defining system requirements
DESCRIPTION
Defining system requirements . Lecturer details . Defining System Requirements CRUD Operations Events and Use Cases. SDLC Activities . Techniques for Identifying Use Cases. 1- user goal technique Analyst talks to all users to get them to describe their goals in using the system - PowerPoint PPT PresentationTRANSCRIPT
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1ISA&D7 /8/2013
Defining system requirements
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2ISA&D7 /8/2013
• Defining System Requirements• CRUD Operations• Events and Use Cases
Lecturer details
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3ISA&D7 /8/2013
SDLC Activities
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4ISA&D7 /8/2013
Techniques for Identifying Use Cases1- user goal technique
– Analyst talks to all users to get them to describe their goals in using the system
2- CRUD technique – Analyst looks at each type of data and includes use cases that create
the data, read or report on the data, update the data, and delete the data
3- elementary business process (EBP) – a task that is performed by one person, in one place, in response to a
business event; it adds measurable business value and leaves the system and its data in a consistent state
– event decomposition technique
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5ISA&D7 /8/2013
• Involves a variety of models to document requirements
• Two key concepts identifying functional requirements
Use cases and the events that trigger them
Things in the users’ work domain
Define system requirement
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6ISA&D7 /8/2013
• Use Case -- An activity the system performs in response to a user request
•Techniques for identifying use cases
User goal technique – by talking to users to get their description of goals in using the system
1. Use Case concept / User goal technique
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7ISA&D7 /8/2013
Four operations with data:
Create
Read
Update
Delete
2. Use Case concept / CRUD technique
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8ISA&D7 /8/2013
• Use case description – a description of the processing steps for a use case
• Actor – a person or thing that uses the system and interacts with the system• Scenario or Instance – a particular set of internal steps/activities to complete a business process
• Preconditions – conditions that must be true before a use case begins•Postconditions - conditions that must be true upon completion of the use case
Use case Description
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9ISA&D7 /8/2013
Example
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10ISA&D7 /8/2013
Event – an occurrence at a specific time and place which requires system to respond• External
Outside system Initiated by external agent or actor (e.g., “Customer places an Order”)
• Temporal Occur as result of reaching a point in time (not external) Based on system (e.g., “Produce a biweekly payroll”)
3. Events and event types
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11ISA&D7 /8/2013
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12ISA&D7 /8/2013
Events and Use Cases in Account Processing
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13ISA&D7 /8/2013
Identifying an Event
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14ISA&D7 /8/2013
• Event table represents events and their details• Trigger: an occurrence that tells the system that an event has occurred• Source: an external agent or actor that supplies data to the system• Activity: behavior that the system performs when an event occurs• Response: an output, produced by the system that goes to a destination• Destination: an external agent or actor that receives data from the system
Documenting an event
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15ISA&D7 /8/2013
Documenting an event example
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16ISA&D7 /8/2013
End
Thank you
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