Analysis and Verification of Service Interaction Protocols - A Brief Survey

Modeling and analysis of interactions among services is a crucial issue in Service-Oriented Computing. Composing Web services is a complicated task which requires techniques and tools to verify that the new system will behave correctly. In this paper, we first overview some formal models proposed in the literature to describe services. Second, we give a brief survey of verification techniques that can be used to analyse services and their interaction. Last, we focus on the realizability and conformance of choreographies.Comment: In Proceedings TAV-WEB 2010, arXiv:1009.330

Extending substitutability in composite services by allowing asynchronous communication

Web services are programs that are self-contained, self-describing, interoperable, platform-independent, and accessible over a network. These properties allow several Web services to be combined together to form a Web service composition. However, when a component service within a Web service composition becomes unavailable or unusable, it is necessary to identify a substitute service that can replace the failed component while preserving the original functionality of the composition. This is the problem of Web service substitution. Most existing work that addresses this problem requires strict functional equivalence between the original component and its substitute. In contrast, Pathak et al. have shown in 2007 that it is sufficient for a substitute service to provide the same functionality with respect to the rest of the composition as the component it is replacing. Pathak et al. apply a technique called quotienting to determine the portion of the composition\u27s overall functionality that is satisfied by the original component. The quotienting operation yields the property that must be satisfied by a substitute for that component. While the use of quotienting allows more possible substitute services to be accepted, it is possible to relax the substitutability condition even further by considering asynchronous communication between component services within the Web service composition model. Our work accomplishes this task by providing a formal framework for representing asynchronous communication within a Web service composition. In our framework, the asynchronous communication is encapsulated in a buffer process, which stores each message until a component is ready to consume it. We prove the correctness of our solution, describe our implementation, and discuss some directions for future research

Strategies for including cloud-computing into an engineering modeling workflow

With the advent of cloud computing, high-end computing, networking, and storage resources are available on-demand at a relatively low price point. Internet applications in the consumer and increasingly in the enterprise space are making use of these resources to upgrade existing applications and build new ones. This is made possible by building decentralized applications that can be integrated with one another through web-enabled application programming interfaces (APIs). However, in the fields of engineering and computational science, cloud computing resources have been utilized primarily to augment existing high-performance computing hardware, but engineering model integrations still occur by the use of software libraries. In this research, a novel approach is proposed where engineering models are constructed as independent services that publish web-enabled APIs. To enable this, the engineering models are built as stateless microservices that solve a single computational problem. Composite services are then built utilizing these independent component models, much like in the consumer application space. Interactions between component models is orchestrated by a federation management system. This proposed approach is then demonstrated by disaggregating an existing monolithic model for a cookstove into a set of component models. The component models are then reintegrated and compared with the original model for computational accuracy and run-time. Additionally, a novel engineering workflow is proposed that reuses computational data by constructing reduced-order models (ROMs). This framework is evaluated empirically for a number of producers and consumers of engineering models based on computation and data synchronization aspects. The framework is also evaluated by simulating an engineering design workflow with multiple producers and consumers at various stages during the design process. Finally, concepts from the federated system of models and ROMs are combined to propose the concept of a hybrid model (information artefact). The hybrid model is a web-enabled microservice that encapsulates information from multiple engineering models at varying fidelities, and responds to queries based on the best available information. Rules for the construction of hybrid models have been proposed and evaluated in the context of engineering workflows

Model-based Adaptation of Behavioural Mismatching Components

International audienceComponent-Based Software Engineering focuses on the reuse of existing software components. In practice, most components cannot be integrated directly into an application-to-be, because they are incompatible. Software Adaptation aims at generating, as automatically as possible, adaptors to compensate mismatch between component interfaces, and is therefore a promising solution for the development of a real market of components promoting software reuse. In this article, we present our approach for software adaptation which relies on an abstract notation based on synchronous vectors and transition systems for governing adaptation rules. Our proposal is supported by dedicated algorithms that generate automatically adaptor protocols. These algorithms have been implemented in a tool, called Adaptor, that can be used through a user-friendly graphical interface

Quantitative policy analysis for sustainable development in water-stressed developing countries : a case study of Morocco

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The demand for housing in the United Stated [sic] and West Germany : a discrete choice analysis

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Economics, 1984.MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY.Vita.Bibliography: leaves 320-327.by Axel Boersch-Supan.Ph.D

The Roles of Corporate IT Infastructure and their Impact on IS Effectiveness

In the strategic alignment model of Henderson and Venkatraman (1993) [1] IT infrastructure has an important but only implicitly defined role. According to evolving literature, IT infrastructure serves many different purposes in large companies. We outline the main missions (roles) of the corporate-wide IT infrastructure and its contribution to IS effectiveness and study the relationship of IT infrastructure with alignment processes and strategic integration. Our empirical tests with data from almost one hundred large companies resulted in three IT infrastructure roles, which reflect the IS communality, strategic, and flexibility dimensions of the corporate-wide IT infrastructure. The roles were not symmetrically related to the IS effectiveness and alignment perspectives. IT infrastructure roles had a significant interplay with strategic integration in improving IS effectiveness. However, the interplay of IT infrastructure roles with alignment perspectives had only marginal effects. Implications of the results for research and practice are discussed

Citizen Adoption in E-Government Systems

Electronic Government (e-Government) refers to a system of information, communication and interaction between government and its citizens. E-Government adoption has been studied for more than a decade with several meta-analytic studies being produced in that time. This study is differentiated from prior meta-analyses as it splits the empirical studies into pre-adoption and post-adoption studies to allow a clearer model of e-Government. We found different determinants and distinct models for pre- and post-adoption of e-Government. In the two models (pre-adoption and post-adoption) trust is only related to pre-adoption studies. Originally, 98 studies were coded but with the focus on pre-adoption and post-adoption, 53 were used in the final models as they contained the attributes of interest

THE MOZAMBICAN PARTICIPATION IN SADC. A LIBERALIZATION PROCESS THROUGH DIFFERENT MODELS AND DIFFERENT CLOSURES

La scelta del modeller riguardo alla chiusura del modello CGE influenza i suoi risultati finali e le sue prescrizioni di policy. In questa tesi, lo scopo è l’analisi e l’identificazione del problema, sia attraverso una discussione teorica che un’ applicazione pratica. Dall’articolo del 1963 di Amartya Sen in poi, la letteratura ha presentato vari articoli sull’argomento. Attualmente, il problema delle chiusure del modello non appare più centrale nel dibattito. Dopo una breve introduzione su cosa siano i CGE, il loro sviluppo e la loro struttura, è presentata una serie di esemplificative maquette con lo scopo di introdurre al concetto di chiusura, come essa influenzi i risultati e come questa scelta del modeller sia intimamente connessa ai fondamenti macroeconomici del sistema. Dopo la teoria, ci si sposta nel mondo reale analizzando con differenti modelli (Neoclassico, “Bastardo Keynesiano”, Strutturalista/Post- Keynesiano) e diverse chiusure per gli aggregati macroeconomici (risparmi privati, pubblici, e stranieri) l’impatto dell’accordo regionale SADC sull’economia mozambicana. I modelli CGE per il Mozambico sono calibrati su una SAM del 2003 e sono svolti con l’ausilio di GAMS/MPSGE. I risultati dimostrano che la chiusura influenza i risultati stessi del modello per cui ognuno presenta una serie di raccomandazioni politiche per l’applicazione dell’accordo SADC.Modellers’ choice on closure rules affects a CGE model results and consequently its policy prescriptions. In this thesis, the aim is to detect and assess this issue, both through a theoretical discussion and an empirical application. Starting from Amartya Sen’s 1963 paper, literature presents many contributions on this topic. Currently, the closure rule problem is not central in the CGE debate. After a brief introduction on CGEs, their development and their structure, a series of simple maquette is presented. They have the exemplary role of introducing the concept of closures, explain how they affect final outcomes and how this modeller’s choice is strictly connected to the macroeconomic foundation of the economic system. After theory, we move into the real World analyzing through different models (Neoclassical, “Bastard Keynesian”, and Structuralist/ Post- Keynesian), and through different closure rules for macro- aggregates (private, public and foreign savings) the impact of the Regional Trade Agreement of SADC with respect to the Mozambican economy. The Mozambican CGE models are calibrated on a 2003 Social Accounting Matrix (SAM) and they are performed using GAMS/ MPSGE. Outcomes show that closure rules affect them and each model presents a set of policy prescription to implement the SADC agreement

SAVCBS 2004 Specification and Verification of Component-Based Systems: Workshop Proceedings

This is the proceedings of the 2004 SAVCBS workshop. The 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 considers formalization of both functional and non-functional behavior, such as performance or reliability