Transcript SYST39409 - Sheridan College

State Diagrams
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Weekly Schedule-SLATE
Assignment No 2
Solutions to ICE’s posted on SLATE
Today
 State charts – continued...
 I-C-E-06
▪ Two ways of modelling
 Summarize Requirements Gathering Process
▪ Car Rental System – Case Study
 Introduce System Sequence Diagrams (SSDs)
 ICE-07
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Typical Amazon Package Tracking Status Report
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Two Versions
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Car Rental System – Posted on SLATE
Week09
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[1] Select the classes that will require statecharts
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[2] List all the status conditions for each group
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[3] Specify transitions that cause object to leave the
identified state
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[4] Sequence state-transition combinations in correct
order
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[5] Identify concurrent paths.
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[6] Look for additional transitions
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[7] Expand each transition as appropriate
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[8] Review and test each statechart
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See SLATE for a posted exercise
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System sequence diagram (SSD)
 Describes flow of information
 Identifies interaction between actors and system
 Message oriented
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Actor “interacts” with the system via input/output
SSDs use object notation
 Box (rectangle) refers to individual object
 Name of the object underlined
 Messages sent/received by objects, not classes
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Lifeline
 Extension of object or actor for duration of the SSD
 Indicates sequence of the messages sent/received
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Sample System Sequence Diagram
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Message syntax can take several forms
 Depends on send/return direction
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Message semantics: actions (like commands)
invoked on destination object
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Begin with detailed description of use case
 Fully developed form
 Activity diagrams
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(4) step process for turning activity diagram into SSD
 [1] Identify the input messages
 [2] Describe messages from external actor to system
 [3] Identify/apply special conditions to input messages
 [4] Identify and add the output return messages
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A Simplified Diagram of the Telephone Order Scenario
An SSD of the Simplified Telephone Order Scenario for the Create New
Order Use Case
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Names of messages reflect services performed
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Important principle for identifying data parameters
 Base the list on the class diagram
 Attributes from the classes listed as parameters
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Iteratively define input/output parameters around
workflows
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Objective: discovery and understanding
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Read & Study Chapter 6 Pages 237 -246
What comes next?
 Sequence Diagrams
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