Sharing and implementation of heterogeneous database for education resource based on XML.

1. Introduction

Nowadays, material resource, energy resource and information resource are three pillar resources during the development of technology and economics. Educational information resource, as an important part of information resource, plays an important role in improving the teaching quality and mining the potential of education. Therefore, many countries have set up national educational resources centers, such as the National Educational Resources Information Center of United States, the National Network for Basic Education Resource held by Basic Education Curriculum Development Center of Ministry of Education and Central Audio-Visual Education Center of China. The construction of educational resources base with corporations such as Resource of China School, K12, Clever, ZhongJiaoYuxing, Cisco Tong Fang, Tuteng, Tinghua Tangfang, becomes more and more mature. Education resource has already become an important part of network resource. It plays important role in solving the problems such as information selection, information identification, information digestion, and information individuation when users get amount of information through education resource base.

It turns out to be the most potential resource for global information transferring and sharing with the rapid development of WWW. The requirements and development of new fields, such as e-commerce, e-books and distance education have made Web data more complex and diverse. Therefore, it is difficult to store and manage all the different Web data by traditional database technology. XML is becoming the data description and exchange standard on Internet. Meanwhile, XML and a series of related standards have been widely accepted and used, including the generation, storage, analysis of XML documents, which lay the foundation for XML as database, as well as offer the possibility to realize the sharing of data in heterogeneous databases. The automatic transforming XML into different relational databases effectively has different ways. Oracle XML SQL Utility models XML documents element as a group of nesting tables, through the element that oracle object data type modeled; IBM DB2 XML Extender saves the XML documents as BLOB type object, decomposes them to a group of tables, and defines the XML collection by the XML 1.0 grammar. Microsoft solves the problem through expanding SQL-92 and involving the OPENXML line collection; Sybase Adaptive Server takes ResultSetXm1 Java class as the foundation of processing XML documents in two directions [1-3].

However, all manufacturers have a general character that the XML durability establishes in a special foundation, and there is no general facility to save all the XML documents. If the XML documents use a new grammar, it needs a special mapping. This is very disadvantageous for the visiting and sharing the different heterogeneous education resource. Firstly, education resource's description is very complex, each education resource's comprehensive description reaches more than 160 terms based on international standard, which has the internationalization request, and needs a standardized description frame. Secondly, the existing education resource's description is not normal, on the one hand we need to preserve its original description; on the other hand, we need a standardized description mapping. Thirdly, when users use an education resource, its description must personalize to meet the users' especial requirements by cutting out and transforming its description. Fourthly, education resource's description attribute value is dissimilar from different understanding aspects based on education resource belonging to different disciplines. Fifthly, the education resource has very wide manifestation, including text, image, sound, video, animation and so on. Its respective description must reflect both the general character and the difference. Only using existing tools given by manufacturers can not solve these problems. This article takes the XML documents as the middle data exchanging model to study the sharing problem of education resource heterogeneous database by taking the multimedia education resource as the study object, embarked from the actual requirements of education teaching.

2. Sharing Technology Selecting for Heterogeneous Database of Education Resource

Heterogeneous database systems [4] are collections of many related database systems which could achieve sharing and transparent accessing the data. Each database system with its own DBMS has already existed before adding in the heterogeneous database system. All components of the heterogeneous database have their own autonomy; each database system still remains its own application characteristics, the integrity control and security control when sharing the data. After carrying out data conversion, on the one hand, all the information to be shared is converted from source database to the destination database; on the other hand, such a conversion can not contain related redundant information. We use the interoperability technology and data integrity technology of heterogeneous database to achieve the tasks of data sharing in heterogeneous database. Heterogeneous databases interoperability is a prerequisite for data integration. The core is data accessing, so as to provide underlying technology for achieving data integration [5-6].

The methods used to achieve the exchanging of data among databases are various. Development tools with data transfer tool, such as data pipeline in the Power-Builder, can be used, but it relies on the database structure, and its flexibility is poor. E-mail system can not meet the data exchange requirement between heterogeneous database systems, but you must connect two databases before data transmission, which in turn lower its flexibility. We solve the referred problems by using XML as a middleware of heterogeneous databases system. First of all, as a middleware, XML makes heterogeneous database system independent, and incompatibility of heterogeneous database systems is solved. If only front desk application can support XML, it can transfer the exchange of information among heterogeneous database systems to mapping relationship between XML. Secondly, XML documents are easy to read and modify. XML documents could be opened and modified by an ordinary WordPad, and the structure is relatively simple which is easy to read, modify and convert. All these increase the flexibility of information exchanging heterogeneous database system and the scalability of XML. Thirdly, XML document format is simple, which reduces the complexity in the process of programming procedure, lowers the workload of programmers, and XML documents' code is easy as well. In view of this, we choose XML as a middleware to achieve data exchange among heterogeneous database systems [7-9].

In this research, education resource in the database includes image, text, video, music, flash and so on. Database's heterogeneities are mainly the DBMS heterogeneities including Oracle database, IBM DB2, Sybase database, Microsoft SQLserver2000 and MySQL. These already operated database systems display differently in many aspects, including data type definition, data access mode, data manifestation and so on. Therefore different database management systems cannot be connected directly to exchange the information. Oracle database, IBM DB2, Sybase database, Microsoft SQLserver2000 and MySQL have provided powerful support to XML. We transform the communication between various business databases into the data transformation between various business databases and the XML, and take image, video, text, music and flash deposited in various business databases into XML documents and import all the data into the dynamic standard database. Therefore, we adopt the following technical option. We preserve the normal primitive tree data by using various manufacturers mapping rule. The data processing frame is established. The database clusters are controlled by code distributing in the pure application procedure, business process, the database level and the application logic between the storage process, and the data processing frame guiding layer is formed by taking the education resource international standard as the foundation. The dynamic unification education resource database is established based on education resource's multiplicity and the education resource description's multiple perspectives of different discipline. User's personalized request is obtained by cutting out unification education resource database with data processing frame.

3. Education Resource Database System Heterogeneous structure

The design of the system structure is divided into three points: the presentation layer, the database layer and the logic layer, as shown in Figure 1.

[FIGURE 1 OMITTED]

The presentation is the browser. Users view the results and the displaying form through browser.

The database layer is composed by Oracle database, IBM DB2, Sybase database, Microsoft SQLserver2000, MySQL, dynamic standard database and the XML documents. We attribute XML document to this layer although XML itself is not a database, since it can be seen as a complete database system with some other tools.

Logic layer consists of two modules: data export/import module and the education resource data frame module. Data export module's function is to export various business databases data and produce corresponding XML documents. Data import module's function is to analyze XML documents and import the data to various business databases. The education resource data frame modular controls all database clusters, and it is responsible to establish the dynamic unification education resource database.

4. Implement of Heterogeneous Database of Education Resource

Oracle XSU draws the XML documents to DOM, and decomposes the XML documents into a group of sub-documents by using XSLT. IBM DB2 XML Extender establishes the mapping through DAD between the database table and the XML documents' structure, storing by DB2 CLOB data type. Microsoft SQLserver OPENXML uses sp_xml_preparedocument as storing process, gaining a XML documents handle through translating XML documents into the internal DOM expression. Sybase uses XML documents type ResultSet to describe a XML documents metadata and the actual line data. The selected data is shown in Figure 2.

Document Object Model is a set of standards set by W3C, which provides an interface parsing the document. Various program languages achieve these interfaces in accordance with the DOM standards, and the parser is given to parse the documents. The parser establishes a tree in memory through reading XML documents. The tags of XML document, tagged text content and entities correspond to a certain node of the tree in the memory. It's easy to deal with XML documents, to read, traverse, modify, add and delete the documents through operating the node of tree in memory. We use DOM parser to do XML programming for an application, which can easily handle XML documents by operating the node of tree in memory to obtain the data needed.

DocumentBuilderFactory class is responsible for creating the instance. DocumentBuilderFactory class calls its newInstance () method to instantiate a DocumentBuilderFactory object. Factory object calls newDocumentBuilder () method to return a DocumentBuilder object. And finally the builder object calls newDocument () method to achieve instantiating Document interface.

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); Document doc = builder.newDocument(); doc.setXmlVersion("1.0"); Element root = doc.createElement("image"); doc.appendChild(root); The CreateXML.xml documents are produced as follows: File file = new File("F:/temp/MatPrjiWebRoot/CreatXml.xml"); if(!file.exists()JJ!file.isFile()){ new FileOutputStream ("F:/temp/MatPrj/WebRoot/CreatXml.xml"); file = new File("F:/temp/MatPrjiWebRoot/CreatXml.xml"); }

StreamResult streamResult = new StreamResult(file); Source inputSource = new DOMSource(doc); TransformerFactory transformerFactory = TransformerFactory.newInstance(); Transformer transformer = transformerFactory.newTransformer(); transformer.transform(inputSource, streamResult);

The XML documents are produced, and the data is imported to XML documents, its education resource spanning tree is shown in Figure 3.

The data processing frame is established to control the database clusters, and the dynamic uniform education resource database is also established as shown in Figure 4 according to the multiplicity of education resource's manifestation and the multiple perspective of the education resource description of different discipline based on international standard of education resource.

The personalization description of education resource is obtained by cutting the dynamic unification education resource database using the data processing frame according to the user's personalized request, as shown in Figure 5.

5. Conclusions

The paper defines a XML document which describes the database structure. We fill the information of the education resource database into self-explanatory XML documents in order to let users create database friendly. And a scheme is made as designing a middleware between the database and its outside. A data processing frame is advanced to process each kind of actual problems which are brought by the complexity, the dynamic and the personalization of the education resource data. The exchanging requests of internal or external education resource data are submitted to the middleware with XML. The interaction of specific education resource database is realized by the middleware and the results are fed back to the requester through XML. All the details in the process have been shielded to achieve transparent sharing access of heterogeneous education resource database.

10.4236/jsea.2009.23027

Received May 11th, 2009; revised July 1st, 2009; accepted July 15th, 2009.

Published Online October 2009 (http://www.SciRP.org/journal/jsea)

REFERENCES

[1] Oracle XML-SQL Utility, http: // www. oracle.com /technology/ index.html. Last accessed on July 27, 2009.

[2] IBM DB2 XML Extender, www.ibm.com/software/data/db2/extenders/xmlext. Last accessed on July 27, 2009.

[3] XML Perspective, In control with FOR XML Explicit. SQL Server Magazine, http://msdn.mcrosoft. com/ library/periodic/. Last accessed on July 27, 2009.

[4] A. P. Sheth and J. A. Larson, "Federated database systems or managing distributed, heterogeneous, and autonomous databases," ACM Computing Survey, Vol. 22, No. 3, pp. 183-236, 1990.

[5] Q. Feng, H. Q. Lv and H. Feng, "The connection of Heterogeneous databases," Computer and Information Technology, Vol. 9, 2001.

[6] X. Wang and S. M. Wei, "Java technology-based distributed heterogeneous database Web access technology," Computer Engineering and Applications, pp. 135-138, 2000.

[7] D. Martin, "XML High-level Programming," Beijing Machinery Industry Press, pp. 77-103, 2001.

[8] D. Motton, "XML programming technology [M]," Beijing Machinery Industry Press, pp. 134-200, 2001.

[9] X. H. Dong [EB/OL], http://www.XML.org.cn, Applications to build XML.

Shixi TANG

YanCheng Teachers University College of Science & Technology, Yancheng, China.

Email: tsxlyhA163.com

Figure 2. Education resource data

imaID   Type                 Major        Object

01001   animal               Bio-engine   Graduate
                               ering        Students
01002   figures              history      Undergraduate
                                            Students
01003   equipment            sports       Undergraduate
                                            Students
01004   board                computer     Graduate
                                            Students

01005   monitor              computer     Undergraduate
                                            Students
01006   natural              geography    Graduate
                                            Students
01007   plant                medicine     Graduate
                                            Students
                                          Undergraduate
01008   animal               computer       Students

imaID   Source               Author       TTime

01001   Southeast            Na Tang      2007/05
          University
01002   Nanjing              Wei ZHAO     2004/06
          University
01003   Suzhou               Liang-Qian   2002/06
          University           Li
01004   Yancheng             Xia Wang     2007/06
          Teachers
          University
01005   Wuhan                Xiaoli
          University           Wang       2001/06
01006   Southeast            Yao Wu       2000/06
          University
01007   Southeast            Hang SUN     2005/02
          University
01008   Peking               Xia Li       2005/06
          University

imaID   Key Word             Formats      Lenght

01001   yeast,               gif          36
          bacteria
01002   background,          jpeg         80
          achievements
01003   function,            jpeg         45
          using methods
01004   CPU, graphics,       jpeg         68
          memory
01005   LCD,                 jpeg         55
          brightness
01006   Earthquake,          gif          38
          plate movement
01007   panda, artificial    gif          74
          rearing
01008   lily,
          photosynthesis     jpeg         38

imaID   resolution           Sweep        Color

01001   640*480              72           002244
01002   1024*768             300          FF0022
01003   320*240              72           000044
01004   1024*768             350          110033
01005   1024*768             300          2244CC
01006   640*480              72           320C14
01007   1280*1024            300          05232B
01008   750*453              72           204A15

Figure 3. Education resource spanning tree

<?xml version="1.0" encoding="UTF-8" standalone-no">,
-<image>
   -<imageinformation>
      <imalD> 01001</imalD>
      <Type> animal</Type>
      <Major> Bio-engineering</Major>
      <Object> Graduate Students</Object>
      <Source> Southeast University</Source>
      <Author> Na Tang</Author>
      <TTime>2007/05</TTime>
      <Key Word>yeast,bacteria</Key Word>
      <Formats> gif</Formats>
      <Lenght> 36</Lenght>
      <Resolution>640*480</Resolution>
      <Sweep> 72</Sweep>
      <Color> 002244</Color>
      <Address>..\\DataSharing\src\image\l.gif</ Address>
      </imageinformation>
-<image>
   -<imageinformation>
      <imalD> 01002</imalD>
      <Type> figures</Type>
      <Major> history</Major>
      <Object> Undergraduate Students</Object>
      <Source> Nanjing  University</Source>
      <Author>Wei Zhao</Author>
      <TTime> 2004/06</TTime>
      <Key Word> background, achievements</Key Word>
      <Formats> jpeg</Formats>
      <Lenght> 80</Lenght>
      <Resolution> 1024*768</Resolution>
      <Sweep> 300</Sweep>
      <Color> FF0022</Color>
      <Address> ..\\DataSharing\src\image\2.gpeg</ Address>
      </imageinformation>

Figure 4. Dynamic uniform education resource database

WU.dbo.image table

imaID   Type                     Major                Object

01001   animal                   Bio-engineering      Graduate
                                                        Students
01002   figures                  history              Undergraduate
                                                        Students
01003   equipment                sports               Undergraduate
                                                        Students

imaID   Source                   Author               TTime

01001   Southeast                Na Tang              2007/05
          University
01002   Nanjing                  Wei ZHAO             2004/06
          University
01003   Suzhou                   Liang-Qian           2002/06
          University             Li

imaID   Key Word                 Formats              Lenght

01001   yeast,                   gif                  36
          bacteria
01002   background,              jpeg                 80
          achievements
01003   function,                jpeg                 45
          using methods

imaID   resolution               Sweep                Color

01001   640*480                  72                   002244
01002   1024*768                 300                  FF0022
01003   320*240                  72                   000044

WU.dbo.text table

TxtID   TxtType                  TxtMajor             TxtObject

2001    Economics Paper          International        Graduate
                                   economic             Students
2002    Economics Paper          China's economy      Undergraduate
                                                        Students
2003    Management Paper         Business             Undergraduate
                                   Management           Students

TxtID   TxtSource                TxtAuthor            Txt Time

2001    Economics                Li Zhang             2007/05
2002    Economics                Ke Ban               2004/06
2003    Management               Xiao-ming WU         2002/06

TxtID   TxtKey Word

2001    Bubble economy,
          Economic globalization
2002    China imported inflation,
          Real estate and living
2003    Enterprise Project Management

WU.dbo.vedio table

VedID   VedType                  VedMajor             VedObject

5001    Computer                 An Introduction      Graduate
                                   to Computer          Students
5002    Computer                 Computer             Graduate
                                   Application          Students

VedID   VedSource                VedAuthor            VedTime

5001    Southern Yangtze         Kequn Wang           2006/05
          University
5002    Suzhou University        Liang Ke             2004/06

VedID   VedKey Word

5001    computer, chip
5002    computer,
          NET,J2EE

WU.dbo.flash table

FlaID   FlaType                  FlaMajor             FlaObject

3001    Computer                 Software             Graduate
                                   Engineering          Students
3002    Education                Chinese Language     Underraduate
                                   & Literature         Students

FlaID   FlaSource                FlaAuthor            FlaTime

3001    Shenyang Polytechnic     Xing Liu             2005/05
          University
3002    Central China Normal     Chuan Zhao           2004/06
          University

FlaID   FlaKey Word

3001    computer,
          C++
3002    literature,
          education

WU.dbo.music table

MusID   MusType                  MusMajor             MusObject

4001    Education                Chinese Language     Graduate
                                   and Literature       Students
4002    Education                Chinese Language     Undergraduate
                                   and Literature       Students

MusID   MusSource                MusAuthor            MusTime

4001    Southeast University     Keyi Zhang           2007/05
4002    Nankai University        Guosheng             2003/06
                                   Huang

MusID   MusKey Word

4001    literature, education
4002    literature, education

Figure 5. The personalization education resource result in
client after cutting out

Imageinformation 0

imaID                 1001
Type                  animal
Major                 Bio-engineering
Object                Graduate Students
Source                Southeast University
Author                Na Tang
Ttime                 2007/05
Key Word              yeast, bacteria
Formats               gif
Length                36
Resolution            640*480
Sweep                 72
Color                 002244
Address               ..\\DataSharing\src\image\1.gif