What is Component Diagram

What is Component Diagram?

8-9 minutes

UML Component diagrams are used in modeling the physical aspects of object-oriented systems that are used for visualizing, specifying, and documenting component-based systems and also for constructing executable systems through forward and reverse engineering. Component diagrams are essentially class diagrams that focus on a system’s components that often used to model the static implementation view of a system.

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Component Diagram at a Glance

A component diagram breaks down the actual system under development into various high levels of functionality. Each component is responsible for one clear aim within the entire system and only interacts with other essential elements on a need-to-know basis.

• The example above shows the internal components of a larger component:
• The data (account and inspection ID) flows into the component via the port on the right-hand side and is converted into a format the internal components can use. The interfaces on the right are known as required interfaces, which represents the services the component needed in order to carry out its duty.
• The data then passes to and through several other components via various connections before it is output at the ports on the left. Those interfaces on the left are known as provided interface, which represents the services to deliver by the exhibiting component.
• It is important to note that the internal components are surrounded by a large ‘box’ which can be the overall system itself (in which case there would not be a component symbol in the top right corner) or a subsystem or component of the overall system(in this case the ‘box’ is a component itself).

Basic Concepts of Component Diagram

A component represents a modular part of a system that encapsulates its contents and whose manifestation is replaceable within its environment. In UML 2, a component is drawn as a rectangle with optional compartments stacked vertically. A high-level, abstracted view of a component in UML 2 can be modeled as:

1. A rectangle with the component’s name
2. A rectangle with the component icon
3. A rectangle with the stereotype text and/or icon

Interface

In the example below shows two type of component interfaces:

Provided interface symbols with a complete circle at their end represent an interface that the component provides – this “lollipop” symbol is shorthand for a realization relationship of an interface classifier.

Required Interface symbols with only a half circle at their end (a.k.a. sockets)represent an interface that the component requires (in both cases, the interface’s name is placed near the interface symbol itself).