• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10a
• /
• pp.243-245
• /
• 2000

W3C(World Wide Web Consortium)가 XML(eXtensible Markup Language)을 차세대 웹 문서 표준으로 제안하면서 많은 응용에서 XML을 사용하려는 다양한 연구가 진행되고 있다. 뷰는 이질적인(heterogeneous) 데이터의 통합 및 여과(filtering) 기능을 통해서 사용자가 요구하는 데이터를 제공한다. 뷰의 구현 기법 중에서 실체 뷰(materialized view)는 뷰의 내용을 직접 저장하는 기법으로서, 사용자의 질의에 빠른 응답시간을 제공할 수 있다. 그러나 실체 뷰는 하부 데이터베이스가 변경되었을 경우에 일관성을 유지해야 하는 오버헤드가 있다. XML은 문서의 구조정보를 나타낼 수 있으므로 기존의 관계 데이터베이스와 객체지향 데이터베이스 등에서 연구되었던 실체 뷰 관리 기법과는 다른 XML 실체 뷰 관리 기법이 요구된다. 본 논문에서는 XML 문서를 대상으로 XML 실체 뷰를 지원하고, 데이터베이스에 저장된 XML 문서가 수정되었을 경우에 XML 실체 뷰에 대해 점진적 갱신(incremental refresh)을 지원하는 XML 실체 뷰 관리 프레임워크(framework)를 제안하였다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2001.04b
• /
• pp.1105-1108
• /
• 2001

점차로 이종의 데이터와 문서가 XML 로 통합되는 것이 요구된다. 현재 데이타베이스 기반의 응용프로그램들은 데이터들이 대부분 테이블에 저장되어 있기 때문에 SQL 을 이용하여 데이터처리를 하고 있다. 한편 현 정보기술 발전 추세는 응용 프로그램에서 처리하고자 하는 단위가 데이터(data-centric)에서 점차 문서(document-centric)로 바뀌어 가고 있다. XML 은 이런 패러다임에에 적합한 해결책이 될 수 있다. 본고에서는 일반적인 데이터에 대한 뷰(view)를 테이블 뷰가 아닌 XML 뷰를 응용 프로그램 개발자에게 제시하는 방법론을 보임으로써, 일관되고 유연한 문서처리 시스템 설계를 하는데 있어 대단히 유용한 또다른 한 방법론을 제공하고자 한다.

• The KIPS Transactions:PartD
• /
• v.10D no.3
• /
• pp.367-374
• /
• 2003

A mediator-wrapper system, which is one of integration methods of heterogeneous databases, preserves a virtual integrated view rather than physical movement of the contents of each database. In order for a mediator to preserve a virtual integrated view, it requires the schema manager of the wrapper which communicates with local databases. This paper presents a schema manager of a wrapper that provides a mediator with XML schema which is generated from relational database schema. The XML schema manager supports a user-defined XML view. We present the view tree model which is used for materializing the use-defined XML view to generate XML schema, and the conversion algorithm based on the proposed view tree model. This model is can be uniformly applied to all schema managers of heterogeneous information sources.

• The KIPS Transactions:PartD
• /
• v.12D no.4 s.100
• /
• pp.553-568
• /
• 2005

In order to integrate distributed biological information sources physically or virtually, it is necessary to overcome the heterogeneity of information sources and support a superior generality and adaptation in order to satisfy user's various demands. In this paper, we present a flexible and general XML query engine of a wrapper system in designing the middleware system to integrate data as well as application programs. Since this query engine applies user-defined XML view, it is possible to composite flexible integrated query. The query processing in a wrapper requires view composition, query translation into local sources, and generation of XML documents from local query results. We present a query processing model based on the view tree, where the n views and the XML queries are represented by the view tree. Moreover, to confirm the generality of our query processing model, we present a methodology of query processing for relational databases, web sources, and application programs whose return types of query results are relational tuples or XML documents.

• The KIPS Transactions:PartD
• /
• v.10D no.4
• /
• pp.621-638
• /
• 2003

As demand of XML documents in the Web increases, Web service applications that manage XML documents as their resource are increasing. The view mechanism for XML data could be considered for effective in query processing in these Web service applications. If the XML query results are maintained as XML materialized views and their relevant XML query is processed using them, the query response time could be reduced. There are two types of processing an in path expression, which is one of the core features of XML query languages, using XML materialized views. One is the type where the complete query result is obtained from the materialized view, and the other is the type where some of the result is obtained from the materialized view and the rest is from the underlying XML documents. In this paper, we investigate the second type. An XML query in this paper is an XML path expression which is one of the core features of XML query languages. We first describe the storage structures of the XML materialized views derived from the underlying XML documents in the XML repository. Then, we propose the algorithms to decompose a given XML query into the subquery against the materialized view and the subquery against the underlying XML documents, and to integrate the results of these subqueries. Through performance evaluation, we figure out the condition under which our XML query decomposition using materialized views is more effective than the conventional processing.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2002.04a
• /
• pp.7-10
• /
• 2002

실체뷰는 질의 처리 성능 향상을 위한 수단으로 널리 연구되어 왔다. 이러한 실체뷰는 하부 데이타가 변경되었을 경우에 일관성을 유지해야 하는데, 그 기법으로는 뷰를 하부 데이타로부터 재생성하는 방법과 변경 내용 중 뷰와 관련 있는 것만 반영하는 점진적 갱신이 있다. 최근 XML 이라는 웹 문서 표준이 대두되면서 여러 응용 분야에서 이를 활용 하려는 노력이 진행 중이다. 본 논문에서는 XML문서를 대상으로 하는 XML 실체뷰를 지원하는 XML 저장 시스템의 구현과, 구현된 시스템을 대상으로 실체뷰를 재생성하는 방법과 점진적으로 갱신하는 기법의 성능을 비교 평가한 결과를 기술한다.

• The Journal of Society for e-Business Studies
• /
• v.11 no.4
• /
• pp.33-48
• /
• 2006

Since the emergence of XML as the standard for data exchange on the Web, XML warehousing technology is required to efficiently support Web business applications such as e-Commerce. When the RDBMS is employed as the storage for XML warehouse, XML materialized views of the XML warehouse could be provided by leveraging the materialized views of the RDBMS Because XML documents are mapped into relational tuples, an XML query defining an XML materialized view needs to be transformed into SQL. If relational materialized views were defined with the transformed SQL statements, the XML materialized view could be obtained just by XML-tagging the tuples of the corresponding relational materialized views. The foremost advantage of such a scheme is that the RDBMS does take care of XML materialized view consistency except XML tagging whenever their source XML documents are updated. In this paper, we proposed such a scheme of providing XML materialized views, and implemented it using a commercial RDBMS equipped with materialized view facility in Java on Windows 2000 Professional environment. XML documents in TPC-W, Web e-Commerce Benchmark, were used in performance experiments. The experimental results showed that our proposed scheme for XML materialized views was very effective.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.05a
• /
• pp.77-80
• /
• 2005

생물정보원은 이질성이 높고 사용자의 요구사항이 다양하다. 본 논문은 이러한 이질성을 해결하고 사용자의 다양한 요구사항에 쉽게 대처할 수 있는 XML 기반의 생물정보원 통합시스템의 설계개념과 구조 및 구현결과를 제시한다. 제시하는 통합시스템은 관계형테이블, 객체, XML, 플랫파일 등 다양한 자료형을 지원하면서, 관계형, 객체관계형, 웹자원, 응용프로그램 등 데이터 관리모델에 무관한 뷰 정의 및 질의처리모델이다. 그리고 사용자정의 XML 뷰 기반의 뷰 관리 및 질의처리를 통하여 사용자의 다양한 요구사항에 쉽게 적응할 수 있는 미디에이터 질의처리 기반의 생물정보원 통합시스템을 제시한다.

• The KIPS Transactions:PartD
• /
• v.11D no.4
• /
• pp.765-774
• /
• 2004

In order to integrate heterogeneous biological information sources, it is necessary to define the view that represents unified viewpoint for the multiple sources by hiding heterogeneity of the data. We present an XML-based view definition model and show Its operating principles in designing the middleware system to integrate biological information sources. This model supports the user-defined XML view to increase flexibility in constructing the integration system and execute integrated queries on higher level ion. Based on the view-definition model, we present a wrapping model for relational database systems and web resources as well as an application program.

• The KIPS Transactions:PartD
• /
• v.11D no.2
• /
• pp.293-304
• /
• 2004

Recently, caching for the database-backed web applications has received much attention. The results of frequent queries could be cached for repeated reuse or for efficient processing of the relevant queries. Since the emergence of XML as a standard for data exchange on the web, today's web applications are to retrieve information from the remote XML sources across the network, and thus it is desirable to maintain the XML query results in the cache for the web applications. In this paper, we describe implementation of an XML query processing system that supports cache-answerability of XML queries, and evaluate its performance. XML path expression, which is one of the core features of XML query languages including XQuery, XPath, and XQL was considered as the XML query. Their result is maintained as an XML materialized view in the XML cache. The algorithms to rewrite the given XML path expression using its relevant materialized view proposed in [13] were implemented with RDBMS as XML store. The major issues of implementation are described in detail. The results of performance experiments conducted with the implemented system showed effectiveness of cache-answerability of XML queries. Comparison with previous research in terms of performance is also Provided.