The Unified Modeling Language (UML) is a comprehensive, standardized approach to technical diagramming. Developers use UML diagrams to visualize, specify, and construct the various elements of a software system more efficiently.
UML diagrams are either structural or behavioral. The first depicts the structure of a process while the latter visualizes the behavior of the system. If you need to model the system’s components or source code, you would do so using a component diagram. Component diagrams are a visual representation of the software pieces that make up a system.
While many diagrams are available to describe the functionality of a system, a component diagram is unique in that it describes the components used to create those functionalities. It models the physical view of system objects that reside within the node, such as files, libraries, and executables.
In this article, we will cover the importance of component diagrams for business as well as their basic symbols and notations. We will also list the steps to create an effective component diagram, including how to create one in MindManager®.
Why use component diagrams for business?
Component diagrams provide a high-level overview of the system components, including their organization, relationships, and dependencies. They differ from other UML structural diagrams that are used to depict the workings of a system or its architecture.
Instead, a component diagram describes how the individual components work together to form a single system. This includes how the components behave during the execution and running of a system program. These diagrams give you an implementation-oriented view of the system, providing valuable insights regarding how the system functions and if it satisfies its tasks and objectives.
Each component is self-contained and can encapsulate elements of any complexity. By encapsulating these elements, component diagrams prevent direct access to the internal data structure of the system. This helps prevent unauthorized access and ensures that users access only the appropriate data elements.
When you use a component diagram, it reduces the complexity of software development and makes it easier to communicate projects and plans with the customer and other key stakeholders. The diagrams are standardized, straightforward, and easy to understand. As the project progresses, a component diagram streams collaboration among teams so that changes can be discussed and implemented appropriately as new requirements emerge or design changes occur.
For project management, component diagrams make projects more efficient and cost-effective. This is because software systems can be modeled from reusable components to define the structured functional relationships.
As an example, rather than recreating components for distinct system designs, the standardized notation of a component diagram makes it easy to visualize the structure and functions and ensure that they interact efficiently for each system.
What goes into a component diagram?
Developers and project teams use component diagrams during the execution phase of a system to analyze and track its performance. By visualizing the connection between system components at runtime, you gain greater insight into complex projects.
UML has standardized symbols and notations for identifying elements of a component diagram. Some of the most important elements of a component diagram include the following:
A component is a flexible part of a system that contains numerous elements that have common features. Components are represented using a rectangular shape that contains the keyword «component». Below the keyword is where you label the particular component.
To better understand the building blocks of a component diagram, assume that you are modeling the structure and functions of a small coffee shop. In this example, your components might include the following:
This alone is not enough information to assess the system’s functionality. Each component has a particular connection or dependency to another component via required or provided interfaces.
An interface describes an operation or group of operations used or created by components. Interfaces are represented by a rectangular shape, the keyword «interface», and the interface’s name.
A provided interface indicates that the connected component offers some sort of functionality for other components to interact with. It is shown as a circle-with-stick notation, which is also known as a lollipop symbol, that comes out from the interface.
A required interface describes what the component needs from the system environment to perform its functions. It is shown using the ball-and-socket notation, which is a half-circle (the “socket”) connected to a horizontal line.
Using the same coffee shop scenario, we can identify the interfaces that exist for the customer component.
The customer provides their order to the barista, which is denoted by the lollipop symbol. Then, they need the barista to tell them the total due for their order to make the payment. Therefore, the customer cannot act until they receive a check or total from the barista, so this is a required interface shown with the ball-and-socket notation. Once received, the customer can then pay the amount owed, which is another provided interface.
A port specifies the service or behavior that a component requires. In a component diagram, each port represents a point of interaction between the component and its environment. It is shown as a small square on the boundary of a component rectangle.
Using our coffee shop scenario, the ports might specify third-party services needed for system operation. For example, the barista might use a point-of-sale system to manage transactions, and the coffee shop might receive its supplies from a grocery store or other distributor. While these services are not explicitly part of the system, they still have interactions and dependencies within the component diagram.
Connections and Dependencies
It is the connection and relationship between various components that defines a system. As such, connections and dependencies are also modeled in the component diagram.
The primary connection type used in a component diagram is an assembly relationship. This type of relationship occurs when the provided interface of one component satisfies the required interface of another component.
Components that are tightly coupled together do not readily separate, which is represented by a solid line between the two components. For example, the customer cannot order their coffee without a menu. Therefore, the menu and customer components are tightly connected.
The relationship between the customer and barista, however, is a looser connection. If you unplug the barista component, you could replace it with an equivalent component such as a shift manager. The shift manager can provide and require the same interfaces as the barista.
To illustrate this relationship in a component diagram, the two components are connected via their connecting interface. For example, this is the assembly relationship between the barista and customer when the customer places their order:
How to create a successful component diagram
A component diagram enables you to visualize and describe the physical components of a system. It helps model implementation details, ensuring that every aspect of the system’s required functionality is covered in the development process.
Use the following steps to create an actionable component diagram:
- Identify all the artifacts in your system or application, such as the files, documents, libraries, executables, and anything else required by the system. This ensures that you include all the necessary information in your diagram.
- Create visuals for each of the elements using standard symbols and notations.
- Figure out the relationships and dependencies between the components. For example, are there required interfaces, provided interfaces, or both?
MindManager’s suite of customizable templates makes it easy to create, share, and co-edit component diagrams. To get started, simply select a template that best fits your needs. Then, follow these steps:
- Use a rectangular block shape to create components.
- Add ports and interfaces to visualize the relationships between system components.
- Use connector lines to illustrate dependencies within the system.
To boost collaboration and productivity within your component diagrams, the co-editing capabilities in MindManager enable users to work together in real-time. This real-time collaboration is possible regardless of where team members are located and what platform or device they use to access MindManager.
In addition to cross-platform co-editing, you can link to other project documents within your component diagram, such as system requirements. With direct access to all the relevant information, all team members can access what they need via a centralized location.