Model-Driven Software Dev Intro

Model-Driven
Software Development
Lecture1: Introduction & Overview

Course IN4308
Eelco Visser
Master Computer Science
http://eelcovisser.org Delft University of Technology
Wednesday, February 3, 2010

Source: Automatiseringsgids January 16, 2010


Source: Automatiseringsgids January 16, 2010

“Generator spits out ‘mobile’ applications”

“Steape has developed a code generator that automatically
generates code for a range of mobile phones”


Software Engineering

implement
Problem Solution
Domain Domain
validate


Programming Languages


"A programming language is low level when its programs
require attention to the irrelevant."

Alan J. Perlis. Epigrams on Programming. SIGPLAN Notices, 17(9):7-13, 1982.


What do programming languages provide to reduce
attention to the irrelevan?


Machine Language to Assembly Language
Program I-I. Disassembly.

., 0360 A9 01    LDA #$01
., 0362 A0 00    LDY #$00 “Let's examine some advantages
., 0364 99 00 80 STA $8000,Y of ML, starting with the main
., 0367 99 00 81 STA $8100,Y one - ML runs extremely fast.”
., 036A 99 00 82 STA $8200,Y
., 036D 99 00 83 STA $8300,Y
., 0370 C8       INY
., 0371 D0 F1    BNE $0364
., 0373 60       RTS
.

Machine Language
169 1 160 0 153 0 128 153 0 129 153 130 153 0 131 200 208 241 96

BASIC
5 FOR I=1 TO 1000: PRINT "A";: NEXT I

Source: http://www.atariarchives.org/mlb/introduction.php

From Instructions to Expressions

mov &a, &c c = a
add &b, &c c += b
mov &a, &t1 t1 = a
sub &b, &t1 t1 -= b
and &t1,&c c &= t1

c = (a + b) & (a - b)

Source: http://sites.google.com/site/arch1utep/home/course_outline/translating-complex-expressions-into-assembly-language-using-expression-trees


From Calling Conventions to Procedures
calc:
push eBP ; save old frame pointer
mov eBP,eSP ; get new frame pointer
sub eSP,localsize ; reserve place for locals
.
. ; perform calculations, leave result in AX
.
mov eSP,eBP ; free space for locals
pop eBP ; restore old frame pointer
ret paramsize ; free parameter space and return

push eAX ; pass some register result
push byte[eBP+20] ; pass some memory variable (FASM/TASM syntax)
push 3 ; pass some constant
call calc ; the returned result is now in eAX
http://en.wikipedia.org/wiki/Calling_convention

f(x) { ... } f(e1,e2,...,en)


From Malloc/Free to Automatic Memory Management

/* Allocate space for an array with ten elements of type int. */
int *ptr = (int*)malloc(10 * sizeof (int));
if (ptr == NULL) {
/* Memory could not be allocated, the program
should handle the error here as appropriate. */
} else {
/* Allocation succeeded. Do something. */
free(ptr); /* We are done with the int objects,
and free the associated pointer. */
ptr = NULL; /* The pointer must not be used again,
unless re-assigned to using malloc again. */
}
http://en.wikipedia.org/wiki/Malloc

int [] = new int[10];
/* use it; gc will clean up (hopefully) */


Abstractions in Progamming Languages

- Structured control-ﬂow
★ if-then-else, while

- Procedural abstraction
★ procedures, ﬁrst-class functions (closures)

- Memory management
★ garbage collection

- Data abstraction
★ abstract data types, objects

- Modules
★ inheritance, traits, mixins


Abstraction Scala
garbage collection

objects

Programming Languages
expressions structured
control-ﬂow

procedures
machine

Linguistic Abstraction

design abstraction
language A language B

use new abstraction

identify pattern


High-level languages reduce problem/solution gap

Problem
HLL Machine
Domain


Do HLLs eliminate all irrelevant detail?

What about
- data persistence
- data services
- concurrency
- distribution
- access control
- data invariants
- workﬂow
- ...


What is the next level of abstraction?

Problem
HLL Machine
Domain


Model-Driven Software Development

Problem
Model HLL Machine
Domain

models further reduce gap between problem domain and implementation

What is a model?


What is a model?

model
thing abstraction of
thing

abstraction = forgetting details

What is a model?

“A model is a simpliﬁcation of a system built with an intended goal
in mind. The model should be able to answer questions in place of
the actual system.” Jean Bézivin


What is a model?

“A model is an abstraction of a (real or language based) system
allowing predictions or inferences to be made.” Kuehne


What is a model?

“Models help in developing artefacts by providing information
about the consequences of building those artefacts before they
are actually made.” Ludewig


What is a model?

“A model of a system is a description or speciﬁcation of that system
and its environment for some certain purpose.” OMG


What is a model?

A model
- is a simpliﬁcation of a system
★ abstraction, description, speciﬁcation, information

- can answer questions in place of actual system
★ analysis, inference, predictions

- is used for a purpose
★ understanding, planing, risk analysis, ...


A model is a UML diagram

simpliﬁcation?
analysis?
purpose?

What is a model about?

- Structure
★ Data
★ Architecture
★ Conﬁguration

- Behaviour
★ User interface
★ Access control
★ Business process

- About any aspects of a system


A model can be a UML diagram ...


A model can be a UML diagram ...

... but it can be any other representation ...

e = x | e + e | e - e | f(e,...,e)

... that serves purpose of abstraction, analysis, etc.

For what purposes are models used?

Description
- of something that exists
Analysis
- understanding of properties
Blueprint
- guidelines to build something
Speciﬁcation
- precise instruction for construction (code gen)


Model-Driven Architecture (MDA)

Vision from OMG
- Models at different level of abstraction
★ Platform Independent Model (PIM)
★ Platform Speciﬁc Model (PSM)

- Model transformation
★ e.g. PIM to PSM to implementation
★ transformations not necessarily automatic

- UML as standard modeling language
★ models are ‘visual’ or ‘graphical’


‘Formal Methods’
Logic

Problem
HLL Machine
Domain


A critique of MDA & formal methods

General purpose modeling languages
- High coverage
★ large class of software systems

- Low expressivity
★ irrelevant details
★ Requirements/implementation gap not reduced


Domain-Speciﬁc Languages

Problem
DSL HLL Machine
Domain

domain-speciﬁc languages: models specialized to an application domain

DSLs provide domain-speciﬁc ...
Abstractions
★ directly represent domain concepts

Concrete syntax
★ natural notation

Optimization
★ based on domain assumptions

Error checking
★ report errors in terms of domain concepts

Tool support
★ interpreter, compiler, code generator, IDE

Example Domain-Speciﬁc Languages (1)

Spreadsheet
★ formulas, macros

Querying
★ SQL, XQuery, XPath

Graph layout
★ GraphViz

Web
★ HTML, CSS, RSS, XML, XSLT
★ Ruby/Rails, JSP, ASP, JSF, WebDSL


Example Domain-Speciﬁc Languages (2)

Games
★ Lua, UnrealScript

Modeling
★ UML, OCL, QVT

Language processing
★ YACC, LEX, RegExp, ANTLR, SDF
★ TXL, ASF+SDF, Stratego


Transformation

Model analysis Model migration Model

construct

extract

System


External DSL

Dedicated language
★ independent of host/target language (portable)
★ implementation with interpreter or compiler

Advantages
★ language tuned to domain
★ domain-speciﬁc errors, analysis, optimizations

Disadvantages
★ cost of learning new language
★ cost of maintaining language


Internal DSL
Library in HLL
★ Haskell, Scala, Ruby, ...
★ API is language
★ language features for ‘linguistic abstraction’

Advantages
★ host language = implementation language

Disadvantages
★ host language = implementation language (encoding)
★ lack of portability
★ no domain-speciﬁc errors, analysis, optimization


This Course


Course Goal

Learn to design and implement
domain-speciﬁc languages

Understand DSL design choices and make
reasoned decisions about their application

Application
DSL
Domain
domain analysis

language deﬁnition
Programming abstraction
Language
Patterns Design


Course Ingredients

Lectures (14x)

Designs (2x)

Cases (6x)

Exams (2x)


Lectures (14x)

Note: no lecture in week 4, moved to week 8

Domain Analysis & Data Modeling

Lecture 2

Abstractions for the Web

Lectures 3-5

Language Workbenches

Lecture 6

Language Modeling

Lectures 6-7

Transformation, Generation, Analysis

Lectures 8-10

Customization

Model

generate

customize Code
Lecture 10

Advanced Topics

- Economics
★ costs and beneﬁts of developing (with) DSLs

- Evolution
★ maintenance of models and languages

- Portability
★ supporting multiple platforms

- Internal DSLs
★ library as a language

- Language composition
★ combining multiple DSLs
Lectures 12-14

Designs (2x)


Designs (= lab project in pairs)

Design 1
★ Web Application with WebDSL

• domain analysis
• software development with a DSL

Design 2
★ DSL with Stratego & Spoofax/IMP

• design and implement a DSL
• use rule-based DSLs for language deﬁnition

You propose web app and language to design
★ (We can give tips if you’re stuck)


Cases (6x)


Cases (= individual home work assignments)
- Goals
★ understand and apply modeling approaches
★ solve small design problems
★ compare alternative solutions

- Six cases
★ domain analysis and data modeling
★ web abstractions
★ language modeling
★ generation, transformation, analysis
★ customization
★ advanced topic


Exams (2x)


Exams

Goals
- test understanding of course material
- small design problems
- comparison of approaches
When
- midterm (after period 3)
- ﬁnal (after period 4)
- if(midterm >= 6) { make half of ﬁnal exam }


Grading

design := 0.4 * design1 + 0.6 * design2

exam := if(exam1 >= 6) {
(exam1 + exam2)/2 }
} else { exam2 }

case := average(i : 1 to 6) { case[i] }

final := 0.4 * design + 0.2 * case + 0.4 * exam

pass := design1 >= 6 && design2 >= 6 && exam >= 6
&& [c | c in case where c >= 6].length >= 4


Feedback

This is a new course
I’d like to get feedback early
Not when it is too late to ﬁx

Volunteers for feedback group?
Short meeting Thursdays at start of lab


Website

http://department.st.ewi.tudelft.nl/course/IN4308

Schedule
Lab this week:
★ Find a partner
★ Make design proposal for a web application
★ WebDSL tutorial

Read
★ Czarnecki: Overview of Generative Development
★ Muller et al.: Modeling Modeling

Next week
★ Domain analysis & data modeling

No lecture week 4, moved to week 8!

Model-Driven Software Dev Intro

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