Adel Mahfoudhi

User Interfaces Modelling of Workflow Information Systems

In the recent years, the workflow system has increasingly gained considerable attention in the Information Systems community. It allows the integration of the various users to reach the objectives of the organization. The users operate their Information Systems through the User Interfaces (UI). Therefore there is a need to take into account the workflow model in the development process of the UI for an Information System. This paper has two objectives to attain. The first one is the proposition of a model driven approach to derive a plastic UIs of a Workflow Information System. The second objective lies in the use of Business Process Modelling Notation (BPMN) for the modelling of the interaction models (Task Model, Abstract User Interface, Concrete User Interface) with the aim of supplying more adapted models for a business expert who represents a main candidate in the success of the organization. It is through a case study applied to a real information system that our approach proves to be reliable.

Towards a user interface generation approach based on object oriented design and task model

This paper presents an approach of generating the user interface from the task model. Our work is situated in the course of approaches based on models. This approach called TOOD (Task Object Oriented Design) is based on a formal notation, which gives quantitative results that may be checked by designers and provide the possibility of performing mathematical verifications on the models. The modelling formalism is based on the joint use of the object approach and high level Petri nets. The TOOD method integrates different models (task model, user model, local model of the interface, abstract model of the interface, and model of the implementation) and their relations. An example, extracted from the air traffic control, is presented to illustrate TOOD methodology.

Incorporating usability requirements into model transformation technologies

Abstract Model transformation plays a key role in the model-driven engineering (MDE) approach. In fact, it describes the process of converting one model into another of the same system. Considering a source model, there may be several ways to transform it into target models. Although alternative target models may be equivalent from the functional viewpoint, they may differ in their usability attributes. One of the key challenges for an automated transformation process is to identify which model transformations will produce a target model with the desired usability attributes. The present paper addresses this issue and provides a parameterized transformation to deal with usability driven in an MDE approach. Specifically, it focuses on how to associate usability attributes with the different alternative transformations and how this can be taken into account in an automated transformation process to obtain user interface model with the desired usability attributes.

From the Formal Specifications of Users Tasks to the Automatic Generation of the HCI Specifications

This paper presents an approach to the construction of a task model of a method, named TOOD (Task Object Oriented Design), used for the development of an interactive system. This approach is based on a formal notation, which gives quantitative results which may be checked by designers and which provide the possibility of performing mathematical verifications on the models. The modelling formalism is based on the joint use of the object approach and high level Petri nets. The concepts borrowed from the object approach make it possible to describe the static aspects of tasks and the Petri nets enable the description of dynamics and behaviour. We also describe a software aid tool for the manipulation of these models, which allows the editing and the simulation of a task model. In order to facilitate thecomprehension of the method, an extremely simple example of the air traffic control will be given.

A MARTE Extension for Global Scheduling Analysis of Multiprocessor Systems

Real-Time Systems are subject to Soft/Hard temporal constraints. Besides, a tasks scheduling step is required to meet the maximum of deadlines, for which there are different scheduling algorithms to do. However, nowadays real-time systems represent a serious issue for the worldwide industry due to their growing complexity. Indeed, since they are more susceptible to failures and deficiencies of development, it is crucial to rely on high level development methods. In this context, some researchers have proposed scheduling analysis within the new profile Modeling and Analysis of Real-Time and Embedded systems (MARTE), which supports both monoprocessor and multiprocessor scheduling algorithms. While supported multiprocessor scheduling algorithms are part of the partitioned approach, global approach algorithms have not been backed by MARTE yet. In the present paper, we seek to improve the meta-models of MARTE stereotypes to establish scheduling analysis for the global approach.

An MDE approach for user interface adaptation to the context of use

With the advent of new media and the delivery of recent means of communication, associated with the progress of networks, the circumstances of software use, as well as the skills and the preferences of the users who exploit them, are constantly varying. The adaptation of the User Interface (UI) has become a necessity due to the variety of the contexts of use. In this paper, we propose an approach based on models for the generation of adaptive UI. To reach this objective, we have made use of parameterized transformation principle in the framework of the Model Driven Engineering (MDE) for the transformation of the abstract interface into a concrete interface. The parameter of this transformation plays the role of the context of use. The paper develops two parts: meta-models for every constituent of the context of use and the adaptation rules.

A model-driven approach for usability engineering of interactive systems

Abstract Usability is considered to be one of the most important quality factors that determine the success/failure in the actual use of an interactive system. This can explain the ever-increasing number of publications addressing the problem of usability evaluation. However, most of these proposals only consider usability evaluations after the application is fully implemented and deployed. Some others are based on reviewing usability principles in intermediate artifacts with regard to their conformance with a set of guidelines. Since the traceability between these artifacts and the final application is not well established, performing usability evaluations by considering these artifacts as input may not ensure the usability of the final application. This problem may be alleviated by using a model-driven engineering (MDE) approach due to its intrinsic traceability mechanisms that are established by the transformation processes. The present paper aims to delineate a method for evaluating usability throughout an MDE development life cycle by considering conceptual models as input. To do this, two main contributions are proposed. The first one, called usability-driven model transformation, aims to ensure that an intermediate artifact with the required level of usability is generated. It controls the model transformation process according to a set of usability attributes. The second contribution, called early usability evaluation, performs the usability evaluation from the conceptual models by defining metrics based on conceptual primitives that constitute the conceptual models. This evaluation would be a significant advantage with regard to saving time and resources. The early usability evaluation is empirically validated by comparing the usability measure obtained by our proposal and the level of usability perceived by the end-users.

Using MDE and priority time petri nets for the schedulability analysis of embedded systems modeled by UML activity diagrams

This paper proposes a model driven approach for the schedulability analysis at an early stage of the embedded system development life-cycle. The activity diagram of Unified Modeling Language (UML) annotated with the profile for the Modeling and Analysis of Real-Time and Embedded systems (MARTE) is mapped into Priority Time Petri Net (PTPN) to enhance formal schedulability test of given real time tasks. The generated PTPN model is interpreted and executed to check whether a schedule of a task execution meets the imposed timing constraints. Therefore, the present paper focuses on the definition of temporal properties and tasks dependency by means of activity diagram and MARTE profile. Besides, it describes the transformation rules from analysis model to formal model.

Compositional specification of real time embedded systems by priority time Petri Nets

An important key challenge in Embedded Real Time Systems (ERTS) analysis is to provide a seamless scheduling strategy. Formal methods for checking the temporal characteristics and timing constraints at a high abstraction level have proven to be useful for making the development process reliable. In this paper, we present a Petri Net modeling formalism and an analysis technique which supports not only systems scheduling analysis but also the compositional specification of real time systems. The proposed Priority Time Petri Net gives determinism aspect to the model and accelerates its execution. Indeed, a compositional specification of a PTPN for complex application and multiprocessor architecture that solves the problem of hierarchy is presented.

Extending UML/MARTE-GRM for Integrating Tasks Migrations in Class Diagrams

There is a growing interest in modeling Real-Time Embedded Systems (RTES) using high-level approaches. The recent extension of Unified Modeling Language (UML) profile for Modeling and Analysis of Real-Time Embedded systems (MARTE) is enclosing a lot of stereotypes and sub-profiles providing support for designers to beat the shortcomings of complex systems development. In particular, the MARTE/GRM (Generic Resource Modeling) package offers stereotypes for annotating class diagrams with the needed information which will be extracted to fulfill a scheduling phase. However, GRM does not allow designers to specify data to be used neither in half-partitioned nor in global scheduling approaches; indeed, it does not support the modeling of task migration concept. Thus, we propose through this paper an extension of MARTE/GRM sub-profile to consider the modeling of information needed for the half-partitioned and global scheduling step.