It is a stereotype ?«rate?» of the UML elements activity edge and parameter.
Elements are transported along an edge between two actions or object nodes. The
interval in which they are transported is important for the specifi cation of that
fl ow. The same applies to activity parameters, which can accept or supply data in
a certain frequency, provided they have fl ow property. The rate specifi es this frequency
(e.g., liters per second).
We distinguish between continuous rate, for example, of a liquid in a pipeline,
and discrete rate, such as work pieces on an assembly line. We use the stereotypes
?«continuous?» and ?«discrete?» (Figure 4.53).
The rate is denoted in curled brackets at the edge. In addition, we can denote
either ?«continuous?» or ?«discrete?» next to it ( Figure 4.52 ).
{rate= < constant value > } or {rate= < distribution definition > }.
4.8.4 Special Object Node Properties
The stereotype ?«nobuffer?» describes object nodes that reject tokens if they cannot
be accepted by subsequent edges or actions.
262 CHAPTER 4 SysML??”The Systems Modeling Language
The stereotype ?«overwrite?» describes object nodes, the tokens of which are
overwritten by newly arriving tokens.
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