Soon-Kyeong Kim

A Formal Mapping between UML Models and Object-Z Specifications

This paper presents a precise and descriptive semantics for core modeling concepts in Object-Z and a formal description for UML class constructs. Given the formal descriptions, it also provides a formal semantic mapping between the two languages at the meta-level, which makes our translation more systematic. Any verification of UML models can take place on their corresponding Object-Z specifications using reasoning techniques provided for Object-Z. With this approach, we provide not only a precise semantic basis for UML but also a sound mechanism for reasoning about UML models.

Formalizing the UML class diagram using object-Z

To produce a precise and analyzable software model, it is essential for the modeling technique to have formality in the syntax and the semantics of its notation, and to allow rigorous analysis of its models. In this sense, UML is not yet a truly precise modeling technique. This paper presents a formal basis for the syntactic structures and semantics of core UML class constructs, and also provides a basis for reasoning about UML class diagrams. The syntactic structures of UML class constructs and the rules for developing a well-formed class diagram are precisely described using the Z notation. Based on this formal description, UML class constructs are then translated to Object-Z constructs. Proof techniques provided for Object-Z can be used for reasoning about these class diagrams.

Teaching software design with open source software

When an introductory course on software design and testing was revised, it was decided to use open source software tools as the major examples and objects of study. The goal was to expose students to realistic software systems and give them experience dealing with large quantities of code written by other people. Using open source software also has the beneficial effect of ensuring that students are aware of the open source software movement, and opens up opportunities to discuss topics such as software piracy and ethics.

Visualization of formal specifications

Formal specification techniques provide precise and analyzable software specifications. However, the formal notations provided by most formal specification techniques are not easy to use and understand for most people. Our approach counters this difficulty by visualizing formal specifications. In this paper, we use various diagrams to visualize a Z specification. In our work, both static and dynamic aspects of formal specifications, including complex constraints, are included in the visualization scope.

Verifying metamodel coverage of model transformations

Since the object management group (OMG) commenced its model driven architecture (MDA) initiative, there has been considerable activity proposing and building automatic model transformation systems to help implement the MDA concept. Much less attention has been given to the need to ensure that model transformations generate the intended results. This paper explores one aspect of validation and verification for MDA: coverage of the source and/or target metamodels by a set of model transformations. The paper defines the property of metamodel coverage and some corresponding algorithms. This property helps the user assess which parts of a source (or target) metamodel are referenced by a given model transformation set. Some results are presented from a prototype implementation that is built on the eclipse modeling framework (EMF).

A formalism to describe design patterns based on role concepts

Design patterns are typically defined imprecisely using natural language descriptions with graphical annotations. It is also common to describe patterns using a concrete design example with implementation details. Several approaches have been proposed to describe design patterns abstractly based on role concepts. However, the notion of role differs in each approach. The behavioral aspects of patterns are not addressed in the role-based approaches. This paper presents a rigorous approach to describe design patterns based on role concepts. Adopting metamodeling and formalism, our work defines an innovative framework where generic pattern concepts based on roles are precisely defined as a formal role metamodel using Object-Z. Individual patterns are specified using these generic role concepts in terms of pattern role models. Temporal behaviors of patterns are also specified using Object-Z and integrated in the pattern role models. Patterns described this way are abstract, separating pattern realization information from the pattern description. They are also precise providing a rigorous foundation for reasoning about pattern properties. This paper also formalizes the properties that must be captured in a class model when a design pattern is deployed. These properties are defined generically in terms of role bindings from a pattern role model to a class model. They provide a precise basis for checking the validity of pattern utilisation in designs. Our work is supported by tools. We have developed an initial role metamodel using an existing modeling framework, Eclipse Modeling Framework (EMF) and have transformed the metamodel to Object-Z using model transformation techniques. Complex constraints are added to the transformed Object-Z model. More importantly, we implement the role metamodel. Using this implementation, pattern authors can develop an initial pattern role model in the same modeling framework and convert the initial model to Object-Z using our transformation rules. The transformed Object-Z model is then enhanced with behavioral features of the pattern. This tool support significantly improves the practicability of applying formalism to design patterns.

An MDA approach towards integrating formal and informal modeling languages

The Model Driven Architecture (MDA) involves automated trans-formations between software models defined in different languages at different abstraction levels. This paper takes an MDA approach to integrate a formal modeling language (Object-Z) with an informal modeling language (UML) via model transformation. This paper shows how formal and informal modeling languages can be cooperatively used in the MDA framework and how the trans-formations between models in these languages can be achieved using an MDA development environment. The MDA model transformation techniques allow us to have a reusable transformation between formal and informal modeling languages. The integrated approach provides an effective V&V technique for the MDA.

A formal object-oriented approach to defining consistency constraints for UML models

We discuss how integrity consistency constraints between different UML models can be precisely defined at a language level. In doing so, we introduce a formal object-oriented metamodeling approach. In the approach, integrity consistency constraints between UML models are defined in terms of invariants of the UML model elements used to define the models at the language-level. Adopting a formal approach, constraints are formally defined using Object-Z. We demonstrate how integrity consistency constraints for UML models can be precisely defined at the language-level and once completed, the formal description of the consistency constraints will be a precise reference of checking consistency of UML models as well as for tool development.

A UML approach to the generation of test sequences for Java-based concurrent systems

Starting with a UML specification that captures the underlying functionality of some given Java-based concurrent system, we describe a systematic way to construct, from this specification, test sequences for validating an implementation of the system. The approach is to first extend the specification to create UML state machines that directly address those aspects of the system we wish to test. To be specific, the extended UML state machines can capture state information about the number of waiting threads or the number of threads blocked on a given object. Using the SAL model checker we can generate from the extended UML state machines sequences that cover all the various possibilities of events and states. These sequences can then be directly transformed into test sequences suitable for input into a testing tool such as ConAn. As an illustration, the methodology is applied to generate sequences for testing a Java implementation of the producer-consumer system.

Using integrated metamodeling to define OO design patterns with Object-Z and UML

Three important goals in describing software design patterns are: generality, precision, and understandability. To address these goals, this paper presents an integrated approach to specifying patterns using Object-Z and UML To achieve the generality goal, we adopt a role-based metamodeling approach to define patterns. With this approach, each pattern is defined as a pattern role model. To achieve precision, we formalize role concepts using Object-Z (a role metamodel) and use these concepts to define patterns (pattern role models). To achieve understandability, we represent the role metamodel and pattern role models visually using UML. Our pattern role models provide a precise basis for pattern-based model transformations or refactoring approaches.