UML Interaction Diagram

As the name suggests, the interaction diagram portrays the interactions between distinct entities present in the model. It amalgamates both the activity and sequence diagrams. The communication is nothing but units of the behavior of a classifier that provides context for interactions.

A set of messages that are interchanged between the entities to achieve certain specified tasks in the system is termed as interaction. It may incorporate any feature of the classifier of which it has access. In the interaction diagram, the critical component is the messages and the lifeline.

In UML, the interaction overview diagram initiates the interaction between the objects utilizing message passing. While drawing an interaction diagram, the entire focus is to represent the relationship among different objects which are available within the system boundary and the message exchanged by them to communicate with each other.

The message exchanged among objects is either to pass some information or to request some information. And based on the information, the interaction diagram is categorized into the sequence diagram, collaboration diagram, and timing diagram.

The sequence diagram envisions the order of the flow of messages inside the system by depicting the communication between two lifelines, just like a time-ordered sequence of events.

The collaboration diagram, which is also known as the communication diagram, represents how lifelines connect within the system, whereas the timing diagram focuses on that instant when a message is passed from one element to the other.

Notation of an Interaction Diagram

Purpose of an Interaction Diagram

The interaction diagram helps to envision the interactive (dynamic) behavior of any system. It portrays how objects residing in the system communicates and connects to each other. It also provides us with a context of communication between the lifelines inside the system.

Following are the purpose of an interaction diagram given below:

1. To visualize the dynamic behavior of the system.
2. To envision the interaction and the message flow in the system.
3. To portray the structural aspects of the entities within the system.
4. To represent the order of the sequenced interaction in the system.
5. To visualize the real-time data and represent the architecture of an object-oriented system.

How to draw an Interaction Diagram?

Since the main purpose of an interaction diagram is to visualize the dynamic behavior of the system, it is important to understand what a dynamic aspect really is and how we can visualize it. The dynamic aspect is nothing but a screenshot of the system at the run time.

Before drawing an interaction diagram, the first step is to discover the scenario for which the diagram will be made. Next, we will identify various lifelines that will be invoked in the communication, and then we will classify each lifeline. After that, the connections are investigated and how the lifelines are interrelated to each other.

Following are some things that are needed:

1. A total no of lifeline which will take part in the communication.
2. The sequence of the message flow among several entities within the system.
3. No operators used to ease out the functionality of the diagram.
4. Several distinct messages that depict the interactions in a precise and clear way.
5. The organization and structure of a system.
6. The order of the sequence of the flow of messages.
7. Total no of time constructs of an object.

Use of an Interaction Diagram

The interaction diagram can be used for:

1. The sequence diagram is employed to investigate a new application.
2. The interaction diagram explores and compares the use of the collaboration diagram sequence diagram and the timing diagram.
3. The interaction diagram represents the interactive (dynamic) behavior of the system.
4. The sequence diagram portrays the order of control flow from one element to the other elements inside the system, whereas the collaboration diagrams are employed to get an overview of the object architecture of the system.
5. The interaction diagram models the system as a time-ordered sequence of a system.
6. The interaction diagram models the system as a time-ordered sequence of a system.
7. The interaction diagram systemizes the structure of the interactive elements.