An incremental prototyping methodology for distributed systems based on formal specifications

This thesis presents a new incremental prototyping methodology for formally specified distributed systems. The objective of this methodology is to fill the gap which currently exists between the phase where a specification is simulated, generally using some sequential logical inference tool, and the phase where the modeled system has a reliable, efficient and maintainable distributed implementation in a main-stream object-oriented programming language. This objective is realized by application of a methodology we call Mixed Prototyping with Object-Orientation (in short: OOMP). This is an extension of an existing approach, namely Mixed Prototyping, that we have adapted to the object-oriented paradigm, of which we exploit the flexibility and inherent capability of modeling abstract entities. The OOMP process proceeds as follows. First, the source specifications are automatically translated into a class-based object-oriented language, thus providing a portable and high-level initial implementation. The generated class hierarchy is designed so that the developer may independently derive new sub-classes in order to make the prototype more efficient or to add functionalities that could not be specified with the given formalism. This prototyping process is performed incrementally in order to safely validate the modifications against the semantics of the specification. The resulting prototype can finally be considered as the end-user implementation of the specified software. The originality of our approach is that we exploit object-oriented programming techniques in the implementation of formal specifications in order to gain flexibility in the development process. Simultaneously, the object paradigm gives the means to harness this newly acquired freedom by allowing automatic generation of test routines which verify the conformance of the hand-written code with respect to the specifications. We demonstrate the generality of our prototyping scheme by applying it to a distributed collaborative diary program within the frame of CO-OPN (Concurrent Object-Oriented Petri Nets), a very powerful specification formalism which allows expressing concurrent and non-deterministic behaviours, and which provides structuring facilities such as modularity, encapsulation and genericity. An important effort has also been accomplished in the development or adaptation of distributed algorithms for cooperative symbolic resolution. These algorithms are used in the run-time support of the generated CO-OPN prototypes

Model driven development implementation of a control systems user interfaces specification tool

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Informátic

Formal specification based prototyping

Rapid prototyping is an approach to software development which attempts to remedy some of the shortcomings of the linear life cycle model, e.g. its inability to cope with fuzzy requirements and system evolution. This thesis first presents a broad survey of rapid software prototyping. It describes the rationale behind the process, the applications of prototyping, and specific techniques which may be used to achieve them. We then describe a system, called EPROS, together with its methodology, which supports a number of prototyping techniques in a coherent framework. The system is comprehensive in its approach and covers the prototyping and development of both functional and human-computer interface aspects of software systems. The former is based on the execution of VDM-based formal specification notation META-IV; the latter is based on a textual representation of state transition diagrams. Dialogue development is further supported by a rich set of abstractions which allow interaction concepts to be specified and directly executed rather than implemented. EPROS is based on a wide spectrum language which supports the main phases of a software development process, namely specification, design, and implementation. Included in this notation is a meta abstraction facility which facilitates its extension by the programmer. The primary application of EPROS is for evolutionary prototyping, where a system is developed iteratively and gradually from the abstract to the detailed, while it undergoes use and while its capabilities evolve. EPROS copes with all the requirements of evolutionary prototyping, namely rapid development, intermediate deliveries and gradual evolution of the system towards the final product. The thesis also describes a number of case studies where the presented ideas are put in practice, and which provide data in support of the effectiveness of the described system

Formal Models and Refinement for Graphical User Interface Design

Formal approaches to software development require that we correctly describe (or specify) systems in order to prove properties about our proposed solution prior to building it. We must then follow a rigorous process to transform our specification into an implementation to ensure that the properties we have proved are retained. When we design and build the user interfaces of our systems we are similarly keen to ensure that they have certain properties before we build them. For example, do they satisfy the requirements of the user? Are they designed with known good design principles and usability considerations in mind? User-centred design approaches, which incorporate many different techniques which we may consider as informal, seek to consider these issues so that the UIs we build are designed around the needs and capabilities of real users. Both formal methods and user-centred design are important and beneficial in the development of underlying system functionality and user interfaces respectively. Given this we would like to be able to use both approaches in one integrated software development process. Their differences, however, make this a challenging objective. In this thesis we present a solution this problem by describing models and techniques which provide a bridge between the existing work of user-centred design practitioners and formal methods practitioners enabling us to incorporate (representations of) informal design artefacts into a formal software development process. We then use these models as the basis for a refinement theory for user interfaces which allows interface designers to retain their informal design methods whilst providing an underlying theory grounded in the trace refinement theory of the Microcharts language

Workshop on Modelling of Objects, Components, and Agents, Aarhus, Denmark, August 27-28, 2001

This booklet contains the proceedings of the workshop Modelling of Objects, Components, and Agents (MOCA'01), August 27-28, 2001. The workshop is organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark and the "Theoretical Foundations of Computer Science" Group at the University of Hamburg, Germany. The papers are also available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop01

Achieving Functional Correctness in Large Interconnect Systems.

In today's semi-conductor industry, large chip-multiprocessors and systems-on-chip are being developed, integrating a large number of components on a single chip. The sheer size of these designs and the intricacy of the communication patterns they exhibit have propelled the development of network-on-chip (NoC) interconnects as the basis for the communication infrastructure in these systems. Faced with the interconnect's growing size and complexity, several challenges hinder its effective validation. During the interconnect's development, the functional verification process relies heavily on the use of emulation and post-silicon validation platforms. However, detecting and debugging errors on these platforms is a difficult endeavour due to the limited observability, and in turn the low verification capabilities, they provide. Additionally, with the inherent incompleteness of design-time validation efforts, the potential of design bugs escaping into the interconnect of a released product is also a concern, as these bugs can threaten the viability of the entire system. This dissertation provides solutions to enable the development of functionally correct interconnect designs. We first address the challenges encountered during design-time verification efforts, by providing two complementary mechanisms that allow emulation and post-silicon verification frameworks to capture a detailed overview of the functional behaviour of the interconnect. Our first solution re-purposes the contents of in-flight traffic to log debug data from the interconnect's execution. This approach enables the validation of the interconnect using synthetic traffic workloads, while attaining over 80% observability of the routes followed by packets and capturing valuable debugging information. We also develop an alternative mechanism that boosts observability by taking periodic snapshots of execution, thus extending the verification capabilities to run both synthetic traffic and real-application workloads. The collected snapshots enhance detection and debugging support, and they provide observability of over 50% of packets and reconstructs at least half of each of their routes. Moreover, we also develop error detection and recovery solutions to address the threat of design bugs escaping into the interconnect's runtime operation. Our runtime techniques can overcome communication errors without needing to store replicate copies of all in-flight packets, thereby achieving correctness at minimal area costsPhDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116741/1/rawanak_1.pd

SAVCBS 2005 Proceedings: Specification and Verification of Component-Based Systems

This workshop is concerned with how formal (i.e., mathematical) techniques can be or should be used to establish a suitable foundation for the specification and verification of component-based systems. Component-based systems are a growing concern for the software engineering community. Specification and reasoning techniques are urgently needed to permit composition of systems from components. Component-based specification and verification is also vital for scaling advanced verification techniques such as extended static analysis and model checking to the size of real systems. The workshop will consider formalization of both functional and non-functional behavior, such as performance or reliability. This workshop brings together researchers and practitioners in the areas of component-based software and formal methods to address the open problems in modular specification and verification of systems composed from components. We are interested in bridging the gap between principles and practice. The intent of bringing participants together at the workshop is to help form a community-oriented understanding of the relevant research problems and help steer formal methods research in a direction that will address the problems of component-based systems. For example, researchers in formal methods have only recently begun to study principles of object-oriented software specification and verification, but do not yet have a good handle on how inheritance can be exploited in specification and verification. Other issues are also important in the practice of component-based systems, such as concurrency, mechanization and scalability, performance (time and space), reusability, and understandability. The aim is to brainstorm about these and related topics to understand both the problems involved and how formal techniques may be useful in solving them

Optimization of Biomanufacturing process for Tissue Engineering applications

Negli ultimi anni, l'ingegneria tessutale ha registrato notevoli progressi, soprattutto grazie all'emergere delle tecnologie di produzione additiva e all'integrazione di biomateriali e cellule. Questa tecnica avanzata consente la creazione di strutture complesse con componenti e proprietà diverse, specificamente progettate per l'uso in applicazioni biomediche. Il vantaggio principale di questa tecnologia è la sua capacità di personalizzazione, che aiuta a ridurre al minimo le difficoltà postoperatorie per i pazienti con impianti ortopedici e coloro che subiscono trapianti di tessuto. A tal fine, i componenti essenziali possono essere sintetizzati a partire dalle cellule del paziente. Tuttavia, ci sono ancora molti ostacoli che devono essere affrontati al fine di ottenere soddisfacenti strutture stampate in 3D. Un problema chiave è la necessità di ottimizzare il biomateriale per soddisfare sia i criteri di biocompatibilità che di stampabilità. Inoltre, la produzione di scaffold per l'ingegneria tissutale è una procedura complessa in quanto richiede che le strutture costruite imitino strettamente la matrice extracellulare al fine di creare un tessuto funzionale. L'obiettivo chiave è quello di produrre scaffold 3D composti da strutture multi-scala realizzate con bioink contenenti cellule. L'obiettivo di questa tesi è quello di creare scaffold 3D per applicazioni di ingegneria tessutale utilizzando tecnologie di produzione additiva. Per raggiungere questo obiettivo, la scelta della tecnologia e dei materiali è di fondamentale importanza. Pertanto, è essenziale ottimizzare sia la tecnica di stampa che il biomateriale selezionato. La letteratura può aiutare a determinare i parametri essenziali da ottimizzare. Tuttavia, ogni applicazione specifica richiede un'indagine approfondita a causa delle diverse e uniche combinazioni tra le tecnologie, i materiali e le strategie di post-processing. Le tecnologie utilizzate sono l'electrospinning, l’extrusion-based bioprinting e il laser powder bed fusion. La diversa gamma di tecnologie fornisce una panoramica di come gli scaffold possono essere costruiti per soddisfare le diverse specifiche di scala. Per la produzione di scaffold con l’extrusion-based bioprinting vengono utilizzati gli idrogeli a base naturale o sintetica. Gli idrogeli sono particolarmente adatti per la loro capacità di imitare struttura della matrice extracellulare, essenziale per la vita cellulare e il conseguente sviluppo di un nuovo tessuto. Inoltre, esprimono una risposta ottimale ai fattori di stampa che sono preziosi per migliorare il processo di stampa stesso, con l'obiettivo di produrre scaffali che soddisfino sia i requisiti biologici che geometrici, compresa la scelta di un metodo di crosslinking adeguato. La lega Ti6Al4V è stata utilizzata per studiare le proprietà superficiali di un impianto ortopedico. Questa lega è particolarmente adatta per la produzione di impianti ortopedici utilizzando la tecnologia laser powder bed fusion. Riassumendo, questa tesi si concentra sulla produzione di scaffold 3D per applicazioni di ingegneria tissutale, utilizzando diverse tecnologie di produzione additiva. Ogni tecnologia ha presentato sfide e problematiche differenti, lo studio e l’ottimizzazione dei relativi parametri di stampa e le operazioni di post-elaborazione hanno dato risultati favorevoli e migliorato la conoscenza dei processi.In recent years, tissue engineering has experienced significant advancements, mostly driven by the emergence of additive manufacturing technologies and the integration of biomaterials and cells. This advanced technique enables the creation of intricate structures with diverse components and properties, specifically designed for use in biomedical applications. The primary benefit of this technology is its ability to be customised, which helps minimise post-operative difficulties for patients with orthopaedic diseases and those undergoing tissue transplants. For this purpose, the essential components can be synthesised by the patient's own cells. However, there are still other obstacles that need to be addressed in order to get satisfactory 3D printed structures. One key problem is the need to optimise the biomaterial to meet both biocompatibility and printability criteria. In addition, the production of scaffolds for tissue engineering is a complex procedure as it requires the built structures to closely mimic the extracellular matrix in order to create a functional tissue. The key goal is to produce 3D scaffolds composed of multiple-scale structures made of cell-loaded bioinks. The objective of this thesis is to create 3D scaffolds for tissue engineering applications using additive manufacturing technologies. In order to accomplish this, the selection of technology and material is of crucial significance. Therefore, it is essential to optimise both the printing technique and the selected biomaterial. The literature can assist in determining the essential parameters to be optimised in this regard. However, each specific application necessitates a thorough investigation due to the diverse and unique combinations of material technology and post-processing methods. The technologies utilised are electrospinning, extrusion-based bioprinting, and laser powder bed fusion. The diverse range of technology provides an overview of how scaffolds can be constructed to meet various scale specifications. Extrusion-based bioprinting utilises hydrogels, including both synthetic and natural variants, as scaffolding materials. These hydrogels are chosen because of their ability to closely mimic the extracellular matrix, which is essential for the growth of new tissue. In addition, they exhibit an optimal response to printing factors that are valuable for enhancing the printing process itself, with the aim of producing scaffolds that meet both biological and geometric requirements, including the selection of an appropriate crosslinking method. The Ti6Al4V alloy was used to study the surface properties of an orthopaedic implant. This alloy is specifically suitable for producing orthopaedic implants using laser powder bed fusion technology. To summarise, this thesis concentrates on the production of 3D scaffolds using additive manufacturing for tissue engineering applications. Every technology posed distinct challenges and concerns that needed to be resolved. In the end, the examination and refinement of the printing parameters and post-processing operations yielded favourable outcomes and improved knowledge of the processes