Node (UML)

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A node (Engl. Node ) is a model element in the Unified Modeling Language (UML), a modeling language for software and other systems.

description

Graphic representation of a node

A node represents an element in a computer network on which artifacts can be installed when software is distributed . Knot is a very general concept that can be fleshed out in two ways. First, the UML offers two specializations with the two model elements device and execution environment . Second, UML profiles can use stereotypes to define special nodes, for example one , one or one . ApplikationsServerArbeitsplatzrechnerDatenbankInstanz

A node is shown graphically as a three-dimensional view of a cuboid.

Special knots

device

Graphic notation for a device

A device (engl. Device ) is a physical resource, for example a computer or a storage area.

Devices are marked with the stereotype «device».

Execution environment

Graphical notation for an execution environment

An execution environment (engl. ExecutionEnvironment ) is a node on the specific types of components can be installed. Typically, a Java application server on which Enterprise Java Beans are installed would be modeled as the execution environment.

Execution environments are marked with the stereotype «executionEnvironment».

Nesting nodes

External and internal knot

UML2 allows nodes to be nested . This can be useful if you want to express that server software is running on a particular computer. The computer is then modeled as a device, the server software as the execution environment. By nesting the two devices, the computer outside and the execution environment inside, one expresses that the execution environment is running on the computer. The execution environment is graphically drawn inside the device, see figure on the right.

Networking nodes

Networking of nodes via communication path

Computers are often part of a network, and a modeling language should enable these relationships between computers to be modeled. In UML2, connections between nodes can be modeled as communication paths , a specialization of association . A communication path between two nodes expresses that the two nodes can exchange signals and messages .

Communication paths do not necessarily have to start or end at nodes. All model elements that are intended as the target of a distribution come into question as end points. In particular, this also includes the characteristic specification .