UML Notations in CommonKADS

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UML Notations in CommonKADS

• Activity diagrams
• State diagrams
• Class diagrams
• Use-case diagrams

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Background UML

• Nineties number of popular object-oriented
  methods
• Unified Modeling Language proposal for set of
  standard notations
• wide attention
• see www.rational.com
• mainly meant for analysis phase

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UML notations used

• Class diagram
• static information structure (data)
• Activity diagram
• combined function/control view
• Use-case diagram
• high level view of system services (functional)
• State diagram
• highly interactive control

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Activity diagram

• Model control and information flow of a procedure
  or process
• Useful if control is mainly synchronous
• otherwise use state diagram
• Use in CommonKADS modeling the organizational
  process
• worksheet OM-2 of the organization model
• Can also be used to model control flow within a
  task method (knowledge model)

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Action state

• State in which some work is being done
• activity, task
• State terminates when the work is finished
• difference with state diagrams
• After termination the action state can lead to
  another action state
• state transition
• Special symbols for being and end of a procedure
  or process

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Basic notation for activity diagram
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Decision

• Sate transition is deterministic
• If transition depends on outcome of the work,
  then introduce a decision

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Introducing concurrency
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Swim lanes

• Process can sometimes be distributed over several
  agents or organizational units
• Notation use compartments
• In particular useful when modeling a business
  process (e.g. in organization model)

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Notation for swim lanes
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Object flow
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Signals
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Business process Housing
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Activity diagram of method control
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State diagrams

• Synonyms state chart, state-transition
  diagram
• Purpose model of dynamic behavior
• Use if control is heavily influenced by
  external events
• Draw a state diagram for object classes with
  interesting behavior
• Activity diagram is alternative
• internal control
• object flow

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State
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State transition

• Event comes from outside the object modeled
• Message generates event for another object
• Guard outcome of internal object computation

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Actions and activities

• Action instantaneous, not interruptible
• on transition
• on state entry action on all incoming
  transitions
• on state exit action on all outgoing
  transitions
• on event
• Activity takes time, interruptible

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State diagram of ticket machine
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State concurrency
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State generalization

• If Object A is in super-state S, then the object
  us in precisely one of the sub-states
• Cf. concurrency and-states

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State diagrams in CommonKADS

• Communication modeling (Ch. 8)
• Asynchronous reasoning control
• real-time applications
• Control specification for the business process
• Overlap with activity diagrams
• state with no outgoing events action state

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State diagram Housing
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Class diagram

• Captures static information structure
• In O-O also functions
• Generalization, inheritance reuse are
  important issues
• Imported into CommonKADS domain- schema notation
• no use made of operation box
• Can also be used in Task Model to sketch task
  information structure

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Objects and classes
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Object class

• Describes a group of objects with similar
  properties
• Abbreviation "class"
• Rationale for introducing classes
• it provides a means for abstraction
• Terminology object is often used in an
  ambiguous way, pointing to both objects (in the
  strict sense) and object classes.

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Attributes

• An attribute describes a value held by objects
  belonging to the class.
• Attribute specification consists of
• Class it is defined on (student)
• Attribute name (name)
• Admissible values (string)
• Optional default value

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Object and Value

• Most O-O approaches distinguish between objects
  and values.
• Difference a value does not have an identity
• it "lives only in connection to a certain
  object.
• RULE 1 an object is not allowed as a possible
  value of an attribute!
• RULE 2 attribute names need only to be unique
  within a class.

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Values and Value Sets

• Values are the primitive things with no internal
  structure from the viewpoint of the application
• Admissible values are defined through a value set
• Typical predefined value-sets
• string, number, integer, real, range, boolean,
  .
• User-defined
• set or list of strings

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Object Identifiers

• In O-O modeling you assume that every object has
  an identity.
• Consequence introduce only attributes that act
  as identifiers, iff the identifier is something
  that exists in the real world.
• Examples student card number, social security
  number.

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Operations

• Definition
• operation is "a function or a transformation that
  can be applied to objects of a class".
• Objects in a class share the same operations.
• Method implementation of an operation
• functional view

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Class notation
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Associations

• Associations are used to link objects to other
  objects
• Majority of associations
• binary (between two objects)
• directional (should be read in a particular
  direction
• Ternary associations come up occasionally.
• Associations between more than three objects are
  rare.

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Association notation
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Multiplicity examples
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Multiplicity

• Also called "cardinality".
• Always connected to one of the classes involved.
• Typical types of multiplicity
• 0-1 Zero or one (optional).
• 1 Precisely one.
• 0 Zero or more,
• 1 One or more.

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Association class

• Modeling an association as a class if the
  association has an internal information structure
• Advantage associations become first-class
  objects.
• Attributes and methods can be defined for the
  association class.

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Notation association class
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Use of an association class
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Associations with specific semantics

• Associations provide a general, "neutral", way of
  connecting object classes.
• Semantics of the association are defined through
  argument typing, multiplicity and (implicitly)
  the name of the association.
• Class diagrams provide specific types of
  associations, with predefined semantics
• generalization ("is a").
• aggregation ("part of").

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Generalization

• Purpose sharing similarities while preserving
  differences
• Is an association between a class that acts as
  super-class and one or more classes called the
  sub-classes.
• Super-classes show the features that the
  sub-classes have in common.
• Each sub-class inherits the attributes and
  operations defined on its super-class(es).

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Notation for generalization
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Aggregation

• Aggregation denotes a binary association in which
  one side is an "assembly" and the other side a
  "part".
• "Assembly" and "part" act as predefined roles
  involved in the aggregation association.
• Cardinality of a part can be defined
• precisely one optional (0-1) many, ...

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Notation for aggregation
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Composition

• Sub-type of aggregation
• Existence of part depends on aggregate

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Aggregation and generalization

• Similarities
• Tree-like structure
• Transitive properties
• Differences
• AND-tree (aggregation) vs. OR-tree
  (generalization)
• instance tree (aggregation) vs. class tree
  (generalization)

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Combined aggregation and generalization
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Use-case diagram

• shows services that can be expected from a system
• provides outsider view (customer)
• terminology
• use case service provided by system
• actor agent using a system service
• used in early phases of system analysis
• use in CommonKADS way to present possible
  solutions to customer

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Use cases for a library
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A small case study

• Course administration system (CAS)
• Context university department
• Required services
• STUDENT update personal data, inspect exam
  results, inspect course info, enroll in course
• TUTOR inspect exam results, update course info,
  inspect enrollments
• ADMIN STAFF enter exam results, inspect exam
  results, update personal data students, inspect
  enrollments

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Use cases
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Class diagram
exam
date date
result 0..10
requires
0
course-exam
1
enrollment
0
student
date date
course
student-card string
course-code string
name string
0
0
year integer
address string
trimester 1-3
date-of-birth data
study-points integer
major Major
learning-goals string
.........
description text
literature text
maximum-students integer
0
university
staff member
title string
1
position string
department string
tutor
telephone string
room string
e-mail string
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Activity diagram for course enrollment procedure
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State diagramupdate student data