The Easy Guide to Component Diagrams

While other UML diagrams, which describe the functionality of a system, component diagrams are used to model the components that help make those functionalities.

In this component diagram tutorial, we will look at what a component diagram is, component diagram symbols, and how to draw one. You can use a component diagram example below to get a quick start.

What is Component Diagram

Component diagrams are used to visualize the organization of system components and the dependency relationships between them. They provide a high-level view of the components within a system.

The components can be a software component such as a database or user interface; or a hardware component such as a circuit, microchip or device; or a business unit such as supplier, payroll or shipping.

Component diagrams

• Are used in Component-Based-Development to describe systems with Service-Oriented-Architecture
• Show the structure of the code itself
• Can be used to focus on the relationship between components while hiding specification detail
• Help communicate and explain the functions of the system being built to stakeholders

Component Diagram Symbols

We have explained below the common component diagram notations that are used to draw a component diagram.

Component

There are three ways the component symbol can be used.

1) Rectangle with the component stereotype (the text <<component>>). The component stereotype is usually used above the component name to avoid confusing the shape with a class icon.

 

2) Rectangle with the component icon in the top right corner and the name of the component.

3) Rectangle with the component icon and the component stereotype.

Provided Interface and the Required Interface

Interfaces in component diagrams show how components are wired together and interact with each other. The assembly connector allows linking the component’s required interface (represented with a semi-circle and a solid line) with the provided interface (represented with a circle and solid line) of another component. This shows that one component is providing the service that the other is requiring.  

Port

Port (represented by the small square at the end of a required interface or provided interface) is used when the component delegates the interfaces to an internal class.

Dependencies

Although you can show more detail about the relationship between two components using the ball-and-socket notation (provided interface and required interface), you can just as well use a dependency arrow to show the relationship between two components.

How to Draw a Component Diagram

You can use a component diagram when you want to represent your system as components and want to show their interrelationships through interfaces. It helps you get an idea of the implementation of the system. Following are the steps you can follow when drawing a component diagram.

Step 1: figure out the purpose of the diagram and identify the artifacts such as the files, documents etc. in your system or application that you need to represent in your diagram.

Step 2: As you figure out the relationships between the elements you identified earlier, create a mental layout of your component diagram

Step 3: As you draw the diagram, add components first, grouping them within other components as you see fit

Step 4: Next step is to add other elements such as interfaces, classes, objects, dependencies etc. to your component diagram and complete it.

Step 5: You can attach notes on different parts of your component diagram to clarify certain details to others.

Component Diagram Examples

Below are component diagram templates for common scenarios that you can instantly edit online. Simply click the template to open it in the Creately editor to apply changes.

Component Diagram for Library Management System

Component Diagram for Online Shopping System

Component Diagram for ATM

Component Diagram for Hospital Management System

Component Diagram for Inventory Management System

What are Your Thoughts on the Component Diagram Tutorial

In this component diagram tutorial, we’ve covered everything you need to know about component diagrams to easily draw one. You can use our UML diagram creator to draw component diagram online.

We recently published guides on UML activity diagrams and class diagrams as well, and if you missed out here are the links;

The Easy Guide to Class Diagrams

The Easy Guide to Activity Diagrams

Don’t forget to let us know your thoughts in the comment section below.