3,324 research outputs found
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Integration with Ontologies
One of today’s hottest IT topics is integration, as bringing together information from different sources and structures is not completely solved. The approach outlined here wants to illustrate how ontologies [Gr93] could help to support the integration process
XML content warehousing: Improving sociological studies of mailing lists and web data
In this paper, we present the guidelines for an XML-based approach for the
sociological study of Web data such as the analysis of mailing lists or
databases available online. The use of an XML warehouse is a flexible solution
for storing and processing this kind of data. We propose an implemented
solution and show possible applications with our case study of profiles of
experts involved in W3C standard-setting activity. We illustrate the
sociological use of semi-structured databases by presenting our XML Schema for
mailing-list warehousing. An XML Schema allows many adjunctions or crossings of
data sources, without modifying existing data sets, while allowing possible
structural evolution. We also show that the existence of hidden data implies
increased complexity for traditional SQL users. XML content warehousing allows
altogether exhaustive warehousing and recursive queries through contents, with
far less dependence on the initial storage. We finally present the possibility
of exporting the data stored in the warehouse to commonly-used advanced
software devoted to sociological analysis
Web and Semantic Web Query Languages
A number of techniques have been developed to facilitate
powerful data retrieval on the Web and Semantic Web. Three categories
of Web query languages can be distinguished, according to the format
of the data they can retrieve: XML, RDF and Topic Maps. This article
introduces the spectrum of languages falling into these categories
and summarises their salient aspects. The languages are introduced using
common sample data and query types. Key aspects of the query
languages considered are stressed in a conclusion
Information Exchange Between Humanitarian Organizations: Using the XML Schema IDML
This article explains challenges that arise when humanitarian organizations want to coordinate their development activities by means of distributed information systems. It focuses on information exchange based on the eXtensible Markup Language (XML) and relational databases. This piece discusses how to save hierarchical XML documents in relational databases. It introduces conversion rules to derive a relational database model from XML schemas. The rules are applied for the design of a database for the management of humanitarian development projects. The underlying schema for the database is the International Development Markup Language (IDML). This exchange standard for development-related activities is described. The article gives details on how a traditional relational database can import or export XML documents, i.e. how it can be XML-enabled
Fund Finder: A case study of database-to-ontology mapping
The mapping between databases and ontologies is a basic problem when trying to "upgrade" deep web content to the semantic web. Our approach suggests the declarative definition of mappings as a way to achieve domain independency and reusability. A specific language (expressive enough to cover some real world mapping situations like lightly structured databases or not 1st normal form ones) is defined for this purpose. Along with this mapping description language, the ODEMapster processor is in charge of carrying out the effective instance data migration. We illustrate this by testing both the mappings definition and processor on a case study
Semantic Web Based Relational Database Access With Conflict Resolution
This thesis focuses on (1) accessing relational databases through Semantic Web technologies and (2) resolving conflicts that usually arises when integrating data from heterogeneous source schemas and/or instances.
In the first part of the thesis, we present an approach to access relational databases using Semantic Web technologies. Our approach is built on top of Ontop framework for Ontology Based Data Access. It extracts both Ontop mappings and an equivalent OWL ontology from an existing database schema. The end users can then access the underlying data source through SPARQL queries. The proposed approach takes into consideration the different relationships between the entities of the database schema when it extracts the mapping and the equivalent ontology. Instead of extracting a flat ontology that is an exact copy of the database schema, it extracts a rich ontology. The extracted ontology can also be used as an intermediary between a domain ontology and the underlying database schema. Our approach covers independent or master entities that do not have foreign references, dependent or detailed entities that have some foreign keys that reference other entities, recursive entities that contain some self references, binary join entities that relate two entities together, and n-ary join entities that map two or more entities in an n-ary relation. The implementation results indicate that the extracted Ontop mappings and ontology are accurate. i.e., end users can query all data (using SPARQL) from the underlying database source in the same way as if they have written SQL queries.
In the second part, we present an overview of the conflict resolution approaches in both conventional data integration systems and collaborative data sharing communities. We focus on the latter as it supports the needs of scientific communities for data sharing and collaboration. We first introduce the purpose of the study, and present a brief overview of data integration. Next, we talk about the problem of inconsistent data in conventional integration systems, and we summarize the conflict handling strategies used to handle such inconsistent data. Then we focus on the problem of conflict resolution in collaborative data sharing communities. A collaborative data sharing community is a group of users who agree to share a common database instance, such that all users have access to the shared instance and they can add to, update, and extend this shared instance. We discuss related works that adopt different conflict resolution strategies in the area of collaborative data sharing, and we provide a comparison between them. We find that a Collaborative Data Sharing System (CDSS) can best support the needs of certain communities such as scientific communities. We then discuss some open research opportunities to improve the efficiency and performance of the CDSS. Finally, we summarize our work so far towards achieving these open research directions
A Method for Mapping XML DTD to Relational Schemas In The Presence Of Functional Dependencies
The eXtensible Markup Language (XML) has recently emerged as a standard for
data representation and interchange on the web. As a lot of XML data in the web,
now the pressure is to manage the data efficiently. Given the fact that relational
databases are the most widely used technology for managing and storing XML,
therefore XML needs to map to relations and this process is one that occurs
frequently. There are many different ways to map and many approaches exist in the
literature especially considering the flexible nesting structures that XML allows. This
gives rise to the following important problem: Are some mappings ‘better’ than the
others? To approach this problem, the classical relational database design through
normalization technique that based on known functional dependency concept is
referred. This concept is used to specify the constraints that may exist in the relations
and guide the design while removing semantic data redundancies. This approach
leads to a good normalized relational schema without data redundancy. To achieve a
good normalized relational schema for XML, there is a need to extend the concept of
functional dependency in relations to XML and use this concept as guidance for the
design. Even though there exist functional dependency definitions for XML, but these definitions are not standard yet and still having several limitation. Due to the
limitations of the existing definitions, constraints in the presence of shared and local
elements that exist in XML document cannot be specified. In this study a new
definition of functional dependency constraints for XML is proposed that are general
enough to specify constraints and to discover semantic redundancies in XML
documents.
The focus of this study is on how to produce an optimal mapping approach in the
presence of XML functional dependencies (XFD), keys and Data Type Definition
(DTD) constraints, as a guidance to generate a good relational schema. To approach
the mapping problem, three different components are explored: the mapping
algorithm, functional dependency for XML, and implication process. The study of
XML implication is important to imply what other dependencies that are guaranteed
to hold in a relational representation of XML, given that a set of functional
dependencies holds in the XML document. This leads to the needs of deriving a set
of inference rules for the implication process. In the presence of DTD and userdefined
XFD, other set of XFDs that are guaranteed to hold in XML can be
generated using the set of inference rules. This mapping algorithm has been
developed within the tool called XtoR. The quality of the mapping approach has
been analyzed, and the result shows that the mapping approach (XtoR) significantly
improve in terms of generating a good relational schema for XML with respect to
reduce data and relation redundancy, remove dangling relations and remove
association problems. The findings suggest that if one wants to use RDBMS to
manage XML data, the mapping from XML document to relations must based be on
functional dependency constraints
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