1. Model Transformation for End-Users
UA Computer Science Department July 28, 2009
Jeff Gray
With Yu Sun (UAB) and Jules White (Vanderbilt)
This work funded in part by NSF CAREER award CCF

2. Summary of Past Visits November 2001 January 2002 February 2005
“Applying Aspect-Oriented Techniques to Domain-Specific Modeling”
January 2002
“Future Research Directions in Aspect-Oriented Programming”
February 2005
“Transformations Across Software Artifacts”
February 2009 (Robert Tairas)
“Maintaining Cloned Software”

3. Invitation: Turing Award Speaker
Fran Allen
2006 Turing Award Winner and first woman to win the award
September 14 at UAB
“Is Computing at a Tipping Point?”
Please send me an if you are interested in more details later

4. Model-Driven Engineering: Customized Languages with Domain-Specific Modeling

5. Categories of End-Users
Spreadsheet
Admin
Assistants
Business
Query Systems
Businessperson
Modeling
Language
Auto Factory
Worker
DSL for
Physics
Scientist

6. Observation
“One size fits all” approach is appearing to be inadequate for many end-user needs
Too complex and contains “kitchen sink” approach providing things most users do not need (UML)
Current trend is to provide “domain-specific” modeling languages that are customized to a specific domain
Notations and abstractions are exactly what the users expect; focused on problem space, not technology solution space
But, how to create such modeling languages and environments?
Expensive to create from scratch for each domain

7. Domain-Specific Modeling (DSM)
DSM involves systematic use of a graphical domain-specific language (DSL) to represent the various facets of a system
DSM supports higher level abstractions, enabling domain experts to develop applications they want

8. Domain-Specific Modeling

9. Model-Driven Engineering (MDE)
MDE: specifies and generates software systems based on high-level models
Domain-Specific Modeling (DSM): a paradigm of MDE that uses notations and rules from an application domain
Metamodel: defines a Domain-specific Modeling language (DSML) by specifying the entities and their relationships in an application domain
Model: an instance of the metamodel
Model Transformation: a process that converts one or more models to various levels of software artifacts (e.g., other models, source code)
The background of this research is MDE. During MDE, high-level models are promoted as the primary artifacts during the software development lifecycle. Models are used for software design, testing, implementation and maintenance.
DSM is a paradigm of MDE that uses notations and rules from an application domain to define a domain – specific modeling language.
Metamodeling is a process for defining domain-specific modeling languages (DSMLs). A metamodel formally defines the abstract syntax and static semantics of a DSM, just like the grammar of a programming language.
A model is an instance of a metamodel, used to represent a system or part of a system.
Model Transformation: A process that creates or modifies the target software artifacts (e.g. models, codes) from the source models.
Vertical Transformation: Refinement across abstraction layers
E.g., generating source code from models.
Horizontal Transformation: Translation between models at the same level of abstraction
E.g., model-to-model transformation.
Commercial Examples:
1)Microsoft modeling tool
2)IBM modeling tool
DSM: address the complexity of software development by raising the specification of software to visual models at a higher-level of abstraction and using notations and rules in an application domain.

10. Question
But what is a model?

11. A very popular model: geographical maps (thanks to Jean Bezivin for this idea)
Models
1819 City Plan
2000 Census Map
The System
Aerial Map
System
Model
repOf
Road Map

12. Every map has a legend
legend = metamodel
Model c2
Metamodel 

13. Another Notation (DSL)
Executable Model
Music notation
Power Tab Editor
Metamodel c2
Model
Sheet music
Two Views:
Traditional notes
Guitar tab

14. Assisted Drawing Tools (e.g., MS/Visio)  c2
Model
Metamodel

15. Schema definitions: Going “Meta”
Domain-Specific
Modeling
Programming
Language Definition
Database Schema
Definition
Schema definition
Metamodel for a
specific domain
(e.g., Petri Net)
Grammar for a specific
language (e.g., Java)
Table, constraint, and stored
procedure definitions for a
(e.g., payroll database)
Schema instance
Domain model
(e.g., Petri Net
model of a teller
machine)
A program written in a
Specific language
Intension of a database at a
specific instance in time
(e.g., the May 2009 payroll
instance)
Schema execution
Model Interpreter
Language
compiler/interpreter
Transactions and behavior of
stored procedures
in an executing application

16. Characteristics of Modeling Languages
Each model conforms to its metamodel
A model is a representation of a system satisfying substitutability
For each question that can be asked of the system, the model produces the same answer
Not true for me and road maps!
(from Jean Bezivin)

17. Background: Domain-Specific Modeling (cont’d)
M e t a m o d e l
Metamodeling
Interface
Application
Domain
Environment Evolution
Application Evolution
Metamodel Definition
App 1
App 2
App 3
DEFINE
Meta-Level
Translation
Modeling Environment
M o d e l
Model Builder
Model
Interpretation
Models
INTERPRET
I n t e r p r e t e r
void CComponent::InvokeEx(CBuilder &buil
der,CBuilderObject *focus, CBui
lderObjectList &selected, long param) {
CString DMSRoot = "";
DMSRoot = SelectFolder("Please Select DMS
Root Folder:");
if (DMSRoot != "") {
DMSRulePath =
MSRuleApplierPath
DMSRoot + RULESPATH + "Rules\\";
= DMSRoot + RULESPATH + "RuleApplier\\";
AfxMessageBox("DMSRulePath =
" + DMSRulePath , MB_OK);
OEPRoot = SelectFolder("Please Selec
CString OEPRoot = "";
Model Interpreters
The Generic Modeling Environment (GME) adopts the DSM approach and provides a plug-in mechanism for extension.

18. Example DSMLs and Applications
An application for a family entertainment center 1 2
An application for automotive manufacturing system 1 2
DuPont manufacturing system : the world's second largest chemical company
Saturn manufacturing system
Family entertainment system
1. Modeling
2. Stepwise model transformations

19. Model Transformation by Demonstration

20. Model Transformation (MT)
A core technology in DSM
Model Evolution
Code Generation
Reverse Engineering
Model Mapping

21. Model Transformation Example 1 UML to RDBMS
Simple UML Metamodel
Simple RDBMS Metamodel
Conforms to
Conforms to
Source UML Model Instance
Target RDBMS Model Instance
Transform To

22. Model Transformation Example 2 MazeGame Refactoring
MazeGame Metamodel
Conforms to
Conforms to
Source Model Instance
Target Model Instance
Transform To
Replace Monsters with Weapons

23. How to Implement Model Transformation?
Manual editing is tedious and error-prone
Using GPL (e.g., Java, C++) is not efficient

24. Model Transformation Languages
Automate model transformations by programming
QVT
Query/View/Transformation
C-SAW
Constraint-Specification Aspect Weaver
GReAT
Graph Rewriting and Transformation
Popular Model Transformation Languages

25. Model Transformation Languages NOT Perfect
Steep learning curve
Deep understanding about Metamodel level definition
Understand Metamodel First

26. Model Transformation Languages NOT Perfect
Steep learning curve
Deep understanding about Metamodel level definition
This is OK for computer scientists, but challenging for general users (e.g., domain experts) who can also contribute to some of the model transformation tasks

27. Model Transformation By Example (MTBE)
An innovative approach to simplify the implementation of model transformations

28. By Example Ideas Query By Example (QBE) Programming By Example (PBE)
XML Transformation By Example (XTBE)
SELECT * FROM Contacts
WHERE Name='Bob' AND State='TX'

29. Limitations of MTBE Semi-automatic rules generation
Users are not fully isolated from using the transformation languages
The quality depends on available source and target models
Only concept mapping. Cannot handle complex attribute transformation (e.g., arithmetic, string operations)
Perfect Source and Target Models

30. Our Approach: Model Transformation By Demonstration (MTBD)
Ask users to demonstrate how the model transformation should be done
An engine records user operations and infers the transformation pattern
Reuse the generated pattern to new model instances

31. Generic Eclipse Modeling System
MT-Scribe
The implementation of the MTBD idea is a plug-in to GEMS in Eclipse
Assists in simplifying model transformation tasks
GEMS
Generic Eclipse Modeling System

32. Main Steps in MT-Scribe
Initial sequence of recorded operations
Pattern Matching
Backtracking Algorithm
Edit a model instance to demonstrate how the transformation should be done
1. Demonstration
1. Recording
3. Infer Pattern
5. Correctness Checking
4. Reuse Pattern
2. Optimization

33. A Model Transformation Example
TASK:
Replace the monster
in a room with a weapon, and set the powerValue attribute of the new weapon to be half of the monster.

34. Demonstrate the Transformation
Step
Operation 1
Select a Monster in a room 2
Delete the Monster 3
Add a new Weapon 4
Set the powerValue of the new Weapon

35. Operation Recording & Transformation Pattern Inference
Step
Operation 1
Select a Monster in a room 2
Delete the Monster 3
Add a new Weapon 4
Set the powerValue of the new Weapon
Optimize and Infer Pattern
Step
Operation Type
Detail 1
Delete Element
Root.MazeFolder.Room.Monster 2
Add Element
Root.MazeFolder.Room (Weapon) 3
Update Element
Root.MazeFolder.Room.Weapon.powerValue (Monster.powerValue / 2)

36. Reuse the Transformation Pattern
Traverse the model instance, find all the possible places where the recorded transformation could be done
Backtracking Algorithm
Re-execute the recorded operations in the new location with the new elements and properties
Correctness checking avoids violating meta definitions

37. Current Status of MT-Scribe
Complete recording of all operations
Recorded operation optimization
Inference of transformation patterns
Automatically match the pattern in new model instances
Exact re-execution of transformation pattern
Correctness checking and undo mechanism

38. Demonstration
Video Demonstration of MTBD

39. Application 1 – Model Refactoring
UML Refactoring in C-SAW

40. Application 2 – Model Scalability
strategy traverseSites(n, i, m, j : integer) {
declare id_str : string;
if (i <= n) then
id_str := intToString(i);
rootFolder().findModel("NewGateway_Federation").findModel("Site " + id_str).addGateWay_r(m, j);
traverseSites(n, i+1, m, j);
endif; }
//recursively add CORBA_Gateways to each existing site
strategy addGateWay_r(m, j: integer)
if (j<=m) then
addGateWay(j);
addGateWay_r(m, j+1);
//add one CORBA_Gateway and connect it to Event_Channel
strategy addGateWay(j: integer)
declare ec, site_gw : object;
id_str := intToString(j);
addAtom("CORBA_Gateway", "CORBA_Gateway" + id_str); //create one CORBA_Gateway
ec := findModel("Event_Channel"); site_gw := findAtom("CORBA_Gateway" + id_str);
addConnection("LocalGateway_EC", site_gw, ec);
Application 2 – Model Scalability
Scale Up

41. Application 3 – Aspect-Oriented Modeling
self.assignTo() = processor0
strategy Assign(limit : integer){
declare static accumulateWCET, processNum : integer;
declare currentWCET : integer;
self.compute.WCET.getInt(currentWCET);
accumulateWCET := accumulateWCET + currentWCET;
if (limit < accumulateWCET) then
accumulateWCET := currentWCET;
processNum := processNum + 1;
endif;
<<CComBSTR aConstraint = "self.assignTo()=processor" +
XMLParser::itos(processNum); >>
AddConstraint("ProcessConstraint", aConstraint); }

42. Future Work Enable more specific precondition inference
Enable more powerful and rich attribute transformation (e.g., max(), min())
Implement exogenous model transformations

43. Questions & Comments ? Additional questions:
More examples and video demos available at:
Additional questions:
This work funded in part by NSF CAREER award CCF