Renata Slota

Grid organizational memory-provision of a high-level Grid abstraction layer supported by ontology alignment

In this paper the problem of managing ontological descriptions for a dynamically-changing Grid environment is addressed. The focus of the research is on unification of semantic descriptions for Grid services and resources through ontologies. The Grid Organizational Memory (GOM) has been designed and implemented to enable storing and accessing Grid metadata, kept in the form of ontologies. In GOM, ontology storage and management are designed to support the natural evolution process both in the knowledge structure and knowledge management services. An important element of the GOM framework is the ontology separation schema, specifying the internal vertical and horizontal dependencies according to the Virtual Organization thematic domains, efficiency of knowledge retrieval and ontology development support. The separation schema is applied in the knowledge base distribution model on the Grid. An ontology alignment-based approach is proposed to minimize user commitment on the Grid ontological metadata, to support ontology usage and development. In particular the ontology similarity based approach is presented as support for ontology updates, e.g. extension with new facts from external ontologies and environments, as well as a more efficient and complete, less implementation-bounded querying process. This paper presents research on semantic description of the Grid environment within the scope of the K-Wf Grid project that addresses knowledge-based semiautomatic workflow construction for applications on the Grid.

Access cost estimation for unified grid storage systems

In typical data grids large amounts of replicated data are stored all over the globe in different storage systems with access latencies ranging from seconds to hours. The task of a replica management system is not only to keep track of the replicas but also to select those replicas that can be accessed by an application program with a minimal response or transfer time. Most wide-area replication research focuses on network-based replica selection. However, our past experience with data grids has shown that often hierarchical storage systems are the main bottleneck rather than network links. This is due to the fact that access latencies of hierarchical storage systems can be of the order of seconds up to hours in case the data resides on a tape that is not mounted yet. We give an overview of our replica management framework called Reptor and a storage system cost estimator that is used. Furthermore, we give details on access estimation of file replicas that reside on hierarchical storage systems. The results show that the access estimates provide a good basis for a replica management system to perform efficient replica selection.

Implementation of replication methods in the grid environment

Data replication methods are often used in Grid environments for improving the access time and data protection level. Dynamic replication allows the system to automatically create and delete replicas in order to follow dynamically changing system parameters and user access patterns keeping the performance high and resource usage in reasonable limits. In this paper we present the replication aspects of the Virtual Storage System developed within one of the grid projects. We also present results from replication tests done in a real grid environment.

Dynamic VO Establishment in Distributed Heterogeneous Business Environments

As modern SOA and Grid infrastructures are being moved from academic and research environments to more challenging business and commercial applications, such issue as control of resource sharing become of crucial importance. In order to manage and share resources within distributed environments the idea of Virtual Organizations (VO) emerged, which enables sharing only subsets of resources among partners of such a VO within potentially larger settings. This paper describes the Framework for Intelligent Virtual Organizations (FiVO), focusing on its functionality of enforcing security (Authentication and Authorization) in dynamically deployed Virtual Organizations. The paper presents the overall architecture of the framework along with different security settings which FiVO can support within one Virtual Organization.

Algorithms for automatic data replication in grid environment

Replication methods can be used for shortening the data access time in Grid environment with heterogeneous storage resources. In this paper we describe the algorithms for automatic replication implemented by us in two grid projects having different requirements concerning data storage.

Knowledge management for organisationally mobile public employees

Public organisations often face knowledge management problems caused by organisational mobility, the continual and pervasive movement of staff between units and departments. This can be a strength, but also introduces problems of loss of experience and reduced efficiency and effectiveness in working. The Pellucid project is developing a knowledge management system to assist in such situations. The projects three pilot applications are described, and an abstracted view of their knowledge management needs is developed. An outline of key parts of the technical solution is given.

Ontology Assisted Access to Document Repositories in Public Sector Organizations

This paper describes a method that combines ontology and full-text indexing to search documents in organizational repositories. The method was used in a system supporting organizational activity by formalizing, sharing and preserving operational experience and knowledge for future use. The paper is based on results obtained from EU IST Pellucid Project.

Distributed Knowledge Management Based on Software Agents and Ontology

In this paper we present the use of ontology for knowledge representation and handling in Software Agent Systems. Motivation has come from Pellucid IST project where we need to capture and capitalize employee’s knowledge in organization. This knowledge is then presented to other employees as they work on particular tasks. The Protege ontology editor and JADE multi-agent system is used for implementation. Ontology is usually used in intra-agent communication for agents to understand each other; we used ontology also as knowledge data model to store knowledge as instances of ontological terms into object database, thus agents can access and manipulate knowledge data directly and still stay lightweight.

MMSRS - Multimedia Storage and Retrieval System for a Distributed Medical Information System

The Multimedia Storage and Retrieval System described in this paper is aimed at storing and retrieving medical multimedia data such as images and videos. There are three significant problems that automatically need to be addressed: providing enough capacity to fit Terabytes of MPEG files, efficient extraction of video fragments from MPEG files and quality of service issues. We are working on two different approaches to build MMSRS. The first one, described in this article, utilizes commercial HSM software for managing the tertiary storage hardware. The second approach that we have started to investigate is an attempt to build a specialised storage management system from scratch.

Data Farming on Heterogeneous Clouds

Using multiple Clouds as a single environment to conduct simulation-based virtual experiments at a large-scale is a challenging problem. This paper describes how this can be achieved with the Scalarm platform in the context of data farming. In particular, a use case with a private Cloud combined with public, commercial Clouds is studied. We discuss the current architecture and implementation of Scalarm in terms of supporting different infrastructures, and propose how it can be extended in order to attain a unification of different Clouds usage. We discuss different aspects of the Cloud usage unification including: scheduling virtual machines, authentication, and virtual machine state monitoring. An experimental evaluation of the presented solution is conducted with a genetic algorithm solving the well-known Travel Salesman Problem. The evaluation uses three different resource configurations: using only public Cloud, using only private Cloud, and using both public and private Clouds.