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This is an
important property for continuous data streams or data arriving quickly in order
to prevent an overfl ow. It is also important when transient values, such as electric
power, are transported, which must not or cannot be buffered. Tokens arriving
at an object node with this property are rejected, unless they are immediately
forwarded.
The stereotype ?«overwrite?» causes object tokens that arrive at an object node
to overwrite existing??”buffered??”tokens as soon as the object node is full (i.e.,
when the specifi ed upper limit ( {upperbound  n} ) is reached) (Figure 4.54).
What is overwritten are the oldest tokens in the object node based on a defi ned
order??”FIFO (default) or LIFO .9 An arriving null token removes all existing tokens.
The stereotype ?«overwrite?» is assigned to a pin that can accept one object token
at most. This means that the subsequent action always gets the most current value.
This does not disable the buffer functionality, in contrast to the ?«nobuffer?» property.
The buffer contains the most current element.


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