root/gaphor-doc/trunk/gaphor-elements.xml

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<chapter id="chap-elements">
  <title>UML elements</title>

  <para>This chapter describes the UML elements that are implemented by
  Gaphor.</para>

  <section id="sect-elements-actor">
    <title>Actor</title>

    <para>Actors are used to describe external entities that interact with the
    system. In this case an external entity can be a user or another system
    which interacts with the system.</para>

    <para>An actor is represented by the <literal>Actor</literal>
    class.</para>

    <para>See also <xref linkend="sect-elements-class"/>,
                   <xref linkend="sect-elements-usecase"/> and
                   [TODO: link to usecase diagram].</para>
  </section>

  <section id="sect-elements-association">
    <title>Association</title>

    <para>Associations are used to define relatinships between classifiers
    (classes, actors, usecases). The most common usage is in Class and UseCase
    diagrams.</para>

    <para>An association is created by one Association instance and two or
    more Property's (in case of Gaphor: two, Gaphor can't handle N-ary
    association at this moment).</para>

    <para>An association end can be navigable or not. If an association end is
    navigable, the class can traverse to the class at the other end.
    If an end is navigable, the property at that end is owned by the class
    (<literal>Property.class_</literal> refers to the class and the property is
    in <literal>Class.ownedAttribute</literal>). If the end is not navigable,
    the property is owned by the association
    (Property.owningAssociation/Association.ownedMember).</para>

    <figure id="fig-elements-association">
      <title>An association</title>
      <graphic fileref="examples/association/associationExample.png"/>
    </figure>

    <para><xref linkend="fig-elements-association"/> shows how an association
    as shown in a diagram (a) is implemented in the data model (b). The
    Association has two properties: one with name <literal>myWheel</literal>
    and one with <literal>theBike</literal>. In (a) an arrow is drawn from
    <literal>Bike</literal> to <literal>Wheel</literal>, meaning that
    instances of <literal>Bike</literal> can traverse to instances of
    <literal>Wheel</literal>, but not visa versa. In the data model (b) this
    is represented as property <literal>myWheel</literal> being an attribute
    of <literal>Bike</literal>. Property <literal>theBike</literal> can not
    be used to go from <literal>Wheel</literal> to <literal>Bike</literal>,
    therefore it's owned by the Association.</para>

    <para>Association is subclass of Namespace. When a new Association is
    created in a diagram, the namespace is set to the namespace of the
    diagram.</para>


  </section>

  <section id="sect-elements-class">
    <title>Class</title>

    <para>Classes are the most well known elements of UML. A class as a unique
    name (within it's namespace) and can contain attributes and operations.
    Relationships with other classes can be established by means of
    associations, dependencies and generalization.</para>

    <section>
      <title>Attributes</title>

      <para>Attributes can be written using OCL syntax:
      <programlisting>
+ name: string
# count: integer = 1</programlisting>
      </para>

      <para>Syntax:
        <synopsis>
attribute     ::= [visibility] [derived] name [':' type] ['=' default] ['{' tagged_values '}']
visibility    ::= ('+'|'#'|'-')
derived       ::= '/'
name          ::= literal
type          ::= literal ['[' multiplicity ']']
multiplicity  ::= mult_value ['..' mult_value]
default       ::= literal
tagged_values ::= tagged_value [, tagged_value]*
tagged_value  ::= literal
mult_value    ::= ('0' .. '9' ['0' .. '9']* | '*')
literal       ::= literal_char [literal_char]*
literal_char  ::= ('A' .. 'Z' | 'a' .. 'z' | '0' .. '9' | '-' | '_')</synopsis>
      </para>

    </section>

    <section>
      <title>Operations</title>

      <para>Syntax:
        <synopsis>
operation     ::= [visibility] name '('[parameterlist]')' [':' type] ['{' tagged_values '}']
visibility    ::= ('+'|'#'|'-')
derived       ::= '/'
parameterlist ::= parameter [',' parameter]
parameter     ::= [direction] name [':' type] ['{' tagged_values '}']
direction     ::= ('in'|'out'|'inout')
name          ::= literal
type          ::= literal ['[' multiplicity ']']
multiplicity  ::= mult_value ['..' mult_value]
mult_value    ::= ('0' .. '9' ['0' .. '9']* | '*')
tagged_values ::= tagged_value [, tagged_value]*
tagged_value  ::= literal
literal       ::= literal_char [literal_char]*
literal_char  ::= ('A' .. 'Z' | 'a' .. 'z' | '0' .. '9' | '-' | '_')</synopsis>
      </para>
    </section>

  </section>

  <section id="sect-elements-comment">
    <title>Comment</title>

    <para>TODO</para>
  </section>

  <section id="sect-elements-dependency">
    <title>Dependency</title>

    <para>TODO</para>
  </section>

  <section id="sect-elements-generalization">
    <title>Generalization</title>

    <para>TODO</para>
  </section>

  <section id="sect-elements-package">
    <title>Package</title>

    <para>TODO</para>
  </section>

  <section id="sect-elements-usecase">
    <title>Use Case</title>

    <para>TODO</para>
  </section>

</chapter>
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