Object node (UML)

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An object node ( english ObjectNode ) is a model element in the Unified Modeling Language (UML), a modeling language for software and other systems.

Object and control nodes are the building blocks from which activities are built. They serve as a temporary buffer for objects that go through the activity.

Types of object nodes

The UML2 knows four types of object nodes:

  1. the pin , an object node to the object flows with actions be connected
  2. the activity parameter node, an object node through which objects are passed to an activity
  3. the buffer node , an object node in which objects can be cached independently of actions
  4. the data storage node, an object node in which all incoming objects are cached

Properties of object nodes

The different types of object nodes have some properties in common. First of all, they all have a capacity , given by an upper bound. An object node can temporarily store a number of tokens up to this upper limit before it forwards them to an outgoing activity edge.

The objects that are temporarily stored in an object node are subject to a certain order , which specifies the order in which objects arriving at the object node leave it, whereby unordered is also a possible value. If the order is FIFO , the first object to arrive leaves the object node first; if it is LIFO , the object that arrived last is hit first. Orders that differ from this can also be modeled by assigning a selection behavior to the object node .

Each object node can also specify that only objects in a certain state are allowed to flow through this node.

Difference to UML 1.x

The object node and its subtypes were newly introduced in UML2.

See also

literature

  • Christoph Kecher: "UML 2.0 - The Comprehensive Manual" Galileo Computing, 2005, ISBN 3-89842-573-8
  • Conrad Bock: UML 2 Activity and Action Models Part 4: Object Nodes , in Journal of Object Technology, vol. 3, no. 1, pp. 27–41, [1]