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{{Short description|Content-based retrieval of XML documents}}
'''XML
Most XML
▲== Queries ==
Taking advantage of the [[Self-documenting|self-describing]] structure of XML
▲Most XML-Retrieval approaches do so based on techniques from the [[information retrieval]] (IR) area, e.g. by computing the similarity between a query consisting of keywords (= [[query]] terms) and the document. However, in XML-Retrieval the query can also contain structural hints. So-called "content and structure" (CAS) queries enable users to specify what structure the requested content can or must have. <br>
Ranking in XML-Retrieval can incorporate both content relevance and structural similarity, which is the resemblance between the structure given in the query and the structure of the document. Also, the retrieval units resulting from an XML query may not always be entire documents, but can be any deeply nested XML elements, i.e. dynamic documents. The aim is to find the smallest retrieval unit that is highly relevant. Relevance can be defined according to the notion of specificity, which is the extent to which a retrieval unit focuses on the topic of request
An overview of two potential approaches is available.<ref>{{Cite journal|url=http://www.sigmod.org/record/issues/0612/p16-article-yahia.pdf|title=XML Search: Languages, INEX and Scoring|last=Amer-Yahia|first=Sihem|author2=Lalmas, Mounia |year=2006|journal=SIGMOD Rec. |volume=35 |issue=4|access-date=2009-02-10|doi=10.1145/1228268.1228271|s2cid=17300151}} {{Dead link|date=October 2010|bot=H3llBot}}</ref><ref>{{Cite CiteSeerX |citeseerx = 10.1.1.109.5986|title=XML Retrieval: A Survey|last=Pal|first=Sukomal|date=June 30, 2006}}</ref> The INitiative for the Evaluation of XML-Retrieval (''INEX'') was founded in 2002 and provides a platform for evaluating such [[algorithm]]s.<ref name="INEX2006" /> Three different areas influence XML-Retrieval:<ref name="INEX2002">{{Cite web|url=http://www.is.informatik.uni-duisburg.de/bib/pdf/ir/Fuhr_etal:02a.pdf |title=INEX: Initiative for the Evaluation of XML Retrieval |last=Fuhr |first=Norbert |author2=Gövert, N. |author3=Kazai, Gabriella |author4=Lalmas, Mounia |year=2003 |work=Proceedings of the First INEX Workshop, Dagstuhl, Germany, 2002 |publisher=ERCIM Workshop Proceedings, France |access-date=2009-02-10 |archive-url=https://web.archive.org/web/20081121135758/http://www.is.informatik.uni-duisburg.de/bib/pdf/ir/Fuhr_etal:02a.pdf |archive-date=November 21, 2008 }}</ref>
▲== Exploiting XML-Structure ==
[[Query language]]s such as the [[W3C]] standard [[XQuery]]<ref>{{Cite web|url=http://www.w3.org/TR/2007/REC-xquery-20070123/|title=XQuery 1.0: An XML Query Language|last=Boag|first=Scott|author2=Chamberlin, Don |author3=Fernández, Mary F. |author4=Florescu, Daniela |author5=Robie, Jonathan |author6= Siméon, Jérôme |date=23 January 2007|work=W3C Recommendation|publisher=World Wide Web Consortium|access-date=2009-02-10}}</ref> supply complex queries, but only look for exact matches. Therefore, they need to be extended to allow for vague search with relevance computing. Most XML-centered approaches imply a quite exact knowledge of the documents' [[Database schema|schemas]].<ref name="Schlieder2002">{{Cite journal|url=http://www.cis.uni-muenchen.de/people/Meuss/Pub/JASIS02.ps.gz |title=Querying and Ranking XML Documents |last=Schlieder |first=Torsten |author2=Meuss, Holger |year=2002 |journal=Journal of the American Society for Information Science and Technology |volume=53 |issue=6 |pages=489–503 |access-date=2009-02-10 |archive-url=https://web.archive.org/web/20070610002349/http://www.cis.uni-muenchen.de/people/Meuss/Pub/JASIS02.ps.gz |archive-date=June 10, 2007 |doi=10.1002/asi.10060 |url-access=subscription }}</ref>
===Databases===
▲Taking advantage of the self-describing structure of XML-documents can improve the search for XML-documents significantly. This includes the use of CAS-queries, the weighting of different XML-elements differently and the focused retrieval of sub-documents. <br>
Classic [[database]] systems have adopted the possibility to store [[Semi-structured model|semi-structured data]]<ref name="INEX2002" /> and resulted in the development of [[XML database]]s. Often, they are very formal, concentrate more on searching than on ranking, and are used by experienced users able to formulate complex queries.
===Information retrieval===
Classic information retrieval models such as the [[vector space model]] provide relevance ranking, but do not include document structure; only flat queries are supported. Also, they apply a static document concept, so retrieval units usually are entire documents.<ref name="Schlieder2002"/> They can be extended to consider structural information and dynamic document retrieval. Examples for approaches extending the vector space models are available: they use document [[subtree]]s (index terms plus structure) as dimensions of the vector space.<ref>{{Cite web|url=http://www.cobase.cs.ucla.edu/tech-docs/sliu/SIGIR04.pdf|title=Configurable Indexing and Ranking for XML Information Retrieval|last=Liu|first=Shaorong|author2=Zou, Qinghua |author3=Chu, Wesley W. |year=2004|work=SIGIR'04|publisher=ACM|access-date=2009-02-10}}</ref>
== Data-centric XML datasets ==
▲== Ranking ==
For data-centric XML datasets, the unique and distinct keyword search method, namely, XDMA<ref>{{Cite journal|last1=Selvaganesan|first1=S.|last2=Haw|first2=Su-Cheng|last3=Soon|first3=Lay-Ki|title=XDMA: A Dual Indexing and Mutual Summation Based Keyword Search Algorithm for XML Databases|journal=International Journal of Software Engineering and Knowledge Engineering|language=en-US|volume=24|issue=4|pages=591–615|doi=10.1142/s0218194014500223|year=2014}}</ref> for XML databases is designed and developed based on dual indexing and mutual summation.
==See also==
▲Ranking in XML-Retrieval can incorporate both content relevance and structural similarity, which is the resemblance between the structure given in the query and the structure of the document. Also, the retrieval units resulting from an XML query may not always be entire documents, but can be any deeply nested XML elements, i.e. dynamic documents. The aim is to find the smallest retrieval unit that is highly relevant. Relevance can be defined according to the notion of specificity, which is the extent to which a retrieval unit focuses on the topic of request <ref> Malik, Sadia; Trotman, Andrew; Lalmas, Mounia; Fuhr, Norbert: Overview of INEX 2006. <br>
*[[Document retrieval]]
*[[Information retrieval applications]]
{{Reflist}}
{{DEFAULTSORT:Xml-Retrieval}}
▲== Existing XML search engines ==
[[Category:XML]]
▲• '''Traditional XML query languages:'''<br>
▲== References ==
▲[[Category:Information Retrieval]]
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