Hien Nam Le

Modeling and Verifying Real-Time Properties of Reactive Systems

SPACE is a model-driven engineering technique for reactive distributed systems. It enables to develop system models from reusable building blocks, formal analysis by model checking as well as automated transformation to executable code. In this paper, we describe an extension of the SPACE formalism which allows to model and verify also real-time behavior. In particular, one specifies real-time constraints in the interface descriptions of the building blocks, so-called Real-Time External State-Machines (RTESMs). The RTESMs are translated to guards, clocks and invariants of Timed Automata which can be analyzed by means of the model checker UPPAAL. The approach is explained by a component protecting an electrical motor controller system against overspeed. In particular, we prove that by keeping certain maximum response times, this system guarantees that the speed of the motor stays within certain limits.

A model-driven framework for component-based development

This paper presents a Model-Driven framework to support component-based development. The framework addresses the following important issues: (1) how to reduce the cost of making component reusable, (2) how to efficiently ensure compatibility among components in a composition, (3) how to relate service composition to system composition. The framework supports three kinds of reusable building blocks: (1) collaborations for global cross-cutting behaviors including services and interfaces; (2) roles or partial components for component compositions; and (3) components for system compositions.

A transaction model for supporting mobile collaborative works

This paper presents a mobile transaction model for supporting mobile collaborative works. The mobile transaction processing system supports data sharing among mobile hosts via the concept of mobile affiliation workgroups. Data sharing among mobile transactions in a mobile affiliation workgroup is supported by export and import transactions in an export-import repository, which is a mobile sharing workspace. This means that the data sharing process is divided into smaller transaction processes and separated from the main transactions. The mobile transaction system also distinguishes two different mechanisms for supporting data sharing in mobile environments, which are sharing data states and sharing data status.

Towards choreography model transformation via graph transformation

We present a Model-Driven method to develop collaborative systems. In our method, we use UML collaborations to capture the requirements and architecture of such a system. The system behavior is specified by two choreography models: an abstract flow-global and a more detailed flow-localized choreography. These choreography models are both described by UML activity diagrams. A graph-based transformation approach carrying out the transformation from the flow-global to the flow-local choreography is the core contribution of this paper. Our approach is illustrated using a case study of the European Rail Traffic Management System (ERTMS).

A collaboration-based testing model for composite components

In this paper, we present a testing model to support the verification and validation for composite components. The testing model supports two types of components: atomic and composite. Atomic components are non-decomposable software units, while composite components are developed by composing existing components. Our main contribution presented in this paper focusing on two issues: (1) to provide a testing model for atomic components while these components are being designed and developed; and (2) to provide a mechanism to construct new testing models for composite components by composing existing testing models of atomic components. In addition, we address how our integrating testing model can support both centralized and distributed testing of composite components.

A Framework to Support the Development of Collaborative Components

In this paper, a framework to support the development of collaborative components is presented. The role of a collaborative component is to support the inter-working among components through their interfaces. By focusing on the behaviors of the collaborative components, the interaction between components can be independently verified and validated. The proposed framework includes: (1) the structural and architecture models of collaborative components; (2) the choreography models to specify the behaviors of the collaborative components; and (3) the orchestration models to specify the behaviors of component types that participate in the inter-working. The orchestration models are created by model transformations from the architecture and choreography models. The created components are placed in the repository so that they can be re-used and composed together.

A Transaction Framework for Mobile Data Sharing Services

This paper discusses a transaction framework that supports data sharing services in mobile environments. The transaction framework is based on the export-import transaction model that has the capacity to enhance data availability in mobile environments. The transaction framework also consists of a set of transaction dependencies and a set of managing operations. The transaction framework possesses an ability to support different data sharing scenarios in mobile environments. The paper demonstrates that different mobile transactions can be synthesized from this transaction framework.

Using the MOWAHS characterisation framework for development of mobile work applications

This paper describes an evaluation of a characterisation framework to analyse mobile work scenarios in order to make corresponding software systems. The framework identifies complexity issues to be taken into account when implementing a system. The framework can also be used to elicit requirements from a scenario. Three research questions are investigated in this evaluation: 1) Can the framework be used to identify relevant challenges in the final system? 2) Can the framework be used to identify functional requirements for the final system? and 3) Can the framework be used to identify non-functional requirements for the final system? The evaluation was performed using the framework to analyse and implement an IT-support scenario. The paper also describes a web-tool for this framework that makes the characterisation process simpler. The tool introduces consistency rules to ensure stricter characterisation of the scenarios.

A Mobile Database Sharing Protocol to Increase Data Availability in Mobile Environments

This paper presents a mobile database sharing protocol to improve data availability in mobile environments. Long disconnection periods of mobile hosts could cause data inconsistency and blocking of mobile transactions. The proposed mobile database sharing protocol allows two conflict data caching modes to reduce the blocking of mobile transactions that access to shared data. Furthermore, data can be directly shared among mobile hosts that are being disconnected from the database servers. Data consistency is ensured via the execution constraints and dependency among transactions.

Transaction Processing with mobile collaborative works

The theme of this research is mobile transaction processing systems, focusing on versatile data sharing mechanisms in volatile mobile environments. The rapid growth of wireless network technologies and portable computing devices has promoted a new mobile working environment. A mobile environment is different from the traditional distributed environment due to its unique characteristics: the mobility of users or computers, the frequent and unpredictable disconnections of wireless networks, and the resource constraints of mobile computing devices. The authors have developed a mobile transaction processing system for MOWAHS. Especially, we have successfully designed, implemented, and tested several important system components such as the mobile locking system and the mobile data sharing system