Calidad de Software: Programación Modular y Anti-Patrones de Proyecto

1. Day 1 : Introduction
   • Factors of software quality
   • Characteristics of OO programming
   • Introduction to the Java language
2. Day 2 : Principles
   • Notation: a bit of UML
   • Principles of class design
   • Principles of package design
3. Day 3 : Patterns
   • Design patterns
   • Parametric polymorphism
   • A tiny bit about data structures
4. Day 4 : Testing
   • Error handling
   • Agile development
   • Testing driven development
5. Day 5 : Conclusion
   • Active objects
   • Inversion of control
   • Anti-patterns

• Exercises.

References

• Quality of Software , by Bertrand Meyer.
• Software Quality.
• ISO 9126

Characteristics of OO programming

• Many languages are called objected oriented: Java, C++, C#, Scala, Eiffel, Ruby, Smalltalk, Python, PHP 5.0, JavaScript, Perl, etc, etc, etc
• Some features are common across most of these languages:
  • Objects and Classes.
  • Computation as message passing
  • Information hiding
  • Exception handling
  • Inheritance
  • Subtyping
  • Overloading
  • Dynamic Binding
  • Run-time type interrogation
  • Heavy heap usage

Let's discuss

• Why is OO programming so popular?

Supplementary material

• Exercises.

References

• Object Oriented Programming
• Not everybody loves OOP.

Introduction to the Java Language

• Java is an imperative language: references, commands, iterations and side-effects
• Virtual Machines
• Interfaces, classes and packages
• Fields and methods: instance and class members.
• Variations: abstract, anonymous and nested classes.

Let's discuss

• Why is Java so popular?

Supplementary material

• Exercises.

References

• The Java Language
• Sun's getting started tutorial on Java.

• Exercises.

References

• Use case diagrams.
• Class diagrams.
• Sequence diagrams.
• Collaboration diagrams.

Principles of Class Design

• The open closed principle (OCP): A module should be open for extension but closed for modification
• The Liskov Substitution Principle (LSP): Subclasses should be substitutable for their base classes
• The Dependency Inversion Principle (DIP): Depend upon abstractions. Do not depend upon concretions
• The Interface Segregation Principle (ISP): Many client specific interfaces are better than one general purpose interface

Let's discuss

• How to set up a job interview to find out if a candidate is a good programmer?

Supplementary material

• Exercises.
• Sample programs.

References

• Design Principles and Design Patterns - pages 1-16.
• Open-closed
• Liskov's substitution
• Interface segregation
• Inversion of dependency

Principles of Package Design

• The Release Reuse Equivalency Principle (REP): The granule of reuse is the granule of release
• The Common Closure Principle (CCP): Classes that change together belong together
• The Common Reuse Principle (CRP): Classes that aren't reused together should not be grouped together
• The Acyclic Dependencies Principle (ADP): The dependencies between packages must not form cycles
• The Stable Dependencies Principle (SDP): Depend in the direction of stability
• The Stable Abstractions Principle (SAP): Stable packages should be abstract packages

Let's discuss

• Do we start a project by designing packages, or classes?
• Instability, according to our definition, is not bad. When should we have instability?

Supplementary material

• Exercises.
• Sample programs.

References

• Design Principles and Design Patterns - Pages 16-28.
• Granularity
• Java packages
• Stability

• Exercises.
• Sample programs.

References

• Design patterns in Java

Parametric Polymorphism

• A value or operation is polymorphic if it has at least two different types.
• Polymorphism ad-hoc presents a finite number of iterations: overloading and coercion.
• Universal polymorphism presents an infinite number of variations: parametric and subtyping.
• Polymorphism parametric, in Java, is known as generics. Not the same as C++'s templates, but similar.

Let's discuss

• How is parametric polymorphism in other languages?

Supplementary material

• Exercises.
• Sample programs.

References

• Generics in Java
• An example of how useful is parametric polymorphism.

Data Structures

• A data-structure is a way to organize data. Examples: lists, hash tables, trees, stacks, etc.
• Java provide a library called Java Collections.

Let's discuss

• Given that so many data-structures are ready for use in a language such as Java, should their implementation be taught in the CS syllabus?

Supplementary material

• Exercises.
• Sample programs.

References

• Josh Bloch's tutorial on Java Collections.
• Interface oriented programming (Portuguese)

• Exercises.
• Sample programs.

References

• 10 good advices about exception handling.
• Exception handling in general programming languages.
• Exception handling in Java.
• checked and unchecked exceptions.

Agile Development

• Requirements change all the time, so it is hard to develop software with static specification methods.
• Agile development is marked by the constant release of software
• Extreme programming has two canonical characteristics: pair programming and test oriented development.

Let's discuss

• What are the trade-offs that we face in pair programming? Is is not contra-productive to put two programmers working on the same machine?

Supplementary material

• Exercises.

References

• On-line chapter about extreme programming.
• Extremme programming in practice.

Testing Driven Development

• There are three basic ways to find bugs: formal verification, translation validation and testing.
• Test Driven Development is a methodology characterized by first writing tests, and then writing the program to pass these tests.
• For each major part in the software development cycle we have a major testing phase.

Let's discuss

• When to stop testing software?

Supplementary material

• Exercises.
• Sample programs.

References

• Test Driven Development

• Exercises.
• Sample programs.

References

• Tutorial sobre Threads em Java

Inversion of Control

• A library is a set of modules that provide functions to be called by a client. Example: Java collections.
• A framework is a set of modules that call methods provided by clients. Example: Java swing.
• Principle of Single Responsability (SRP): there should never be more than one reason for a class to change

Let's discuss

• Which famous frameworks and libraries do we know?

Supplementary material

• Exercises.
• Sample programs.

References

• A good introductory reading about IoC , (in Portuguese).
• The Hollywood principle.
• The Single Responsibility Principle.
• Dependency injection.

Anti-patterns

• An anti-pattern is a design pattern that, although may seem good at first, compromises the quality of the software.
• Some common characteristics: repetitive, easily documented, it can be removed by means of well known solutions.
• There are many types of anti-patterns: organizational, management, analysis, project, programming, methodology, etc

Let's discuss

• Are there any examples from real life that we could share?

Supplementary material

• In the last class we will not have exercises. Instead, we will organize a debate about anti-patterns. Choose your topic.

References

• Anti-patterns