SOEN 343 Software Design Section H Fall 2006 Dr Greg Butler http://www.cs.concordia.ca/~gregb/home/soen343h-f06.html Course Introduction • • • • • • • • Course People Course Components What the course is What the course is not Enterprise Application (Assignments) Larman’s Design Process What is OO Analysis and Design Design Pattern Example - Command Course People – Section H Instructor: Dr Greg Butler Office Hours: Wednesdays 15:00 to 16:00 Or by appointment But ask questions in class please TAs: Asif Dogar & Rajiv Abraham Course Coordinator: Dr Patrice Chalin Course Components Lectures: WF 13:15 to 14:30 CL-220 Tutorials: F 14:45 to 15:35 In Lab to be announced; start week 2 Assignments: 3-4, every 2 weeks, start week 8, worth 5-15% Midterm Exam: week 7, worth 25-35% Quizzes: 2-3, approx. weeks 4, 10,.. worth 5-10% Final Exam: worth 50-60%; you must pass final Basic Questions (Let’s Discuss) What is software design? How is it different from software programming? Software development? How do we design software? What is the role of objects, layers, architecture, ..? What is the role of tests, responsibilities, patterns, models, …? How does design fit into the software lifecycle? What is good design? How does software design differ from … design? Course Objectives • “Think in Objects” • Practice • Analyze requirements with • Apply agile modeling use cases • Design object solutions • Create domain models – Assign responsibilities to objects • Apply an iterative & agile Unified Process (UP) • Relate analysis and design artifacts • Read & write highfrequency UML – Design collaborations – Design with patterns – Design with architectural layers – Understand OOP (e.g., Java) mapping issues What the course is: A (first) look at OO design! Design process: domain model, use cases, design Emphasis: models, GRASP principles, design patterns, responsibility, collaboration Mentions: RDD, TDD, MDD, extensibility Closely follows textbook! What the course is not: A course in UML, Java • You should know the basics of these • And become expert (as needed) yourself A course in tools: Eclipse, XDE, JUnit • You can work through tutorials yourself A course in UI design, DB design A course in software engineering, software architecture, software reuse, … Lectures Review of Java and object-oriented programming Responsibility Driven Design following Larman • Each object has responsibility (ies) • GRASP principles for distribution of responsibilities • GoF design patterns • Application of principles and patterns to examples/assignments Domain Modeling Introduction to Enterprise Applications • Fowler’s patterns • Application of GRASP principles in Fowler’s patterns • Application in assignments Transition from requirements to design following Larman Enterprise Applications Patterns Assignments (and some lectures) are about building web-based systems for enterprise applications Involve Presentation on the web Business Logic and Business Objects Data storage and access use book of Martin Fowler, “Patterns of Enterprise Application Architecture” Data Source Domain Presentation Fowler’s EA Patterns Page Controller Template View Front Controller Transform View Transaction Script Active Record Domain Model Table Module Data Mapper Row Data Gateway Table Data Gateway Larman’s Design Process Sample UP Artifact Relationships Domain Model Sale Business Modeling Sales LineItem 1..* 1 date ... ... ... quantity Use-Case Model Process Sale Process Sale use case names Cashier Requirements Use Case Diagram starting events to design for, and detailed postcondition to satisfy Design non-functional requirements functional requirements that must be realized by the objects Use Case Text system events ideas for the postconditions inspiration for names of some software domain objects Supplementary Specification 1. Customer arrives ... 2. ... 3. Cashier enters item identifier. domain rules : System Glossary Operation: enterItem(…) Post-conditions: -... : Cashier system operations make NewSale() enterItem (id, quantity) item details, formats, validation System Sequence Diagrams Operation Contracts Design Model : Register : ProductCatalog enterItem (itemID, quantity) d = getProductDescription(itemID) addLineItem( d, quantity ) Register ProductCatalog ... makeNewSale() enterItem(...) ... ... * 1 getProductDescription(...) ... : Sale Domain Model Pays-for-overdue-charges  VideoRental CashPayment Pays-for  amount : Money 1 1 date 1 1 1 * dueDate returnDate returnTime 1..* * Initiates  1 0..1 RentalTransaction Records-rental-of  1 Rents 1..* Customer VideoStore Rents-from  address name 1 phoneNumber address name phoneNumber 1 * 1 1 Maintains Has  Video Stocks * ID * 1 Owns-a  1 1 * Membership Catalog ID startDate 1 Described-by  1 1..* VideoDescription LoanPolicy 1 Defines perDayRentalCharge perDayLateCharge 1..* 1 1..* 1 title subjectCategory Determines-rental-charge  * Use Case Model Partial artifacts, refined in each iteration. Use-Case Model :System foo( x ) Requirements bar( y ) text use cases use case diagrams system sequence diagrams system operations system operation contracts Typical Software Architecture Layers handles presentation layer requests workflow session state window/page transitions consolidation/transformation of disparate data for presentation handles application layer requests implementation of domain rules domain services (POS, Inventory) - services may be used by just one application, but there is also the possibility of multi-application services very general low-level business services used in many business domains CurrencyConverter (relatively) high-level technical services and frameworks Persistence, Security low-level technical services, utilities, and frameworks data structures, threads, math, file, DB, and network I/O UI (AKA Presentation, View) more app specific Application (AKA Workflow, Process, Mediation, App Controller) dependency GUI windows reports speech interface HTML, XML, XSLT, JSP, Javascript, ... Domain (AKA Business, Application Logic, Model) Business Infrastructure (AKA Low-level Business Services) Technical Services (AKA Technical Infrastructure, High-level Technical Services) Foundation (AKA Core Services, Base Services, Low-level Technical Services/Infrastructure) width implies range of applicability Typical Software Architecture Layers (Simplified) UI Swing not the Java Swing libraries, but our GUI classes based on Swing Web Domain Sales Payments Taxes Logging RulesEngine Technical Services Persistence What is Design? Developing a blueprint (plan) for a mechanism that performs the required task, … taking into account all the constraints, & … making trade-offs between constraints when they are in conflict. What is OO Analysis and Design • Object-Oriented Analysis • Object-Oriented Design – Important domain concepts or objects? – Design of software objects – Vocabulary? – Responsibilities – Collaborations – Visualized in the UP Domain Model – Design patterns – Visualized in the UP Design Model Important Concepts Model • Abstraction hiding (unimportant) details • Eg, cover of Larman’s book GRASP Principle • for assigning responsibility Design pattern • Solution to design problem in context • Eg, Command pattern Responsibility-Driven Design (RDD) • Detailed object design is usually done from the point of view of the metaphor of: – Objects have responsibilities – Objects collaborate • Responsibilities are an abstraction. – The responsibility for persistence. • Large-grained responsibility. – The responsibility for the sales tax calculation. • More fine-grained responsibility. The 9 GRASP Principles 1. 2. 3. 4. 5. 6. 7. 8. 9. Creator Expert Controller Low Coupling High Cohesion Polymorphism Pure Fabrication Indirection Protected Variations Overview of Patterns •Present solutions to common software problems arising within a certain context •Help resolve key software design forces •Capture recurring structures & dynamics among software participants to facilitate reuse of successful designs •Generally codify expert knowledge of design strategies, constraints & “best practices” AbstractService service Client Proxy service Service 1 1 service The Proxy Pattern •Flexibility •Extensibility •Dependability •Predictability •Scalability •Efficiency Command Pattern Problem: How to allow the same command to be invoked by – Menu selection – Alt-ctrl shortcut – Commandline text entry, etc • How to allow (unlimited) undo/redo • How to keep a log/audit/history of commands invoked • How to allow “macro” commands to be defined Command Pattern • You have commands that need to be – executed, – undone, or – queued • Command design pattern separates – Receiver from Invoker from Commands • All commands derive from Command and implement do(), undo(), and redo() • Also allows recording history, replay