Programming Research Group
Research Report RR-01-22
A pattern for concurrency in UML
Charles Crichton,
Jim Davies, and
Alessandra Cavarra.
December 2001, 15pp.
Abstract
This paper presents a pattern of usage for the Unified Modeling
Language (UML), intended for the description of systems in which two
or more operations may be acting concurrently upon the same object.
The pattern addresses two common problems - inadequate models, and
complicated state diagrams - with a simple separation of concerns.
Changes in attribute state, and changes in operation state, are
described separately, using two different types of diagram.
Simple examples are used to demonstrate the application of the
pattern: at an implementation level, and at a more abstract, design
level. The semantics for concurrency within UML is examined, not only
to clarify the interpretation of the pattern, but also to explain why
the existing provision - concurrent composite states and concurrency
attributes - is not applicable.
This paper is available as a 551,903 bytes pdf file.
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