UML Component Diagram Template

About the Component Diagram Template

A component diagram shows components, wiring, and artifacts as part of a physical system. It is commonly used to illustrate how complex systems — e.g., software systems, servers, etc. — are organized and wired together in the physical world.

Keep reading to learn more about what a component diagram is and how to create one using this template.

What is a component diagram?

Most UML diagram types describe digital assets and the relationships between them. A component diagram is different — it shows the physical relationships between the components of an object-oriented system.

A UML component diagram depicts physical objects and artifacts and the wiring that connects them. Instead of describing what these objects and artifacts do, it simply describes where they are and how they’re connected.

An example of a typical component diagram might show the physical components of a digital e-commerce system, e.g., a data warehouse, warehouse terminals, and end users’ devices.

Benefits of component diagrams

The first benefit of a component diagram is the ability to see a system’s physical components using simple-but-powerful visuals. Systems, especially large ones, can be difficult to understand and explain. This can make it challenging to plan, create, and optimize them. Component diagrams simplify things by giving teams an easy way to view physical systems and their components.

The second benefit of a component diagram is the ability to see how components are organized and wired together. This can help you plan physical space, shop for components, and see any gaps that need to be filled with equipment or wiring. When used with other UML diagram types, a component diagram can help give a 360-degree view of a system by matching physical components with actions, processes, decisions, etc.

The third benefit of component diagrams is the ability to work with complex ideas and physical systems more easily. For example, a component diagram can make it easy to identify an exact physical problem that needs to be addressed inside a system. It can also make it easy to optimize, reverse-engineer, and change an existing system.

Finally, component diagrams can help system architects, developers, and others. They do this by giving system creators helpful insights into what’s physically happening inside a system. This is especially valuable in component-based software development (CBD).

Component diagram elements

The most common shapes and elements you’ll see in a component diagram are the following:

Components are illustrated using a square or rectangular block. Examples include a larger component that contains most of the system, e.g., a server rack, as well as internal components, e.g., a wireless router or a hard drive. Components can include equipment, locations, and individuals.

Ports are represented using smaller squares. They mark the connection points between a larger component and external interfaces or components. Put more simply — they tell you where wiring crosses into or out of a component or the system it contains.

Provided interfaces are illustrated using circles. They mark interfaces and ports provided by a system or an individual component. They look a little like a lollipop and are usually connected to another system or component’s required interface.

Required interfaces are shown using semi-circles. They represent interfaces that components require rather than provide. A required interface is almost always connected to another system or component’s provided interface.

Dependencies are shown using connector lines, arcs, and arrows. The exact shape or line used will vary based on the dependency you’re illustrating.

Create your own component diagram

Miro’s whiteboard tool is the perfect canvas to create and share component diagrams. Get started by selecting this Component Diagram template. Then, follow these steps:

Step 1: Use a square or rectangular block shape to plot components. In components made up of smaller components, place the internal components into a larger shape. If two components are connected via wiring or dependencies, leave some free space between them.

Step 2: Add ports to show where a system or component ends. Be careful here — drawing non-existent ports will confuse and complicate things later on.

Step 3: Add provided and required interfaces to illustrate the relationships between systems and components in your diagram. Do your best to illustrate them appropriately — confusing these two similar-but-different elements will misrepresent your system.

Step 4: Use connector lines to show dependencies and wiring inside your system. Once finished, take another look at your diagram to make sure you haven’t missed anything.

Step 5: Using Miro, share the diagram for better, faster team collaboration.

Component diagram example: e-commerce website

An e-commerce website component diagram will illustrate all the physical components and artifacts that make up an e-commerce system. Components can include:

• Suppliers. This can include warehouses, which stock and re-sell goods or fulfill physical orders. It can also include production facilities (e.g., factories, workshops, etc.). Supplier components will usually connect to transportation, logistics, manufacturing, and other adjacent components.

• Goods. Physical goods are another potential component of an e-commerce website. They can be visualized independently of other components. They can also be illustrated as being inside a factory, a store, a warehouse, etc.

• The receiving customer. Who’s going to receive an order once it’s been fulfilled? The receiving customer. Since the receiving customer is a physical entity, you can easily represent them using your component diagram. This time, it’s likely that the customer will be outside most of your other system components (i.e., the e-commerce operator’s assets).

Component diagram example: banking systems

Here’s another example of a component diagram: a bank. Let’s consider a part-on-premises software part-distributed system with components that include:

• An ATM. An ATM could be a larger component that contains smaller components: cash, terminal monitor, security devices, etc. It could also be part of an even larger component, e.g., a physical bank.

• The bank’s database. In terms of physical components, a bank’s database may be composed of servers, on-premises software, physical security devices, or any auxiliary devices (e.g., a monitor used to access the machine). The database would have direct or indirect dependencies with bank employee computers, ATMs, etc.

• Call center. Another possible component is a bank’s call center, where employees help customers and bank account holders. This component, like the ATM, would likely be connected to the bank’s database and some form of client verification system.

How are component diagrams used in UML?

Component diagrams can be used alone or together with other UML diagrams. One type of diagram that’s often used together with component diagrams is the activity diagram. An activity diagram shows how a system is made up of digital or business processes. A component diagram shows how a system is made up of physical components. Together, the two diagram types give you a 360-degree view of a system.

When used as a single diagram, component diagrams can help you plan, shop for, create, and optimize physical systems. Whether you need to know what to build or buy or how to optimize an existing system’s components in physical space, component diagrams can help.