A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing

Data Grids have been adopted as the platform for scientific communities that need to share, access, transport, process and manage large data collections distributed worldwide. They combine high-end computing technologies with high-performance networking and wide-area storage management techniques. In this paper, we discuss the key concepts behind Data Grids and compare them with other data sharing and distribution paradigms such as content delivery networks, peer-to-peer networks and distributed databases. We then provide comprehensive taxonomies that cover various aspects of architecture, data transportation, data replication and resource allocation and scheduling. Finally, we map the proposed taxonomy to various Data Grid systems not only to validate the taxonomy but also to identify areas for future exploration. Through this taxonomy, we aim to categorise existing systems to better understand their goals and their methodology. This would help evaluate their applicability for solving similar problems. This taxonomy also provides a "gap analysis" of this area through which researchers can potentially identify new issues for investigation. Finally, we hope that the proposed taxonomy and mapping also helps to provide an easy way for new practitioners to understand this complex area of research.Comment: 46 pages, 16 figures, Technical Repor

Transitioning Applications to Semantic Web Services: An Automated Formal Approach

Semantic Web Services have been recognized as a promising technology that exhibits huge commercial potential, and attract significant attention from both industry and the research community. Despite expectations being high, the industrial take-up of Semantic Web Service technologies has been slower than expected. One of the main reasons is that many systems have been developed without considering the potential of the web in integrating services and sharing resources. Without a systematic methodology and proper tool support, the migration from legacy systems to Semantic Web Service-based systems can be a very tedious and expensive process, which carries a definite risk of failure. There is an urgent need to provide strategies which allow the migration of legacy systems to Semantic Web Services platforms, and also tools to support such a strategy. In this paper we propose a methodology for transitioning these applications to Semantic Web Services by taking the advantage of rigorous mathematical methods. Our methodology allows users to migrate their applications to Semantic Web Services platform automatically or semi-automatically

Comparison of web service architecture based on architecture quality properties

Web service research has been focused on the issues of automatic binding, performance, scalability, and security, however, little research has been done in evaluation of web service architectures, namely Broker based. Examples of these are Matchmaker Broker, Layered Matchmaker, Facilitator, Layered facilitator, and Peer to peer (P2P) based, such as P2P Discovery, Match Maker and P2P, Split Code and P2P execution, Mobile Code with P2P etc. Another consideration is its impact on the adoption in distributed Internet environment. In this paper we introduce a methodology for measuring and evaluating web service architecture style, and we present our development of a set of architectural quality properties, and use these quality properties to carry out comparison and contract of current web services architectures. We provide a detailed analysis and critique of these, and these could be served as a guidelines for the next generation of web services development, which could adopted into the distributed environment

Ubiquitous web services

Ubiquitous coming from the Latin word ubique, means existing or being everywhere, especially at the same time. Web Services are loosely specified and coupled components distributed over the internet [23] with the purpose of being accessed and used ubiquitously by suppliers, customers, business and trading partners. This must be done independently of any tools or environment in use by any party involved. The basic service oriented architecture is based on the publishing of a service by a service provider, the location of a service by a service requestor and the interaction between the two based on the service description. The necessary functionality for the full adoption of such web services must include routing, reliable messaging, security, transactions, binary attachments, work- flow, negotiation and management, web services description languages, choreography, orchestration and non-repudiation. A large number of companies and organizations are promoting this adoption and shifting their strategy to include this useful technology. A multitude of proposed standards and products have emerged in an attempt to meet the needs of this worldwide community of web services adopters. The core established standards include the Web Services Description Language (WSDL), the Simple Object Access Protocol (SOAP) and the Universal Description, Discovery and Integration (UDDI). The Web services Inspection Language (WSIL) is a more lightweight yet complimentary specification for service discovery[1]. Other definitions produced to tackle the re- quired functions have not been fully standardized and many are still competing. For the needed functionality to be produced a number of related issues must be tackled. Here we look at some of the important ones, and how they are being tackled, we then shortly describe our proposed project and related works.peer-reviewe

Extensions to the self protecting object model to facilitate integrity in stationary and mobile hosts

M.Sc. (Computer Science)In this dissertation we propose extensions to the Self Protecting Object (SPO) model to facilitate the sharing of information in a more effective manner. We see the sharing ofinformation as the sharing of objects that provide services. Sharing objects effectively is allowing the objects to be used in a secure environment, independent of their location, in a manner usage was intended. The SPO model proposed by Olivier [32] allows for objects in a federated database to be moved from one site to another and ensures that the security policy of the object will always be respected and implemented, regardless of its location. Although the SPO model does indeed allow for objects (information) to be shared effectively, it fails to address issues of maintaining integrity within objects. We therefore define the notion of maintaining integrity within the spa model and propose a model to achieve it. We argue that ensuring an SPO is only used in a way usage was intended does not suffice to ensure integrity. The model we propose is based on ensuring that modifications to an SPO are only executed if the modification does not violate the constraints defined for the Sf'O, The model" allows for an spa to maintain its unique identity in addition to maintaining its integrity. The SPO model is designed to be used in a federated database on sites that are stationary. Therefore, having addressed the issue of maintaining integrity within SPOs on stationary sites in the federated database, we then introduce the notion of a mobile site: a site that will eventually disconnect from the federated database and become unreachable for some time. Introducing the mobile site into the federated database allows us to propose the Mobile Self Protecting Object (MSPO) and its associated architecture. Because of the nature of mobile sites, the original model for maintaining integrity can not be applied to the MSPO architecture. We therefore propose a mechanism (to be implemented in unison with the original model) to ensure the integrity of MSPOs on mobile sites. We then discuss the JASPO prototype. The aim of the prototype was to determine if the Self Protecting Object model was feasible using current development technologies. We examine the requirements identified in order for the prototype to be successful and discuss how these were satisfied. Several modifications were made to the original spa model, including the addition of a new module and the exclusion of others, we discuss these modifications and examine why they were necessary

The Semantic Web in Federated Information Systems: A Space Physics Case Study

This paper presents a new theoretical contribution that provides a middle-of-the-road approach to formal ontologies in federated information systems. NASA’s space physics domain, like many other domains, is relatively unfamiliar with the emerging Semantic Web. This work offers a new framework that garners the benefits of formal logic yet shields participants and users from the details of the technology. Moreover, the results of a case study involving the utilization of the Semantic Web within NASA’s space physics domain are presented. A real-world search and retrieval system, relying on relational database technology, is compared against a near identical system that incorporates a formal ontology. The efficiency, efficacy, and implementation details of the Semantic Web are compared against the established relational database technology

The mediated data integration (MeDInt) : An approach to the integration of database and legacy systems

The information required for decision making by executives in organizations is normally scattered across disparate data sources including databases and legacy systems. To gain a competitive advantage, it is extremely important for executives to be able to obtain one unique view of information in an accurate and timely manner. To do this, it is necessary to interoperate multiple data sources, which differ structurally and semantically. Particular problems occur when applying traditional integration approaches, for example, the global schema needs to be recreated when the component schema has been modified. This research investigates the following heterogeneities between heterogeneous data sources: Data Model Heterogeneities, Schematic Heterogeneities and Semantic Heterogeneities. The problems of existing integration approaches are reviewed and solved by introducing and designing a new integration approach to logically interoperate heterogeneous data sources and to resolve three previously classified heterogeneities. The research attempts to reduce the complexity of the integration process by maximising the degree of automation. Mediation and wrapping techniques are employed in this research. The Mediated Data Integration (MeDint) architecture has been introduced to integrate heterogeneous data sources. Three major elements, the MeDint Mediator, wrappers, and the Mediated Data Model (MDM) play important roles in the integration of heterogeneous data sources. The MeDint Mediator acts as an intermediate layer transforming queries to sub-queries, resolving conflicts, and consolidating conflict-resolved results. Wrappers serve as translators between the MeDint Mediator and data sources. Both the mediator and wrappers arc well-supported by MDM, a semantically-rich data model which can describe or represent heterogeneous data schematically and semantically. Some organisational information systems have been tested and evaluated using the MeDint architecture. The results have addressed all the research questions regarding the interoperability of heterogeneous data sources. In addition, the results also confirm that the Me Dint architecture is able to provide integration that is transparent to users and that the schema evolution does not affect the integration

SEMANTICALLY INTEGRATED E-LEARNING INTEROPERABILITY AGENT

Educational collaboration through e-learning is one of the fields that have been worked on since the emergence of e-learning in educational system. The e-learning standards (e.g. learning object metadata standard) and e-learning system architectures or frameworks, which support interoperation of correlated e-learning systems, are the proposed technologies to support the collaboration. However, these technologies have not been successful in creating boundless educational collaboration through e-learning. In particular, these technologies offer solutions with their own requirements or limitations and endeavor challenging efforts in applying the technologies into their elearning system. Thus, the simpler the technology enhances possibility in forging the collaboration. This thesis explores a suite of techniques for creating an interoperability tool model in e-learning domain that can be applied on diverse e-learning platforms. The proposed model is called the e-learning Interoperability Agent or eiA. The scope of eiA focuses on two aspects of e-learning: Learning Objects (LOs) and the users of elearning itself. Learning objects that are accessible over the Web are valuable assets for sharing knowledge in teaching, training, problem solving and decision support. Meanwhile, there is still tacit knowledge that is not documented through LOs but embedded in form of users' expertise and experiences. Therefore, the establishment of educational collaboration can be formed by the users of e-learning with a common interest in a specific problem domain. The eiA is a loosely coupled model designed as an extension of various elearning systems platforms. The eiA utilizes XML (eXtensible Markup Language) technology, which has been accepted as the knowledge representation syntax, to bridge the heterogeneous platforms. At the end, the use of eiA as facilitator to mediate interconununication between e-leaming systems is to engage the creation of semantically Federated e-learning Community (FeC). Eventually, maturity of the FeC is driven by users' willingness to grow the community, by means of increasing the elearning systems that use eiA and adding new functionalities into eiA

Autonomy and Intelligence in the Computing Continuum: Challenges, Enablers, and Future Directions for Orchestration

Future AI applications require performance, reliability and privacy that the existing, cloud-dependant system architectures cannot provide. In this article, we study orchestration in the device-edge-cloud continuum, and focus on AI for edge, that is, the AI methods used in resource orchestration. We claim that to support the constantly growing requirements of intelligent applications in the device-edge-cloud computing continuum, resource orchestration needs to embrace edge AI and emphasize local autonomy and intelligence. To justify the claim, we provide a general definition for continuum orchestration, and look at how current and emerging orchestration paradigms are suitable for the computing continuum. We describe certain major emerging research themes that may affect future orchestration, and provide an early vision of an orchestration paradigm that embraces those research themes. Finally, we survey current key edge AI methods and look at how they may contribute into fulfilling the vision of future continuum orchestration.Comment: 50 pages, 8 figures (Revised content in all sections, added figures and new section

Interoperability of heterogeneous Systems of Systems: from requirements to a reference architecture

Interoperability stands as a critical hurdle in developing and overseeing distributed and collaborative systems. Thus, it becomes imperative to gain a deep comprehension of the primary obstacles hindering interoperability and the essential criteria that systems must satisfy to achieve it. In light of this objective, in the initial phase of this research, we conducted a survey questionnaire involving stakeholders and practitioners engaged in distributed and collaborative systems. This effort resulted in the identification of eight essential interoperability requirements, along with their corresponding challenges. Then, the second part of our study encompassed a critical review of the literature to assess the effectiveness of prevailing conceptual approaches and associated technologies in addressing the identified requirements. This analysis led to the identification of a set of components that promise to deliver the desired interoperability by addressing the requirements identified earlier. These elements subsequently form the foundation for the third part of our study, a reference architecture for interoperability-fostering frameworks that is proposed in this paper. The results of our research can significantly impact the software engineering of interoperable systems by introducing their fundamental requirements and the best practices to address them, but also by identifying the key elements of a framework facilitating interoperability in Systems of Systems