How to draw a Timing Diagram in UML
Timing diagrams are a sub-type of sequence diagrams in UML. Read this tutorial for a simple, step-by-step guide to creating a timing diagram of your own. You'll love the end result!
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How to Create a Timing Diagram
Timing diagrams can be confusing when first getting started, so it's important to understand the UML basics. Try reviewing our Timing diagram overview, along with this tutorial on Unified Modeling Language. Once you have a solid understanding you'll be able to start creating UML diagrams with Lucidchart.
PICK A UML TOOL
Remember that timing diagrams are actually sub-types of the sequence diagram, whose notation is also dictated by UML. When you begin building UML diagrams, you'll realize the benefits of choosing an adaptive tool. While pen and paper or even whiteboards are useful for sketching basic outlines, anything more requires a robust program—one that's designed for simple sharing, editing, and storing.
We'll proceed as though you're using Lucidchart. Our program allows you to draw accurate diagrams with little training, as well as to collaborate in real-time with other users.
UNDERSTAND NECESSARY ELEMENTS
Begin your timing diagram by making a new document in Lucidchart. To display a custom view, click “More Shapes” and turn on the UML shape library. You'll be using shapes primarily from the sequence diagram section of the UML shape library.
You may also want to open up the BPMN shape library in order to access swimlane shapes and other BPMN symbols—many of them have the same meaning and potential application within timing diagrams.
Before you start clicking and dragging, it's helpful to create a list of tasks, or states, in your timing diagram. States are the activities that the system must complete. For example, an ATM timing diagram may include states like the customer inserting a bank card, the card being validated by the machine, the customer entering a PIN, and so on.
Now that you've determined states, figure out which objects will be involved. Objects are the most important participants in the process, and they don't have to be people. Sometimes called actors, objects perform tasks in the sequence and send messages back and forth. After you know which objects will be included, match them up with their tasks and order them logically.
ADD TEXT AND SHAPES
Once your information is mapped out textually, it's simply a matter of transferring it to a visual format. To position shapes on the page, just drag and drop from the toolbox to the canvas. Repeat that action to adjust symbols once they're in place. Select a horizontal swimlane shape from the toolbox and indicate the appropriate number of rows. At the bottom of the swimlane shapes, you should add labeled tick marks to indicate the passage of time. If you don't know which increments you'll be using, evenly-spaced labels of 0T, 1T, 2T, and so on are acceptable. Time flows along this horizontal axis from left to right, as seen below.
Double-click the title text in the swimlanes and replace it with the name of the object. Make sure that only participants that contribute meaningful actions to the sequence are represented in the diagram. Next, list the tasks to be completed in the correct swimlane, right next to the object name.
Remember to represent the movement of activity across tasks and objects. There are two ways to do so: with state lifelines or value lifelines. The image you see below is an example of a timing diagram with value lifelines, which generally makes for a cleaner chart that's easier to read.
- Using state lifelines - Simply press the L key to draw a line that tracks progress from task to task and state to state. You can also draw arrows and timing constraints to indicate trigger events and how the triggered activity affects other objects. Remember that state lifelines list states next to the swimlane title and use dynamic lines to represent progress.
- Using value lifelines - Add stretched hexagonal shapes to model progress in the sequence over time. Instead of a jagged or squared-off line, the shapes narrow to a point and include the states or values internally.
Lucidchart's features are constantly evolving to keep pace with industry standards. To see which UML shapes are currently offered, sign up for free and explore the product.
Timing Constraint Notation
Add these labels to your events to describe the duration of a particular event.
Lucidchart can help you create UML diagrams for work or school. Our cloud-based software works on any platform, so users can access Lucidchart anywhere, any time. Try it and see for yourself!