Ch4: Software Architecture and Design

1 The role of analysis and design  Software construction may be partitioned into the following phases:  Req. analysis:  S/w architecture:  High-level/early design:  Detailed design:  Implementation:  Testing:

2 The Role of Analysis and Design  Analysis:  OO Analysis:  Design:  OO design:

3 Guidelines for designing classes Specifying “Good” Classes  Identifying a good class is hard work  A well-defined class is:

4 Guidelines for design of classes (contd..) Understanding the utility of classes  Three categories of software in application:  Domain independent (20%):  Domain-specific (65%):  Application-specific (15%):  Organizations must strive for domain and organization specific reuse.

5 Guidelines for designing classes  Containment vs. inheritance  Class D “Is-A-Kind-Of” class C:  Class D “Has-A” class C:  Choose How and when to apply reuse, relationship among classes. Need discussion, communication and cooperation among engineers.

6 History of OO design  Booch: The Booch method  Object-Oriented Design with Application,” Benjamin/Cummings,  Rumbaugh: OMT  “Object-Oriented Modeling and Design,” Prentice-Hall,  Meyer: Client/Server contract approach  “Object-Oriented Software Construction,” Prentice-Hall,  Jacobson: Use-cases and software engineering  “Object-Oriented Software Engineering: A Use Case Driven Approach,” Addison-Wesley, 1992.

7 History of OO design (contd..)  Coleman: The Fusion method  “Object-Oriented Development - The Fusion Method,” Prentice- Hall,  Lieberherr: Adaptive OO software  “Adaptive OO Software: The Demeter Method with Propagation Patterns,” PWS,  Gamma: Design Patterns  “Design Patterns: Elements of Reusable Object-Oriented Software,” Addison-Wesley,  Booch and Rumbaugh: UML Predecessor  “Unified Method for Object-Oriented Development,” Rational TR, 1995

8 The emergence of UML  The Unified Modeling Language (UML) is the object-oriented analysis and design equivalent of Java  UML is a language for  Web address:  UML unifies:  Object-oriented analysis and design: Grady Booch approach.  Object-oriented modeling and design: Jim Rumbaugh  Object-oriented SE, A use case drive approach: Jacobson  A modeling language provides:

9 Seven goals of UML  Ready-to-use, expressive visual modeling language that promotes development/exchange  Extensibility/specialization of core concepts  Independent of programming languages and development processes  Formal basis for understanding language  Encourage growth of OO tools market  Support higher level design concepts:  Collaborations, frameworks, etc.  Collaborations, frameworks, ptterns, etc.  Integrate the best practices of all OOD

10 Characteristics of UML  Generic syntax:  Syntax is independent of:  Flexible syntax:

11 UML modeling constructs/diagrams  User interaction diagrams  Use-case diagrams  Static structure diagrams  Class diagrams  Object diagrams  Behavior diagrams  Statechart diagrams  Activity diagrams  Interaction diagrams  Sequence diagram  Collaboration diagram  Implementation diagrams  Component diagram  Deployment diagram

12 Class diagrams  Class in UML:  Representation of classes:  Designer develops classes as sets of compartments that grow over time to incrementally add functionality and features

13 Example class diagram CustomerAccount + Account: Int + Name: String + Address: String + Balance: Float + AddCustomer() + DeleteCustomer() + GetBalance() Name Attributes Operations “+” indicates that the attribute/operation is public “-” indicates that the attribute/operation is private “#” indicates that the attribute/operation is protected

14 Relationships among classes  Inheritance  Association  Aggregation

15 Generalization/Specialization (Inheritance) BankAccount CheckAccount SavAccount Checking Account and Savings Account are special cases of Bank Account

16 Generalization/Specialization (Inheritance) Employee Admin_staff Tech_staff Administrative Staff and Technical Staff are special cases of the class Employee

17 Association Course 1 * Instructor Multiplicity constraints indicate how many objects participate in the association. May be specified as -- upper_bound….lower_bound 1, 1:1 – Only one object *, 1:* - At least one object * -- any number of objects between 0 and infinity Relationship among instances of objects of one class and instances of objects among other classes. Represent using a line, label each end With how many objects participate in the association.

18 Association (contd..) Multiplicity 1:3 indicates that each Instructor teaches at least one course but no more than three courses. Course 1 1:3 Instructor

19 Association (contd..) * 1 TechStaff Manager 1 Project 1…* project_member manages

20 Aggregation Store Depts. 5 Objects are composed of simpler objects. Triangle consists of three points.

21 Class Diagram: High Tech SuperMarket System Consider the process of updating the inventory in the high-tech supermarket system. Central to the process is an inventory order. An inventory assistant in the HTSS is responsible for managing a inventory order. In addition, each inventory assistant may be involved in managing several inventory orders. An inventory order is associated with a list of items. Each item in the list can be of three types, namely, snack item, liquor item, and canned item. Each inventory order is submitted to three wholesale stores. Each wholesale store caters to a specific set of items. For example, the Liquor Store is responsible for delivering liquor items. These three wholesale stores, are, namely, Liquor Store, Produce Store, and Snack Store. Construct a UML class diagram to model the process of inventory update in the HTSS.

22 Class diagram: HTSS InvenOrder InvenAssist WholeStore ItemList Item LiqStore ProdStore SnStore PerishItem NPerishItem 1 * * …3 1

23 UML tools  Argo UML   Object Domain   Rational Rose:   Microsoft Visio