Component diagrams

In UML, component diagrams show the structure of the software system, which describes the software components, their interfaces, and their dependencies. You can use component diagrams to model software systems at a high level or to show components at a lower, package level.

This type of diagram supports component-based development in which a software system is divided into components and interfaces that are reusable and replaceable.

Component diagrams are useful for the following reasons:

Defining the executable and reusable aspects of a software system
Revealing software configuration issues through dependency relationships
Showing an accurate depiction of a software application before you make changes or enhancements

You can also use component diagrams to depict the following physical parts of a software system:

Source code files that you develop in an integrated development environment
Executable files that are necessary to deliver a running system
Physical databases that store information in the tables of a relational database or in the pages of an object-oriented database
Adaptable systems that have components that migrate for load balancing and failure recovery

Note: Component diagrams are distinct from deployment diagrams. A component diagram defines the composition of components and artifacts in the system. A deployment diagram shows components and artifacts in relation to where they are used in the deployed system.

The following topics describe model elements in component diagrams:

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