Subtitles of the Movie

This movie introduces component diagrams and deployment diagrams. Component diagram such as the one you see here show the system in terms of modules, each component represents a part of the systems software that is encapsulated, replaceable and reusable. In other words components can be thought of as the building blocks of your system. Component diagrams show the system's components and the interfaces through which those components communicate. So let's take a look at the elements that go into a component diagram. Components can do the same things as classes so there's really no notation here except for the symbol in the upper right corner that indicates a component. A component is the building block, the module, the piece of encapsulated, replaceable, reusable software. Components communicate with each other through interfaces and the way to show interfaces in a component diagram is to use the assembly connector, the ball and cup notation. The ball or the lollipop version represents a provided interface. A provided interface is one that the component implements or in UML terminology realizes. The cup represents a required interface and that is an interface that the component requires in order to provide its functionality. Components can be expanded to include other components or to include classes. When you do that you use a port which is this little rectangle here and the port is simply a doorway into a component through which communication can pass. So we have this provided interface passing information into this component to this one. Here's another interface and then here's another port through which communication can leave the component. So components are very useful at showing the system in terms of modules and specifying the interfaces through which the components communicate. Here's an example of a deployment diagram, deployment diagrams model the physical layout of a system, mapping software artifacts to the hardware on which they execute and showing communication paths. Deployment diagrams depict nodes and a node is something that can host software. A node can be a device which is a piece of hardware or it can be an execution environment which is software that can host other software such as an operating system. Other elements of deployment diagrams include artifacts and artifacts are physical manifestations of software such as files, these diagrams also show communication paths, communication paths are simply associations between nodes that show how those nodes communicate and communication paths can be labeled with information about the communication protocol to be used such as http or rmi. You can show the deployment of artifacts to a particular node either by using this method which places the artifacts within the node that hosts them or using this method which uses a dependency arrow labeled with the deployed stereotype to show that this artifact is deployed to this node. So deployment diagrams are very simple but they're very useful at showing the physical deployment of the system. So to sum all this up use component diagrams to divide your system into it's building blocks and show the interfaces through which the components communicate and you can also use component diagrams to take things down a level by showing the classes or components, that a component contains. Use a deployment diagram to show which software is deployed to which node and also how the nodes communicate.