單元 4 ：數位家庭軟體開發與再利用 chapter 4-3 – mapping models to code

Software Engineering for Digital Home

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單元 4：數位家庭軟體開發與再利用Chapter 4-3 – Mapping Models to Code


Software lift cycle

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Software life cycle

Development cycle

Design Implementation Testing

Maintenance

RequirementsEngineering

System design

Object design

Analysis Model(Class diagrams)

RequirementsElicitation

Analysis

SRSODD

(Class diagram)Code

ODD(Class diagram)

Sourcecode

Mapping


Mapping Activities

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Object Design model (Doc.)

(Class diagram)

1.Mapping Associations (concept)

Unidirectional, one-to-many association

Source Code

RDB Table

Aggregation

2.Mapping Contracts to Exceptions

3.Mapping Object Models to a Persistent Storage Schema

Mapping

Bidirectional, one-to-many association


Class Diagram

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使用者

老師

個人作業

學生

修課

1

*

課程

作業資料1* 上傳


Mapping Object Models to RDB

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編號名稱學期說明課程老師帳號

帳號密碼使用者電子郵件電話

帳號 Office Hour老師辦公室

帳號學生系別

修課學生帳號組別課程編號

編號個人作業

名稱截止日期課程編號作業或報告檔名

作業資料

大小學生帳號功課編號


What is mapping?

• A transformation aims at improving one aspect of the model (e.g., its modularity) while preserving all of its other properties (e.g., its functionality).

(model在改善某一方面所做的轉變，同時維持其功能的特性 )

• A transformation is usually localized, affects a small number of classes, attributes, and operations, and is executed in a series of small steps.

(這些轉變是經過一些連續的步驟，是局部的、影響少數的class, attributes, operation)

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Four types of transformations

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Source code spaceForward engineering(CH 4-3)

Refactoring (CH 4-3)Reverse engineering

Object Model space

Modeltransformation

(CH 3-6)


Model Transformation Example

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Object design model before transformation:

Object design model after transformation:

學生+Id:String+Password:String

老師+Id:String+Password:String

使用者+Id:String+Password:String

學生老師

+OfficeHour:String


Reuse concepts

• The focus of inheritance during object design is to “reduce redundancy” and “enhance extensibility”.(目的為降低系統重覆提高延展性 )

• Steps of design inheritance:– Step1: to factor all redundant behavior into a single

superclass.(步驟一：把重複的屬性操作都放到一個 superclass)

– Step2: we reduce the risk of introducing inconsistencies during changes since we have to make changes only once for all subclass.(步驟二：為了降低不一致的狀況發生，同時間我們只做一次步驟一的行為，換句話說，就是一次只產生一個 superclass)

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Refactoring Example: Pull Up Field

Before Refactoring

public class Student{private String Id;private String Password;//...

}public class Teacher{

private String Id;private String Password;//...

}

After Refactoring

public class User {private String Id;private String Password;

}

public class Student : User {//...

}public class Teacher : User {

//...}

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Forward Engineering Example Realization of User and Teacher

public class User{

public String Id;public String Password;

}

public class Teacher:User

{

public string OfficeHour;

public string Room;

}

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Object design model before transformation

Source code after transformation

使用者+Id:String+Password:String

老師+OfficeHour:String+Room: String


Transformation Principles

• To avoid introducing new errors, all transformations should follow these principles：– Each transformation must address a single criteria.

( 每個 Transformation是滿足一單一標準，是增進系統在單一目的，如一個 transformation是為了簡化類別 )

– Each transformation must be local. (Transformation是只有少數的 method or class)

– Each transformation must be applied in isolation to other changes.

(Transformation與其他的改變是隔離 )– Each transformation must be followed by a validation step.

(Transformation是人工的，應該要有確認的步驟以維持功能需求）

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Unidirectional one-to-many association

public class HomeworkData{

private TakeCourse _tc;

private File _file;

public Student getStudent() {

return _tc.getStudent(); }

public File getFile(){ return _file; }

public HomeworkData(TakeCourse tc){

_tc = tc;

}

//…

}

public class TakeCourse{private Course _course;private Student _student;public TakeCourse(){

}public Student getStudent(){

return _student;}//…

}

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修課作業資料1* 上傳


Bidirectional one-to-many association

public class Student : User{private Collection<TakeCourse>

_takeCourses;public Collection<TakeCourse>

getTakeCourses(){

return _takeCourses;}

}

public class TakeCourse{private Student _student;private Course _course;public Student getStudent(){

return _student;}public void setStudent(Student student){

_student = student;}public Course getCourse(){

return _course;}

}

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修課1 *修課

學生


Aggregation

public class Teacher: User {

private Collection <Courses > _courses;

public List getCourses(){

return _courses;

}

}

public class Course {

private Teacher _teacher;

public Teacher getTeacher(){

return _teacher;

}

public void setTeacher(Teacher teacher){

_teacher = teacher;

}

}

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老師課程


Class diagram contracts with OCL

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Public class HomeworkData{ context HomeworkData::setFile(file:File) pre: file.size <= 3145728 and file.size > 0 and !file.FileName.EndWith.include(‘.bat’, ‘.exe’)

context HomeworkData::setFile(file:File) post: self._uploadDate = DateTime.Now self._file = file}

HomeworkData

-_student : Student-_file : File-_uploadDate: DateTime

+setFile(file: File ) : void+getFile() : File+getStudent(): Student+setStudent(student: Student ) : void+getUploadDate() : DateTime+setUploadDate() : void


Mapping Contracts to Exceptions

Public class HomeworkData{

//…

Public void setFile(File file){

if(file.size() > 3145728 || file.size () <= 0) throw new OutofRangeException(“..”) ;

if( file.size () <= 0) throw new OutofRangeException(“..”) ;

const string[] filter = new string[]{“.bat”,”.exe”};

foreach(string s in filter){

if( file.FileName.EndWith(s) ) throw new SecurityException(“..”) }

//…

_uploadData = DateTime.Now;

_file = file;

}

//..

}

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Mapping Object Models to a Persistent Storage Schema

• UML object models mapping to relational databases:

• UML mappings

– Each class is mapped to a table(每個類別映射到一個資料表 )

– Each class attribute is mapped onto a column in the table(每個屬性對應到資料表的一個欄位 )

– An instance of a class represents a row in the table(資料表中的每個資料錄是對映到 class 的 instance)

– Inheritance association

– A one-to-many association is implemented as buried foreign key(一對多的關連是用外來鍵實做 )

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Inheritance Association

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Primary key

Foreign key referencing

帳號CHAR(20)

密碼CHAR(20)

使用者電子郵件CHAR(50)

電話CHAR(20)

帳號CHAR(20)

Office HourCHAR(20)

老師辦公室

CHAR(50)帳號

CHAR(20)系別

CHAR(20)

學生

…

Foreign key referencing

使用者

老師學生


Mapping Object

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學生修課1 *

課程

帳號CHAR(20)

系別CHAR(20)

學生

… 編號BIGINT

課名CHAR(20)

課程

…

學生帳號CHAR(20)

課程編號BIGINT

修課組別INT

Primary key


Mapping Object

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修課作業資料1* 上傳

編號BIGINT

檔名CHAR(255)

作業資料

大小BIGINT

檔案BINARY

學生帳號BINARY

作業項目編號BIGINT

學生帳號CHAR(20)

課程編號BIGINT

修課組別INT

Primary key

單元 4 ：數位家庭軟體開發與再利用 chapter 4-3 – mapping models to code

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