1. Model Driven Engineering
UML
class diagrams
object diagrams and constraints
metamodeling
examples
MDE →
finally! basics of
Model Driven Engineering

2. MDE
Is about automating the development of rote well-understood software everything that I talk about you have done or will do manually
Generalizes standard Engineering practices engineering with a capital “E” where one creates a model or models of what needs to be built, and tools transform this model or models into an engineering artifact. Ex: Next generation space shuttle
Software development becomes creating models and applying M2M and M2T transformations to generate source code. Instead you write models of programs, or if you are advanced you write model-to-model (M2M) or model-to-tool (M2T) or tool-to-model (T2M) transformations

3. Quick Sketch of MDE
General idea is to have domain experts draw a diagram model of what they want
Press a button and the model translated to a database
Database is checked for constraint violations
If no violations, transform to code or code shell that has to be filled in
T2M
M2T
Violet or
UML Drawing
Tool
Constraint
Verification
Let’s look at an
example to make
this concrete

4. An MDE Model
Here is a finite state machine (FSM) model of my eating habits:
In general, a model is a graph
different nodes have different icons to represent different semantics
edges possibly directed represent relationships
different edges have different icons to represent different semantics

5. Everything is a Graph to MDE nothing special about FSMs
Everything is a Graph to MDE nothing special about FSMs. hence the generality of MDE
Message Sequence Charts
Logic Circuit Diagram
Data Flow Model
Petri Net
Network Architecture
Flow Chart

6. All are Object Diagrams
Everything is a Graph to MDE nothing special about FSMs. hence the generality of MDE
Message Sequence Charts
Logic Circuit Diagram
Data Flow Model
All are Object Diagrams
Petri Net
Network Architecture
Flow Chart

7. MDE FSM Engineer has 2 Tasks
To use a special tool to draw the desired FSM graph

8. MDE FSM Engineer has 2 Tasks
To press a button not shown to generate code that implements the drawn graph
Basic questions to ask:
how does the FSM tool work internally?
how is application source generated?
FSM Application Engineer
FSM tool
FSM source code
draws FSM
presses button to generate

9. to answer these questions, we need to look a bit deeper
Metamodels

10. Draw its UML Class Metamodel
MDE Metamodel
It is a specification of all legal graphs of a kind
Show simplest UML class diag. that represents all FSM graphs as below?
node = class
edge = association or inheritance relationship
Answer on next slide
Draw its UML Class Metamodel

11. MDE Metamodel A schema for this diagram is: do Node schema first node#
name
type
trans#
startsAt
endsAt
of type Node#
note: things like “1” and “*” are expressed by constraints.
In this case, every transition MUST have non-empty StartsAt and EndsAt fields.

12. Populating Tables with Tuples
Given the following FSM instance:
Its tabular representation is:
trans#
startsat
endsat t1
nstart
nReady t2
nDrink t3
nEat t4 t5 t6 t7 t8
nFam t9
t10
nstop
node#
name
type
nstart
start
nReady
Ready
state
nDrink
Drink
nEat
Eat
nFam
Family…
nstop
stop

13. Recall Actions of Engineer
Draw FSM and push button
Press button arrow is a composition of 3 more primitive arrows a.k.a. steps
presses button to generate
FSM source code
FSM tool
draws FSM
using
Application Engineer
parse graph
into tables
FSM model
xform tables to code
FSM source code
validate
constraints

14. From Relational Tables…
Can generate code because FSM application domain is well-understood
The essence of MDE!
rote mapping
Called a Model
to Text (M2T) transformation

15. I previously used Velocity, which sucked, and now I’m using Running Bear
a Model to Text tool

16. Model to Text Mapping Running Bear (RB) is a teeny-weeny Java package
There are lots of “off-the-shelf” tools; I previously used Apache Velocity but RB is much better.
Database tables in RB are database tuples or prolog facts
Example: class diagrams with no methods or associations – translate them to Java code. What is the simplest metamodel of these instances?
Answer on next slide

17. Example Metamodel and Instances
What is the schema of this metamodel? do class schema first
What are the tuples? do class table first
class#
name
attribute#
name
type
ofclass
class#
name c1
City c2
Account
attribute#
name
type
ofclass a1
String c1 a2
state a3
number
Integer c2 a4
balance
Double

18. Translation to Databases
Relational tables:
Relational database ≈ prolog fact file
data.pl
dbase(data,[class,attribute]).
table(class,[cid,name]).
class(c1,city).
class(c2,account).
table(attribute,[aid,name,type,ofclass]).
attribute(a1,name,string,c1).
attribute(a2,state,string,c1).
attribute(a3,number,integer,c2).
attribute(a4,balance,double,c2).
class#
name c1
City c2
Account
green is schema
black is data
attribute#
name
type
ofclass a1
String c1 a2
state a3
number
Integer c2 a4
balance
Double

19. All 6 RB Methods
static void setOut(PrintStream out) // set file output, stdout is default static void l(String fmt, Object... args) { out.format(fmt + "\n", args); } static void l() { out.println(); } // print new blank line static void p(String fmt, Object... args) { out.format(fmt, args); } static void close() // close file output, reset to stdout marquee(String… args) // main processing

20. > java RBProgram <database> [output-file]
Hello World!
General calling sequence of an RB program:
> java RBProgram <database> [output-file]
> java helloworld ignore.db.pl
supply
dummy
argument
produces:

21. Example RB Program data.pl > java gen data.pl gen.java class city {
string name;
string state; }
class account {
integer number;
double balance;
data.java
> java gen data.pl
dbase(data,[class,attribute]).
table(class,[cid,name]).
class(c1,city).
class(c2,account).
table(attribute,[aid,name,type,cid]).
attribute(a1,name,string,c1).
attribute(a2,state,string,c1).
attribute(a3,number,integer,c2).
attribute(a4,balance,double,c2).
data.pl
gen.java
gen.java

22. Example RB Program data.pl > java gen data.pl gen.java
class city {
string name;
string state; }
src/city.java
class account {
integer number;
double balance;
src/account.java
> java gen data.pl
dbase(data,[class,attribute]).
table(class,[cid,name]).
class(c1,city).
class(c2,account).
table(attribute,[aid,name,type,cid]).
attribute(a1,name,string,c1).
attribute(a2,state,string,c1).
attribute(a3,number,integer,c2).
attribute(a4,balance,double,c2).
data.pl
gen.java

23. Time for Perspective

24. In Programming Assignment P1
You translated Java bytecode files into an MDELite database
Called a Tool-to-Model transformation – generally it is a Java program
RB is a tool that translates a MDELite database into a text file; called a Model-to-Text (or Model-to-Tool) transformation
T2M
M2T

25. A Possible Programming Assignment
Write the M2T transformation using the RB tool and Apache Velocity for comparison -- I’ll give you the FSM database to translate
M2T
mapping

26. Programming assignments P2 and P3
big picture for P2 and P3
Programming assignments P2 and P3

27. Your 2nd Programming Assignment
Verify that a Violet UML class diagram is “correct”, meaning that it conforms to sensible constraints
Violet was given to you
Violett.ClassParser was given to you
You wrote VPL.Conform
Violett.ClassParser
VPL.Conform
Violet to draw a class diagram

28. Your 3RD Programming Assignment
vpl2ypl
ClassUnparser P3
ClassParser P2
.Conform
P3 is next step in this chain – You translated a VPL database into a YPL database, and used an existing tool that converted a YPL database into a Yuml spec. This is a M2M (model-2-model) transformation
Doing so, you wrote your first simple (MDE) application!
public static void main(String… args) {
MDL.VioletClassParser.main(args[0],args[1]); // produces new.vpl.pl VPL.Conform(args[1]); M2M.vpl2vpl(args[1], “new.ypl.pl”);
Yuml.ClassUnParser(“new.ypl.pl”,”new.yuml.yuml”); }
Approximate

29. Oops ! Not quite right What is missing?
ClassParser
vpl2ypl
ClassUnparser P3 P2
Conform
Conform
What is missing?
Ans: YPL.Conform ! Just as VPL databases have conformance rules, so too do YPL databases. These rules are very similar to that of VPL.
Yuml.Conform already exists, so you could call it immediately after your vpl2ypl program finishes execution.

30. Big Picture of MDE
All categories: domains of design artifacts and arrows are programs
Conform
ToYumlSpec
ClassParser

31. Big Picture of MDE
All categories: domains of design artifacts and arrows are programs
MDE programs are traversals of arrows of a category
Violet MM
VPL
Boolean
yUML Specs
Conform
ClassParser
ToYumlSpec
Conform
ClassParser
ToYumlSpec

32. If I were to Give Another MDE Programming Assignment
I’d have you integrate P1, P2, P3 or use RB to generate Java stubs
genStub
MDE is linking
these domains
together into an
interoperable
ecosystem
introspect P4
prog1toVPL
ClassParser
vpl2ypl
yumlspec
Conform
Conform

33. Recap
FSM Application Engineer uses an FSM tool to draw a desired FSM
The tool internally stores a model as a set of relational tables
Database is validated
Tool translates these tables into source code using RB
Conform
Application Engineer
FSM tool
relational tables
draws FSM
using
stores FSM graph in
RB script translates to code
application source code
Questions?

34. Refactorings Next Lecture
Other transformations are used to build models and meta-models called:
They are also a centerpiece for Java and OO program development
Refactorings