138 research outputs found
Patterns for Heterogeneous TBox Mappings to Bridge Different Modelling Decisions
Correspondence patterns have been proposed as templates of commonly used alignments between heterogeneous elements in ontologies, although design tools are currently not equipped with handling these definition alignments nor pattern alignments. We aim to address this by, first, formalising the notion of design pattern; secondly, defining typical modelling choice patterns and their alignments; and finally, proposing algorithms for integrating automatic pattern detection into existing ontology design tools. This gave rise to six formalised pattern alignments and two efficient local search and pattern matching algorithms to propose possible pattern alignments to the modeller
Towards a Visual SPARQL-DL Query Builder
Querying ontologies is an every-day activity that users need.
This interaction will improve when the query is more expressive and easier to develop. For this purpose, a visual query language is an ideal mean for users and ontology engineers for creating queries taking advantage of the easy-to-understand and low time and cost characteristics, specially, for users which does not know textual query languages. On the other side, SPARQL-DL is a powerful and expressive textual query language for OWL-DL based ontologies that can combine TBox/ABox/RBox queries.
Considering the advantage of both, we present in this work a visual query language that can be interpreted as SPARQL-DL sentences and thus being used for querying ontologies for its structure and/or instance information. Altogether, we use this idea to create a modified version of crowd, a Web modelling tool with reasoning support, that enables to implement and tests the presented graphical language along with the needed SPARQL-DL support for solving queries with the user’s provided OWL 2 ontologies in any of its linearisations.X Workshop Innovación en Sistemas de Software (WISS)Red de Universidades con Carreras en Informática (RedUNCI
Towards a Visual SPARQL-DL Query Builder
Querying ontologies is an every-day activity that users need.
This interaction will improve when the query is more expressive and easier to develop. For this purpose, a visual query language is an ideal mean for users and ontology engineers for creating queries taking advantage of the easy-to-understand and low time and cost characteristics, specially, for users which does not know textual query languages. On the other side, SPARQL-DL is a powerful and expressive textual query language for OWL-DL based ontologies that can combine TBox/ABox/RBox queries.
Considering the advantage of both, we present in this work a visual query language that can be interpreted as SPARQL-DL sentences and thus being used for querying ontologies for its structure and/or instance information. Altogether, we use this idea to create a modified version of crowd, a Web modelling tool with reasoning support, that enables to implement and tests the presented graphical language along with the needed SPARQL-DL support for solving queries with the user’s provided OWL 2 ontologies in any of its linearisations.X Workshop Innovación en Sistemas de Software (WISS)Red de Universidades con Carreras en Informática (RedUNCI
Semantically defined Analytics for Industrial Equipment Diagnostics
In this age of digitalization, industries everywhere accumulate massive amount of data such that it has become the lifeblood of the global economy. This data may come from various heterogeneous systems, equipment, components, sensors, systems and applications in many varieties (diversity of sources), velocities (high rate of changes) and volumes (sheer data size).
Despite significant advances in the ability to collect, store, manage and filter data, the real value lies in the analytics. Raw data is meaningless, unless it is properly processed to actionable (business) insights. Those that know how to harness data effectively, have a decisive competitive advantage, through raising performance by making faster and smart decisions, improving short and long-term strategic planning, offering more user-centric products and services and fostering innovation. Two distinct paradigms in practice can be discerned within the field of analytics: semantic-driven (deductive) and data-driven (inductive).
The first emphasizes logic as a way of representing the domain knowledge encoded in rules or ontologies and are often carefully curated and maintained. However, these models are often highly complex, and require intensive knowledge processing capabilities. Data-driven analytics employ machine learning (ML) to directly learn a model from the data with minimal human intervention. However, these models are tuned to trained data and context, making it difficult to adapt.
Industries today that want to create value from data must master these paradigms in combination. However, there is great need in data analytics to seamlessly combine semantic-driven and data-driven processing techniques in an efficient and scalable architecture that allows extracting actionable insights from an extreme variety of data. In this thesis, we address these needs by providing:
• A unified representation of domain-specific and analytical semantics, in form of ontology models called TechOnto Ontology Stack. It is highly expressive, platform-independent formalism to capture conceptual semantics of industrial systems such as technical system hierarchies, component partonomies etc and its analytical functional semantics.
• A new ontology language Semantically defined Analytical Language (SAL) on top of the ontology model that extends existing DatalogMTL (a Horn fragment of Metric Temporal Logic) with analytical functions as first class citizens.
• A method to generate semantic workflows using our SAL language. It helps in authoring, reusing and maintaining complex analytical tasks and workflows in an abstract fashion.
• A multi-layer architecture that fuses knowledge- and data-driven analytics into a federated and distributed solution.
To our knowledge, the work in this thesis is one of the first works to introduce and investigate the use of the semantically defined analytics in an ontology-based data access setting for industrial analytical applications. The reason behind focusing our work and evaluation on industrial data is due to (i) the adoption of semantic technology by the industries in general, and (ii) the common need in literature and
in practice to allow domain expertise to drive the data analytics on semantically interoperable sources, while still harnessing the power of analytics to enable real-time data insights. Given the evaluation results of three use-case studies, our approach surpass state-of-the-art approaches for most application scenarios.Im Zeitalter der Digitalisierung sammeln die Industrien überall massive Daten-mengen, die zum Lebenselixier der Weltwirtschaft geworden sind. Diese Daten können aus verschiedenen heterogenen Systemen, Geräten, Komponenten, Sensoren, Systemen und Anwendungen in vielen Varianten (Vielfalt der Quellen), Geschwindigkeiten (hohe Änderungsrate) und Volumina (reine Datengröße) stammen.
Trotz erheblicher Fortschritte in der Fähigkeit, Daten zu sammeln, zu speichern, zu verwalten und zu filtern, liegt der eigentliche Wert in der Analytik. Rohdaten sind bedeutungslos, es sei denn, sie werden ordnungsgemäß zu verwertbaren (Geschäfts-)Erkenntnissen verarbeitet. Wer weiß, wie man Daten effektiv nutzt, hat einen entscheidenden Wettbewerbsvorteil, indem er die Leistung steigert, indem er schnellere und intelligentere Entscheidungen trifft, die kurz- und langfristige strategische Planung verbessert, mehr benutzerorientierte Produkte und Dienstleistungen anbietet und Innovationen fördert. In der Praxis lassen sich im Bereich der Analytik zwei unterschiedliche Paradigmen unterscheiden: semantisch (deduktiv) und Daten getrieben (induktiv).
Die erste betont die Logik als eine Möglichkeit, das in Regeln oder Ontologien kodierte Domänen-wissen darzustellen, und wird oft sorgfältig kuratiert und gepflegt. Diese Modelle sind jedoch oft sehr komplex und erfordern eine intensive Wissensverarbeitung. Datengesteuerte Analysen verwenden maschinelles Lernen (ML), um mit minimalem menschlichen Eingriff direkt ein Modell aus den Daten zu lernen. Diese Modelle sind jedoch auf trainierte Daten und Kontext abgestimmt, was die Anpassung erschwert.
Branchen, die heute Wert aus Daten schaffen wollen, müssen diese Paradigmen in Kombination meistern. Es besteht jedoch ein großer Bedarf in der Daten-analytik, semantisch und datengesteuerte Verarbeitungstechniken nahtlos in einer effizienten und skalierbaren Architektur zu kombinieren, die es ermöglicht, aus einer extremen Datenvielfalt verwertbare Erkenntnisse zu gewinnen. In dieser Arbeit, die wir auf diese Bedürfnisse durch die Bereitstellung:
• Eine einheitliche Darstellung der Domänen-spezifischen und analytischen Semantik in Form von Ontologie Modellen, genannt TechOnto Ontology Stack. Es ist ein hoch-expressiver, plattformunabhängiger Formalismus, die konzeptionelle Semantik industrieller Systeme wie technischer Systemhierarchien, Komponenten-partonomien usw. und deren analytische funktionale Semantik zu erfassen.
• Eine neue Ontologie-Sprache Semantically defined Analytical Language (SAL) auf Basis des Ontologie-Modells das bestehende DatalogMTL (ein Horn fragment der metrischen temporären Logik) um analytische Funktionen als erstklassige Bürger erweitert.
• Eine Methode zur Erzeugung semantischer workflows mit unserer SAL-Sprache. Es hilft bei der Erstellung, Wiederverwendung und Wartung komplexer analytischer Aufgaben und workflows auf abstrakte Weise.
• Eine mehrschichtige Architektur, die Wissens- und datengesteuerte Analysen zu einer föderierten und verteilten Lösung verschmilzt.
Nach unserem Wissen, die Arbeit in dieser Arbeit ist eines der ersten Werke zur Einführung und Untersuchung der Verwendung der semantisch definierten Analytik in einer Ontologie-basierten Datenzugriff Einstellung für industrielle analytische Anwendungen. Der Grund für die Fokussierung unserer Arbeit und Evaluierung auf industrielle Daten ist auf (i) die Übernahme semantischer Technologien durch die Industrie im Allgemeinen und (ii) den gemeinsamen Bedarf in der Literatur und in der Praxis zurückzuführen, der es der Fachkompetenz ermöglicht, die Datenanalyse auf semantisch inter-operablen Quellen voranzutreiben, und nutzen gleichzeitig die Leistungsfähigkeit der Analytik, um Echtzeit-Daten-einblicke zu ermöglichen. Aufgrund der Evaluierungsergebnisse von drei Anwendungsfällen Übertritt unser Ansatz für die meisten Anwendungsszenarien Modernste Ansätze
Aspects of semantic ETL
Tesi en modalitat de cotutela: Universitat Politècnica de Catalunya i Aalborg UniversitetBusiness Intelligence tools support making better business decisions by analyzing available organizational data. Data Warehouses (DWs), typically structured with the Multidimensional (MD) model, are used to store data from different internal and external sources processed using Extract-Transformation-Load (ETL) processes. On-Line analytical Processing (OLAP) queries are applied on DWs to derive important business-critical knowledge. DW and OLAP technologies perform efficiently when they are applied on data that are static in nature and well organized in structure. Nowadays, Semantic Web technologies and the Linked Data principles inspire organizations to publish their semantic data, which allow machines to understand the meaning of data, using the Resource Description Framework (RDF) model. In addition to traditional (non-semantic) data sources, the incorporation of semantic data sources into a DW raises the additional challenges of schema derivation, semantic heterogeneity, and schema and data management model over traditional ETL tools. Furthermore, most SW data provided by business, academic and governmental organizations include facts and figures, which raise new requirements for BI tools to enable OLAP-like analyses over those semantic (RDF) data. In this thesis, we 1) propose a layer-based ETL framework for handling diverse semantic and non-semantic data sources by addressing the challenges mentioned above, 2) propose a set of high-level ETL constructs for processing semantic data, 3) implement appropriate environments (both programmable and GUI) to facilitate ETL processes and evaluate the proposed solutions. Our ETL framework is a semantic ETL framework because it integrates data semantically. We propose SETL, a unified framework for semantic ETL. The framework is divided into three layers: the Definition Layer, ETL Layer, and Data Warehouse Layer. In the Definition Layer, the semantic DW (SDW) schema, sources, and the mappings among the sources and the target are defined. In the ETL Layer, ETL processes to populate the SDW from sources are designed. The Data Warehouse Layer manages the storage of transformed semantic data. The framework supports the inclusion of semantic (RDF) data in DWs in addition to relational data. It allows users to define an ontology of a DW and annotate it with MD constructs (such as dimensions, cubes, levels, etc.) using the Data Cube for OLAP (QB4OLAP) vocabulary. It supports traditional transformation operations and provides a method to generate semantic data from the source data according to the semantics encoded in the ontology. It also provides a method to connect internal SDW data with external knowledge bases. On top of SETL, we propose SETLCONSTUCT where we define a set of high-level ETL tasks/operations to process semantic data sources. We divide the integration process into two layers: the Definition Layer and Execution Layer. The Definition Layer includes two tasks that allow DW designers to define target (SDW) schemas and the mappings between (intermediate) sources and the (intermediate) target. To create mappings among the sources and target constructs, we provide a mapping vocabulary called S2TMAP. Different from other ETL tools, we propose a new paradigm: we characterize the ETL flow transformations at the Definition Layer instead of independently within each ETL operation (in the Execution Layer). This way, the designer has an overall view of the process, which generates metadata (the mapping file) that the ETL operators will read and parametrize themselves with automatically. In the Execution Layer, we propose a set of high-level ETL operations to process semantic data sources. Finally, we develop a GUI-based semantic BI system SETLBI to define, process, integrate, and query semantic and non-semantic data. In addition to the Definition Layer and the ETL Layer, SETLBI has the OLAP Layer, which provides an interactive interface to enable OLAP analysis over the semantic DWLes eines d’Intel·ligència Empresarial (BI), conegudes en anglès com Business
Intelligence, donen suport a la millora de la presa de decisions empresarials
mitjançant l’anà lisi de les dades de l’organització disponibles. Els magatzems
de dades, o data warehouse, (DWs), tĂpicament estructurats seguint el model
Multidimensional (MD), s’utilitzen per emmagatzemar dades de diferents
fonts, tant internes com externes, processades mitjançant processos Extract-
Transformation-Load (ETL). Les consultes de processament analĂtic en lĂnia
(OLAP) s’apliquen als DW per extraure coneixement crĂtic en l’à mbit empresarial.
Els DW i les tecnologies OLAP funcionen de manera eficient quan
s’apliquen sobre dades de natura està tica i ben estructurades. Avui en dia,
les tecnologies de la Web SemĂ ntica (SW) i els principis Linked Data (LD) inspiren les organitzacions per publicar les seves dades en formats semĂ ntics,
que permeten que les mà quines entenguin el significat de les dades, mitjançant
el llenguatge de descripciĂł de recursos (RDF). Una de les raons per
les quals les dades semà ntiques han tingut tant d’èxit és que es poden gestionar i fer que estiguin disponibles per tercers amb poc esforç, i no depenen d’esquemes de dades sofisticats.
A més de les fonts de dades tradicionals (no semà ntiques), la incorporació
de fonts de dades semĂ ntiques en un DW planteja reptes addicionals
tals com derivar-hi esquema, l’heterogeneïtat semà ntica i la representació de
l’esquema i les dades a través d’eines d’ETL. A més, la majoria de dades SW
proporcionades per empreses, organitzacions acadèmiques o governamentals
inclouen fets i figures que representen nous reptes per les eines de BI per tal
d’habilitar l’anà lisi OLAP sobre dades semà ntiques (RDF). En aquesta tesi, 1)
proposem un marc ETL basat en capes per a la gestiĂł de diverses fonts de
dades semà ntiques i no semà ntiques i adreçant els reptes esmentats anteriorment, 2) proposem un conjunt d’operacions ETL per processar dades semà ntiques, i 3) la creació d’entorns apropiats de desenvolupament (programà tics i GUIs) per facilitar la creació i gestió de DW i processos ETL semà ntics, aixà com avaluar les solucions proposades. El nostre marc ETL és un marc ETL semà ntic perquè Es capaç de considerar e integrar dades de forma semà ntica.
Els segĂĽents parĂ grafs elaboren sobre aquests contribucions.
Proposem SETL, un marc unificat per a ETL semĂ ntic. El marc es divideix
en tres capes: la capa de definiciĂł, la capa ETL i la capa DW. A la
capa de definició, es defineixen l’esquema del DW semà ntic (SDW), les fonts
i els mappings entre les fonts i l’esquema del DW. A la capa ETL, es dissenyen
processos ETL per popular el SDW a partir de fonts. A la capa DW,
es gestiona l’emmagatzematge de les dades semà ntiques transformades. El
nostre marc dĂłna suport a la inclusiĂł de dades semĂ ntiques (RDF) en DWs,
a mĂ©s de dades relacionals. AixĂ, permet als usuaris definir una ontologia
d’un DW i anotar-la amb construccions MD (com ara dimensions, cubs, nivells,
etc.) utilitzant el vocabulari Data Cube for OLAP (QB4OLAP). També
admet operacions de transformació tradicionals i proporciona un mètode per
generar semà ntica de les dades d’origen segons la semà ntica codificada al
document ontologia. També proporciona un mètode per connectar l’SDW
amb bases de coneixement externes. Per tant, crea una base de coneixement,
composta per un ontologia i les seves instĂ ncies, on les dades estan
connectades semĂ nticament amb altres dades externes / internes. Per fer-ho,
desenvolupem un mètode programà tic, basat en Python, d’alt nivell, per
realitzar les tasques esmentades anteriorment. S’ha portat a terme un experiment
complet d’avaluació comparant SETL amb una solució elaborada amb
eines tradicional (que requereixen molta més codificació). Com a cas d’ús,
hem emprat el Danish Agricultural dataset, i els resultats mostren que SETL
proporciona un millor rendiment, millora la productivitat del programador i
la qualitat de la base de coneixement. La comparaciĂł entre SETL i Pentaho
Data Integration (PDI) mostra que SETL és un 13,5% més rà pid que PDI. A
més de ser més rà pid que PDI, tracta les dades semà ntiques com a ciutadans
de primera classe, mentre que PDI no contĂ© operadors especĂfics per a dades
semĂ ntiques.
A sobre de SETL, proposem SETLCONSTUCT on definim un conjunt de
tasques d’alt nivell / operacions ETL per processar fonts de dades semà ntiques
i orientades a encapsular i facilitar la creació de l’ETL semà ntic. Dividim
el procés d’integració en dues capes: la capa de definició i la capa
d’execució. La capa de definició inclou dues tasques que permeten definir
als dissenyadors de DW esquemes destà (SDW) i mappings entre fonts (o resultats intermedis) i l’SDW (potencialment, altres resultats intermedis). Per
crear mappings entre les fonts i el SDW, proporcionem un vocabulari de mapping anomenat Source-To-Target Mapping (S2TMAP). A diferència d’altres
eines ETL, proposem un nou paradigma: les transformacions del flux ETL es
caracteritzen a la capa de definiciĂł, i no de forma independent dins de cada
operació ETL (a la capa d’execució). Aquest nou paradigma permet al dissenyador tenir una visió global del procés, que genera metadades (el fitxer de mapping) que els operadors ETL individuals llegiran i es parametritzaran automà ticament.
A la capa d’execució proposem un conjunt d’operacions ETL d’alt nivell per processar fonts de dades semà ntiques. A més de la neteja, la unió i la transformació per dades semà ntiques, proposem operacions per generar semà ntica multidimensional i actualitzar el SDW per reflectir els canvis
en les fonts. A més, ampliem SETLCONSTRUCT per permetre la generació
automà tica de flux d’execució ETL (l’anomenem SETLAUTO). Finalment, proporcionem una à mplia avaluació per comparar la productivitat, el temps de
desenvolupament i el rendiment de SETLCONSTRUCT i SETLAUTO amb el marc anterior SETL. L’avaluació demostra que SETLCONSTRUCT millora considerablement sobre SETL en termes de productivitat, temps de desenvolupament i rendiment. L’avaluació mostra que 1) SETLCONSTRUCT utilitza un 92% menys de carà cters mecanografiats (NOTC) que SETL, i SETLAUTO redueix encara més el nombre de conceptes usats (NOUC) un altre 25%; 2) utilitzant SETLCONSTRUCT, el temps de desenvolupament es redueix gairebé a la meitat en comparació amb SETL, i es redueix un altre 27 % mitjançant SETLAUTO; 3) SETLCONSTRUCT es escalable i té un rendiment similar en comparació amb SETL.
Finalment, desenvolupem un sistema de BI semĂ ntic basat en GUI SETLBI
per definir, processar, integrar i consultar dades semĂ ntiques i no semĂ ntiques.
A mĂ©s de la capa de definiciĂł i de la capa ETL, SETLBI tĂ© una capa OLAP, que proporciona una interfĂcie interactiva per permetre l’anĂ lisi OLAP
d’autoservei sobre el DW semà ntic. Cada capa està composada per un conjunt
d’operacions / tasques. Per formalitzar les connexions intra i inter-capes
dels components de cada capa, emprem una ontologia. La capa ETL amplia
l’execució de la capa de SETLCONSTUCT afegint operacions per processar
fonts de dades no semà ntiques. Per últim, demostrem el sistema final mitjançant el cens de la població de Bangladesh (2011).
La solució final d’aquesta tesi és l’eina SETLBI . SETLBI facilita (1) als dissenyadors del DW amb pocs / sense coneixements de SW, integrar semà nticament les dades (semà ntiques o no) i analitzar-les emprant OLAP, i (2) als usuaris de la SW els permet definir vistes sobre dades semà ntiques, integrar-les amb fonts no semà ntiques, i visualitzar-les segons el model MD i fer anà lisi OLAP. A més, els usuaris SW poden enriquir l’esquema SDW generat amb construccions RDFS / OWL. Prenent aquest marc com a punt de partida, els investigadors poden emprar-lo per a crear SDWs de forma interactiva i automà tica. Aquest projecte crea un pont entre les tecnologies BI i SW, i obre la porta a altres oportunitats de recerca com desenvolupar tècniques de DW i ETL comprensibles per les mà quines.(Danskere) Business Intelligence (BI) værktøjer understøtter at tage bedre forretningsbeslutninger,
ved at analysere tilgængelige organisatoriske data. Data Warehouses
(DWs), typisk konstrueret med den Multidimensionelle (MD) model,
bruges til at lagre data fra forskellige interne og eksterne kilder, der behandles
ved hjælp af Extract-Transformation-Load (ETL) processer. On-Line
Analytical Processing (OLAP) forespørgsler anvendes på DWs for at udlede
vigtig forretningskritisk viden. DW og OLAP-teknologier fungerer effektivt,
nĂĄr de anvendes pĂĄ data, som er statiske af natur og velorganiseret i struktur.
I dag inspirerer Semantic Web (SW) teknologier og Linked Data (LD) principper
organisationer til at offentliggøre deres semantiske data, som tillader
maskiner at forstå betydningen af denne, ved hjælp af Resource Description
Framework (RDF) modellen. En af grundene til, at semantiske data er blevet
succesfuldt, er at styringen og udgivelsen af af dataene er nemt, og ikke er
afhængigt af et sofistikeret skema.
Ud over problemer ved overførslen af traditionelle (ikke-semantiske) databaser
til DWs, opstår yderligere udfordringer ved overførslen af semantiske
databaser, sĂĄsom skema nedarvning, semantisk heterogenitet samt skemaet
for data repræsentation over traditionelle ETL værktøjer. På den anden side
udgør en stor del af den semantiske data der bliver offentliggjort af virksomheder,
akademikere samt regeringer, af figurer og fakta, der igen giver
nye problemstillinger og krav til BI værktøjer, for at gøre OLAP lignende
analyser over de semantiske data mulige. I denne afhandling gør vi følgende:
1) foreslĂĄr et lag-baseret ETL framework til at hĂĄndterer multiple
semantiske og ikke-semantiske datakilder, ved at svare pĂĄ udfordringerne
nævnt herover, 2) foreslår en mængde af ETL operationer til at behandle
semantisk data, 3) implementerer passende miljøer (både programmerbare
samt grafiske brugergrænseflader), for at lette ETL processer og evaluere den
foreslåede løsning. Vores ETL framework er et semantisk ETL framework,
fordi det integrerer data semantisk. Den følgende sektion forklarer vores
bidrag.
Vi foreslĂĄr SETL, et samlet framework for semantisk ETL. Frameworket
er splittet i tre lag: et definitions-lag, et ETL-lag, og et DW-lag. Det semanvii
tiske DW (SWD) skema, datakilder, samt sammenhængen mellem datakilder
og deres mĂĄl, er defineret i definitions-laget. I ETL-laget designes ETLprocesser
til at udfylde SDW fra datakilderne. DW-laget administrerer lagring
af transformerede semantiske data. Frameworket understøtter inkluderingen
af semantiske (RDF) data i DWs ud over relationelle data. Det giver
brugerne mulighed for at definere en ontologi for et DW og annotere med
MD-konstruktioner (såsom dimensioner, kuber, niveauer osv.) ved hjælp af
Data Cube til OLAP (QB4OLAP) ordforrådet. Det understøtter traditionelle
transformations operationer, og giver en metode til at generere semantiske
data fra de oprindelige data, i henhold til semantikken indkodet i ontologien.
Det muliggør også en metode til at forbinde interne SDW data med
eksterne vidensbaser. Herved skaber det en vidensbase, der er sammensat af
en ontologi og dets instanser, hvor data er semantisk forbundet med andre
eksterne / interne data. Vi udvikler et høj niveau Python-baseret programmerbart
framework for at udføre de ovennævnte opgaver. En omfattende
eksperimentel evaluering, der sammenligner SETL med en traditionel løsning
(hvilket krævede meget manuel kodning), om brugen af danske landbrugsog
forretnings datasæt, viser at SETL præsterer bedre, programmør produktivitet
og vidensbase kvalitet. Sammenligningen mellem SETL og Pentaho
Data Integration (PDI) ved behandling af en semantisk kilde viser, at SETL
er 13,5% hurtigere end PDI.
Udover SETL, foreslår vi SETLCONSTRUCT hvor vi definerer et sæt ETLoperationer
på højt niveau til behandling af semantiske datakilder. Vi deler
integrationsprocessen i to lag: Definitions-lag og eksekverings-lag. Definitionslaget
indeholder to opgaver, der giver DW designere muligheden for at definere
(SDW) skemaer, og kortlægningerne mellem kilder og målet. For
at oprette kortlægning mellem kilderne og målene, leverer vi et kortlægnings
ordforrĂĄd kaldet Source-to-Target Mapping (S2TMAP). Forskelligt fra
andre ETL-værktøjer foreslår vi et nyt paradigme: vi karakteriserer ETLflowtransformationerne
i definitions-laget i stedet for uafhængigt inden for
hver ETL-operation (i eksekverings-laget). PĂĄ denne mĂĄde har designeren
et overblik over processen, som genererer metadata (kortlægningsfilen), som
ETL operatørerne vil læse og parametrisere automatisk. I eksekverings-laget
foreslår vi en mængde høj niveau ETL-operationer til at behandle semantiske
datakilder. Udover rensning, sammenføjning og datatypebaseret transformationer
af semantiske data, foreslĂĄr vi operationer til at generere multidimensionel
semantik pĂĄ data-niveau og operationer til at opdatere et SDW for
at afspejle ændringer i kilde-dataen. Derudover udvider vi SETLCONSTRUCT
for at muliggøre automatisk ETL-eksekveringsstrømgenerering (vi kalder det
SETLAUTO). Endelig leverer vi en omfattende evaluering for at sammenligne
produktivitet, udviklingstid og ydeevne for scon og SETLAUTO med
den tidligere ramme SETL. Evalueringen viser, at SETLCONSTRUCT forbedres
markant i forhold til SETL med hensyn til produktivitet, udviklingstid og ydeevne. Evalueringen viser, at 1) SETLCONSTRUCT bruger 92% færre antal
indtastede tegn (NOTC) end SETL, og SETLAUTO reducerer antallet af brugte
begreber (NOUC) yderligere med 25%; 2) ved at bruge SETLCONSTRUCT, er
udviklingstiden næsten halveret sammenlignet med SETL, og skæres med
yderligere 27% ved hjælp af SETLAUTO; 3) SETLCONSTRUCT er skalerbar og
har lignende ydelse sammenlignet med SETL.
Til slut udvikler vi et GUI-baseret semantisk BI system SETLBI for at
definere, processere, integrere og lave forespørgsler på semantiske og ikkesemantiske
data. Ud over definitions-laget og ETL-laget, har SETLBI et
OLAP-lag, som giver en interaktiv grænseflade for at muliggøre selvbetjenings
OLAP analyser over det semantiske DW. Hvert lag er sammensat af en
mængde operationer/opgaver. Vi udarbejder en ontologi til at formalisere
intra-og ekstra-lags forbindelserne mellem komponenterne og lagene. ETLlaget
udvider eksekverings-laget af SETLCONSTUCT ved at tilføje operationer
til at behandle ikke-semantiske datakilder. Vi demonstrerer systemet ved
hjælp af Bangladesh population census 2011 datasættet.
Sammenfatningen af denne afhandling er BI-værktøjet SETLBI . SETLBI
fremmer (1) DW-designere med ringe / ingen SW-viden til semantisk at integrere
semantiske og / eller ikke-semantiske data og analysere det i OLAP
stil, og (2) SW brugere med grundlæggende MD-baggrund til at definere MDvisninger
over semantiske data, der aktiverer OLAP-lignende analyse. Derudover
kan SW-brugere berige det genererede SDW-skema med RDFS / OWLkonstruktioner.
Med udgangspunkt i frameworket som et grundlag kan
forskere sigte mod at udvikle yderligere interaktive og automatiske integrationsrammer
for SDW. Dette projekt bygger bro mellem de traditionelle BIteknologier
og SW-teknologier, som igen vil åbne døren for yderligere forskningsmuligheder
som at udvikle maskinforstĂĄelige ETL og lagerteknikker.Postprint (published version
Towards a Visual SPARQL-DL Query Builder
Querying ontologies is an every-day activity that users need.
This interaction will improve when the query is more expressive and easier to develop. For this purpose, a visual query language is an ideal mean for users and ontology engineers for creating queries taking advantage of the easy-to-understand and low time and cost characteristics, specially, for users which does not know textual query languages. On the other side, SPARQL-DL is a powerful and expressive textual query language for OWL-DL based ontologies that can combine TBox/ABox/RBox queries.
Considering the advantage of both, we present in this work a visual query language that can be interpreted as SPARQL-DL sentences and thus being used for querying ontologies for its structure and/or instance information. Altogether, we use this idea to create a modified version of crowd, a Web modelling tool with reasoning support, that enables to implement and tests the presented graphical language along with the needed SPARQL-DL support for solving queries with the user’s provided OWL 2 ontologies in any of its linearisations.X Workshop Innovación en Sistemas de Software (WISS)Red de Universidades con Carreras en Informática (RedUNCI
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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