UML Interaction Overview Diagram Tutorial

Understand the use of Interaction Overview Diagram in UML to make more complicated system activities easier to understand.

 uml interaction overview diagram tutorial

Unified Modeling Language (UML) is key for developers. It plays a pivotal role in their lifecycle. They have to identify the project before working on it. UML interaction diagram comes in handy in projects where a certain behavior or message flows between multiple components within the system. UML interaction diagrams show the flow of these messages in real time. They visualize it in a certain system.

The UML interaction overview diagram focuses on the flow of control. It shows the interactions' flow. It creates a descriptive visualization. This diagram makes development easy. It also lets an individual present their project idea to stakeholders in a big way.

In this article
  1. What Is the UML Interaction Overview Diagram?
  2. Interaction Diagrams Symbols and Terminologies
  3. Why Use an Interaction Diagram
  4. Complete the Process of Creating an Interaction Diagram
  5. Interaction Overview Diagrams Examples
  6. Conclusion

Part I. What Is the UML Interaction Overview Diagram?

The Interaction Overview Diagram effectively gives a high-level view of the project before its actual implementation and development. This includes the demonstration of how different interactions will occur within a certain system, more like a roadmap.

For example, if you are an employee at a department in an organization and want to navigate to your desk, you have to undergo multiple checkpoints before finding it.

Scenarios like these require an Interaction Overview Diagram. Similarly, the Interaction Overview Diagram is made using a series of Interaction Diagrams. This can include a Sequence Diagram. It shows the exact sequence of the messages or the flow of communication between modules.

It can also be a Communication Diagram. This type highlights the structure and shows the involvement of each object and their connection during each interaction. The combination of these diagrams together creates a versatile visualization of your system.

An IOD is perfect when you need to understand the bigger picture. It helps you identify and answer the questions that sum up the effectiveness of your system in the bigger run. Such as how different parts of the system interact to achieve a specific goal. What are the key decision points and alternative paths the interaction can take?

By using IODs, you can see how your complex system works as a whole. This makes it easier to spot potential issues and ensure everything works well.

Part II. Interaction Diagrams Symbols and Terminologies

Interactive Diagram consists of some of the important symbols that lay its foundation. The proper use of these symbols plays a crucial role in making your system understandable and flawless during its development phase. The symbols and their functions are:


It refers to the vertical line that represents the object's lifetime and its participation in the interaction labeled with the object name.



A user-like figure that represents the external entities interacting with the system. It can be a user or another system.



A message is represented by an arrow and describes the communication between multiple objects. Different arrow styles indicate different message types.


Two-sided message: It is represented by a solid line arrow. It is used when a sender waits for a reply before continuing with other processes.

Asynchronous Message: A single-sided message, which is represented by a dashed line arrow, is used when a sender does not wait for the message and keeps going with other processes.

asynchronous message

Return Message: A message which is sent back in response to a call message.

return message

Create Message: A message that creates a new instance of an object.

create message

Destroy Message: A message that destroys an existing object.

destroy message

Activation Bar

An activation bar is a rectangular bar that is placed on lifelines and shows the information activeness and processes of an object.

activation bar


It is invoked when a certain object calls or sends a message to itself.

Combined Fragment

It is used to group related message interactions, like loops or alternative flows.

Interaction Operand

An interaction operand is represented by a rectangular box and contains an optional guard condition that determines whether the enclosed messages are executed or not.

Some of the terminologies which you will hear in Interaction Overview Diagrams are:

Guard Condition

A boolean expression that determines the flow of messages during an interaction operand.

Understanding these key symbols and terminologies is important to creating a well-structured diagram with labeled objects. This helps ensure message transmission throughout the system. If an error occurs, a good diagram can help a person find its cause. This cuts debugging time.

Part III. Why Use an Interaction Diagram

Following are some of the scenarios where you can use the UML Interaction Overview Diagram:


From visiting the website to placing an order, we go through multiple phases where interaction occurs. Moreover, there are points where decisions are required. For example, adding a product to a wishlist and similarly adding it to a cart requires a series of decisions. Situations like these require an Interactive Diagram to understand the working procedure in a better way.

Banking Application:

Signing up for a bank account might seem easy yet is a complex task. It not only requires a strong authentication process but also multiple conditions based on which a certain transaction occurs. Situations like these involve an Interaction Overview Diagram.

Customer Support Workflow:

The Interaction Overview Diagram would detail the flow of a customer query through different stages, including branching based on query type and the final resolution.

Learning Management System:

The Learning Management System (LMS) requires many users and their separate roles. These roles segregate their functions. We can use an Interaction Overview Diagram to tell the roles apart. It describes each role in a separate sequence or communication diagram.

Part IV. How to Create an Interaction Diagram

Step 1: Select the topic and define the scope

Understand the specific process or the system interaction that you want to model. Let's take an example of the Online Shopping Process in our case. After identifying the topic, let's just define the main interaction involved such as browsing products, adding them to a cart, checking out, and processing the payment.

Step 2: Identify the key use cases

Identify the main use cases or interactions that you can include in the diagram. This includes browsing the products, adding to cart functionality, check-out, and payment processing methods. Once done, describe the purpose of each of these use cases and its involvement with the system.

Step 3: Break down each use case into sub-interactions

Once the key components are identified, break down each of those use cases into relevant sub-interactions as well. Decompose them into smaller and more manageable interactions or steps.

For example, if we talk about browsing the product, we know that we can divide it further. We can divide it into "View Product Categories, Filter the Products, Product Details". Similarly, the Add To Cart functionality features tasks such as "Select Product", "Specify Quantity" and "Check-out".

Step 4: Draft the flow and identify decision points

Highlight the sequence of interactions and then identify the decision points where the flow might divide into branches. For example, consider the "Start with Browsing Product".

Here you can be asked whether the user selected a product. If the answer is No, the flow reverts to the initial node, and if Yes, it proceeds to Add To Cart. Similarly, after proceeding to the next step, it asks whether the user wants to checkout.

Step 5: Create the initial diagram layout

Begin sketching the diagram, placing the initial node, interactions, decision points, and control flows. You can use symbols like:

  • Initial Node: Start point (filled black circle).
  • Interaction Use: Referenced interactions (rectangles with corners folded over).
  • Decision Node: Decision points (diamond shapes).
  • Control Flows: Arrows indicating the direction of flow.
  • Final Node: Endpoint (black circle with a border).
Step 6: Label the diagram clearly and verify

Label each node, interaction, decision point, and control flow arrow with descriptive names. Make sure that each interaction has a clear label such as "Browse Products," "Add to Cart," "Checkout," and "Payment Processing." Control flows should be directional with arrows pointing to the next step or interaction.

Part V. Interaction Overview Diagrams Examples

1. Sales processing system

The UML interaction diagram depicts the sale process. It illustrates the interactions between a user and the system for creating a sale record. The process starts with the user initiating a request to search for an item. The system then searches for the item.

If the item is found, the system allows the user to check out. If not found, the user can cancel the sale. If the user decides to check out, the system asks for confirmation to finalize the sale. Once confirmed, a record is created. If the user cancels the sale, the interaction ends.

2. Online shopping system

The UML interaction diagram shows the process of booking a hotel room. It focuses on the flow of the interaction. It does not focus on the order of messages. The process starts with the user identifying the room type, date, and duration of their stay.

The system then checks if the request is valid. If the request is valid, the system checks if any available rooms match the user's criteria. If a room is available, the system asks the user for their billing information. Once the billing information is confirmed, the reservation is booked.

3. Financial report generation system

The UML interaction diagram depicts a financial report generation system. It shows how parts of the system interact. The system makes financial reports.

The process starts with scheduling a task action. The system checks if it’s less than two weeks before the scheduled date. If so, it triggers an alert. Then, the report creation process starts. This involves gathering data, reviewing it, and filing a report.


Understanding this is an essential part of Software Requirement Engineering. It is key to know how to make an interactive overview diagram. UML Interaction Overview Diagram is undoubtedly a powerful tool that allows detailed modeling of complex interaction sequences and decision flows within a system. Not only this, it is also essential in understanding as well as analyzing major aspects of your system's behavior.

Using the UML interaction diagram helps. It lets devs and stakeholders talk. By following the step-by-step guide, one can create a comprehensive and coherent diagram that clearly illustrates the system's workflow along with the deeper understanding and interactive components of the system.

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Zac Jenkins
Zac Jenkins Jul 04, 24
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