Meta Data Services

About: Meta Data Services is a research topic. Over the lifetime, 2564 publications have been published within this topic receiving 40102 citations.

Partial Replication of Metadata to Achieve High Metadata Availability in Parallel File Systems

Abstract: This paper presents PARTE, a prototype parallel file system with active/standby configured metadata servers (MDSs). PARTE replicates and distributes a part of files' metadata to the corresponding metadata stripes on the storage servers (OSTs) with a per-file granularity, meanwhile the client file system (client) keeps certain sent metadata requests. If the active MDS has crashed for some reason, these client backup requests will be replayed by the standby MDS to restore the lost metadata. In case one or more backup requests are lost due to network problems or dead clients, the latest metadata saved in the associated metadata stripes will be used to construct consistent and up-to-date metadata on the standby MDS. Moreover, the clients and OSTs can work in both normal mode and recovery mode in the PARTE file system. This differs from conventional active/standby configured MDSs parallel file systems, which hang all I/O requests and metadata requests during restoration of the lost metadata. In the PARTE file system, previously connected clients can continue to perform I/O operations and relevant metadata operations, because OSTs work as temporary MDSs during that period by using the replicated metadata in the relevant metadata stripes. Through examination of experimental results, we show the feasibility of the main ideas presented in this paper for providing high availability metadata service with only a slight overhead effect on I/O performance. Furthermore, since previously connected clients are never hanged during metadata recovery, in contrast to conventional systems, a better overall I/O data throughput can be achieved with PARTE.

Characterization of Educational Resources in e-Learning Systems Using an Educational Metadata Profile

Abstract: Introduction Metadata are "machine-readable information about electronic resources or other things" (Berners-Lee, 1997) and are used to describe the features of a resource, thus making easier its management and retrieval. A set of metadata elements combined so as to serve a specific purpose, constitute a metadata schema. Although the adoption of a single metadata standard would assure reusability of resources and interoperability among applications, there exists no metadata schema yet, appropriate to fulfil the requirements and needs of every application. Some schemas focus on technical metadata, other on educational metadata while some other on more specialized elements. When existing approaches are not sufficient enough to cover the special requirements of an institution or organization, the use of application profiles is suggested. According to Heery & Patel (2000), an application profile is an aggregation of metadata elements selected from one or more different schemas and combined into a new compound schema. Particularly, in the case of educational recourses, the set of metadata used to describe their characteristics, should be able to capture their educational and pedagogical aspects. Therefore, apart from author, title or type--fields that are common in all metadata schemas--an educational metadata schema should also include information regarding the resource's particular learning type, its intended end users, the instructional context and many more. A kind of educational resource that is increasingly used by Educational Institutions in recent years is the Learning Object (LO). According to Nikolopoulos, Solomou, Pierrakeas & Kameas (2012) LOs are pieces of educational material that directly correlate the knowledge they convey with specific objectives (learning outcomes) of the learning process. But although LOs constitute a common trend in organizing educational material and have been utilized by many modern e-learning systems (Schreurs & Al-Zoubi, 2007), they cannot be used effectively because there exists no metadata schema capable of capturing all of their characteristics. This insufficiency becomes even greater in the case of LOs that are designed for use in the context of distance learning courses, where the proper handling and dissemination of LOs is crucial for the success of the learning process, because in most cases, contrary to what happens in a classroom, no human tutor would be continuously available to monitor students' path or progress through the educational process. Hellenic Open University (HOU) is a Higher Education Institute specialized in distance and lifelong learning that the last two years seeks to re-organize its material and to provide its students with advanced services for delivering knowledge. Such services require the consumption of adequately characterized LOs, using a metadata schema that is capable of capturing as many as possible of their pedagogical aspects and especially those considered to be important according to distance learning principles. To the best of our knowledge, no such a schema or application profile exists, able to satisfy these requirements. Consequently, through this work we propose an application profile of the IEEE LOM standard with special focus on the field of distance learning. After reviewing existing approaches for describing educational resources, as well as several binding methods (section Background), we move on to the presentation of our proposed Educational Metadata Profile (EMP), in section EMP: New Elements and Modifications. Its ontological binding is given in the subsequent section (The EMP ontology), whereas section Evaluation of the EMP ontology presents an evaluation of this ontology model, through its application for characterizing real LO instances. Conclusions follow, in our last section. Background In literature, several metadata standards and profiles have been proposed, each serving different purposes and needs. …

A message conversion system, XML-based metadata semantics description language and metadata repository

Abstract: Metadata can be used to precisely represent data semantics. It can also serve to improve data sharing and exchange. Because the various types of metadata are created in different ways, they can suffer from a problem of inconsistency. Recently, metadata gateway methods have been researched to solve this problem. However, the performance of the existing approaches based on metadata schemas is poor and their maintenance (adaptation of metadata changes) is time consuming. In this paper, a novel message conversion system is proposed, which functions by separating the heterogeneous mapping information from the mapping rules of the metadata, in order to overcome the drawbacks of the existing metadata gateway methods. The proposed system controls the standardized data elements dynamically based on the Metadata Registry (MDR), which is one of the most important elements of the ISO/IEC 11179 standard. The problems associated with adding supplementary metadata are resolved, since the standard provides for incorporating additional data elements created in the future. MSDL is defined as a protocol which can be used for exchanging messages between heterogeneous systems, and which ensures that all of the systems have their own independent metadata schemas.

Actual use of learning objects and metadata: an empirical analysis

Abstract: Learning Object technology is being considered as the natural form of content re-use that will considerably decrease the cost of developing electronic learning (educational) material. The focus of my research is evaluating and tracking the actual use made of learning objects, metadata and their associated toolsets in Learning Object Repositories. This will enable users and tools to learn from the way users use learning objects and technology in general, and hereby, improve the use of learning objects and their associated toolsets.