The Unified Modelling Language (UML) is intended to express complex ideas
in an intuitive and easily understood way. It is important because it is widely
used in software engineering and other disciplines. Although an official definition
document exists, there is much debate over the precise meaning of UML models.
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In response, the academic community have put forward many different proposals
for formalising UML, but it is not at all obvious how to decide between
them. Indeed, given that UML practitioners are inclined to reject formalisms as
non-intuitive, it is not even obvious that the definition should be formal at all.
Rather than searching for yet another formalisation of UML, our main aim is to
determine what would constitute a good definition of UML.
¶
The first chapter sets the UML definition problem in a broad context, relating
it to work in logic and the philosophy of science. More specific conclusions about
the nature of model driven development are reached in the beginning of Chapter 2.
We then develop criteria for a definition of UML. Applying these criteria to the
existing definition, we find that it is lacking in clarity. We then set out to test the
precision of the definition. The test is to take an apparently inconsistent model, and
determine whether it really is inconsistent according to the definition.
¶
Many people have proposed that UML models are graphs, but few have justified
this choice using the official definition of UML. We begin Chapter 3 by arguing
from the official definition that UML models are graphs and that instantiation
is a graph homomorphism into an interpretation functor. The official definition of
UML defines the semantics against its abstract syntax, which is in turn defined by
a UML model. Chapters 3 and 4 prepare for our test by resolving this apparent
circularity. The result is a semantics for the metamodel fragment of the language.
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In Chapter 5, we find, contrary to popular belief, that the official definition does
provide sufficient semantics to classify the example model as inconsistent. Moreover,
the sustained study of the semantics in Chapters 3 to 5 confirms our initial
argument that the semantic domain is graphs. The Actions are the building blocks
of UMLs prescriptive dynamics. We see that they can be naturally defined as graph
transformation rules. Sequence diagrams are the main example of descriptive dynamics,
but we find that their official semantics are broken. The recorded history
approach should be replaced, we suggest, by a graph-oriented dynamic logic.
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Chapter 6 presents our early work on dynamic logic for UML sequence diagrams
and further explores the proposed semantic repairs. In Chapter 7, guided
by the criteria developed in Chapter 2, we critically survey the UML formalisation
literature and conclude that an existing body of graph transformation based work
known as dynamic metamodelling is very close to what is required.
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The final chapter draws together our conclusions. It proposes a category theoretic
construction to merge models of the syntax and semantic domain, yielding
a type graph for the graph transformation system which defines the dynamic semantics
of the language. Finally, it outlines the further work required to realise a
satisfactory definition of UML.
| Identifer | oai:union.ndltd.org:ADTP/282439 |
| Date | January 2010 |
| Creators | O'Keefe, Greg, gregokeefe@netspace.net.au |
| Publisher | The Australian National University. Computer Science Laboratory, Research School of Information Sciences and Engineering |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://www.anu.edu.au/legal/copyrit.html), Copyright Greg O'Keefe |
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