Information Systems Analysis and Design CSC340 Information Systems Analysis and Design State Diagrams Statecharts IV State Diagrams State diagrams model processes business processes machine processes or anything in between States Transitions Events conditions and actions all optional Event Condition Action Initial and final states State Diagrams Events and States Superstates 2004 John Mylopoulos State Diagrams 1 Information Systems Analysis and Design CSC340 2004 John Mylopoulos Checking Dispatching all items in stock Do package items start initial some item not In stock event action deliver package Item received all items in stock Item received some item not In stock end final Waiting 2004 John Mylopoulos State Diagrams 3 Information Systems Analysis and Design CSC340 An event is a happening that the system needs to know about In UML there are four types of events Change events occur when a condition becomes true e g when balance 0 Signal events designate the receipt of an explicit real time signal from outside Call events indicate the receipt of a call for execution from outside Time events mark the passage of a designated period of time from the moment a state was entered exited e g after 10 seconds 2004 John Mylopoulos offerNewCourse set count 0 create CourseRoster addStudent count 10 count 10 Closed quarterStarted cancel end state Lochovsky98 Cancelled 2004 John Mylopoulos CSC340 States Initialization cancel State Diagrams 4 Information Systems Analysis and Design Course Lifetimes Open CSC340 Events condition Do check items State Diagrams 2 Information Systems Analysis and Design State Diagram for Purchase Order Order order received CSC340 delete CourseRoster State Diagrams 5 A state represents a time period during which A predicate is true e g budget expenses 0 An action is being performed or Someone waits for an event to happen A state can be on or off States can have associated activities Special activity constructs include do stateDiagramName parameterList calls another state diagram entry action carry out the action when entering the activity exit action carry out the action when exiting 2004 John Mylopoulos State Diagrams 6 Information Systems Analysis and Design CSC340 Information Systems Analysis and Design Course Lifetimes Again Superstates Initialization do Initialize A superstate consists of two or more substates There are AND and OR superstates When an AND superstate is on all its states are also on When an OR superstate is on one of its states is on createCourse count 0 CourseRoster Create addStudent count 10 Open entry RegisterStudent exit CourseRoster AddStudent student count 10 cancel cancel Cancelled CSC340 Closed do FinalizeCourse CourseRoster Delete quarterStarted 2004 John Mylopoulos State Diagrams 7 Information Systems Analysis and Design CSC340 2004 John Mylopoulos State Diagrams 8 Information Systems Analysis and Design CSC340 More on Transmission An OR Superstate Transmission Transmission select R Neutral select R Neutral select N select N select N Reverse select N Reverse select F select F Forward upshift stop Forward First downshift 2004 John Mylopoulos State Diagrams 9 Information Systems Analysis and Design CSC340 State Diagrams 10 Information Systems Analysis and Design CSC340 Additional Readings Cancelled Checking Third downshift 2004 John Mylopoulos An AND Superstate Waiting upshift Second cancel Booch99 Booch G et al The Unified Modeling Language User Guide Chapters 19 20 21 24 Addison Wesley Fowler00 Fowler M UML Distilled A Brief Guide to the Standard Object Modelling Language Chapters 8 9 AddisonWesley Dispatching Delivered Authorizing approve Authorized reject Rejected Fork 2004 John Mylopoulos Join unlabelled outgoing transition State Diagrams 11 2004 John Mylopoulos State Diagrams 12
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