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An Analysis of the Current Development Stage of the eXtensible Markup Language (XML) and its Usage for Database Systems

Masterarbeit 2002 81 Seiten

Informatik - Wirtschaftsinformatik

Leseprobe

Contents

Disclaimer

List of Figures

List of tables

Abstract

Chapter 1: Introduction
1.1 Background to this Study
1.2 Research Question
1.3 Task Settings and Objectives
1.4 Dissertation Sections

Chapter 2: Database Environment
2.1 The Database Approach
2.2 Three Level Architecture
2.3 Database Languages
2.4 Data Modelling and Database Design
2.5 Relational Data Model
2.6 Data Normalisation

Chapter 3: Research Topic
3.1 A Brief History About XML
3.2 Concept of XML
3.2.1 Logical and Physical Structure of an XML Document
3.2.2 Document Type Definition
3.2.3 Style Sheets
3.3 Additional XML Features
3.4 The Acceptance of XML
3.5 Technological XML Developments
3.6 Drawbacks of XML
3.7 Where is it All Going to?

Chapter 4: XML And Databases
4.1 Methodology
4.2 XML Related Databases
4.3 The Problem of Finding the Right Database for XML Content
4.3.1 Documents Versus Data
4.4 Native XML Databases Versus XML Enabled Relational Databases
4.4.1 Data Modelling
4.4.2 Retrieval Speed and Searching
4.4.3 Static Versus Dynamic Structures
4.5 An Evaluation Checklist
4.6 Assessing the Current XML Database Adoption
4.7 A Native XML Database as a Base for a Content Management System
4.8 Conclusion

Chapter 5: Change Management within IT
5.1 Change Management
5.2 Types of Resistance and Constraints
5.3 Implementation of IT Projects
5.3.1 IT Management Process
5.4 Implementation of an XML Database
5.5 Conclusion

Chapter 6: Conclusions and Review
6.1 Summary
6.2 Problems and Experiences
6.3 Further Studies

Appendix 1: XML Document and XSLT Style Sheet Example

Appendix 2: XLink and XPointer Example

List of Figures

Figure 2-1: Basic Database System Architecture

Figure 2-2: The Three Level Structure of a Database System

Figure 2-3: Basic ER Diagram

Figure 2-4: Structure of a Relational Table

Figure 2-5: ER Diagram with Primary and Foreign Key

Figure 2-6: Data Normalisation Process

Figure 3-1: Structure of an XML Document

Figure 3-2: XSL Transforming and Formatting Process

Figure 3-3: XML Concerns and Challenges

Figure 3-4: Use of XML for e-commerce Transactions

Figure 4-1: Methodology Diagram

Figure 4-2: Native XML Database Features

Figure 4-3: Structured and Unstructured Data Management

Figure 4-4: Content Management System

Figure 5-1: Project Implementation Life Cycle

List of tables

Table 3-1: Supporting XML Techniques

Table 3-2: Percentage of Programmers Making Use of XML

Table 4-1: XML Versus Relational Databases

Table 4-2: XML Database Feature Checklist

Table 5-1: Challenges for IT Projects

Table 6-1: When to Choose which XML Database

Disclaimer

The material contained within this dissertation is presented in good faith and neither the author nor the University of Stirling can accept liability for the results of any actions taken on the basis of it.

Abstract

The eXtensible Markup Language (XML) is receiving a great deal of attention from computing and Internet communities. This is mainly because of its ability to reduce obstacles in sharing data among diverse applications and databases by providing a common format for expressing data structure and content.

The scope of this project is to investigate the current stage of XML and its usage for database systems. In order to understand the XML database technology a general introduction to both database systems and XML is provided to the reader in chapter two and three. Chapter four and five deal with the methodology and findings of this project. These chapters rely on articles, case studies and surveys which are examined and evaluated. Finally, a conclusion and review chapter is included.

The analysis of the current adoption of XML among software developers revealed that in Spring 2001 more than one third of international developers already used XML. In 2001 they spent about 5.4% of their development time using XML. For 2002 it is predicted that they will spend an average of 9% of their development time using XML.

Concerning XML databases there are currently two major XML related database types available. These are native XML and XML enabled relational databases. Native XML databases are constructed to use the recommended XML standards to the most possible extent. Thereby, the XML document is the fundamental unit of storage. XML enabled relational databases are relational databases equipped with an additional layer to map XML content in to the relational tables. XML documents are only used as a means of transport between the database systems. Native XML databases are better suited for dealing with document structured content whilst XML enabled relational databases are more appropriate to handle data structured content such as numbers and pieces of text.

The implementation process of an XML related database system into an organisation requires the right management of change to be able to handle both the technology involved and the people affected by the database system. Therefore effective change management must cover the whole project life cycle from the formulation of the strategy to the achievement of the benefits.

Chapter 1: Introduction

The business world is always changing in order to meet new challenges and opportunities. Due to the increased amount of automation and computerisation that is on the market, organisations must carefully select what kind of technology brings them competitive advantage. Therefore, managing change in technology is very important for the success of every organisation and to enable organisations to keep a lead in technology over other competitors. One of these technologies has been the eXtensible Markup Language (XML) which has attracted widespread interest amongst different industry sectors. But as many companies have little or no experience with this area of technology they do not really know whether it is worth investing in XML related products.

1.1 Background to this Study

XML is a programming language that can be used to structure data in documents. So, for example, a page in a book can be broken down into parts by using a markup code. This markup code can then be used to identify the different parts for purposes such as manipulating the text structure, exchanging documents with other applications or storing them into a database system.

The main part of this dissertation deals with XML and its usage for database systems. This topic has been chosen because storing XML content into a database system offers a new way to place whole documents into a database without decomposing them into data fractions. Such XML database systems differ essentially from traditional relational databases in many ways. Hence, this dissertation pays particularly attention to the differences between these two types and for what data formats either type is better suited. In order understand how XML can be modelled into a database system it is very important to comprehend the structure of XML. Thus, this research gives an introduction to the structure of XML and what is needed to build proper XML documents. Moreover, some other features which support the XML standard are discussed. To be able to implement an XML database system into an organisational structure it is essential to know how to manage Information Technology (IT) projects because IT projects typically have attributes which involve special management challenges. Since implementation may require significant changes in an organisation due to the replacement or extension of another database system, this research also discusses and analyses the processes and the requirements needed to carry out such changes.

1.2 Research Question

The starting point of this research is the question: “What is the current stage of development of XML and what type of XML related database system should be used to deal with XML content?” Also, this research discusses how an organisation could implement an XML database system from a management perspective, while taking into account the necessary change processes required for such a new technology.

1.3 Task Settings and Objectives

This dissertation aims to give an insight into XML and the use of XML for database systems. Therefore, the main objectives are to answer the following questions and to examine the following areas:

- What are the reasons for developing XML?
- What impact has XML on organisations?
- How do XML documents perform as a data storage format?
- What are native and XML enabled relational databases?
- What are the main differences between relational and XML databases?
- How to change an organisation by using an XML related database?
- What are the required project guidelines for a successful implementation of an XML database?

1.4 Dissertation Sections

The overall project is divided into the following sections:

Chapter 1: The first chapter gives an introduction to the dissertation outline. Also, the aims and the objectives are specified and the different sections are previewed.
Chapter 2: The second chapter gives an introduction to databases as well as to the different levels on which they are built. Furthermore, the main database languages and the relational data model are described.
Chapter 3: This chapter examines the eXtensible Markup Language (XML) and describes how documents are structured. Moreover, the purpose of Document Type Definitions (DTD), XML schemas and additional features which support the XML technology are discussed.
Chapter 4: The fourth chapter introduces the reader to native and XML enabled relational databases. It discusses their main advantages and disadvantages and for what kind of data format both database systems are best suited.
Chapter 5: This chapter gives an overview about change management and the requirements to carry out change in an organisation. A change management process is then applied to the implementation of an XML database system, replacing or extending an already existing one. The key drivers to successfully installing such a database are also considered.
Chapter 6: The last chapter summarises the outline research question and gives recommendations concerning XML, databases and change management within IT. Furthermore problems encountered during the project and the personal gains and experiences from this dissertation are mentioned. Finally, it discusses the possibility of further analysis and study based on the findings of this research.

Chapter 2: Database Environment

Due to the increased amount of data organisations have to deal with, they are forced to have proper means for storing and managing data. To cope with this, databases and Database Management Systems (DBMS) are widely used in business sectors to manage these large amounts of data. Hence, this chapter will give an overview on databases and their different features.

2.1 The Database Approach

The terms database and database management systems are often used in the same way for describing data stores but their actual meanings are very different. A database is basically an “integrated collection of data organised to meet the needs of one or more users” while a DBMS is more “computer software with the capability to store data in an integrated structured format and to enable users to retrieve, manipulate and manage the data”.1 A combination of DBMS and database, shown in Figure 2-1, is called a database system (DBS). It provides information on user demand and is described by definition as a computerised record-keeping system.2 While talking about databases, it is also important to distinguish between the terms data and information. Data is factual information, especially that used for analysis or reasoning. Data on its own has no meaning, but becomes information when it is interpreted. Information is a collection of facts or data. However, in many contexts they are considered and are used as synonyms.3

illustration not visible in this excerpt

Figure 2-1: Basic Database System Architecture

Source: Saake, G., (1997), Objektdatenbanken4

2.2 Three Level Architecture

A general proposal for a database systems architecture was developed by the American National Standards Institute (ANSI) and the S tandards P lanning A nd Requirements Committee (SPARC) in 1975. The ANSI/SPARC architecture provides a reference model which most database systems follow reasonably well.5 The proposal considers database systems on three different levels of abstraction: external, conceptual and internal, all shown in Figure 2-2 The external level has the users' views of the database system. Depending on their needs, different users access different parts of the database. For example, a doctor performing drug tests should be able to access the patients' medical data but not their hospital bills. The conceptual level describes the logical structure of the entire database, including descriptions of the data and relationships among the data. In a relational database this would resemble the form of tables, their attributes and the relationships between the tables. The internal level gives the details of the physical storage of the database on the computer. It contains such details as the number of bytes for each data item, ordering of records, building indexes and data compression.6

Each level of the architecture is described accordingly with a schema. A schema typically defines the rules of valid construction and operation within each of the three levels.7

illustration not visible in this excerpt

Figure 2-2: The Three Level Structure of a Database System

Source: Date, C. (1995), An Introduction To Database Systems

One of the main objectives which should be achieved with the three level architecture is data independence. There are two main kinds of data independence, logical and physical. The logical data independence specifies that changes in the conceptual schema has no impact to the external schema, e.g. any change of relationships in the conceptual schema has no effect to the external schema such as application programs. The physical data independence refers to the fact that modifications in the internal schema have no impact to the conceptual schema, e.g. changes in file organisations have no effect to relationships in the conceptual schema.

2.3 Database Languages

Database languages are an essential part for every database to interact between users and the database itself. The end user of a database is provided a data sub-language which consists of two parts. First, there is the Data Definition Language (DDL) which is used to define the structure of a database as well as to create the relationships between the different entities in a database. Second, there is the Data Manipulation Language (DML) which is a language for the manipulation of data in a database. There are two types of DMLs, procedural and non-procedural. Procedural DMLs allow the user to retrieve the data record by record. They describe how the data is obtained from the database. Non-Procedural DML’s describe what data is required from the records within a database.8

The Structured Query Language (SQL) is the main database language being used today. It offers both functions for DDL and DML. DDL commands in SQL can be used interactively to define database components, e.g. through the commands CREATE or DROP for a table in a relational database. DML commands can also be used interactively and include SQL statements like INSERT, UPDATE or DELETE.

2.4 Data Modelling and Database Design

A data model is a conceptual representation of the data structures that are required by a database. The data structures include the data objects, the associations between data objects and the rules and constraints governing the operations on the objects. As the name implies, the data model focuses on what data is required and how it should be organised rather than what operations will be performed on the data. A data model is independent of hardware or software constraints. Rather than trying to represent the data as a database would see it, the data model focuses on representing the data as the user sees it in the "real world".9 Data models serve as a bridge between the concepts that make up real world events and processes and the physical representation of those concepts in a database.

There are two major methodologies used to create a data model: the Entity-Relationship (ER) approach and the hierarchical model. The ER model is the more common data model used in the design process while the hierarchical model is taken for more specific developments related to object oriented and hierarchical databases.

The ER model is a conceptual data model that views the real world as entities, their attributes and the relationships between the entities. A basic component of the model is the ER diagram which is used to visually represent data objects. Figure 2-3 represents a basic ER diagram with the two entities customer and order as well as its corresponding attributes. The connection line between the two entities, reflects the type of relationship both entities have to each other.

For a database designer, the utility of the ER model is:10

- It maps well to the relational model. The constructs used in the ER model can easily be transformed into relational tables.
- It is simple and easy to understand with a minimum of training. Therefore, the model can be used by the database designer to communicate the design to the end user.
- The model can be used as a design plan by the database developer to implement a data model in a specific database management software.

illustration not visible in this excerpt

Figure 2-3: Basic ER Diagram

Data modelling can be seen as a means for the database design process. Database design is defined as "design the logical and physical structure of one or more databases to accommodate the information needs of the users in an organisation for a defined set of applications".11 The design process roughly follows five consecutive steps:

1. Planning and analysis
2. Conceptual design
3. Logical design
4. Physical design
5. Implementation

The data model is one part of the conceptual design process. The other is typically the functional model. The data model focuses on what data should be stored in the database while the functional model deals with how the data is processed. To put this in the context of relational databases, the data model is used to design the relational tables while the functional model is used to design the queries which accesses and performs operations on those tables.12 Data modelling is probably the most labour intensive and time consuming part of the development process. The overall goal of the data model is to make sure that all data objects required by the database are completely and accurately represented.

2.5 Relational Data Model

Much of today's database markets consist of relational databases based on the relational data model proposed in the late 1960s and early 1970s by Edgar Frank Codd, an IBM researcher.13 In terms of the relational data model, relational databases are regarded as a collection of relational tables which are also simply called relations. A relational table is a flat file composed of a set of named columns, also known as attributes, and an arbitrary number of unnamed rows. The columns of the tables contain information about the table. The rows of the table represent occurrences of the "real world thing" represented by a table. A data value is stored in the intersection of a row and column. Each named column has a domain, which is the set of values that may appear in that column.14 Figure 2-4 shows a relational table with its basics key words.

illustration not visible in this excerpt

Figure 2-4: Structure of a Relational Table

The values in the columns and rows are atomic which means that they are not repeating. Each row in a relational table is unique so that no two rows are identical. Each column has a unique name so that no specific sequence of the columns is required. In addition to this, tables have relationships between each other. A relationship is regarded as an association between two or more tables. Relationships are expressed in the data values of the primary and foreign keys. A primary key is a column or columns in a table whose values uniquely identify each row in a table. A foreign key is a column or columns whose values are the same as the primary key of another table. Foreign keys can be viewed as a copy of primary key from another relational table.15 The relationship is made between two relational tables by matching the values of the foreign key in one table with the values of the primary key in another. Figure 2-5 shows the ER diagram from Figure 2-3 indicating the primary key (PK) and foreign key (FK) of the two entities customer and order. An entity is represented as a table in the relational model. Each attribute corresponds to one column heading in a table.

illustration not visible in this excerpt

Figure 2-5: ER Diagram with Primary and Foreign Key

Keys are fundamental for the relational model because they enable tables in the database to be related with each other. Navigation around a relational database depends on the ability of the primary key to unambiguously identify specific rows of a table. Navigating between tables requires that the foreign key is able to reference the values of the primary keys of a related table.

Another important feature of the relational model is data integrity. Data integrity means that you can correctly and consistently navigate and manipulate the tables in the database. There are two basic rules to ensure data integrity; entity integrity and referential integrity. The entity integrity rule states that the value of the primary key can never be a null value (a null value is one that has no value). Because a primary key is used to identify a unique row in a relational table, its value must always be specified and should never be unknown. The integrity rule requires that insert, update, and delete operations maintain the uniqueness and existence of all primary keys. The referential integrity rule states that if a relational table has a foreign key, then every value of the foreign key must either be null or match the values in the relational table in which that foreign key is a primary key.16

2.6 Data Normalisation

Normalisation is a design technique that is widely used as a guide in designing relational databases. Normalisation is essentially a two step process that puts data into tabular form by removing repeating groups and then removing duplicated data from the relational tables. The normalisation theory is based on the concepts of Normal Forms (NF). A relational table is said to be a particular normal form if it satisfies a certain set of constraints. There are currently six normal forms that have been defined, designated as 1NF, 2NF, 3NF, Boyce/Codd normal form (BCNF), 4NF and 5NF.17

The goal of normalisation is to create a set of relational tables that are free of redundant data and that can be consistently and correctly modified. That means that all tables in a relational database should be at least in the 3NF. A relational table is in 3NF if and only if all non-key columns are (a) mutually independent without any repeating groups and (b) fully dependent upon the primary key. Mutual independence means that no non-key column is dependent upon any combination of the other columns. The first two normal forms are intermediate steps in achieving the goal of having all tables in 3NF. Figure 2-6 shows the data normalisation process up to the 3NF.

illustration not visible in this excerpt

Figure 2-6: Data Normalisation Process

Source: McFadden, F. and Hoffer, J. (1991), Database Management

Chapter 3: Research Topic

The purpose of this chapter is to provide a basic understanding of the eXtensible Markup Language (XML) as well as its main benefits and current drawbacks related to industry applications. Furthermore, this chapter looks at a number of business developments using XML.

3.1 A Brief History About XML

In February 1998 XML was firstly approved as an official standard by the World Wide Web Consortium (W3C). The W3C is one of the most important web organisations which was founded in October 1994 in order “[…] to lead the World Wide Web to its full potential by developing common protocols that promote its evaluation and ensure its interoperability”18. One example of these protocols is the HyperText Markup Language (HTML) which is used as common basis for web-publishing. By bringing together competing organisations around the world the W3C discusses the latest ideas related to the World Wide Web (WWW) and proclaims industry-wide standards.

XML itself is a subset of the previously-existing Standard Generalized Markup Language (SGML), a language specifically designed to make it easy to interchange structured documents over the Internet. The W3C’s SGML Working Group, formed in August 1996, was responsible for the conception of XML. The group was finally renamed to the XML Working Group.19 The first XML working draft was announced at the SGML 1996 conference in November of that year. Successive versions of this draft were completed in 1997, with the fifth being in November. A proposed recommendation was announced in December 1997 at the SGML/XML conference. Voting by member-organisations took place, and on 10 February, 1998 XML 1.0 was announced as a W3C recommendation. As the '1.0' suggests, successive versions of this specification may be developed. Current XML-related working drafts include eXtensible Stylesheet Language (XSL), XML Linking Language (XLink), and the XML Pointer Language (XPointer) .

3.2 Concept of XML

XML is used as a method for defining the structure in documents. It belongs to the area of meta languages which allow the development of other languages by using a set of rules. In the case of XML the developed language is called ‘markup’ language.20 The philosophy behind the markup is that information in a document, e.g. text or images are identified through these set of rules. Different software applications, such as a web browser can then interpret, display or process the identified data. XML itself has some similarities with the HTML syntax because they both share the common heritage SGML. HTML was originally created as a simple means to format data for the presentation in a web browser. Thus, the flexibility and extensibility of HTML is limited. In order to get a greater variety XML was specifically developed to be extensible and more flexible in terms of using descriptive markup to categorise the content of a document. The main XML design goals, taken from the W3C specification are to 21

- enable internationalised media-independent electronic publishing.
- allow industries to define platform-independent protocols for the exchange of data, especially the data of electronic commerce.
- deliver information to user agents in a form that allows automatic processing after receipt.
- make it easier to develop software to handle specialized information distributed over the Web.
- make it easy for people to process data using inexpensive software.
- allow people to display information the way they want it, under style sheet control.
- make it easier to provide metadata - data about information - that will help people find information and help information producers and consumers find each other.

3.2.1 Logical and Physical Structure of an XML Document

According to the XML specification 1.0 XML documents have both a logical and a physical structure. Logically the document is composed of elements, attributes, declarations, comments and processing instructions.22 Element and attribute names are entered between matched pairs of angle brackets <…> which are also called tags. The start and end of each logical element has to be clearly identified by entry of a start-tag <…> and an end-tag </...>. Declarations, comments and processing instructions are also entered between angle brackets but consist only of a single start-tag. Physically, the document is composed of units called entities. Entities can either be pieces of characters or text constructs or non-XML objects such as images, audio or Portable Document Format (PDF) files. An entity may refer to other entities to cause their inclusion in the document.

An XML document is basically divided into the two parts called ‘Prolog’ and ‘Body’. The prolog begins with the XML version followed by the ‘root’ element of the body. A sample document is shown in Figure 3-1.

<?xml version="1.0“?> <Country> <City> <Name>Glasgow</Name> <Population>app. 1,000,000</Population> </City> <City> <Name>Edinburgh</Name> < Population >app. 600,000</ Population > </City > </Country> <!---Place to add comments-->

illustration not visible in this excerpt

Figure 3-1: Structure of an XML Document

A software module called XML processor or XML parser is used to read XML documents and to provide access to their content and structure. The XML processor does its work on behalf of another module called ‘application’. The application describes the required behaviour of an XML processor in terms of how it must read XML data and how information is provided to the application.

3.2.2 Document Type Definition

The structure of an XML document can be expressed similarly to a computer programming language grammar which tells how elements can stand in relation to each other. The grammar for a set of documents with the same structure is defined in a Document Type Definition (DTD). DTDs are not mandatory in XML documents but if they exist, they define the XML tags and structure for one or more documents. The first thing an XML parser does when it finds an XML document is to look for the existence of such a DTD. By reading a DTD, the parser knows how to interpret the markup. If the parser finds a syntax error in the document it will quit and declare the document not being well-formed.23

DTDs are also used to validate the correctness of XML data. They contain information such as what elements are allowed in a file, what type of data is allowed in each element or whether a certain structure can repeat. The DTD for an XML document can either be included in the document itself or referenced externally.24 DTDs are preferably used to define markup tags for a specific industry sector so that they can be used as a common tag base for exchanging information.

3.2.3 Style Sheets

Because XML does not use predefined tags like HTML the meanings of these tags are not understood by a web browser. Therefore, the browser does not know how to display an XML document. To be able to display XML documents it is necessary to have a mechanism which specifies how the content of a document should be presented. One such mechanism is Cascading Style Sheets (CSS). CSS is a special style language that can be used in conjunction with HTML or XML to define the visual presentation of a web page. In the case of XML, CSS are too inflexible to display documents in the required variety. Therefore, a new style sheet language was developed by the W3C, called the ‘eXtensible Style Sheet Language’ (XSL). The power of XSL style sheets is that the formatting process is completely independent from the XML content. Additionally, XSL style sheets allow the manipulation of XML documents. These features enable programmers to use one or more style sheets together to present data in whatever display form or format necessary and supported.25 The XSL family consists principally of two parts:

- XSL-Transformation (XSLT): a method for transforming XML documents
- XSL-Formatting Objects (XSL-FO): a method for formatting XML documents

XSLT can be used to transform an XML document into a format that is recognisable to a web browser. One such format is, e.g. HTML or the Wireless Markup Language (WML), shown in Figure 3-2. XSLT does this by transforming each XML element into an HTML element. XSLT can also add completely new elements into the output file or to remove elements. It can rearrange and sort the elements, test and make decisions about which elements to be displayed.26 An example of an XSLT style sheet which transforms an XML document into an HTML document is attached in appendix 1. XSL-FO provides a method to format XML data into a sophisticated layout model for print formats like PDF or Rich Text Format (RTF). A special formatting style sheet language is used to convert tags and its content into the required output format. The actual formatting process is then carried out by a rendering software tool.27

illustration not visible in this excerpt

Figure 3-2: XSL Transforming and Formatting Process

3.3 Additional XML Features

Besides XML itself there are many other features which support the XML standard. A summary of the most important support mechanisms are described in Table 3-1. Appendix 2 of this dissertation shows an example for both XLink and XPointer, which are mentioned in Table 3-1.

Table 3-1: Supporting XML Techniques

illustration not visible in this excerpt

3.4 The Acceptance of XML

XML as a standard has garnered widespread support from minor and major industry players alike. Perhaps most significantly, the technology has won Microsoft’s backing. Microsoft is supporting XML across a wide range of its products which is most notable in Office 2000 and newer packages. According to a survey conducted by the Evans Data Corporation in Spring 200128 more than one third of international software developers already use XML. By contrast these developers spent in 2001 an average of 5.4% of their development time using XML. Table 3-2 shows the context between the usage of XML during the time developing and the corresponding percentage of developers making use of it for 2001.29

Table 3-2: Percentage of Programmers Making Use of XML

illustration not visible in this excerpt

Source: Evans Data Corporation (Spring 2001), International Developer Survey

[...]


1 Dowling, N. (1998), Database Design & Management. Gosport, Ashford Colour Press, pp.6-7

2 Date, C. (1995), An Introduction To Database Systems. Sixth edition. New York, Addison Wesley, p.2

3 McFadden, R. and Hofler, J. (1991), Database Management. Redwood City, California, Benjamin/Cummings Publishing Company, p.5

4 Saake, G. (1997), Objektdatenbanken. Bonn, Germany, International Thomson Publishing Company, p.2

5 Date, C. (1995), pp.28-29

6 Connolly, T. and Begg, C. (1999), Database Systems. Second edition. Harlow, Addison Wesley, pp.40-42

7 Gorman, M. (1991), Database Management Systems. Oxford, Butterworth-Heinemann Ltd, p.441

8 Connolly, T. and Begg, C. (1999), pp.45-47

9 Goldstein, R. (1985), Database: Technology And Management. New York, John Wiley & Sons, p.37

10 Diehr, G. (1989), Database Management. Glenview, Illinois, Foresman and Company, p.308

11 Connolly, T. and Begg, C. (1999), p. 210

12 McFadden, R. and Hofler, J. (1991), pp.115-119

13 Connolly, T. and Begg, C. (1999), pp.72-73

14 Connolly, T. and Begg, C. (1999), pp.74-76

15 Diehr, G. (1989), pp.80-84

16 Connolly, T. and Begg, C. (1999), p.86

17 Diehr, G. (1989), pp.323-324

18 World Wide Web Consortium (2002). Available at: http://www.w3c.org/Consortium/ [Accessed 15 July 2002]

19 Pardi, W. (1999), XML in Action. Redmond, Washington, Microsoft Press, p.18

20 Hoque, R. (2000), XML For Real Programmers. San Diego, California, Academic Press, p.1

21 World Wide Web Consortium (2002). Available at: http://www.w3c.org/XML/Activity [Accessed 15 July 2002]

22 Hogue, R. (2000), pp.8-21

23 Goldfarb, C. and Prescod, P. (2000), The XML Handbook. Second edition. London, Prentice Hall International, pp. 654-655

24 Bryan, M. (1997), An Introduction to the Extensible Markup Language (XML). Available at: http://www.personal.u-net.com/ [Accessed 05 August 2002]

25 Ray, E. (2001), Learning XML, p.105

26 Rusty Harold, E. (1999), XM L Bible. New York, IDG Books, pp. 435-439

27 Rusty Harold, E. (1999), pp.513-524

28 Evans Data Corporation (2001), International Developer Survey. Available at: http://www.evansdata.com/Int01TOC.htm [Accessed 09 July 2002]

29 Evans Data Corporation (2001). Available at: http://www.evansdata.com/xmlnow.htm [Accessed 09 July 2002]

Details

Seiten
81
Erscheinungsform
Originalausgabe
Jahr
2002
ISBN (eBook)
9783832458881
ISBN (Buch)
9783838658889
Dateigröße
697 KB
Sprache
Englisch
Katalognummer
v221345
Institution / Hochschule
University of Stirling – unbekannt
Note
1,0
Schlagworte
datenbanken change management datenmodellierung relationale

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Titel: An Analysis of the Current Development Stage of the eXtensible Markup Language (XML) and its Usage for Database Systems