Last lectureActivity Diagrams

Specification and Documentation Techniques:Graphical Notations (4)

CS/SE 3RA3

Ryszard Janicki

Department of Computing and Software, McMaster University, Hamilton,Ontario, Canada

Ryszard Janicki Graphical Notations (4) 1/15

Last Lecture: State Machine Diagrams

Notation:

Example: Hotel reservation

Last Lecture: Use Case Diagrams

Use case diagram: example

operation interactionenvironment component

Check Request

Initiator <<extend>>Unauthorized

AskConstraints

CollectConstraints

ParticipantUnauthorized

Deny Requestvariant

operation

DetermineSchedule

C fli t<<include>>

MergeConstraints

R l

software component

Scheduler

ConflictResolver

ResolveConflictsParticipant

suboperation

operation performer

Last lectureActivity Diagrams

UML activity diagrams

Activity diagrams are specialized state machine diagrams anda modified version of classical flowcharts.

Activity diagrams illustrate the dynamic nature of a system bymodeling the flow of control from activity to activity.

An activity represents an operation on some class in thesystem that results in a change in the state of the system.

Typically, activity diagrams are used to model workflow orbusiness processes and internal operation.

Basic elements in activity diagrams are activities, branches(conditions or selections), transitions, forks and joins (tomodel parallelism), and swim lines.

Swim lanes are useful when a designer wants to express howrelated activities can be grouped

Ryszard Janicki Graphical Notations (4) 4/15

UML activity diagrams: workfow of building a house

UML activity diagrams: web based record storeSwim lines:Customer,Shop systemShop assistant

UML activity diagrams: passenger checking in for a flight

Last lectureActivity Diagrams

Most important graphical notations

Conceptual structures: entity-relationship diagrams

Information flows: context diagrams and dataflowdiagrams

System behaviors: state machine diagrams

System operations: use case diagrams

Modeling scenarios and workflows : activity diagrams

You will have to use all of them in Assignment 2, some ofthem for the midterm and all of them for the exam.

Ryszard Janicki Graphical Notations (4) 8/15

Example (Elevator: Positive Scenario)

Q7[5+5+5=15]

17

Example (Elevator: Positive Scenario)

Q7[5+5+5=15]

17

Example (Elevator: Negative Scenario)

18

Example (Elevator: Negative Scenario)

18

Example (Elevator: Abnormal Scenario)

19

Example (Elevator: Abnormal Scenario)

19

Graphical notations: pros and contras

Diagrammatic notations: pros & consp

Formal declaration of different system facets + informal annotations of properties for higher precision

Graphical declaration => overview & structuring of important aspects d d i easy to understand, communicate surface-level analysis, supported by tools (e.g. query engines)

Semi formal specification > Semi-formal specification => language semantics may be vague (different interpretations)

only surface-level aspects formalized not item properties only surface-level aspects formalized, not item properties limited forms of analysis functional and structural aspects only functional and structural aspects only

=> formal specification needed for mission-critical aspects