UML User Guide Study Notes (6)

Reprinted: http://jeffrey.blogbus.com/logs/66085.html

 

Chapter 6 public mechanism

In the UML introduction in Chapter 2, the common mechanism of UML is mentioned, including Specification Description, modification, General Division and extension mechanism. This chapter details the Modification and extension mechanisms.

① Note)
Annotation is a graphical symbol appended to an element or element set to represent a constraint or annotation. Annotations can contain text, illustrations, or URLs.
Usage principles:
(1) The attachment should be placed in the corresponding element, and the dependency link annotation and corresponding element should be used.
(2) only display the annotation as needed.
(3) If the annotation is too long, you can consider placing it in external text and specifying the position using the link.
(4) discard the notes without retaining value.

② Other modifiers
For example, it is used to modify the associated roles and multiple features. For classes, components, nodes, and other things, you can also add a separator column at the bottom of the graph to fill in the modifier information.

③ Construction type)
The constructor is used to expand the vocabulary of UML. It can be used to regard constructor as a meta-type, because each constructor creates an equivalent of a new class in the UML meta-model. New constructor blocks can have their own characteristics, semantics, and representation. The simplest constructor can be to add a name to the thing Graphics of UML.
Usage principles:
(1) confirm that basic UML cannot express what you want to describe.
(2) We should select the most similar graph from the basic UML to construct a new building block.
(3) define a set of tag values and constraints to describe the features and semantics of newly constructed blocks.
(4) You can use the new icon to clearly mark the new construction block.

④ Togged Value)
The simplest tag value is to add a tag with {content} under the name of the UML thing graphics. For example, specify the enumerated value.
Usage principles:
(1) confirm that basic UML cannot express the features you want to describe.
(2) general application rules: a tag value defined for an element can be applied to its children and grandchildren.

⑤ Constraints
With constraints, you can add new semantics or change existing rules. A constraint can be marked with {content} and placed near the relevant element.
Usage principles:
(1) confirm that basic UML cannot express the semantics you want to describe.
(2) Place the constraint to the attachment of the corresponding element and connect it with the dependency.
(3) If You Need To describe new meanings more accurately and formally, you can use OCL to write new meanings. (What does OCL mean)

In general, you can use basic UML to describe your system. In some cases, you may not be able to fully meet your needs, so you can use an extension mechanism to make up for it. Use the basic elements defined by UML as much as possible to ensure that your UML can be understood by others.