Deployment units in UML models and topologies
- Deployment unit
- The generic deployment unit represents any facet of an application component at run time or deployment time.
- Execution deployment unit
- The execution deployment unit represents an instance of the component at run time, which indicates where the component is stored in memory and where its run unit is processed.
- Data deployment unit
- The data deployment unit represents data storage space that is reserved for the component's use, not the data itself.
- Presentation deployment unit
- The presentation deployment unit represents an interface between the component and a user, external system, or other unit
Not all components need a DU of each type; for example, data deployment units are unnecessary if the component does not store data or if the location of the data is not relevant.
A component can have more than one DU of each type; for example, an application might run more than one instance of a component at one time, thus requiring more than one execution DU.
Also, components can share DUs; for example, more than one component might use the same data, logic, or interface as another component.
You can use deployment units in both UML models and topologies. You can also coordinate the deployment units between UML models and topologies as described in Importing elements from UML models into topologies.
Deployment units in UML models
DUs are part of the Deployment Analysis profile. They are valid only in freeform diagrams.
In UML models, DUs are attributes of components. The following picture shows a component with two attributes; the types of these attributes are two DUs in the model.
Deployment units in topologies
In topologies, DUs are members of a component unit that represent the software application. DUs that are members of a component have implicit hosting links to that component, although you can override this implicit hosting link with a hosting link to a different unit. The components that contain the DUs consume the constraints and requirements of the member DUs. Later, you can resolve the components onto units that represent more specific types of applications.
The following picture shows a component unit with two DUs as members.
