Lecture 21 Detailed Design Dynamic Modeling with UML

Transcription

1 Lecture 21 Detailed Design Dynamic Modeling with UML Software Engineering ITCS 3155 Fall 2008 Dr. Jamie Payton Department of Computer Science University of North Carolina at Charlotte November 18, 2008

2 Announcements Deliverable 3 due date November 25 at 11:59 pm Deliverable 4 due date December 16 11:59 pm Final exam December 16 11:30 am 2:30 pm Woodward 130 READ: Transforming conceptual models, Ch

3 Lecture Overview Chapter 12 Detailed design Dynamic class models 3

4 Detailed Design Stages Mid-level design Specifying software at level of medium-size components Compilation units or class Their properties Their relationships Their interactions Essentially: DESCRIPTR Design patterns (later) Low-level design Activity of filling in small details at lowest level of abstraction PAID 4

5 Mid-level Design and Modeling Static modeling Captures structure of parts of software system UML Class Diagrams Dynamic modeling Captures behavior (interactions) of parts of software system UML Sequence Diagrams Static and dynamic models are complementary Need both to capture design of software system 5

6 Mid-level Design and Dynamic Modeling Goal is to express the behavior of the system as it executes over time Capture the interactions between individuals Communication between individuals that exchange information to accomplish a task Individuals involved may be users, actors, objects (instances of classes) 6

7 UML Interaction Diagrams Notations for dynamic modeling of collaborations among individuals UML interaction diagrams Sequence diagram Shows sequence of messages passed among communicating individuals Highlight temporal nature of communication Communication diagram Shows messages passed among communicating individuals Highlights collaborations Interaction overview diagram Activity diagram + Sequence diagrams Timing diagram Shows change in state of individual over time 7

8 Example Interaction Diagrams: Sequence Diagram 8

9 Example Interaction Diagrams: Collaboration Diagram 9

10 Example Interaction Diagrams: Interaction Overview 10

11 Example Interaction Diagrams: Timing Diagram 11

12 UML Sequence Diagrams Most widely used notation for describing interactions Clearly expresses message flow between individuals Highlights time ordering of interactions 12

13 UML Sequence Diagram Notation: Frame sd ButtonPress name compartment :User :Button :ButtonListener :Light press actionperformed(event) toggle getstate() Rectangle that encloses the diagram with pentagonshaped name compartment Name can be simple name or operation name (with params) 13

14 UML Sequence Diagram Notation: Lifeline Lifeline sd UseComponent client supplier create :Component destroy X Represents a participating individual Usually an object (instance of class) Modeled as rectangle with dashed line extending down Time is represented vertically in diagram Dashed line represents individual s existence Rectangle is labeled with lifeline identifier 14

15 Lifeline Creation and Destruction New object appears at the point it is created Destroyed object has a truncated lifeline marked with an X Persistent objects have lifelines that run the length of the diagram sd UseComponent client supplier create :Component destroy X 15

16 Lifeline Identifier Format Name Selector typename simple name, or self Used when interaction depicted is owned by the individual Expression to select an individual from a collection Format not specified in UML Type of the individual Format not specified in UML Can omit name or :typename But not both! name[selector] : typename 16

17 UML Sequence Diagram Notation: Message Arrows sd ButtonPress :User :Button :ButtonListener :Light press actionperformed(event) toggle getstate() Three types Synchronous messages Asynchronous messages Synchronous message return or instance creation 17

18 Message Specification Format Variable name Simple name of a variable assigned a result Optional; if omitted, so is the equals sign Simple name of the message argumentlist variable = name argumentlist Comma-separated list of arguments in parentheses Possible formats: varname = paramname paramname = argumentvalue Optional; parentheses may appear even if omitted Message specification may be * (any message) 18

19 Message Specification Examples hello hello() msg = getmessage( hellomessage ) x = sin( a/2 ) x = sin( angle = a/2 ) trim( result = astring ) Warning Assigning a value to a parameter and assigning a returned out parameter to a variable cannot be distinguished Use variable/parameter assignments in correct order of parameters Don t define assignment based on names of parameters 19

20 UML Sequence Diagram Notation: Execution Occurrence sd ButtonPress execution occurrence :User :Button :ButtonListener press actionperformed(event) toggle :Light getstate() Indicates an object is active Object is active if one or more operations is active Operation is executing Process is running code Operation is suspended Waiting on return of control from synchronous message 20

21 Combined Fragments A combined fragment is a marked part of an interaction diagram that shows Branching Loops Concurrent execution Other properties 21

22 Optional Fragment A portion of an interaction that may be done Equivalent to a conditional (guarded) statement Conditional based on satisfaction of guard A guard is a Boolean expression Placed in square brackets in UML Examples [isenrolled] [isauthorized] [else] is a special guard true if every other guard is false 22

23 Optional Fragment Example sd print( f : File ) self:printserver f:file :Printer iscmprsd=iscompressed() opt [iscmprsd] decompress() print(f) Denoted by opt fragment operator Single opt operand is enclosed by rectangle 23

24 Alternative Fragment A combined fragment with mutually exclusive conditional statements sd toggle() self:light :Bulb Equivalent to a case or switch statement alt [state==on] turnoff() Operator is the keyword alt [state==off] turnon() alt can be applied to one or more operands 24

25 Break Fragment A combined fragment that uses a guarded statement to determine to discontinue typical execution Similar to a break statement Operator is the keyword break Operates only on one operand 25

26 Break Fragment Example sd print( f : File ) self:printserver stderr f:file :Printer readable=canread() break [!readable] print(errmsg) iscmprsd=iscompressed() opt [iscmprsd] decompress() print(f) 26

27 Loop Fragment Single loop body operand that may have a guard Operator has the form loop( min, max ) [guard] Parameters are optional if omitted, so are the parentheses min is a non-negative integer max is a non-negative integer min <= max <= * max is optional; if omitted, so is the comma In this case, max = min Default guard is true 27

28 Loop Fragment Example sd Iteration controller i = iterator() o:object :Collection i:iterator create ismore = hasnext() loop [ismore] o = next() process() ismore = hasnext() destroy X 28