581 research outputs found
Database independent Migration of Objects into an Object-Relational Database
This paper reports on the CERN-based WISDOM project which is studying the
serialisation and deserialisation of data to/from an object database
(objectivity) and ORACLE 9i.Comment: 26 pages, 18 figures; CMS CERN Conference Report cr02_01
Mapping Large Scale Research Metadata to Linked Data: A Performance Comparison of HBase, CSV and XML
OpenAIRE, the Open Access Infrastructure for Research in Europe, comprises a
database of all EC FP7 and H2020 funded research projects, including metadata
of their results (publications and datasets). These data are stored in an HBase
NoSQL database, post-processed, and exposed as HTML for human consumption, and
as XML through a web service interface. As an intermediate format to facilitate
statistical computations, CSV is generated internally. To interlink the
OpenAIRE data with related data on the Web, we aim at exporting them as Linked
Open Data (LOD). The LOD export is required to integrate into the overall data
processing workflow, where derived data are regenerated from the base data
every day. We thus faced the challenge of identifying the best-performing
conversion approach.We evaluated the performances of creating LOD by a
MapReduce job on top of HBase, by mapping the intermediate CSV files, and by
mapping the XML output.Comment: Accepted in 0th Metadata and Semantics Research Conferenc
Content diffusion in ALERT clinical applications
Estágio realizado na ALERT e orientado pelo Eng.º Tiago SilvaTese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 200
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A flexible approach for mapping between object-oriented databases and xml. A two way method based on an object graph.
One of the most popular challenges facing academia and industry is the development
of effective techniques and tools for maximizing the availability of data as the most
valuable source of knowledge. The internet has dominated as the core for
maximizing data availability and XML (eXtensible Markup Language) has emerged
and is being gradually accepted as the universal standard format for platform
independent publishing and exchanging data over the Internet. On the other hand,
there remain large amount of data held in structured databases and database
management systems have been traditionally used for the effective storage and
manipulation of large volumes of data. This raised the need for effective
methodologies capable of smoothly transforming data between different formats in
general and between XML and structured databases in particular. This dissertation
addresses the issue by proposing a two-way mapping approach between XML and
object-oriented databases. The basic steps of the proposed approach are applied in a
systematic way to produce a graph from the source and then transform the graph into
the destination format. In other words, the derived graph summarizes characteristics
of the source whether XML (elements and attributes) or object-oriented database
(classes, inheritance and nesting hierarchies). Then, the developed methodology
classifies nodes and links from the graph into the basic constructs of the destination,
i.e., elements and attributes for XML or classes, inheritance and nesting hierarchies
for object-oriented databases. The methodology has been successfully implemented
and illustrative case studies are presented in this document
Dynamic Assembly for System Adaptability, Dependability, and Assurance
(DASASA) ProjectAuthor-contributed print ite
Native XML Interface for a Relational Database
XML je dominatním jazykem pro výměnu dat. Vzhledem k velkém množství dostupných XML dokumentů a jejich vzájemnému přenosu, vzniká protřeba jejich ukládání a dotazování v nich. Jelikož většina firem stále používá systémy založené na relačních databázích pro ukládání dat, a často je nutné kombinovat nově získané XML data s původním daty uloženými v relační databázi, je vhodné se zabývat uložením XML dokumentů v relačních databázích. V této práci jsme se zaměřili na strukturované a semi-strukturované XML dokumenty, protože jsou nejčastěji používanými formáty pro výměnu dat a mohou být snadno validovány pomocí XML schémat. Předmětem teoretického rozboru je modifikovaný Hybrid algoritmus pro rozdělení dokumentu do relací na základě XSD schémat a dále umožnujeme zavést redundanci pro urychlení dotazování. Naším cílem je vytvořit systém podporujicí nejnovější standardy, který zároveň poskytne větší výkon a vertikální škálovatelnost než nativní XML databáze.XML has emerged as leading document format for exchanging data. Because of vast amounts of XML documents available and transfered, there is a strong need to store and query information in these documents. However, the most companies are still using a RDBMS for their data warehouses and it is often necessary to combine legacy data with the ones in XML format, so it might be useful to consider storage possibilities for XML documents in a relation database. In this thesis we focused on structured and semi-structured data-based XML documents, because they are the most common when exchanging data and they can be easily validated against an XML schema. We propose a slightly modified Hybrid algorithm to shred doc- uments into relations using an XSD scheme and we allowed redundancy to make queries faster. Our goal was not to provide an academic solution, but fully working system supporting latest standards, which will beat up native XML databases both by performance and vertical scalability.
A Syntactical Reverse Engineering Approach to Fourth Generation Programming Languages Using Formal Methods
Fourth-generation programming languages (4GLs) feature rapid development with minimum configuration required by developers. However, 4GLs can suffer from limitations such as high maintenance cost and legacy software practices.
Reverse engineering an existing large legacy 4GL system into a currently maintainable programming language can be a cheaper and more effective solution than rewriting from scratch. Tools do not exist so far, for reverse engineering proprietary XML-like and model-driven 4GLs where the full language specification is not in the public domain.
This research has developed a novel method of reverse engineering some of the syntax of such 4GLs (with Uniface as an exemplar) derived from a particular system, with a view to providing a reliable method to translate/transpile that system's code and data structures into a modern object-oriented language (such as C\#).
The method was also applied, although only to a limited extent, to some other 4GLs, Informix and Apex, to show that it was in principle more broadly applicable. A novel testing method that the syntax had been successfully translated was provided using 'abstract syntax trees'.
The novel method took manually crafted grammar rules, together with Encapsulated Document Object Model based data from the source language and then used parsers to produce syntactically valid and equivalent code in the target/output language.
This proof of concept research has provided a methodology plus sample code to automate part of the process. The methodology comprised a set of manual or semi-automated steps. Further automation is left for future research.
In principle, the author's method could be extended to allow the reverse engineering recovery of the syntax of systems developed in other proprietary 4GLs. This would reduce time and cost for the ongoing maintenance of such systems by enabling their software engineers to work using modern object-oriented languages, methodologies, tools and techniques
A semantic and agent-based approach to support information retrieval, interoperability and multi-lateral viewpoints for heterogeneous environmental databases
PhDData stored in individual autonomous databases often needs to be combined and
interrelated. For example, in the Inland Water (IW) environment monitoring domain,
the spatial and temporal variation of measurements of different water quality indicators
stored in different databases are of interest. Data from multiple data sources is more
complex to combine when there is a lack of metadata in a computation forin and when
the syntax and semantics of the stored data models are heterogeneous. The main types
of information retrieval (IR) requirements are query transparency and data
harmonisation for data interoperability and support for multiple user views. A
combined Semantic Web based and Agent based distributed system framework has
been developed to support the above IR requirements. It has been implemented using
the Jena ontology and JADE agent toolkits. The semantic part supports the
interoperability of autonomous data sources by merging their intensional data, using a
Global-As-View or GAV approach, into a global semantic model, represented in
DAML+OIL and in OWL. This is used to mediate between different local database
views. The agent part provides the semantic services to import, align and parse
semantic metadata instances, to support data mediation and to reason about data
mappings during alignment. The framework has applied to support information
retrieval, interoperability and multi-lateral viewpoints for four European environmental
agency databases.
An extended GAV approach has been developed and applied to handle queries that can
be reformulated over multiple user views of the stored data. This allows users to
retrieve data in a conceptualisation that is better suited to them rather than to have to
understand the entire detailed global view conceptualisation. User viewpoints are
derived from the global ontology or existing viewpoints of it. This has the advantage
that it reduces the number of potential conceptualisations and their associated
mappings to be more computationally manageable. Whereas an ad hoc framework
based upon conventional distributed programming language and a rule framework
could be used to support user views and adaptation to user views, a more formal
framework has the benefit in that it can support reasoning about the consistency,
equivalence, containment and conflict resolution when traversing data models. A
preliminary formulation of the formal model has been undertaken and is based upon
extending a Datalog type algebra with hierarchical, attribute and instance value
operators. These operators can be applied to support compositional mapping and
consistency checking of data views. The multiple viewpoint system was implemented
as a Java-based application consisting of two sub-systems, one for viewpoint
adaptation and management, the other for query processing and query result
adjustment
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