What are the Common Notation Used in UML Interaction Diagram


Unified Modeling Language (UML) is a standard graphical language used for modeling software systems. One of the key UML diagrams used for modeling dynamic behavior is the interaction diagram. An interaction diagram is a diagram that shows how objects interact with each other to achieve a specific task. There are two types of interaction diagrams in UML: sequence diagrams and communication diagrams. In this article, we will discuss the common notations used in both types of interaction diagrams.

Sequence Diagram Notations:

  1. Lifeline: A lifeline represents an instance of a class or an object. It is represented as a vertical line with a box at the top that contains the name of the class or the object. A lifeline can also have a symbol at the bottom that represents the destruction of the instance.
  2. Activation Bar: An activation bar represents the time during which an object is performing an action. It is represented as a horizontal line that is aligned with the lifeline of the object. The length of the activation bar represents the duration of the action.
  3. Message: A message represents a communication between two objects. It is represented as an arrow that starts from the lifeline of the sender object and ends at the lifeline of the receiver object. A message can be synchronous, asynchronous, or a return message.
  4. Self-Message: A self-message represents a message that is sent from an object to itself. It is represented as a loop on the lifeline of the object.
  5. Combined Fragment: A combined fragment represents a group of messages that are executed under a specific condition. It is represented as a box that contains a condition that determines when the messages will be executed. There are three types of combined fragments: alternative, option, and loop.

Communication Diagram Notations:

  1. Object: An object represents an instance of a class or an entity. It is represented as a rectangle that contains the name of the object.
  2. Message: A message represents a communication between two objects. It is represented as an arrow that starts from the sender object and ends at the receiver object. A message can be synchronous, asynchronous, or a return message.
  3. Association: An association represents a relationship between two objects. It is represented as a line that connects the objects. The association can have a name and a multiplicity.
  4. Self-Message: A self-message represents a message that is sent from an object to itself. It is represented as a loop on the object.
  5. Constraint: A constraint represents a condition that must be satisfied for a message to be sent. It is represented as a box that contains the condition.

Conclusion:

Interaction diagrams are a powerful tool for modeling the dynamic behavior of a software system. Sequence diagrams and communication diagrams are the two types of interaction diagrams in UML. The notations used in these diagrams are standardized and well-defined. Understanding these notations is essential for creating accurate and effective interaction diagrams. By using these notations, developers can create models that are easy to understand, maintain, and modify.

       

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