Node (UML)

Two execution environments instances nested in a device instance

A node In the Unified Modeling Language (UML) is a computational resource upon which UML artifacts may be deployed for execution. ^[1]

There are two types of nodes: device nodes and execution environments.

• A device represents hardware devices: a physical computational resource with processing capability upon which UML artifacts may be deployed for execution. Devices may be complex (i.e., they may consist of other devices).^[1]
• An execution environment represents software containers (such as operating systems, JVM, servlet/EJB containers, application servers, portal servers etc.) This is a node that offers an execution environment for specific types of components that are deployed on it in the form of deployable artifacts.^[1]

Execution environments can be nested. Nodes can be interconnected through communication paths to define network structures. A communication path is an "association between two DeploymentTargets, through which they are able to exchange signals and messages".^[1]

Usage

When modeling devices, it is possible to model them in several different ways:

• Name a device using the type and make, for instance "IBM RS6000", "HP 9000".
• Name a device using its intended function, for instance "Database Server", "High Speed Switch"
• Name a device using the operating system deployed on it, for instance "Linux Server", "Solaris Server".

Use tagged values to specify characteristics of devices / execution environments, for instance "Memory=2GB", "Disk Space=32GB", "Version=2.5.1".

References

1. OMG (2008). OMG Unified Modeling Language (OMG UML), Superstructure, V2.1.2 p.199-210.