1. Unified Modeling Language (UML) for OO domain analysis CSE432 Prof Glenn Blank

2. Notation wars Early 90’s: 6-10 different notations Bertrand Meyer: circles and arrows Bertrand Meyer: circles and arrows Bertrand Meyer Bertrand Meyer Distinguishes inheritance and client/supplier relationships Distinguishes inheritance and client/supplier relationships Grady Booch: clouds, lines and decorations Grady Booch: clouds, lines and decorations Grady Booch Grady Booch GardeningPlan – Association- Environmental Controller GardeningPlan – Association- Environmental Controller Heater and Cooler – Generalization/Specialization-> Actuator Heater and Cooler – Generalization/Specialization-> Actuator Environmental Controller ●-“has a”- Heater (Cooler, Light) Environmental Controller ●-“has a”- Heater (Cooler, Light) Actuator o– “using” – Temperature (client/supplier) Actuator o– “using” – Temperature (client/supplier) Actuator is an abstract class (‘A’ in a triangle) Actuator is an abstract class (‘A’ in a triangle) Peter Coad, Ed Yourdon & Jill Nicola: Peter Coad, Ed Yourdon & Jill Nicola: Peter Coad, Ed Yourdon & Jill Nicola Peter Coad, Ed Yourdon & Jill Nicola Rounded boxes and annotated lines Rounded boxes and annotated lines Line bisected by semi-circle represents generalization (inheritance) Line bisected by semi-circle represents generalization (inheritance) Line bisected by triangle represents whole/part Line bisected by triangle represents whole/part So, what’s your reaction to all these (and more) notations? So, what’s your reaction to all these (and more) notations? “Can’t we all get along?” Hence three amigos create UML in mid-90’s “Can’t we all get along?” Hence three amigos create UML in mid-90’s

3. Closer look at Coad & Nicola Two different boxes grouping classes: HIC (Human Interaction Component) HIC (Human Interaction Component) PDC (Problem Domain Components) PDC (Problem Domain Components) Why is “Separation of Concerns principle” a good idea? Why is “Separation of Concerns principle” a good idea? First person scenarios Coad & Nicola call this the "I'm alive principle": Coad & Nicola call this the "I'm alive principle": Objects can be better understood by thinking about them and talking about them in the first person: "I know my own ____ and I can ___ myself." What goes in the blanks? What goes in the blanks? Attributes and behaviors Why is putting these scenarios in the first person a good idea? Why is putting these scenarios in the first person a good idea? Promotes “object-think”: objects are autonomous, performing behaviors Similarly, Kent Beck talks about the need for anthropomorphism in responsibility-driven design

4. Class diagrams in UML Class diagrams in UML Classes are boxes, lines are associations Add decorations to lines to refine them Add decorations to lines to refine them But before we study the decorations…. But before we study the decorations….

5. A heuristic for class diagram design Don't put any decorations on the associations at first Semantics of relations tends to be vague “Is a" relationship can mean SUBTYPE ("a square is a polygon") “Is a" relationship can mean SUBTYPE ("a square is a polygon") or INSTANCE ‑ OF ("George is a square") or INSTANCE ‑ OF ("George is a square") or IDENTICAL ‑ TO ("The morning star is the evening star") or IDENTICAL ‑ TO ("The morning star is the evening star") or PROPERTY ‑ OF ("A circle is a round object") or PROPERTY ‑ OF ("A circle is a round object") or ROLE ‑ OF ("George is a President") or ROLE ‑ OF ("George is a President") or MADE ‑ OF ("My house is a brick one") or MADE ‑ OF ("My house is a brick one") or simply EXISTS (“To be or not to be…"). or simply EXISTS (“To be or not to be…"). In many languages, there is no verb "is" at all, or it’s rarely used. In many languages, there is no verb "is" at all, or it’s rarely used. Let the meaning of relations emerge from what they relate Vagueness is natural: start off vague, get more specific gradually Vagueness is natural: start off vague, get more specific gradually UML supports this heuristic by starting with simple undirected lines (associations) Later, add detail to your relationship structures

6. Two basic relationships of O-O OOA typically distinguishes two relations: is ‑ a and has ‑ a Why two? That’s what O-O programming languages implement: Smalltalk and Java: instance variables and inheritance Smalltalk and Java: instance variables and inheritance C++: data members and class derivation C++: data members and class derivation Meyer calls these inheritance and client/supplier Booch: generalization/specialization and association or aggregation or composition Coad and Yourdon: gen/spec and whole/part UML calls these generalization and association or aggregation or composition

7. Generalizations (inheritance) Extract commonality among specializations Extract commonality among specializations UML uses arrow UML uses arrow Generalizations form a hierarchy Generalizations form a hierarchy Multiple inheritance forms a lattice Multiple inheritance forms a lattice

8. Associations Client-supplier/association/whole ‑ part Typically parts or members of a class Typically parts or members of a class Multiplicity: numbers at connection ends Manager -1――* -> Employee Manager -1――* -> Employee Denotes 1 to many (*) relationships Denotes 1 to many (*) relationships 0 to many, 1 to 1 relationships also common 0 to many, 1 to 1 relationships also common From Extended Entity ‑ Relation models (EER) From Extended Entity ‑ Relation models (EER) Role names at one connection end: Role names at one connection end: Manager ―― sales rep -> Employee Manager ―― sales rep -> Employee Employee's role is sales rep Employee's role is sales rep

9. Five activities of OOA Coad, Yourdon and Nicola: 1) Class ‑ & ‑ object: describe problem domain in terms of classes of objects 2) Structure: describe relationships between classes 3) Subject: organize classes into clusters or packages 4) Attributes: describe data held by objects 5) Services: describe behaviors that objects can perform Which of these five activities are analysis and which are design?

10. Class & Object analysis Another look at Coad & Nicola notation Another look at Coad & Nicola notationCoad & Nicola notationCoad & Nicola notation Why do all the classes except Count have extra grey boxes? Why do all the classes except Count have extra grey boxes? An abstract class has one or more operations that must be implemented by subclasses An abstract class has one or more operations that must be implemented by subclasses UML represents an abstract class by italicizing the class name or adding the constraint label {abstract} UML represents an abstract class by italicizing the class name or adding the constraint label {abstract}

11. Structure (association) analysis Lines connecting classes In UML, simple line is an association Decorations for multiplicity, role names, constraints Decorations for multiplicity, role names, constraints See example from Fowler Fowler What does {ordered} constraint mean? What does {ordered} constraint mean? Aggregations and compositionAggregations and composition: Aggregations and composition Arrow denotes navigability Arrow denotes navigability e.g., Polygon and Circle refer to Point but not vice versa e.g., Polygon and Circle refer to Point but not vice versa A black-filled diamond denotes a composition A black-filled diamond denotes a composition a part, unique to this whole A white-empty diamond denotes an aggregation A white-empty diamond denotes an aggregation a part, but not unique to this whole E.g., A Point may appear in only one Polygon or Circle but a Style could appear in both E.g., A Point may appear in only one Polygon or Circle but a Style could appear in both An alternative notation for composition in boxes composition in boxescomposition in boxes

12. Attributes and operations A class box may have three parts Class name, attributes and operations Class name, attributes and operations Attributes in middle section Typically attributes are built-in types Typically attributes are built-in types UML lets you include information about default values and visibility (+,-,#) UML lets you include information about default values and visibility (+,-,#) E.g., - name: String [1] = “Untitled” {readonly} private : type multiplicity default {property} (unmodifiable) private : type multiplicity default {property} (unmodifiable) I recommend you hold off on these details until design Operations in bottom section of class box Represent services, functions or methods Represent services, functions or methods Again, UML has a bit more notation, for information about parameters, default values and visibility Again, UML has a bit more notation, for information about parameters, default values and visibility E.g., + balanceOn(date:Date): Money Again, I recommend you hold off on these details until design

13. Your next assignments http://www.cse.lehigh.edu/~glennb/oose/afruit.htm Note that there are two problems: fruit and undo Due Sunday, February 19 Project analysis due Monday, February 27

14. Eclipse with plug-ins Open Source IDE for O-O and Java Plug-ins add more features Plug-ins add more features DrJava plug-in provides Java interpreter DrJava plug-in provides Java interpreter Omondo plug-in adds UML class diagrams Omondo plug-in adds UML class diagrams Available on campus by running “eclips” Available on campus by running “eclips” http://www.lehigh.edu/~sgh2/ (version 2.1) http://www.lehigh.edu/~sgh2/ (version 2.1) http://www.lehigh.edu/~sgh2/ or http://www.lehigh.edu/stem/teams/dieruff (3.0) www.lehigh.edu/stem/teams/dieruff

15. Dynamic behaviors Class diagrams represent static relationships. Why? What about modeling dynamic behavior? Interaction diagrams model how groups of object collaborate to perform some behavior Typically captures the behavior of a single use case Typically captures the behavior of a single use case Use Case: Order Entry Use Case: Order Entry 1) An Order Entry window sends a “prepare” message to an Order 2) The Order sends “prepare” to each Order Line on the Order 3) Each Order Line checks the given Stock Item 4) Remove appropriate quantity of Stock Item from stock 5) Create a deliver item Alternative: Insufficient Stock 3a) if Stock Item falls below reorder level then Stock Item requests reorder

16. Sequence diagram Sequence diagram Vertical line is called an object’s lifeline Represents an object’s life during interaction Represents an object’s life during interaction Object deletion denoted by X, ending a lifeline Horizontal arrow is a message between two objects Horizontal arrow is a message between two objects Order of messages sequences top to bottom Messages labeled with message name, optionally arguments and control information Control information, in brackets, may express conditions, such as [hasStock], or iteration Returns (dashed lines) are optional; use them to add clarity Sequence diagrams can also represent concurrent processes: concurrent processesconcurrent processes UML 1 models asynchronous messages as horizontal lines with half arrow heads UML 1 models asynchronous messages as horizontal lines with half arrow heads UML 2 makes this distinction by not filling an arrowhead UML 2 makes this distinction by not filling an arrowhead Fowler prefers older notation. Why? Which do you prefer? Fowler prefers older notation. Why? Which do you prefer? After setting up Transaction Coordinator, invoke concurrent Transaction Checkers If a check fails, kill all the Transaction Checker processes If a check fails, kill all the Transaction Checker processes Note use of comments in margin – When is this a good idea?

17. Collaboration diagrams Collaboration diagrams Objects are rectangular icons e.g., Order Entry Window, Order, etc. e.g., Order Entry Window, Order, etc. Messages are arrows between icons e.g., prepare() e.g., prepare() Numbers on messages indicate sequence Also spatial layout helps show flow Also spatial layout helps show flow Which do you prefer: sequence or collaboration diagrams? Fowler now admits he doesn’t use collaboration diagrams Interaction diagrams show flow clearly, but are awkward when modeling alternatives Interaction diagrams show flow clearly, but are awkward when modeling alternatives UML notation for control logic has changed in UML 2 but Fowler isn’t impressed

18. From CRC cards to Interaction diagrams Fowler recommends first using CRC cards to begin modeling scenarios Then document with UML sequence (or collaboration) diagrams Why might this be a good approach? Sequence diagrams show collaborations among many objects in a single use case State diagrams show the behavior of a single object across many use cases State diagrams show the behavior of a single object across many use cases We’ll examine state diagrams when we get to design We’ll examine state diagrams when we get to design