1. UML Overview 1

2. 2 UNIFIED Modeling Language  OMG adopted UML in November 1997 as the standard for object-oriented modeling  Combines commonly accepted concepts from many OO methods  Seamless from requirements to deployment  Applicable to any domain  Language and platform independent  Usable with any development process

3. UML Overview 3 Unified MODELING Language  All engineering disciplines have adopted modeling techniques  Allows to capture the important aspects of a system while omiting the rest  Model is easier to use than final system  Help all software systems stakeholders understand what the system will be and what are the possible options available  Multiple models reveal different perspectives on the system

4. UML Overview 4 Unified Modeling LANGUAGE Language for: Visualizing: Graphical models with precise semantics Specifying: Models are precise, unambigous and complete to capture all important Analysis, Design, and Implementation decisions. Constructing: Models can be directly connected to programming languages, allowing forward and reverse engineering Documenting: Diagrams capture all pieces of information collected by development team, allowing to share and communicate the embedded knowledge.

5. UML Overview 5 UML Bird’s Eye View Building Blocks:  Things: abstractions, main concepts in a model  Relationships: tie the things together  Diagrams: group interesting collections of things

6. UML Overview 6 UML in a Nutshell  Static Structure  Dynamic Behavior  Model Management  Extensibility Constructs

7. UML Overview 7 Diagrams in the UML Class diagram Object diagram Use case diagram Sequence diagram Collaboration diagram Statechart diagram Activity diagram Component diagram Deployment diagram

8. UML Overview 8 Things in the UML Structural Things (7)  static part of a model, conceptual or physical elements  nouns of UML Models Behavioral Things (2)  dynamic parts of models  verb, representing behavior over time and space Grouping Things (1)  Organizational parts of models, decomposition element Annotational Things (1)  explanatory parts of models, comments about other elements

9. UML Overview 9 Behavioral Modeling  Use Cases / Use Cases Diagrams  Interactions / Interaction Diagrams  Activity Diagrams

10. UML Overview 10 Use Cases  Description of a set of sequences of actions, that a system performs to yield an observable result to an end- user  Categories of interactions between the system to be built and external actors  Identify high-level services provided by the system  Specify the behavior of a system  Popularized by Ivar Jacobson with Objectory  Have been adopted by or have influenced many methods (eg. OMT, Fusion, Booch)

11. UML Overview 11 Use Cases (cont.)  Can be applied to whole system as well as part of system such as a subsystem or a class  Sources of integration tests and system tests  May have variants: specialized use cases or extension of use cases.  Do not specify any implementation detail  Main communication tool with end-user  Each use case must have a name (simple or path name)

12. UML Overview 12 Actors  Objects outside the system which play a particular role  Represent the user(s) of the system  Interact with the system through use cases  May participate in more than one use case  May or may not be represented as a class or object in the object model  Also known as agents (Jacobson)

13. UML Overview 13 UML Use Case Graphical Representation Delivery Collection StatusClerk Manager Storage depot system Storage Actor Use case

14. UML Overview 14 Why Modeling Use Cases  Use Case model describes WHAT the system will do at a high-level  User focus -Capture requirements from user's perspective. -Users are involved.  Goal is to scope the project and give the application some structure -Use Cases are the unit of estimation -Uses Cases are smallest unit of delivery -One way of estimating the percentage of requirements captured. -Prioritizing use cases for "phased delivery" according to user's immediate needs. -Better way of estimating the percentage of requirements completed during development

15. UML Overview 15 Benefits of use cases  Good way to start identifying objects from scenarios.  Test plan can be immediately generated based on use cases.  Easier user validation.  Helps technical writers in structuring the overall work on the users manuals at an early stage.  Better traceability throughout the system development process.  Quality of the software is improved by identifying the exception scenarios earlier in the development process.

16. UML Overview 16 Problems with use cases  What is the right granularity  What is a correct Use Case  Explosion of different scenarios  Focus on functions, with potential for functional decomposition  Too often too informal

17. UML Overview 17 Use Cases and Scenarios  Scenario is a specific sequence of actions  Scenario is one instance of a Use Case  Typically many scenarios correspond to one Use Case  Example:  Use Case = Hire Employee  Scenarios -Hire at Job Fair -Hire through newspaper ad -Hire from internal promotion -Hire Temp

18. UML Overview 18 Use Cases and Collaborations  Use Case captures WHAT the system does  Use Cases do not specifies HOW the System does it  Development effort is aimed at implementing the use cases by creating a society of classes working together  These interacting classes are modeled using Collaborations  A Collaboration is the realization of a Use Case  A Collaboration represents how responsibilities are distributed across objects  A Collaboration has a Static and a Dynamic aspect

19. UML Overview 19 Organizing Use Cases Relationships: Generalization, Include (Use) and Extend Generalization: – Like for Classes Include: -Use: Contains another complete use-case Extend: -Extends another use-case -used for optional separate flow (exception) Beware: -Over-use of extends = functional decomposition -Rumbaugh says Use = aggregation and Extend = inheritance

20. UML Overview 20 Hints and Tips Each Use Case should represent a single, identifiable and reasonably atomic part of the behavior of the system Factors Common Behavior by pulling such behavior from other use cases that it includes Factors variants by pushing such behavior into other use cases that extend it Describe flow of vents clearly enough for anyone to easily understand it Each Use Case is described by a number of scenarios that specify the normal and variants

21. UML Overview 21 Use Case Diagrams  system is represented by a large rectangle  uses cases are represented as ellipses within the system rectangle  actors are represented as stick figure outside the system  an arrow connects the initiating actor to the use case (ending at the use case)  other participating actors are joined by arrows terminating at the actor

22. UML Overview 22 Banking System Use Case Diagram open_account withdraw_cash loan_application clear_checks get_report Customer Manager Loan Officer Clerk Cash Dispenser

23. UML Overview 23 Use Case Identification Steps Determine the boundary of the system -consider system as a single “black box” object Identify who is going to be using the system directly - e.g. hitting keys on the keyboard. These are the Actors -start by considering physical object -an individual object may play several roles Choose One of these Actors and determine the fundamental ways in which each actor uses the system -each of these is a use case -must be enumerable -for each of those Use Cases decide on the most usual course when that Actor is using the system. What normally happens. This is the basic course

24. UML Overview 24 Use Case Identification Steps (2) Describe it as "Actor does something, system does something. Actor does something, system does something." but keep it at a high level.  do not mention any GUI specifics  only describe things that the system does that the actor would be aware of and conversely you only describe what the actor does that the system would be aware of.  do not worry about the alternate paths (extends) or common courses (uses) - Yet - Review each Use Case descriptions against the descriptions of the other Use Cases. Once basic course is OK, consider the alternates and add those as extending use cases.

25. UML Overview 25 Use Case Identification Steps (3) Good way of getting started with Use Case modelling. Once started and comfortable with this process, next step:  understand the trade-offs that can be made  simplicity versus "completeness"  putting too much in is the most common mistake.

26. UML Overview 26 Use Case Textual Descriptions -a clerk requests the system to create a new account OPEN_ACCOUN T WITHDRAW_CASH CLEAR_CHECKS LOAN_APPLICATION GET_REPORT -a customer requests the system to withdraw a specified amount of money from a specified account -a clerk instructs the system to update all accounts according to specified transactions including checks -a customer files a loan application -a manager or loan officer requests a report of the days transactions from the system

27. UML Overview 27 Use Cases Diagram Hint and Tips Put all the Use Cases that describe one aspect of the system together Contains only those use cases and actors essential to understanding that aspect Diagram should be named to communicate its purpose Minimize crossing lines Don’t draw too many use cases or too many relationships in one diagram

28. UML Overview 28 UML Basic Structural Modeling

29. UML Overview 29 Basic Structural Modeling Classes  Attributes, Operations, Responsibilities Relationships  Dependency, Generalization, Association, Role, Multiplicity, Aggregation Common Mechanisms  Specifications, Adornments, Common Divisions, Extensibility Mechanisms Diagrams  Class, Object, Component, Deployment Dagrams

30. UML Overview 30 Classes AstronautPlanet  Most important building block of any object-oriented system  Description of a set of Objects  Implements one or more interfaces  Abstraction of the entities existing in the problem domain Shuttle::Astronaut simple namespath names

31. UML Overview 31 Attributes  named properties of classes that describe a range of values  represent some property of the thing being modeled  each attribute has one value for each object  listed in the attribute compartment underneath the name box  normally no need for an explicit “ID” attribute Shuttle weight : Integer age : Integer status: enum = on-ground Mission start : Date end : Date cost : Dollars

32. UML Overview 32 Operations  implementation of a service that can be requested from any object of the class  what you can do to/with an object  are listed in an additional box underneath the attribute box  SYNTAX- name (arg1 : type, arg2 : type...) : result Shuttle start_engines() stop_engines() fuel_level() : integer launch(t:time)

33. UML Overview 33 Organizing Attributes and Operations Ellided Empty compartment  drawing an empty compartment makes no statement about the absence of attributes or operations Prefix groups with Stereotypes to  group together attributes / operations with common characteristics  represent a metaclassification of the attributes / operations

34. UML Overview 34 Responsibility Contract or obligation of a class Starting point for modeling a class Responsibilities are translated into a set of attributes and operations Free-form text, in separate compartment at the bottom of the class Shuttle Responsibilities -- Carry astronauts and payload to low orbit space

35. UML Overview 35 Other Features When need to separate the implementation of a class from its specification, use Interface Advanced features such as  attribute or operation visibility  language-specific features Common pre-specified classes modeled with  active classes  components  nodes

36. UML Overview 36 Modeling Classes What is a Class? Where do I find a Class? Where do I find Attributes? What the difference between a Class and an Attribute? How do I set responsibilities within Classes ?

37. UML Overview 37 Hints and Tips Classes should map to relevant abstraction in problem (and solution) domain Embodies small set of well defined responsibilities Understandable and simple, yet extensible and adaptable Contain only the relevant properties

38. UML Overview 38 Relationships Connection among things How Classes are related to one another (Almost) As important as Classes Ways things collaborate Three main type:  Dependencies  Generalizations  Associations

39. UML Overview 39 Dependency Using Relationships A Change in one thing may affect the other thing that uses it. Most often between a class that uses another clas as a parameter to an operation Shuttle start_engines() stop_engines() fuel_level() : integer launch(t:time) Engine

40. UML Overview 40 Generalization Relationship which organizes classes based on their similarities and differences Relationship between a general thing (the superclass) and a more specific thing (the subclass) sometimes called “is-a-kind-of” or “is-a” relationship Child is substitutable for the parent Child inherit properties of parent corresponds to inheritance in object-oriented languages NOTATION -  an arrow whose head is next to the specialization Shuttle Spacecraft

41. UML Overview 41 Subclasses  inherit the attributes, operations and associations of their superclass(es)  must obey all semantic restrictions of their superclass(es)  can override the implementation of an operation vehicle size speed land vehicle wheels water vehicle draft

42. UML Overview 42 Ancestors/Descendants  the terms ancestor and descendant refer to generalization across multiple levels.  an instance of a class is simultaneously an instance (transitively) of all its ancestors fruit granny smiths apple cox...

43. UML Overview 43 Associations  describe a group of links with common structure and semantics  are to links what classes are to objects  can have a different name in each direction Dan Goldin NASA Bill GatesMicrosoft John Smith Rockwell... Works-for Person Organization Works-for Employs

44. UML Overview 44 Associations Continued  defined solely by the classes which they connect  associations are not part of the participating classes  associations should not be modelled by attributes Astronaut Mission full_name : string Assigned_to Mission full_name : string Astronaut assigned_to : string WRONG RIGHT

45. UML Overview 45 Roles  correspond to one end of an association  each end of an association may be assigned a role which serves as its unique identifier  provide a way of traversing a binary association from one object to a set of related objects  represent a form of specialization  are written next to the association line Experiment Astronaut conducts mission-specialist 0.. *

46. UML Overview 46 Multiplicity  the number of instances of one class that may be related to an instance of another  constrains the number of links between objects Class many (zero or more) optional (zero or one) mandatory (one or more) numerically specified 1.. * 2..4, 6..8 exactly one 0.. * 0..1 1

47. UML Overview 47 Aggregation  a special form of association between a whole and its parts  relates an assembly class to its component classes  is transitive but not symmetric (commutative)  depicted by a diamond at the assembly end  two kinds - -a part cannot be in more than one “whole” physical catalog -a part can be in several “wholes”

48. UML Overview 48 Aggregation Examples DocumentSentenceWord 1.. * CrewAstronaut 4..6 Space Center Building Shuttle Wings 2 Engines 3 * * 1.. *

49. UML Overview 49 Aggregation Example - Graphical interface Window PaneTitleBarScrollBarBorder Close ButtonTitleArrowIndicator * 2 0..2

50. UML Overview 50 Aggregation - Tree-like Notation Window PaneTitleBarScrollBarBorder Close ButtonTitleArrowIndicator * 2 0..2

51. UML Overview 51 Lab Work on UML - Part 1 Review Use Case Development Process from Rational Unified Process  Use Case Finding  Use Case Details Develop Use Case Model using Rational Rose Develop Use Case Specification Document

52. UML Overview 52 Lab Work on UML - Part 2 Review Class Diagram Development Process from Rational Unified Process Develop Class Model using Rational Rose