HAS

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HAS
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Patterns

• The use of patterns is essentially the reuse of
  well established good ideas. A pattern is a named
  well understood good solution to a common problem
  in context. Patterns describe how objects
  communicate without become entangled in each
  others data models and methods. Keeping this
  separation has always been an objective of good
  OO programming, objects should mind their own
  business, but obviously need the services of
  other objects as well. Definition Patterns
  identify and specify abstractions that are above
  the level of single classes and instances, or of
  components. Patterns can exist at many levels
  from very low level specific solutions to broadly
  generalised system issues . Patterns are often
  described using UML together with a pattern
  template A template describes a pattern. Typical
  template may contain Name, Intent, AKA,
  Motivation, Application, Structure,
  Participation, Collaborations, Consequences,
  Implementation, Sample Code, Known Uses, Related
  Patterns.
• Main advantages capture best practice, reuse,
  fairly standard way of describing patterns.
• Disadvantages advanced topic, learning design
  patterns is a long multiple step process
  Acceptance, Recognition, Internalisation, on the
  other hand they are worth learning. Role of
  experience. More geared to OO than other
  computing paradigms.

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Patterns

• The use of patterns is essentially the reuse of
  well established good ideas. A pattern is a named
  well understood good solution to a common problem
  in context. Patterns describe how objects
  communicate without become entangled in each
  others data models and methods. Keeping this
  separation has always been an objective of good
  OO programming, objects should mind their own
  business, but obviously need the services of
  other objects as well.
• Definition Patterns identify and specify
  abstractions that are above the level of single
  classes and instances, or of components.
  Patterns can exist at many levels from very low
  level specific solutions to broadly generalised
  system issues
• Patterns are often described using UML together
  with a pattern template. A template describes a
  pattern. Typical template may contain Name,
  Intent, AKA, Motivation, Application, Structure,
  Participation, Collaborations, Consequences,
  Implementation, Sample Code, Known Uses, Related
  Patterns.
• Main advantages capture best practice, reuse,
  fairly standard way of describing patterns
• Disadvantages advanced topic, learning design
  patterns is a long multiple step process
  Acceptance, Recognition, Internalisation, on the
  other hand they are worth learning. Role of
  experience. More geared to OO than other
  computing paradigms.

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Action Languages

• ALs can create, delete, directly change (via
  assignment) and send state changing messages to
  objects. The action language is executable and
  allows us to describe and execute the actions an
  object performs when receiving a stimulus. AL
  features
• Sequential Logic
• Access to the data described by the Class Diagram
• Access to the data supplied by signals initiating
  actions
• The ability to generate signals
• Access to timers
• Access to synchronous operations provided by
  classes and objects
• Access to operations provided by other MDA domains

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Action Languages

• ALs can create, delete, directly change (via
  assignment) and send state changing messages to
  objects. The action language is executable and
  allows us to describe and execute the actions an
  object performs when receiving a stimulus. AL
  features
• Sequential Logic
• Access to the data described by the Class Diagram
• Access to the data supplied by signals initiating
  actions
• The ability to generate signals
• Access to timers
• Access to synchronous operations provided by
  classes and objects
• Access to operations provided by other MDA domains

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Action Languages

• OMG only define Action Language Semantics (ASL)
  (not syntax), hence many possible flavors. Unlike
  conventional languages, there is no concept of a
  main function or routine where execution
  starts. Rather, ASL is executed in the context of
  a number of interacting state machines, all of
  which are considered to be executing concurrently
  and in the context of synchronous call stacks
  invoked from these state machines or directly
  from outside the system. Any state machine, on
  receipt of a signal (from another state machine
  or from outside the system) may respond by
  changing state. On entry to the new state, a
  block of processing is performed. This processing
  can, in principle execute at the same time as
  processing associated with another state machine.
  In short ALs support concurrency and animate UML
  models, In particular statecharts and interaction
  diagrams can be run by
• 1) creating objects with the keyword create
• 2) linking objects with the keyword link
• 3) sending messages with the keyword generate

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Action Languages

• Role in development.
• Because ALs can create objects and send messages
  to objects, they permit a range of modelling,
  prototyping and testing tasks.
• ALs can be used during analysis and design to
  specify and test (or check) general purpose
  constraints and other modeling needs.
• MDA aspect.
• ASL (Action Specification Language ) is designed
  to fill the semantic gap in UML and conforms to
  the UML Action Semantics Request for Proposal
  issued by the OMG. It supports platform
  independently action specifications PIMS for
  UML models and provides easy-to-understand
  operations on UML classes, objects and
  associations (which is not the case in usual
  programming languages).
• Realtime
• ASL useful for real-time embedded system, with
  high concurrency and timers/triggers required.
• ASL can directly model behavior whereas OCL can
  only model constraints about behavior.