept that a message can have different meanings to different objects. -Example: the message "good-night" signals to a parent to read a bed time story to the child, however the same message to a dog tells the dog to sleep. The "good-night" message to the child signifies that it should get ready for bed.

Black Box

Process symbol, where the inputs, outputs, and general functions of the process are known but underlying details and logic of the process are hidden. -Example: A router, we can see they carry data in and out of the router, but the internal operations are not revealed.

Class

a group of similar objects

Superclass

a more general category into which a class falls.

Use Case Diagram

is a visual summary of several related use cases within a system or sub-system. For example, consider a small auto-service department; the service department involves customers, service writers who prepare work orders and invoices, and mechanics who perform the work.

Subclass

more specific categories within a class

Use case

represents the steps in a specific business function or process in UML (Unified Modelling Language). An external entity, called an actor, initiates this by requesting the system to perform a function or process. For example, in a medical office system, a patient (Actor) can make an appointment (this thing)