OO Administrative
Introduction Basics
Lecture 1 Wednesday March 8, 2006
Instructor
Dr. Ying ZHOU ([e-mail]) Office: Madsen G89
Consultation: Wednesday 4-5pm
Lectures
Wednesday 6-8 pm Carslaw Lecture Theatre 373
Labs
Wednesday 8-9 Carslaw Lab 202 B/C
Course Website:
http://www.cs.usyd.edu.au/~comp5028/s1_2006
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Agenda
Administrative Course objective and outline OO Basics
Whats OOAD? Functional decomposition and its problem Whats UML? Software Development Process
Objectives
Learn O-O A&D methodology Understand why a methodology is useful for real software projects Learn UML (Unified Modeling Language) Learn O-O design patterns Build something that illustrates the concepts
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Expectations
Assumed Knowledge
Java or other similar OO language (C#) Java is the official language in this course
Assessment Components
Two project assignments
Assignment 1 (15%)
System analysis Due on week 6
Assignment 2 (25%)
System design and implementation ( Java ) Due on week 11 Demo on week 12 & 13
Before each lecture
Download and printout the lecture slides Read the related chapter and lectures notes Read the tutorial instruction
Make sure you keep up with the progress
Consult course staff EARLY enough for difficulties and problems!
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Results will be published on webCT two weeks after the due date, please check webCT to make sure that your results are correctly recorded. Any discrepancies should be resolved within one week after the result being published! Final Exam (60%)
Closed book Sample exam will be given Should expect question regarding coding No upset in the exam
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Course Outline
Four Major parts of the content
Inception (2 weeks) Elaboration Iteration 1 (4 week)
Analysis, basic design, design to code
Team Work
Software development is a team-oriented activity Two assignments will work around the same project You need to work in the same team for both assignments Preferred team size: 2-3 students Form your team as early as possible
Elaboration iteration 2 (3 weeks)
Design principles and patterns
Elaboration iteration 3 (4 weeks)
More design patterns
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Team project
Your client:
Charites Inc. a search engine company
Our Textbook
Craig Larman, Applying UML and Patterns: An Introduction to ObjectOriented Analysis and Design and the Unified Process, 3rd edition, Prentice Hall PTR, 2005 Detailed Intro to ObjectOriented Analysis & Design Unified Modeling Language (UML) Design Patterns Unified Process
Your goal:
Design a system to collect information from weblogs Provide an interface for users to retrieve certain link information of a weblog posting Provide a web services API for applications which needs to analyze those links
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Possible team tasks (subject to further refinement)
Reference Books
Martin Fowler, UML Distilled, 3rd edition, AddisonWesley, 2004 Robert C. Martin, Agile Software Development: Principles, Patterns and Practices, Prentice Hall, 2003 Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides, Design Patterns, Addison-Wesley, 1995 Allan Shalloway ,James R. Trott Design patterns explained: A new perspective on Object-Oriented Design, 2nd edition, Addison-Wesley, 2005. Martin Fowler, Kent Beck, John Brank, William Opdyke, Don Roberts, Refactoring, Addison-Wesley, 1999
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Write concept document, sketch architecture, list requirements questions Draft requirements document, list use cases, specify user interface Write use cases, model domain classes Model solution (design) classes & behavior Model package structure Initial prototype implementation of a subset of the critical functional requirements
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Software
Microsoft Visio
Licensed software Installed on the lab
Todays lecture topic
Whats OOAD? Functional decomposition and its problem Whats UML? Software Development Process
JCreator
Free Java IDE
JUnit
Open source software Test-driven development
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Rule of Conducts
Okay to discuss ideas and problem approaches All work must be your own creation Plagiarism will not be tolerated under any circumstance! What is plagiarism Copying all or part of another students work (with or without their knowledge) Using another persons ideas without acknowledgement Obtaining material (code or other) from the web or a book and passing it off as your own
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What is Analysis and Design
Analysis emphasizes an investigation of the problem rather than how a solution is defined Design emphasizes a logical solution, how the system fulfills the requirements
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Analysis and Design (cont)
Division between A & D is fuzzy A & D activities exist on a continuum Some practitioners can classify an activity as analysis while others put it into design category
More analysis oriented More design oriented
Object vs. Function Oriented Analysis
Library Info System
O-O A&D
Decompose by objects and concepts
Structured A&D
Decompose by functions and processes
-what -requirements -investigation of domain -understanding of problem
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-how -logical solution -understanding and description of solution
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Catalog
Librarian
System
Book
Library
Record Loans
Add Resource
Report Fines
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What is O-O A&D?
The essence of O-O A&D is to consider a problem domain and logical solution from the perspective of objects (things, concepts, or entities) O-O Analysis emphasizes finding and describing the objects or concepts- in the problem domain O-O Design emphasizes defining logical software objects (things, concepts, or entities) that have attributes and methods
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Functional Decomposition
A very simple development case
You are asked to write code to access a list of shapes that were stored in a database then display them
What steps we need to achieve this?
1. 2. 3. 4.
Locate the list of shapes in the database Open up the list of shapes Sort the list according to some order Display the individual shapes on the monitor
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Functional Decomposition
We might breakdown some step further
a. b. c.
A software like option
Steps: Get list of people in the class For each person on this list, do the following: Find the next class he or she is taking Find the location of that class Find the way to get from your classroom to the personas next class Tell the person how to get to his or her next class
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Identify the type of shapes Get the location of the shape Call the appropriate function that will display the shape, giving it the shapes location
This is called functional decomposition because the analyst breaks down (decomposes) the problem into the functional steps that compose it.
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Procedures needed: A way of getting the list of people in the class A way of getting the schedule for each person in the class A program that gives someone directions from your classroom to any other classroom A control program that works for each person in the class and does the required steps for each person
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How do people do things
Case:
You are an instructor at a seminar. People in your seminar have another class to attend following yours, but dont know where it is located. One of your responsibilities is to make sure everyone knows how to get to the next class.
A human like option
Whats the alternatives?
Post a directions to go from this classroom to the other classrooms and tell everyone in the class
I have posted the locations of the other classes following this in the back of the room, as well as the locations of the other classrooms. Please use them to go to your next classroom.
Assume everyone knows what his or her next class is
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Difference?
Option 1: giving explicit directions to everyone pay attention to lots of details. You are responsible for everything Option 2: giving general instructions and then expect each person will figure out how to do the task individually Key point: Shift of responsibility!
Dealing with changing requirements
What makes it happen?
The people are responsible for their own behavior The control program can talk to different types of people as if they were exactly the same The control program does not need to know about any special steps that students might need to take when moving from class to class
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Dealing with changing requirements
Impact
What if you need to distinguish postgraduate from students undergraduate students? Option 1: change the control program a lot Option 2: add an additional routine for graduate students to follow
Unified Modeling Language
A language for specifying, visualizing and constructing the artifacts of software system [Booch, Jacobson, Rumbaugh] It is a notational system aimed at modeling systems using O-O concepts not a methodology not a process
The second case can minimize changes
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Ways of using the UML
UML as sketch
Developers use the UML to communicate some aspects of a system: selectivity Forward engineering Reverse engineering
What is legal UML?
Legal UML is what is defined as well formed in the specification Prescriptive rules A language with prescriptive rules is controlled by an official body that states what is or isnt legal in the language and what meaning you give to utterances in that language Descriptive rules A language with descriptive rules is one which you understand its rules by looking at how people use the language in practice
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UML as blueprint: completeness
CASE tools: do code generation or build diagrams from code
UML as programming language
Draw UML diagrams that are compiled directly into executable code.
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UML diagrams
Use case diagram Class diagram Behavior diagrams:
statechart diagram activity diagram interaction diagrams:
Key Steps in OOAD [1]
Define use cases Define domain model Define interaction diagrams Define design class diagrams
Use Case: a textual description or story describing the system Example: Play A Dice Game: A player picks up and rolls the dice. If the dice face values total seven, they win; otherwise, they lose.
Sequence diagram Collaboration diagram Implementation diagrams:
component diagram deployment diagram
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Key steps in OOAD [2]
Define use cases Define domain model Define interaction diagrams Define design class diagrams
Key steps in OOAD [4]
Define use cases Define domain model Define interaction diagrams Define design class diagrams
Domain Model: diagram(s) showing domain concepts, attributes, and associations Example:
name 1 Plays 1 DiceGame 1 Includes Player 1 Rolls 2 Die faceValue 2
Class Model: shows attributes, methods and associations for software (solution) objects (not domain objects!) Example:
DiceGame die1 : Die die2 : Die play() 1 2
Die faceValue : int getFaceValue() : int roll()
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Key steps in OOAD [3]
Define use cases Define domain model Define interaction diagrams Define design class diagrams
Iterative and Evolutionary Development
Iterative development
Development is organized into a series of short, fixed-length mini-projects called iterations. The outcome of each is a tested, integrated, and executable partial system. Known as iterative and incremental development
Interaction Diagram: shows the flow of messages between software objects (method invocation) Example:
:DiceGame play() roll() fv1 := getFaceValue() roll() fv2 := getFaceValue() die1 : Die die2 : Die
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Iterative and evolutionary development
Requirements Design Implementation & Test & Integration & More Design Final Integration & System Test Time Requirements Design Implementation & Test & Integration & More Design Final Integration & System Test Feedback from iteration N leads to refinement and adaptation of the requirements and design in iteration N+1.
How long should an iteration be?
Most iterative methods recommend an iteration length between two and six weeks. Iteration are timeboxed, or fixed in length Date slippage is illegal If it seems difficult to meet the deadline, the recommended response is to de-scope remove tasks or requirements from the iteration, and include them in a future iteration
4 weeks (for example) Iterations are fixed in length, or timeboxed . The system grows incrementally.
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Handle change on iterative project
Early iterations are farther from the "true path" of the system. Via feedback and adaptation, the system converges towards the most appropriate requirements and design. In late iterations, a significant change in requirements is rare, but can occur. Such late changes may give an organization a competitive business advantage.
The oldest waterfall lifecycle
Attempt to define all or most of the requirements before programming. To create a thorough design before programming Strongly associated with high rates of failure, lower productivity, and higher defect rates. 45% of the features in waterfall requirements are never used, early waterfall schedules and estimates vary up to 400% from the final actuals.
one iteration of design, implement, integrate, and test
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Mini workshop
Which one of the following is true iterative development
Ive done five iterations on requirement collection and the client finally satisfied and signed off the requirement document. We take iterative method to achieve good database design. After the first interview with the client, we make an initial design of the database and brought this to t...