Requirements Workflow

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Requirements Workflow

• Phases Inception, Elaboration, Construction,
  Transition
• Life cycle stages Requirements, Analysis,
  Design, Implementation, Test

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Requirements Metamodel

• Software requirements specifications (SRS)
  Grouping mechanism (package), models in package,
  containment

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Requirements Workflow Tasks
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Well-Formed Requirements

• Model ltidgt The ltsystemgt shall ltfunctiongt
• Example of functional requirements
• The ATM system shall check the validity of the
  inserted ATM card
• The ATM system shall validate the PIN number
  entered by the customer
• The system shall dispense no more than 250
  against any ATM card in any 24-hour period.
• Example of non-functional requirements
• The ATM system shall be written in C
• The ATM system shall communicate with the bank by
  using 256-bit encryption
• The ATM system shall validate an ATM card in
  three seconds or less
• The ATM system shall validate a PIN in three
  seconds or less.

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Taxonomical Representation

• Large, unstructured sea of requirements into
  smaller manageable domains

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Requirements Attributes

• MoSCoW approach RUP semantics for attributes

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Finding Requirements

• Requirements engineering generally starts with a
  vision document that outlines what the system is
  going to do, and what benefits it will deliver to
  the stake holders.
• Chomsky Syntactic structures and
  transformational grammar. Cognitive limitation
• Deletion information is filtered out
• Distortion information is modified by related
  mechanism creation and hallucination
• Generalization information is abstracted into
  rules, beliefs, and principles about truth and
  falsehood (all, everyone, always, never, nobody,
  none)

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Cognitive Challenges and Responses(Examples)

• Example They use the system to borrow books
  deletion
• Challenge Who specifically uses the system to
  borrow books?
• Response Library members, other libraries, and
  librarians
• Example Borrowers cant borrow another book
  until all overdue books have been returned
  distortion
• Challenge Are there any circumstances under
  which someone could borrow a new book before all
  overdue had been returned?
• Response Actually, there are two circumstances
  under which a borrowers right to borrow may be
  restored. First all overdue books are returned
  second, any overdue book that has not been
  returned has been paid for.
• Example Everyone must have a ticket to borrow
  books - generalization
• Challenge Is there any user of the system who
  might not need to have a ticket?
• Response Some users of the systems, such as
  other libraries, may not need a ticket or may
  have a special type of ticket with different
  terms and conditions.