Kevin Lano - Agile Model-Based Development Using UML-RSDS

Agile Model-Based Development Using UML-RSDS

Agile Model-Based Development Using UML-RSDS

Kevin Lano

Department of Informatics Kings College London, London United Kingdom

CRC Press

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Model-based development is moving into the mainstream of software engineering, and it is an approach that all software developers should know about as one option to use in solving software problems. In this book we give a practical introduction to model-based development, model transformations and agile development, using a UML and Java-based toolset, UML-RSDS. Guidance on applying model-based development in a range of domains is provided, and many examples are given to illustrate the UML-RSDS process and techniques. The book is suitable both for professional software engineers and for postgraduate and undergraduate teaching.

I would like to acknowledge the contributions of my research team members and colleagues who have helped in the development of the UML-RSDS tools and method: Kelly Androutsopoulos, Pauline Kan, Shekoufeh Kolahdouz-Rahimi, Sobhan Yassipour-Tehrani, Hessa Alfraihi, David Clark, Howard Haughton, Tom Maibaum, Iman Poernomo, Jeffery Terrell and Steffen Zschaler. The support of Imperial College London, Kings College London and the EPSRC is also acknowledged.

I dedicate this book to my wife, Olga.

Contents

In this chapter we introduce model-based development and UML-RSDS, and discuss the context of software development which motivates the use of such methods and tools.

Model-based development (MBD) is an approach which aims to improve the practice of software development by (i) enabling systems to be defined in terms closer to their requirements, abstracted from and independent of particular implementation platforms, and (ii) by automating development steps, including the writing of executable code.

A large number of MBD approaches, tools and case studies now exist, but industrial uptake of MBD has been restricted by the complexity and imprecision of modelling languages such as UML, and by the apparent resource overheads without benefit of many existing MBD methods and tools [].

UML-RSDS has been designed as a lightweight and agile MBD approach which can be applied across a wide range of application areas. We have taken account of criticisms of existing MBD approaches and tools, and given emphasis on the aspects needed to support practical use such as:

Lightweight method and tools: usable as an aid for rapidly developing parts of a software system, to the degree which developers find useful. It does not require a radical change in practice or the adoption of a new complete development process, or the use of MBD for all aspects of a system.

Independent of other MBD methods or environments, such as Eclipse/EMF.

Non-specialist: UML-RSDS uses only a core subset of UML class diagram and use case notations, which are the most widely-known parts of UML.

Agile: incremental changes to systems can be made rapidly via their specifications, and the changes propagated to code.

Precise: specifications in UML-RSDS have a precise semantics, which enables reliable code production in multiple languages.

The benefits of our MBD approach are:

Reduction in coding cost and time.

The ability to model an application domain, to define a DSL (domain specific language) for a domain, and to define custom code generators for the domain.

Reducing the gap between specification and code, so that the consequences of requirements and specification choices can be identified at an early development stage.

The ability to optimize systems at the platform-independent modelling level, to avoiding divergence between code and models caused by manual optimization of generated code.

The ability to formally analyse DSLs and systems at the specification stage.

These capabilities potentially reduce direct software development costs, and costs caused by errors during development and errors persisting in delivered products. Both time-to-market and product quality are potentially improved.

shows the software production process which is followed using UML-RSDS: specifications are defined using UML class diagrams and use cases, these can be analysed for their internal quality and correctness, and then platform-independent designs are synthesised (these use a pseudocode notation for a subset of UML Activity diagram notation). From these designs executable code in a particular object-oriented programming language (currently, Java, C# or C++) can then be automatically synthesised.

Figure 1.1: UML-RSDS software production process

Unlike many other MBD approaches, which involve the management of multiple models of a system, UML-RSDS specifies systems using a single integrated Use Case and Class Diagram model. This simplifies the specification and design processes and aligns the approach to Agile development practices which are also based on maintaining a single system model (usually the executable code).

Some typical uses of UML-RSDS could be:

Modelling the business logic of an application and automatically generating the code for this, in Java, C# or C++.

Modelling and code generation of a component within a larger system, the remainder of which could be developed using traditional methods.