Designing Reusable Systems that Can Handle Change - Description-Driven Systems : Revisiting Object-Oriented Principles

In the age of the Cloud and so-called Big Data systems must be increasingly flexible, reconfigurable and adaptable to change in addition to being developed rapidly. As a consequence, designing systems to cater for evolution is becoming critical to their success. To be able to cope with change, systems must have the capability of reuse and the ability to adapt as and when necessary to changes in requirements. Allowing systems to be self-describing is one way to facilitate this. To address the issues of reuse in designing evolvable systems, this paper proposes a so-called description-driven approach to systems design. This approach enables new versions of data structures and processes to be created alongside the old, thereby providing a history of changes to the underlying data models and enabling the capture of provenance data. The efficacy of the description-driven approach is exemplified by the CRISTAL project. CRISTAL is based on description-driven design principles; it uses versions of stored descriptions to define various versions of data which can be stored in diverse forms. This paper discusses the need for capturing holistic system description when modelling large-scale distributed systems.Comment: 8 pages, 1 figure and 1 table. Accepted by the 9th Int Conf on the Evaluation of Novel Approaches to Software Engineering (ENASE'14). Lisbon, Portugal. April 201

JSB Composability and Web Services Interoperability Via Extensible Modeling & Simulation Framework (XMSF), Model Driven Architecture (MDA), Component Repositories, and Web-based Visualization

Study Report prepared for the U. S. Air Force, Joint Synthetic Battlespace Analysis of Technical Approaches (ATA) Studies & Prototyping Overview: This paper summarizes research work conducted by organizations concerned with interoperable distributed information technology (IT) applications, in particular the Naval Postgraduate School (NPS) and Old Dominion University (ODU). Although the application focus is distributed modeling & simulation (M&S) the results and findings are in general easily applicable to other distributed concepts as well, in particular the support of operations by M&S applications, such as distributed mission operations. The core idea of this work is to show the necessity of applying open standards for component description, implementation, and integration accompanied by aligned management processes and procedures to enable continuous interoperability for legacy and new M&S components of the live, virtual, and constructive domain within the USAF Joint Synthetic Battlespace (JSB). JSB will be a common integration framework capable of supporting the future emerging simulation needs ranging from training and battlefield rehearsal to research, system development and acquisition in alignment with other operational requirements, such as integration of command and control, support of operations, integration of training ranges comprising real systems, etc. To this end, the study describes multiple complementary Integrated Architecture Framework approaches and shows, how the various parts must be orchestrated in order to support the vision of JSB effectively and efficiently. Topics of direct relevance include Web Services via Extensible Modeling & Simulation Framework (XMSF), the Object Management Group (OMG)’s Model Driven Architecture (MDA), XML-based resource repositories, and Web-based X3D visualization. To this end, the report shows how JSB can − Utilize Web Services throughout all components via XMSF methodologies, − Compose diverse system visualizations using Web-based X3D graphics, − Benefit from distributed modeling methods using MDA, and − Best employ resource repositories for broad and consistent composability. Furthermore, the report recommends the establishment of necessary management organizations responsible for the necessary alignment of management processes and procedures within the JSB as well as with neighbored domains. Continuous interoperability cannot be accomplished by technical standards alone. The application of technical standards targets the implementation level of the system of systems, which results in an interoperable solution valid only for the actual 2 implementation. To insure continuity, the influence of updates, upgrades and introduction of components on the system of systems must be captured in the project management procedures of the participating systems. Finally, the report proposes an exemplifying set of proof-of-capability demonstration prototypes and a five-year technical/institutional transformation plan. All key references are online available at http://www.movesinstitute.org/xmsf/xmsf.html (if not explicitly stated otherwise)

On Methods for the Formal Specification of Fault Tolerant Systems

This paper introduces different views for understanding problems and faults with the goal of defining a method for the formal specification of systems. The idea of Layered Fault Tolerant Specification (LFTS) is proposed to make the method extensible to fault tolerant systems. The principle is layering the specification in different levels, the first one for the normal behavior and the others for the abnormal. The abnormal behavior is described in terms of an Error Injector (EI), which represents a model of the erroneous interference coming from the environment. This structure has been inspired by the notion of idealized fault tolerant component but the combination of LFTS and EI using Rely/Guarantee reasoning to describe their interaction can be considered as a novel contribution. The progress toward this method and this way to organize fault tolerant specifications has been made experimenting on case studies and an example is presented.Comment: Presented and published at DEPEND 201

Context Aware Middleware Architectures: Survey and Challenges

Abstract: Context aware applications, which can adapt their behaviors to changing environments, are attracting more and more attention. To simplify the complexity of developing applications, context aware middleware, which introduces context awareness into the traditional middleware, is highlighted to provide a homogeneous interface involving generic context management solutions. This paper provides a survey of state-of-the-art context aware middleware architectures proposed during the period from 2009 through 2015. First, a preliminary background, such as the principles of context, context awareness, context modelling, and context reasoning, is provided for a comprehensive understanding of context aware middleware. On this basis, an overview of eleven carefully selected middleware architectures is presented and their main features explained. Then, thorough comparisons and analysis of the presented middleware architectures are performed based on technical parameters including architectural style, context abstraction, context reasoning, scalability, fault tolerance, interoperability, service discovery, storage, security & privacy, context awareness level, and cloud-based big data analytics. The analysis shows that there is actually no context aware middleware architecture that complies with all requirements. Finally, challenges are pointed out as open issues for future work

Smart Sensor Webs For Environmental Monitoring Integrating Ogc Standards

Sensor webs are the most recent generation of data acquisition systems. The research presented looks at the concept of sensor webs from three perspectives: node, user, and data. These perspectives are different but are nicely complementary, and all extend an enhanced, usually wireless, sensor network. From the node perspective, sensor nodes collaborate in response to environmental phenomena in intelligent ways; this is referred to as the collaborative aspect. From the user perspective, a sensor web makes its sensor nodes and resources accessible via the WWW (World Wide Web); this is referred to as the accessible aspect. From the data perspective, sensor data is annotated with metadata to produce contextual information; this is referred to as the semantic aspect. A prototype that is a sensor web in all three senses has been developed. The prototype demonstrates theability of managing information in different knowledge domains. From the low-level weather data, information about higher-level weather concepts can be inferred and transferred to other knowledge domains, such as specific human activities. This produces an interesting viewpoint of situation awareness in the scope of traditional weather data

A framework for abstraction and virtualization of sensors in mobile context-aware computing

110 p.[EN] The latest mobile devices available nowadays are leading to the development of a new generation of mobile applications that are able to react to context. Context- awareness requires data from the environment, usually collected by means of sensors embedded in mobile devices or connected to them through wireless networks. Developers of mobile applications are faced with several challenges when it comes to the creation of context-aware applications. Sensor and device heterogeneity stand out among these challenges. In order to assist designers, we propose a layered conceptual framework for sensor abstraction and virtualization, called Igerri. Its main objective is to facilitate the development of context-aware applications independently of the specific sensors available in the user environment. To avoid the need to directly manage physical sensors, a layered structure of virtual and abstract sensors is conceived. Two software components, based on the proposed framework, have been designed in order to test Igerris robustness. The first one processes the information from the successive sensor layers and generates high-level context information. The second is responsible for managing network aspects and real time settings. This implementation has been tested using a representative context-aware application in different scenarios. The results obtained show that the implementation, and therefore the conceptual framework, is suitable for dealing with context information and hiding sensor programming.[EU] Gaur egungo gailu mugikor puntakoenek inguruneari erantzuteko gai diren aplikazio mugikorren garapenean oinarritzen dira. Testuingurua nabaritzeko ingurunearen informazioa behar da, zeina gailu mugikorretan txertatutako sentsoreen edo haririk gabeko sareen bitartez biltzen den. Aplikazio mugikorren garatzaileek erronka askori aurre egin behar izaten diete testuingurua kontuan hartzen duten aplikazioak garatzerakoan. Erronka na- gusien artean, sentsoreen eta gailuen heterogeneotasuna izaten dira. Garatzaileei laguntzeko asmoz, Igerri izeneko sentsoreen abstrakzio eta birtualizaziorako marko kontzeptual bat proposatzen dugu. Bere helburu nagusia, testuinguruaren aplikazio hautemangarrien garapena erraztea da, erabiltzailearen ingurunean dauden sentsore espezifikoak edozein direla ere. Sentsore fisikoak zuzenean ma- nipulatu behar izatea saihesteko, sentsore birtual eta abstraktuen egitura bat asmatu da. Igerri-ren sendotasuna egiaztatzeko, proposatutako markoan oinarritutako bi software osagai diseinatu dira. Lehenak, sentsore geruzen informazio geruzak prozesatu eta maila altuko testuinguru informazioa ematen du. Bigarrenak, sare aukerak kudeatu eta sentsoreen konfigurazioa denbora errealean burutzen ditu. Inplementazio hau testuingurua hautemateko gai eta adierazgarria den aplikazio batekin egoera desberdinetan frogatu da. Lortutako emaitzek erakusten dute inplementazioa, eta ondorioz marko kontzeptuala ere, aproposa dela testuinguruaren informazioa erabiltzeko eta sentsoreen programazioa ezkutatzeko.[ES] Los dispositivos móviles disponibles en la actualidad facilitan el desarrollo de una nueva generación de aplicaciones móviles que son capaces de reaccionar al contexto. La computación sensible al contexto requiere datos del entorno que normalmente se obtienen por medio de sensores embebidos en dispositivos móviles o conectados a ellos a través de redes inalámbricas. Los desarrolladores de aplicaciones móviles se enfrentan a varios retos para crear aplicaciones sensibles al contexto. Entre estos retos destaca la necesidad de tratar la heterogeneidad de los sensores y de los dispositivos móviles. Con el fin de ayudar a los desarrolladores, esta tesis propone un marco conceptual para la abstracción multinivel y la virtualización de sensores, llamado Igerri. Su principal objetivo es facilitar el desarrollo de aplicaciones sensibles al contexto independientemente de los sensores específicos que se encuentren en el entorno. Para evitar la necesidad de manipular directamente los sensores físicos, se ha concebido una estructura multinivel de sensores virtuales y abstractos. Se han diseñado dos componentes software basados en el marco propuesto para comprobar la robustez de Igerri. El primero procesa la información de la estructura multinivel de sensores y genera información de contexto de alto nivel. El segundo es responsable de administrar, en tiempo real, las opciones de red y la configuración de los sensores. Esta implementación ha sido probada en diferentes escenarios usando una aplicación representativa y sensible al contexto. Los resultados obtenidos muestran que la implementación, y por tanto el marco conceptual que le da soporte, es adecuada para tratar la información de contexto y ocultar los problemas de programación de los sensores.Borja Gamecho held a PhD scholarship from the Research Staff Training Programme of the Basque Government from 2011 to 2014. This work also has been supported by the Department of Education, Universities and Research of the Basque Government under Grant IT395-10, by the Ministry of Economy and Competitiveness of the Spanish Government and by the European Regional Development Fund (project TIN2014-52665-C2-1)