Understanding the UML Diagram: Everything You Need to Know

The software industry developed what became UML diagrams in the mid-’90s. Ever since then, they have used them throughout businesses to help developers plan their work. Today, they are common not only in the software industry but in many other areas, and knowing what one is may save you a great deal of time in the future.

In this article, we will be going through everything you might want to know about what such a diagram is, as well as how to use one for yourself.

UML Diagram

What Is a UML diagram?

In the late 20th century, there was a significant number of software companies grew to prominence. Alongside this, various engineers moved between said companies regularly.

Soon enough, it became necessary for the industry to form several standards for how they developed their work. Through this, they were able to share good practices and speed up development.

As such, the industry created a system of visualizations over several years of collaboration. These graphs included information developers need to understand the relationships of data in a system. Using this, they could develop a framework for building that software or debug it at short notice.

These days, developers use UML diagrams for more than software development. They also use a simplified version to display an office or team hierarchy or several other purposes. In fact, many use it to indicate any relationship diagram.

A detailed UML diagram, however, is generally used for software alone. Due to the nature of what people intend to display within it.

What Would You Use One For?

There are two primary types of UML diagrams, and people use them for different purposes. These two types are structural or behavioral diagrams.

Behavioral diagrams show what should happen in a system and how different parts interact or behave about one another. For example, an activity diagram is one form of a behavioral diagram that shows each part of a step-by-step process. A use case diagram is another type, which describes each of the components in the diagram and how they relate to each other.

Structural diagrams instead describe the objects in the system; they do not detail how they would interact. They may detail a set of steps or list several objects and what they contain but relate their data to the current state of the application. This is instead of about other objects.

There are many other types of UML diagrams, some of which go into a lot more information. For additional information on these, many sites can help you understand the nature of different UML diagrams. Sites such as https://setapp.com/how-to/uml-diagram-guide give good examples of how to create them.

How Do I Make One?

To put together a UML diagram, you should start by breaking down what you are trying to map out. Define it by its parts, as these will become the body of the elements in the diagram.

If this is a piece of software, this would be the different classes or objects in the software. Whereas if it is a structure diagram, this would be all the roles in the company or group.

After this, you should determine how the items in your diagram move work or data between one another. This could be displaying delegation of responsibility if this were a work structure diagram. Alternatively, this would relate to the movement of a single item of development if this were a workflow UML.

With a piece of software, this could be displaying the passing of data from one class to another in a software UML diagram. Also, you can use UML diagrams to show whether a class inherits its traits from elsewhere in the program or not.

There are standards for exactly how to display these relationships. You can find more details on how to do this elsewhere if you want to continue learning.

Generally, UML diagrams “flow down,” so the item with the highest importance sits on the top and/or left. After working through these relationships, you should have a solid idea of organizing the whole diagram.

What Goes in These Boxes?

When you have determined the flow of information and the objects to be in the UML diagram, the next step is to list all the items’ functions. In a corporate diagram, this might be a list of the individuals who take up that position of responsibility. In a piece of software, these would be all the attributes and operations within the class.

By inserting these into the diagram, you will display how attributes and operations feed down through the system. You will be able to determine items that inherit from the higher-level objects.

You will also work out if various UML objects must inherit values from elsewhere that you did not consider before following this process.

Finally, at this stage, you should have a complete UML diagram. As you have attached every technical item, you can add notes and clarifications for others who may use it in the future. So long as you have the basics already listed, it would help if you ended up with a useful document for use by others.

More Learning

Now you understand the basics of what a UML diagram is and what it takes to build one. You should now be good to go in discussing these concepts with your company.

Be aware that there is far more to UML diagrams than we could fit in this article. For additional information on understanding technical concepts such as this, make sure to visit our blog.

Jay Hunter
Beer trailblazer. Internet lover. Gamer. Passionate zombie advocate. Troublemaker. Spent 2002-2008 selling wool in the aftermarket. My current pet project is getting my feet wet with cigarettes in the aftermarket. What gets me going now is implementing catfish in Naples, FL. Spent childhood testing the market for weed whackers in Africa. Spent several months getting to know g.i. joes in New York, NY. Spent a year developing strategies for sheep on the black market.