Assignment Help

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Assignment Help

• From Requirements Elicitation to
• Implementation

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Requirements Elicitation

• Requirements Elicitation communication between
  developers, clients and users for defining a new
  system.
• In our case developers clients users.
• Developers construct a model of the application
  domain by observing users.
• Result system specification (contract between
  developers and client). Form use cases.

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Requirements Elicitation

• System specification is further developed into an
  analysis model during analysis.
• System specification and analysis model represent
  same information differ in language and
  notation.
• System specification English.
• Analysis model formal or semi-formal notation.

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Requirements Elicitation

• A scenario describes an example of system use in
  terms of a series of interactions between the
  user and the system.
• A use case is an abstraction that describes a
  class of scenarios.
• Both written in natural language.

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Analysis Model

• Program P, consider join points during execution
  of P, consider a predicate JPP on join points,
  report all join points not satisfying JPP.
• Offer a choice of JPP related to the LoD.

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Singleton Aspects

• aspect Id ...
• aspect Id issingleton ...
• By default, or by using the modifier issingleton,
  an aspect has exactly one instance that cuts
  across the entire program. That instance is
  available at any time during program execution
  with the static method aspectOf() defined on the
  aspect -- so, in the above examples, A.aspectOf()
  will return A's instance. This aspect instance is
  created as the aspect's classfile is loaded.

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perthis

• Per-object aspects
• aspect Id perthis(Pointcut) ...
• If an aspect A is defined perthis(Pointcut), then
  one object of type A is created for every object
  that is the executing object (i.e., "this") at
  any of the join points picked out by Pointcut.
  The advice defined in A may then run at any join
  point where the currently executing object has
  been associated with an instance of A.

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perthis

• The static method call A.aspectOf(Object) can be
  used to get the aspect instance (of type A)
  registered with the object. Each aspect instance
  is created as early as possible, but not before
  reaching a join point picked out by Pointcut
  where there is no associated aspect of type A.

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End
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percflow

• you can use a percflow aspect to ferry additional
  state to a callee without changing intervening
  signatures.