어쨌건간에 흘러가는 者

본 포스트는 개인 스터디 용으로 작성된 Ian Sommerville의 Software Engineering, 8/E의 요약본입니다.

1. Object-oriented development
- Object-oriented analysis, design and programming are related but distincted.
- OOA is concerned with developing an object model of the application domain.
- OOD is cencerned with developing an object-oriented system model to implement requirements
- OOP is cencerned with realising an OOD using an OO programming language

2. Characteristics of OOD
- Objects are abstractions of real-world or system entities and manage themselves
- indenpendent with each other, encapsulate state, communicate by message passing

3. Objects and object classes
- Objects are entities in a S/W system which represent instances of real-world and system entities
- Object classes are templates for objects

4. UML
- An integration of notations which describe object oriented analysis and designs
- De facto standard for object oriented modelling

5. Object communication
- Conceptually, objects communicate by message passing
- In practice, messages are often implemented by procedure calls(procedure name and parameter list)

6. Generalisation and inheritance
- Classes may be arranged in a class hierarchy where one class (a super-class) is a generalisation of one or more other classes (sub-classes)
- A sub-class inherits the attributes and operations from its super class and may add new methods or atributes of its own
- Advantages : Inheritance classify entities, make reuse mechanism at both the design & the programming level, and provide organisational knowledge about domains and systems.

7. An object-oriented design process : Structured design processes
- involve developing a number of differnet system models
- require a lot of effort for development and maintenance of these models
- For small systems, this may not be cost-effiective
- However, for large systems developed by different groups design models are an essential communication mechanism

8. Process stages
1) Define system context and model of system use : A static model that describes other systems in the environment, a dynamic model that describes how the system interacts with its environment(Use Case used)
2) Design the system architecture : e.g. layered architecture(several layered sub-system composition). There should normally be no more than 7 entities in an architectural model
3) Identify the principal system objects:
  - Grammatical approach (based on natural lagnuage)
  - idenfitying concrete things in the application domain
  - Behavioural approach (what participates in what behaviour)
  - Scenario-based analysis (objects in scenario)
4) Develop design models
  - Static model : show relationships between object classes
  - Dynamic model : show relationships between objects
  - e.g. sub-system model, sequence model, state machine model(statechart), use-case models, aggregation, generalisation model, etc.
5) Object interface specification
  - Object interfaces have to be specified so that the object and other components can be designed in parallel
  - UML uses class diagram

본 포스트는 개인 스터디 용으로 작성된 Ian Sommerville의 Software Engineering, 8/E의 요약본입니다.

Chapter 8.

1. System modelling
- being performed for understandability & communication with customers.
- reflect several different perspectives.
- System models are generated via requirements elicitation & analysis(Requirements engineering process step 2(/4) )

2. System model type
- Context models : defines boundary & environment. e.g. architectural models.
- Behavioral models : Data processing models, State machine models(stimulus/response models)
- Data models : Semantic data models
- Object models

3. Behavioral models
1) Data processing models
    - Data Flow Diagram(DFD) is used.
2) State machine models
    - being described by stimulus and response event
    - this it meets real-time system's requirements
    - Statecharts! It allows model decomposition

4. Semantic data models
1) describe the logical structure of data
2) widely used in DB design
3) data dictionary : lists of all of the names used in the system models

5. Object models
1) natural ways of reflection the real-world entities
2) model types (UML used frequently)
    - Inheritance models : class diagram(hierarchy)
    - Aggregation models : class diagram(aggregation)
    - Interaction models : sequence diagram

6. Structured methods
1) defiles rules and guidelines where the system models apply to and contains the system models : System modelling framework
2) do not model non-functional system requirements

7. CASE workbenches
1) set of tools that support S/W process activities(e.g. analysis, design, testing)
2) support system modelling during requirements engineering and system design

Use case model

정의
    - 유스케이스(Use Case): 시스템이 사용자에 의해서 어떠한 형태로 사용되는지를 기술하는 UML의 표준 표기법
    - Use case model: 유스케이스의 구성 요소인 액터(Actor)와 유스케이스, 그리고 이들간의 관계를 나타낸 다이어그램을 통해 시스템의 기능적 요구사항(functional requirements)을 기술한 모형

유스케이스의 특징
- 유스케이스는 크게 두 가지로 구성됨: 유스케이스 모델과 유스케이스 기술서
1. 유스케이스 모델(Use case model) : 표준에 의해 구성요소가 정의됨(액터, 유스케이스, 액터와 유스케이스 간의 관계).
2. 유스케이스 기술서(Use case description) : 문서의 형태로 존재. 표준으로 정의되어 있지 않으며 방법론 등에서 각기 달리 기술서의 형태가 어떠하여야 하는지를 제시하고 있음.

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