UML Sequence Diagram Template

About the UML Sequence Diagram Template

A sequence diagram template is a tool that helps teams get a better overview of their work process, depicting object interaction in a system in sequential order. Many use a system sequence diagram to map the customer journey through an eCommerce store or to get a high-level overview of specific business functions. In the first scenario, the customer is the "actor" or external entity interacting with the diagram elements. The diagram for the second example does not necessarily need to have an "actor."

Teams also use the sequence diagram to analyze existing work systems. However, one of its primary use cases is in requirements documents for future systems implementation, so when staff or analysts design a new system, one or more sequence diagrams are used to showcase how this system will behave.

How to use the UML sequence diagram template

Miro is the perfect online sequence diagram tool to create your diagram from scratch and share it with your team. Miro also has its own template that you can customize to suit your needs. Simply select the UML sequence diagram template and then follow these steps:

1. Identify your lifelines

Lifelines represent the roles or object instances that are interacting. There can be two or more lifelines in a sequence. Each lifeline is placed in a box at the top of the diagram with a vertical dashed line below it.

2. Create messages

A message is an interaction between the lifelines. It is represented using a horizontal arrow. Seven different types of messages can be used in a sequence diagram.

3. Define your actor

An actor is an external entity that interacts with the sequence but is not a part of that sequence. In online shopping, for example, the "actor" is the customer, while the shopping system (e.g. "Add to cart"-"Total"-"Confirm order") is the sequence.

4. Add action bars

An activation bar is a thin rectangle that is placed under a lifeline to represent the time it takes to complete a task. You can add multiple activation bars on the lifelines.

5. Include any other important features

In complex sequence diagrams, you can add Alternatives, Options, and Loops to represent different sequences.

Examples of a UML sequence diagram

Let's use the example of a fast-food restaurant's ordering system to understand how a sequence diagram works.

The following interactions take place during this sequence when a customer wants to place an order:

• They go to the cash counter and place an order

• The cashier confirms the order and gives order details to the kitchen

• The kitchen staff prepare the food and deliver it back to the counter

• The cashier hands the order to the customer.

A sequence diagram example for this scenario will have the customer, the cashier, and the kitchen as the three lifelines. They deliver messages back and forth.

The actions that take place during this sequence are the messages. Such as "Place an order," "Order confirmation," "Order details for preparation," and "Order delivery."

Benefits of using the UML sequence diagram template

Let’s walk through the four benefits of using a sequence diagram template.

1. Discover interface and logical problems early

Since creating a sequence diagram requires teams to flesh out all the details of a system, it helps them find problems well before the implementation phase.

2. Collaborate with teammates

A sequence diagram is an excellent option when you want to clearly depict how a system works or should work during team meetings or projects. Because of this, you can use it as a collaboration diagram.

3. Get a bird’s-eye view

With a sequence diagram, analysts can examine a system, whether that's a shopping kiosk or a new app, at various levels of abstraction. You can start with a high-level view of the system and then delve into the details as required.

4. Update it easily

Teams can update every element within a sequence diagram to match changing events or circumstances without overhauling the entire diagram.