A REFACTORING TOOL FOR DESIGN PATTERNS

WITH MODEL TRANSFORMATIONS

Zekai DemirezenYasemin Topaloğlu

Ege UniversityDepartment of Computer Engineering

zekai@mail.ege.edu.tryasemin.topaloglu@ege.edu.tr

2/23NWUML06, 12 June 2006

Agenda• Background

– Design Pattern: A Target for Refactoring– Pattern Specification and Metamodeling– Transformation MetaModels– XML Metadata Interchange

• Tool Architecture– Components of the tool– Transformations

• Case Study: Observer Design Pattern– Example MetaModels and Models– Screen Shots

• Conclusions

3/23NWUML06, 12 June 2006

OTHER INPUTS ????

Design Pattern: A Target for Refactoring

Design Model Design Model with design patterns

4/23NWUML06, 12 June 2006

+Applicant()+ApplicantInfo()+MakeApplication()

-companyName : CString-experience : CString-reference1 : CString-reference2 : CString-reference3 : CString

Applicant

+Person()+PersonInfo()

-personID : unsigned long-surname : CString-givenName : CString-middleInitial : char-streetAddress : CString-postCode : CString-countryname : CString-eMailAddress : CString

Person

-is taught by

1

-teaches

0..*+CourseSession()+CourseSessionInfo()

-courseSessionID : unsigned long-courseDate : unsigned long-courseID : unsigned long-courseLocation : CString

CourseSession

+AppStatus()+AppStatusInfo()

-statusCode : char-statusName : CString

AppStatus

+CourseRegistration()+CourseRegistrationInfo()

-registrationDate : unsigned long-completionFlag : bool-confirmedDate : unsigned long

CourseRegistration

+Test()+TestInfo()

-testScore : unsigned long

Test

+Application()+ApplicationInfo()

-productNr : unsigned long-certificationLevel : unsigned long-applicationDate : unsigned long

Application

+PermittedStatusChange()+StatusChangeInfo()

-fromStatus : char-toStatus : char

PermittedStatusChange

+ExamSession()+ExamSessionInfo()

-examSession : unsigned long-examlocation : CString-examDate : unsigned long

ExamSession

-gives0..*

-is achieved1

-is made by

1

-makes

0..*

-allows change in

0..*

-has a

1..*

-is taken by1

-takes0..*

-is made by a1

-made a1..*

-is in1

-is filled by0..*

-uses

1

-is used in

0..*

-applies to a0..*

-is for a1

+Exam()+ExamInfo()

-examID : unsigned long-certificationLevel : unsigned long

Exam

+Employee()+GetCurrentAge()+EmployeeInfo()

-jobType : CString-roomNr : unsigned long-department : CString-division : CString-jobTitle : CString-manager : unsigned long-headsDept : CString-headsDivision : CString-mobileNr : CString-birthDate : unsigned long

Employee

+registrationform()

RegistrationForm

-uses**

ApplicantApplicantList PersonList

findApplicant()

ApplicationRegForm

Applicant()

findPerson()

addPerson()

addApplication()

Application()

MakeApplication()

ApplicationList

"from human-readable ……………………to computer-understandable"

Pattern Specification

5/23NWUML06, 12 June 2006

Role-Based Meta-Modelling• In order to process models in transformation activities, meta-

modeling is required. Meta-modeling defines the rules and the structures of models. Role-based meta-modeling technique is proposed by (France et al,2004) for design pattern meta-modeling.

•Structural Pattern Specification (SPS)

•Interaction Pattern Specification (IPS)

•State Machine Pattern Specification (SMPS)

6/23NWUML06, 12 June 2006

OMG 4 Layer Architecture

What we wantto transform

7/23NWUML06, 12 June 2006

Transformation Meta-Models• Source Meta-Model defines the models that the transformation will be

applied.• Transformation Meta-Model defines the transformation rules and the

steps.• Target Meta-Model defines the output model of the transformation

activity.

Model bModel a

instanceOf

Source Meta-Model

instanceOf

Definition of transformation T: A->B

An application of transformation T(a) = b

instanceOf

Target Meta-Model

8/23NWUML06, 12 June 2006

Tool Inputs

Design Model Design Model with design patterns

Source MetaModel Target MetaModel

Transformation MetaModel

9/23NWUML06, 12 June 2006

XML Metadata Interchange(XMI)XMI is a widely used interchange format for sharing objects using XML.

10/23NWUML06, 12 June 2006

Tool Architecture• Model editor is a standard modeling tool such as Rational Rose that can be

used to prepare the application design models. • Rule editor is used to prepare the source and the target meta-models • Transformation Preparer takes the application model and the source and

the target meta-models as inputs and then matches the application model elements with the meta-elements.

• Transformation machine executes the transformation steps defined in transformation meta-model

Tool Architecture (A. Wagner, 2002)

11/23NWUML06, 12 June 2006

Subcomponents of the Tool• Representation Transformer (RT): It transforms the meta-model’s

XMI representation to object representations by transforming • Transformation Pattern Generator (TPG): This component

produces transformation meta-model at run-time by analyzing structural differences between the source and target meta-models

• Rol-ModelElement Transformer (REM): This component matches the roles with application model elements. Matching activity is a kind of searching process of role’s structural properties in the application model.

• Transformation Machine(TM): It is the last component that executes the transformation meta-model tasks on the application model. Add, delete and update operations assign the role properties in to the selected model elements

12/23NWUML06, 12 June 2006

Transformations-1• XML Representation-Object Representation

Transformation: The source, target and the application models in XMI are transformed into the objects representations.

•Composite Transformation •Transformation Reuse is defined in Appukuttan et al 2003

13/23NWUML06, 12 June 2006

• MetaModel-Model Transformation: The roles constituting the target meta-model are matched with the application model elements and the source meta-model-source model transformation is the result of this matching

Transformations-2

14/23NWUML06, 12 June 2006

• Application Model-Result Application Model Transformation: Model elements in the application model are transformed into the model elements of the target model by processing the steps in the transformation model. Transformation specifications in the transformation machine are applied on the

application model in this transformation.

Transformations-3

15/23NWUML06, 12 June 2006

• Result Application Model Object Representation-XMI Representation Transformation: This step transforms the result model of the transformation process into the XMI format. Each model element is transformed into the

corresponding element in the XMI format

Transformations-4

16/23NWUML06, 12 June 2006

Overview

17/23NWUML06, 12 June 2006

Case Study• We demonstrate the usage of our tool for

the Observer [Gamma et al.] pattern.

• Observer pattern describes the situation in which a one-to-many dependency between objects is present.

• In this case, when one object changes state, all its dependents are notified and updated automatically

18/23NWUML06, 12 June 2006

Case Study:Source Meta-Model• Preparing the Observer Source MetaModel Specification

• Applicability and motivation sections of the patterns in the catalogue are problem definitions for patterns

• In some parts we use stereotypes in order to provide problem semantics. During stereotype usage, we prefer to use universal standard stereotypes.

19/23NWUML06, 12 June 2006

Case Study:Target Meta-Model• Preparing Observer Target MetaModel Specification

• The target specification is the solution of the design pattern. We use the Class structure and the Participants sections of the GOF Design Pattern catalogue to derive this specification.

• Semantic parts of the design pattern target specification are supported by the stereotype usage.

20/23NWUML06, 12 June 2006

Case Study: Application of the ToolAfter the rule definition activities, tool is executed for transformation with the application

model.

21/23NWUML06, 12 June 2006

Case Study: Transformation ModelTPG Component takes these

two models and prepares transformation model with using

• Add• Delete• Update • Unchanged labels.

22/23NWUML06, 12 June 2006

Case Study:Screen Shots

23/23NWUML06, 12 June 2006

Conclusions• We introduced a transformation tool that

performs horizontal transformations for design pattern refactorings on design models.

• Since XMI is not a query language, we could not generate complex definitions of the source model.

• However, our approach in the implementation of the tool does not require to define transformation meta rules which simplifies the transformation implementation.