Alan Cameron Wills

The Amsterdam Manifesto on OCL

In November 1998 the authors participated in a two-day workshop on the Object Constraint Language (OCL) in Amsterdam. The focus was to clarify issues about the semantics and the use of OCL, and to discuss useful and necessary extensions of OCL. Various topics have been raised and clarified. This manifesto contains the results of that workshop and the following work on these topics. Overview of OCL.

Defining UML family members using prefaces

The Unified Modeling Language is extensible, and so can be regarded as a family of languages. Implicitly or explicitly, any particular UML model should be accompanied by a definition of the particular UML family member used for the model. The definition should cover syntactic and semantic issues. This paper proposes a mechanism for associating models with such definitions. Any particular definition would form what we call a preface. The name is intended to suggest that the definition of a particular UML family member must conceptually come before any model built using that family member. A preface would be large, and should be organised using packages. This would allow large amounts of sharing between different prefaces. The paper proposes that prefaces should have an axiomatic style of semantics, through not necessarily fully formal, and it offers a general approach to semantics that would reduce problems of inconsistency within a large preface, based on the idea of general cases and special cases.

Defining the context of OCL expressions

Expressions written in Object Constraint Language (OCL) within a UML model assume a context, depending upon where they are written. Currently the exact nature of this context is not fully defined. Furthermore there is no mechanism for defining the context for OCL expressions in extensions to UML. This paper defines the context of OCL expressions, and proposes precise and flexible mechanisms for how to specify this context.

Advanced Methods and Tools for a Precise UML

Imagine for a moment you are a software ‘architect’ in the year 2003. You’re working at home as usual, and decide to use your quantum computer to do some system modelling. Imagine also that the UML is ‘still’ the de-facto language for software engineering. As a language it has made some big advances of the last few years. The last three versions (3.0-5.0) have all had a precise semantics - even the mysteries of aggregation have been resolved - and its applicability has been widened to every kind of system imaginable. Standardisation has also been good for the software profession. CASE vendors and methodologists, no longer able to invent new notations, have devoted their energies to building increasingly sophisticated tools and processes. Thus, the tool and methods you are about to use incorporates a maturity of software technology that has never been realised before...

Agile development with Domain Specific Languages scaling up agile: is Domain-Specific Modeling the key?

This workshop will investigate the application of Domain Specific Languages within Agile development. A Domain Specific Language (DSL) is designed to express the requirements and solutions of a particular business or architectural domain. SQL, GUI designers, workflow languages and regular expressions are familiar examples. In recent years, Domain-Specific Modeling has yielded spectacular productivity improvements in domains such as telephony and embedded systems. By creating graphical or textual languages specific to the needs of an individual project or product line within one company, DSM offers maximum agility. With current tools, creating a language and related tool support is fast enough to make DSM a realistic possibility for projects of all sizes.

Extreme Programming and Modelling

Extreme Programming (XP:see http://www.xprogramming.com ,developed by Kent Beck and others,has recently taken the OO development world by storm. It can be seen as an antidote to over-documented,in flexible development pro- cesses;by taking certain good practices (testing,iteration and code reviewing, for example)to extremes,its adherents claim to achieve better results at lower cost.

Catalysis: precision modeling and design for components

Summary form only given, as follows. The business value of components is derived from their configurability: like Lego or logic chips, they can be rewired and substituted to make new software end-products, keeping pace with business change. Like these hardware analogies, software component kits are viable only if there is a clear definition of the interface definitions that they all conform to. In the case of enterprise-scale components, this means much more than the COM, CORBA or RMI interface, and includes a common understanding of the business concepts and business rules. In this session, we¿ll look at what an architecture team needs to work out in order to make a kit of components coherent; how to use UML for that purpose; and some innovative modelling techniques well suited to CBD. The material is based on the presenter¿s Catalysis approach, developed with Desmond D¿Souza (Objects, Frameworks and Components in UML, Addison-Wesley 1998).