UML Diagrams: Sequence and Class Diagrams

Posted on Feb 21, 2025 in Computers

Sequence Diagram

This tool is part of the UML diagrams and allows dynamic plot the sequence of steps or activities that are run on a particular use case. Elements are:

  • Objects: Represented by a rectangle with the name at the bottom, a broken line which we call lifeline. On this is placed a vertical rectangle which call activities which indicates when an object is in operation.
  • Messages: Represent information sent from the lifeline of an object to the lifeline of another. They can be of three different types:
    • Simple: Indicates the transfer of control from one object to another.
    • Synchronous: Indicates that responses should be expected to continue with the process.
    • Asynchronous: An automatic message, also called, is not expected to answer or make transfer of control.
  • Time: Represented by the dotted line beneath the objects, i.e., the longer the line, the longer the object within the process.

Class Diagram

Concept: This is one of the most important diagrams in object-oriented design. It describes all classes of a system and their corresponding relations, but never describes the dynamic, graphical representation of a class. A class is a rectangle which has a name at the top, some attributes or characteristics on the front and a method or procedure used at the bottom.

Relationships are the ways of how to associate different classes. It takes generalization relationship, which can manage complexity through a legal system in the form of the kind which allows the bundling of characteristics of a class in a more general class. The most common names are super-class, sub-class.

It is also called hierarchical relationship between classes. There are two types of inheritance: inheritance and herenciaria simple.

Multiplicity ratio: This ratio indicates how much of a class of objects relates to a class object. The line used for this relationship is a continuous line and the ends placed the number of objects that are related. It is the equivalent to the cardinality in the case of use.