CS 846: Model-Based Software Engineering Winter 2012

Transcription

1 CS 846: Model-Based Software Engineering Winter 2012 Jo Atlee David R. Cheriton School of Computer Science University of Waterloo January 16, 2012 Software Models

2 What is Being Modelled? <postal-address> ::= <name-part> <street-address> <zip-part> <name-part> ::= <personal-part> <last-name> <opt-jr-part> <EOL> <personal-part> <name-part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a KLOC b

3 Models as Views Architect's View Carpenter's View Mason's View Electrician's View Tax Collector's View Plumber's View Landlord's / Tenant's View Zoning Law View Interior Designer's View Interior Designer's View Every view obtained by a different projection, abstraction, translation may be expressed in a different notation (modelling language) reflects a different intent [ Example from J. Bezivin, J. Dingel ]

4 Modelling Paradigms Fundamental modelling paradigms, each emphasizing some basic view of the software to be developed. Structure Data Schema System Functionality Functionality Software Architecture Use Cases Deployment Algorithms Constraints Scenarios Constraints System Behaviour System Interactions Behaviour

5 Entity-Relationship Diagrams An ER diagram is a structural model representing a software system's data elements and relationships among them. entity relationship attribute title course no. course enrolled student name id originally invented for model database design (Chen, 1976) emphasizes concepts/data relationships can represent associations, navigability, containment, dependencies, etc.

6 UML Class Diagrams UML Class Diagrams are an elaborate form of ER diagram. class attributes operations Patron! patron ID:integer! name : string! address : string! fines : real! checkfines() : {fine, nofine};! increase fines(amount:real);! pay fines(amount:real);! recallnotify(pub:publication)! association *! Publication! *! 0..1! borrows! 0..*! borrower! association class Loan! due date : Date! overdue fine : real! calc due date(operation:string)! calc overdue fine()! renew()! recall()! call number : string! title : string! value : real! depreciation : real! loan period : Duration! fine rate : real! reserve loan period : Duration! reserve fine rate : real! recall period : Duration! loan state: {inlibrary, onloan}! reserve state : {stacks, reserve}! find(title : string) : Publication! buy()! lose ()! borrow(patron:patron)! return()! reserve()! unreserve()! decreasevalue()! Book! author : string! Periodical! editor: string! volume : integer! number : integer! loan period : Duration! fine rate : real! [ Figure from Pfleeger, Atlee, 2009] Article! author : string!

7 Software Architecture A software architecture is high-level model of code structure. Typically modelled as a "box and arrow" diagram, with a key explaining the types of components (boxes) and connectors (arrows). [ Figure from Pfleeger, Atlee, 2009]

8 UML "Software Architecture" Models The closest that UML comes to a software architecture model are UML Package Diagrams and UML Deployment Diagrams. UML Package Diagram UML Deployment Diagram

9 Data Flow Diagrams (DFDs) Descriptive model of functional decomposition of the system, and the data dependencies between functions. actor data flow process Thermometer air temp Thermostat on/off commands Furnace set air temp data store thermostat settings DFDs model collection of functions sources and sinks of data data dependencies

10 Data Flow Diagrams (DFDs) Although DFDs are good for communicating the big picture, they are inherently incomplete, undetailed, and ambiguous. [ Figure from M. Jackson, 1995 ]

11 UML Use Case Diagrams Use Case Diagrams are a very high-level data-flow diagram. function Online Book Store Making Purchase actor Credit Authorization Service actor Customer Managing Shopping Cart Managing Customer Info actor Bookseller Inventory Log In Administrator Managing Inventory data flow

12 Flowcharts Flowcharts are an ancient modelling notation, for representing behaviour in terms of steps of an algorithm. Depict control flow rather than data flow start / stop input / output activity branch

13 UML Activity Charts UML Activity Charts are a variation on flowcharts that support concurrent flows of control. swimlanes (assign activities to person / role) activity fork control flow join object flow [ Figure from M. Blaha, J. Rumbaugh, 2005 ]

14 Event Traces Dynamic model of behaviour showing communication among entities in one scenario (execution trace). Shows a slice of behaviour, not complete behaviour. entities, actors, systems, subsystems, objects Visitor Turnstile Visitor Turnstile event, message coin slug buzzer slug Time push rotated slug life line of participant

15 UML Sequence Diagrams UML Sequence Diagrams are elaborate event traces... event, method call entities, objects, systems, subsystems, actors Time :PurchaseOrder :Product :Product :Product printreceipt() print() print() result print() return message lifeline of object execution occurrence

16 UML Sequence Diagrams... including branches, loops, concurrency, optional subsequences, references to other sequence diagrams. sd AuthenticateUser : A : B : C : B : C dox doa authenticate(id) ref dob AuthenticateUser authenticate(id) dom1 dom2 ref DoFoo sd DoFoo : B : C interaction occurrence note it covers a set of lifelines note that the sd frame it relates to has the same lifelines: B and C dox doy doz Larman, Appliying UML and Patterns, 3ed

17 State Machines Compact representation of all event traces. input event output event slug coin/buzzer locked unlocked initial state transition /rotated rotating push state

18 UML StateMachine Diagrams UML StateMachine Diagrams borrow heavily from David Harel's statecharts. / req1 = false / req2 = false / floor = 1 Stopped Elevator VARIABLES req1 : boolean := false (* outstanding request for floor1 *) req2 : boolean := false (* outstanding request for floor2 *) floor : {1, 2} (* current location of elevator *) Closed [req1 floor=1] Open entry /open after (5 sec) [floor=1] / req1 = false after (5 sec) [floor=2] Closing / req2 = false entry /close [instate(closed) req2 floor=1] MovingUp entry /dir=up entry /move [req2 floor=2] blockage closed arriving2 / floor=2 [instate(closed) req1 floor=2] stopped MovingDown entry /dir=down entry /move arriving1 / floor=1 Slowing entry /stop Requests but1 / req1 = true but2 / req2 = true butup / req1 = true butdown / req2 = true

19 Logic Logic is the basis for a number of languages that express constraints on allowable interpretations of other models. allowable instantiations of data models invariants among attribute values in data models pre/post conditions of functions event conditions in event traces guard conditions in state machines

20 Object Constraint Language OCL was designed for expressing constraints on UML diagrams. 0..* program 0..* partner ProgramPartner 0..* 1..* name : String provider Service description: String condition : Boolean pointsearned: Integer pointsburned: Integer 1 FrequentFlyer Program ServiceLevel name : String 0..* * program 1 0..* 0..* Membership memberid : Integer points : Integer 1 0..* 1 Transaction unitpurchases: Integer points: Integer date : Date 1..* card Customer name: String title: String address: String dateofbirth: Date owner card 1..* CustomerCard valid: Boolean validfrom: Date goodthru: Date colour : enum {gold, sliver} printedname: String Utility Class Date today : Date = (d : Date) : Boolean isbefore (d : Date) : Boolean isafter (d : Date) : Boolean diff() : Duration context CustomerCard inv self.printedname = (self.owner.title.concat(self.ownername)) context CustomerCard inv (self.valid and self.colour=gold) implied self.membership.servicelevel = "gold"

21 UML: 13 Different Diagram Types Structural Class Diagrams Object Diagrams Composite Structure Diagrams Component Diagrams Package Diagrams Deployment Diagrams Functional Use Case Diagrams Behavioural Interaction Overview Diagrams Activity Diagrams Sequence Diagrams Communication Diagrams State Machine Diagrams Timing Diagrams OCL is a separate language that was invented for writing constraints on UML models

22 Next Week 3 Prominent Modelling Languages Alloy Statecharts Scala

23 References [BlRu05] M. Blaha, J. Rumbaugh, Object-Oriented Modeling and Design with UML, 2ed, Prentice hall, [BRJ05] G. Booch, J. Rumbaugh, I. Jacobson. UML User Guide. 2nd Edition. Addison Wesley [EJ09] S. Easterbrook, T. Johns, "Engineering the Software for Understanding Climate Change," Computing in Science and Engineering, pp , November/December, 2009 [Jac95] M. Jackson, Software Requirements and Specifications, ACM Press, [Kra07] J. Kramer. "Is Abstraction the key to Computing?" Communications of the ACM. April 2007/Vol. 50, No. 4. [KSLB03] G. Karsai, J. Sztipanovits, A. Ledeczi, T. Bapty. "Model- Integrated Development of Embedded Software.", Proc. IEEE, Jan 2003, pp

24 References [KT08] S. Kelly and J.-P. Tolvanen. Domain-Specific Modeling: Enabling Full Code Generation. Wiley [Lud04] Ludewig, J "Models in software engineering--an introduction". Software and Systems Modeling 2, [PfAt09] S. Pfleeger, J. Atlee, Software Engineering: Theory and Practice, Prentice Hall, [RJB05] Rumbaugh, Jacobson, Booch, The Unified Modeling Language Reference Manual, 2nd ed., Addison-Wesley, [Sch06] D.C. Schmidt. "Model-Driven Engineering." IEEE Computer, vol. 39, no. 2, Feb Page(s):25-31 [Sei03] Ed Seidewitz. "What Models Mean." IEEE Software, vol. 20, no. 5, pp , Sep./Oct [Sel03] Bran Selic, "The Pragmatics of Model-Driven Development," IEEE Software, vol. 20, no. 5, pp , Sep./Oct [Sta73] H. Stachowiak, Allgemeine Modelltheorie, Springer-Verlag, 1973.