The document discusses model-driven engineering (MDE) and its advantages. It describes a case study where two development teams, one using traditional development and one using model-driven development (MDA), built a simple e-commerce system. The MDA team achieved a 35% increase in productivity compared to the traditional team. Overall, using MDE approaches can yield an average of 26% savings in development time and costs. MDE promotes higher levels of abstraction, automation, and standards-compliance to help manage increasing demands on modern software.

1. MODEL-DRIVEN ENGINEERING
in Practice

2. The $800-Million Bombshell (Motivation)
• The following was the code for controlling long-distance
phone traffic routing in USA:
• …
switch (caseIndex) {
case‘A’: route = routeA;
…
break;
…
case‘M’: route = routeM;
…
case‘N’: route = routeN;
…
break;
…}
Missing “break”
statement!
When this code ran (in 1990), the entire US Northeast lost
long-distance phone service

3. Engineering Model
A reduced representation of some system that highlights
the properties of interest from a given viewpoint
Functional ModelModeled system
 We don’t see everything at once
 We use a representation (notation) that is easily understood for
the purpose on hand

4. Models vs. Systems
Differences due to:
• Unique properties of actual
construction materials
• Construction methods
• Scaling-up effects
• Skill sets/technologies
• Misunderstandings
Can lead to serious errors and
discrepancies in the realization

5. Characteristics of Useful Models
• Abstract
• Emphasize important aspects while removing irrelevant ones
• Understandable
• Expressed in a form that is readily understood by observers
• Accurate
• Faithfully represents the modeled system
• Predictive
• Can be used to answer questions about the modeled system
• Inexpensive
• Much cheaper to construct and study than the modeled system
To be useful, engineering models must satisfy
all of these characteristics!

6. ModelTransformations • Computation-independent
Model
• Uses natural language
• Ex: state-chart diagram
CIM
• Platform-independent Model
• Does not specify any technology
PIM
• Platform-specific Model
• Built for a specific technology
• When technology evolves, a
new PSM can be generated
rather than rewriting it
PSM
BusinessAnalyst
Architect / Designer
Developer /Tester

7. Machine Code
Impossible?
TheAbstraction Gap
• Middleware makes MDA a potential reality
Level of
Abstraction
Generators
1
0..*
security
mortgages
1
0..*
borrower
mortgages
10..*
ownerhouses
House
-value:Money
Person
-ssn:Integer
-salary:Money
+getMortgage(sum:Money,security:House):Mortgage
Mortgage
-principal:Money
-monthlyPayment:Money
-start:Date
-end:Date
Machine Code with Operating System
Impractical?Use Operating System facilities
Unlikely?Use Middleware
Practical(ly)
Middleware with
Framework
Today!
AbstractionGap

8. Model Execution
X = cos (h + p/2)
+ x*5
X = cos (h + p/2)
+ x*5
?
 By formal analysis
 mathematical methods
 reliable (theoretically)
 software is very difficult to
model mathematically!
?
X = cos (h + p/2)
+ x*5
X = cos (h + p/2)
+ x*5
 By experimentation (execution)
 more reliable than inspection
 direct experience/insight
X = cos (h + p/2)
+ x*5
X = cos (h + p/2)
+ x*5
?
 By inspection
 mental execution
 unreliable

9. MDE Prospects
• The problem:
• We cannot keep implementing our applications using the
programming technologies of the late Fifties’
• The demands on functionality, reliability, dependability,
availability, security, and performance demanded of modern
software.
• We need to, can do, and have already done better!
• MDE:
• Increased levels of abstraction
• Open unified standards
• Increased levels of automation

10. Primary Forms of Automation for MDE
• Computer-based validation
• Formal methods (qualitative and quantitative)
• Computer-based testing
• Automated test generation, setup, and execution
• Computer-based model execution
• Particularly execution of abstract and incomplete models
-- when most of the important decisions are made
• Model transformations
• Code generation, between PSMs, …

11. MDE - Case Study
Project Description
• A simple web-based J2EE e-commerce system (Pet Store)
• Users can sign into a system and manage their accounts.
• Users can browse a catalogue of pets on the web site
(such as birds, fish or reptiles).
• Shopping cart functionality: Users can add pets to their
shopping cart and manage their shopping carts.
• Order functionality: Users can place an order for the
contents of their shopping carts.
• Web services. Users can query orders via a web service.

12. MDE - Case Study
Teams Description
• 2 development teams
• Traditional development lifecycle
• Model-driven Development style
• 1 senior J2EE architect + 2 experienced J2EE programmers per team
• Each team uses the same HTML, images and database schema.
• MDA team was required to use an MDA tool
• Traditional team was required to use leading J2EE IDE
• Both teams must use EJB in their code bases
• No further constraints

13. Savings Achieved
0% 36% 46% 28% No data
available
Total average savings achieved: 26%

14. Quantitative Results
development hours spent by each team:
Team Original Estimated
Hours
Actual Number of
Hours
Traditional team 499 507,5
MDA team 422 330
this corresponds to a 35% increase in
productivity when using MDA

15. Thank you!
Hussein Alshkhir