ISOM221+Lecture+13+-+Object-Oriented+Modeling+III+_Elaborated+Use+Case+Model_

ISOM221+Lecture+13+-+Object-Oriented+Modeling+III+_Elaborated+Use+Case+Model_

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ISOM221 Information Systems Analysis and Design Lecture 13: Object-Oriented Modeling III (Elaborated Use Case Model) 1 Agenda Elaborated use case descriptions Conditional flow of events Alternative use cases 2
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Levels of Use Cases Initial Use Case Include only Base Use Case Provide a Elaborated Use Case Add alternative and general use case descriptions complete description of the normal set of primary interactions (flows of events) conditional flows of events, if any Develop extended and included use cases, if appropriate 3 Elaborating on the Base Use Cases Base use cases provide an excellent perspective of the system, but we need to add more detailed information about the system’s behavior to complete the analysis Base Use Cases describe “sunny day” scenarios that fulfill the goals of the actor(s) involved (e.g., get cash) During the execution of a use case there will be variations such as alternatives and exceptions that occur as a result of the interactions between the actors and the system. Elaborated Use Cases also include “rainy day” scenarios, some of which don’t fulfill actors’ goals (e.g., insufficient funds, no cash in the ATM machine) Later, we will also add Included and Extended Use Cases, and also Generalizations (will be discussed in next Lecture) 4
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What is Added in the Elaborated Use Case? More details about the activities performed during the flow of events of a Base use case, as needed Conditional flow of events and alternative use cases to document exception and alternative processing as needed Splitting the Base Use Case into two or more narrowly focused Elaborated Use Cases, when the Base Use Case is too broad or complex 5 Conditional Flow of Events vs. Alternative Use Cases The are both very similar Conditional flow of events are described within the use case Alternative use cases are described in separate but related Use Cases When to use Conditional Flow of Events : Variations are key to understanding the Use Case Variations occur frequently Variations are short and simple When to use Alternative Use Cases : Variations are long and complex Variations have different priorities 6
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Conditional Flow of Events As more elaborated functionality is discovered, conditional logic can be a useful approach to represent the functional complexity Be sure to keep the conditional logic at a manageable level of detail The objective is to understand the functionality, not to write the software code Use IF statements to initiate conditional flows For example: 7. If ATM machine is out of cash 7.1 Notify customer of no cash availability 7.2 Log customer out 7.3 Notify ATM service group 7 Conditional Flow of Events Base Use Case Elaborated Use Case with Conditional If xxx Flow of Events If zzz 8
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Use Case Form with Conditional Flow Use Case ID (e.g., UC 101) Use Case Actors Description Pre-conditions Flow of Events 1. 2. If xx (conditional flow listed where it occurs)
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This note was uploaded on 12/22/2010 for the course ISOM ISOM221 taught by Professor Sheunhhee during the Spring '09 term at HKUST.

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ISOM221+Lecture+13+-+Object-Oriented+Modeling+III+_Elaborated+Use+Case+Model_

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