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FOR XML in SQL Server 2005 289 Executing FOR XML Queries from ADO.NET 290 XML Data Type in SQL Server 2005 298 Working with XML Data Type Columns from ADO.NET 303 Using XML Schema on the

Professional ASP.NET 2.0 XML

Professional ASP.NET 2.0 XML

Thiru Thangarathinam

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About the Author

Thiru Thangarathinamworks for Intel Corporation in Phoenix, Arizona He is an MCAD (MicrosoftCertified Application Developer) and specializes in architecting and building Distributed N-Tier applica-tions using ASP.NET, Visual C#.NET, VB.NET, ADO.NET, and SQL Server 2000 He has co-authored anumber of books for Wrox Press in NET technologies Thiru is also a regular contributor to print and

online magazines such as Visual Studio Magazine, Visual Studio NET Professional, SQL Server

Professional, DevX, ASPToday.com, 15seconds.com, and Developer.com At Intel, he is part of the teamthat is focused on developing the Enterprise Architecture and Service Oriented Architectures for Intel

He can be reached at thiru.thangarathinam@intel.com

Quality Control Technician

Brian H Walls, Joe Niesen

Proofreading and Indexing

TECHBOOKS Production Services

Administration and Management 35

Design Goals for XML Support in NET Framework 2.0 41

Chapter 4: Reading and Writing XML Data Using XmlReader and XmlWriter 61

Summary 130

XML Document Loaded in a DOM Tree 132

Contents

Working with XmlDocument Class 139 Programmatically Creating XML Documents 149 The XmlDocumentFragment Class 159 XPath Support in XML DOM 159 Validating XML in an XmlDocument 171

Advanced XSLT Operations 207 Debugging XSLT Style Sheets 209

FOR XML in SQL Server 2005 289 Executing FOR XML Queries from ADO.NET 290 XML Data Type in SQL Server 2005 298 Working with XML Data Type Columns from ADO.NET 303 Using XML Schema on the Client 317 Multiple Active Result Sets (MARS) in ADO.NET 323 XML Data Type and a DataSet 326

Summary 333

Chapter 11: Building an Airline Reservation System

Asynchronous Invocation of Web Services from a Client Application 443 Asynchronous Invocation of Web Services from a Browser Using IE Web Service Behavior 448 Asynchronous Web Service Methods 454 Controlling XML Serialization Using IXmlSerializable 457 Using Schema Importer Extensions 460 Miscellaneous Web Service Features in NET

New Configuration Sections in ASP.NET 2.0 468 WebConfigurationManager Class 471 Retrieving Configuration from Predefined Sections 473 Encrypting and Decrypting Configuration Sections 478 Enumerating Configuration Sections 482 Reading Configuration Sections 483 Creating a Custom Configuration Section 487 Built-in Configuration Management Tools 491

Summary 495 Chapter 15: Building a ShoppingAssistant Using XML Web Services 497

Contents

Implementation of ShoppingAssistant Web Application 513 Using Asynchronous Invocation of Web Services and Windows Service 526 Modifying the ShoppingAssistant Web Pages to Consume XML Files 531 Implementation of FileSystemWatcher to Facilitate Reporting Data Collection 532 Putting It All Together 538

Summary 539

I would like to acknowledge my wife Thamiya, my parents and my family for their constant supportand encouragement throughout while I spent nights and weekends working on this book

This book will cover the intersection between two great technologies: ASP.NET and XML

XML has been a hot topic for some time The massive industry acceptance of this W3C Recommendation,which allows data communication and information storage in a platform independent manner, has beenastounding XML is seen and used everywhere—from the display of data on various browsers using thetransformation language XSLT, to the transport of messages between Web services using SOAP

.NET is Microsoft’s evolutionary and much vaunted new vision It allows programming of applications

in a language independent manner, the sharing of code between languages, self-describing classes, andself-documenting program code to name but a few of its capabilities .NET, in particular ASP.NET, hasbeen specifically designed with Web services and ease of development in mind With the release of NET2.0 Framework, NET includes significant enhancements to all areas of ASP.NET For Web page develop-ment, new XML data controls like XmlDataSource, and TreeView make it possible to display and editdata on an ASP.NET Web page without writing code reducing the required amount of code by as much

as 70% in some cases ADO.NET 2.0 includes many new features that allow you to leverage the newXML features introduced with SQL Server 2005 (the next major release of SQL Server)

To achieve this exciting new Web programming environment, Microsoft has made extensive use of XML

In fact, no other technology is so tightly bound with ASP.NET as XML It is used as the universal dataformat for everything from configuration files to metadata, Web Services communication, and objectserialization All the XML capabilities in the System.Xml namespace were significantly enhanced foradded performance and standards support The new model for processing in-memory XML data,editable XPathNavigator, new XSLT processor, strong typed support for XmlReader, and XmlWriterclasses, are some of the key XML related improvements Connected to this is the new support for XMLthat ADO.NET 2.0 has Because of the new ADO.NET 2.0 features, the programmer now has the ability

to access and update data in both hierarchical XML and relational database form at the same time

Who This Book Is For

This book is aimed at intermediate or experienced programmers who have started on their journeytoward ASP.NET development and who are already familiar with XML While I do introduce the reader

to many new ASP.NET 2.0 concepts in Chapter 2, this book is not intended as a first port of call for thedeveloper looking at ASP.NET, since there are already many books and articles covering this area.Instead, I cut straight to the heart of using XML within ASP.NET Web applications To get the most out

of the book, you will have some basic knowledge of C# All the code examples will be explained in C#

In a similar vein, there are many books and articles that cover the XML technologies that you will need

to use this book I assume a general knowledge of XML, namespaces, and XSLT, and a basic ing of XML schemas

understand-What This Book Covers

This book explores the array of XML features and how they can be used in ASP.NET for developing Webapplications XML is everywhere in the NET Framework, from serialization to Web services, and fromdata access to configuration In the first part of this book, you’ll find in-depth coverage of the key classesthat implement XML in the NET platform Readers and writers, validation, schemas, and XML DOM arediscussed with ASP.NET samples and reference information Next the book moves on to XPath and XSLTransformations (XSLT), XML support in ADO.NET and the use of XML for data display

The final part of this book focuses on SQL Server 2005 XML Features, XML Serialization, XML Web services, and touches on XML based configuration files and its XML extensions You’ll also find a couple

of case studies on the use of XML related features of ASP.NET and Web services that provide you with areal life example on how to leverage these features

How This Book Is Str uctured

The book consists of 15 chapters including two case studies The book is structured to walk the readerthrough the process of XML development in ASP.NET 2.0 I take a focused approach, teaching readersonly what they need at each stage without using an excessive level of ancillary detail, overly complextechnical jargon, or unnecessary digressions into detailed discussion of specifications and standards Abrief explanation of each of the chapters is as follows:

An Introduction to XML

XML finds several applications in business and, increasingly, in everyday life It provides a commondata format for companies that want to exchange documents using Web services This chapter is aboutXML as a language and its related technologies The XML technologies that I will specifically introduce

in this chapter are: XML document elements, namespaces, entities, DTD, XDR, XSD, XSD schema datatypes, XSLT, XML DOM, XPath, SAX, XLink, XPointer, and XQuery

An Introduction to ASP.NET 2.0

In Chapter 2, I aim to give the reader an overview of the new features of ASP.NET 2.0 I will highlightthe new ASP.NET page architecture, new data controls, and code sharing features I ask, “What is masterpages” and go on to talk about how master pages and themes aid in creating consistent Web sites Later

on, I look at security controls and Web parts framework and illustrate how ASP.NET 2.0 enables 70%code reduction Finally, I will look at the new caching and administration and management functionali-ties of ASP.NET 2.0

XML Classes in the NET Framework

In Chapter 3, I take a brisk walk through all the new XML classes in the NET Framework, which will bediscussed in more detail throughout the rest of the book

Microsoft has introduced several new applications of XML in NET 2.0 and has also done some tive work to improve the core XML API I start with a discussion on the use of XML in configurationfiles, DOM, XSD schema validation, XSLT transformations, XML serialization, Web services, and XML

innova-Introduction

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support in ADO.NET and look at the namespaces and classes that are available for this purpose I willalso illustrate the new ASP.NET configuration enhancements and take a quick look at the configurationclasses in NET Framework 2.0

Reading and Writing XML

Chapter 4 starts a section of chapters (4 through 6) that look at the functionality contained within theSystem.Xml in more detail

In particular, here I look at the fast, forward-only read-only mechanisms provided by the NETFramework for reading and writing XML documents, namely the XmlReader and XmlWriter classes Iexplore the new XML reading and writing model and talk about the various ways using, which you canread and write XML data I also go onto discuss node order, parsing attributes, customizing reader andwriter settings, white spaces handling, and namespace handling, and other namespace support

Validating XML

In Chapter 5, I take a look at different options for the XML validation grammars: DTDs, XDR schemas,and XSD schemas I also go on to look at all the ways you can create an XSD schema in Visual Studio2005: using the XML designer, from a DTD, using the XSD generator, from an XML document, from anXDR schema, or from an assembly I also discuss the schema object and see how to link XML documents toDTDs, XDR schemas, and XSD schemas, and how to then perform validation using the XmlReaderSettings

in conjunction with the XmlReader class I also illustrate the use of the XmlSchemaSet class to keep a cache

of schemas in memory, to optimize performance, and also deal with unqualified/namespace-qualified tent in XML documents

con-XML DOM Object Model

In Chapter 6, I look at the DOM functionality within the NET Framework provided within the System.Xmlnamespace of classes I look at programmatically creating XML documents, opening documents fromURLs, or strings in memory, and searching and accessing the contents of these documents, before serializ-ing them back out to XML strings I also take a look at the differences between the XmlDocument objectand the XmlReader and XmlWriter classes, and where using each is more appropriate Finally, I demon-strate the XPath capabilities of the XmlDocument class and also highlight the new editing capabilities ofthe XPathNavigator class to modify an XML document in memory

Transforming XML Data with XSLT

The NET Framework provides robust support for XSLT and XPath processing and with NETFramework 2.0, the XSL support has been completely redesigned and a new XSLT processor is intro-duced In Chapter 7, I look at the technologies used for XSL transformations in the NET Framework,namely the System.Xml.Xsl namespace, and System.Xml.XPath namespaces, as well as the newly intro-duced XslCompiledTransform class The NET Framework fully supports the XSLT and XPath specifica-tion as defined by the W3C, but also provides more helpful extensions to these specifications, whichenhance the usability of style sheets within NET applications To this end, I look at using embeddedscript with <msxsl:script> for transforming XML documents and show how to extend style sheets withextension objects Towards the end of the chapter, I discuss advanced XSLT operations such as how topass a node set to a style sheet and how to resolve external style sheets using XmlResolver

Introduction

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XML Support in ADO.NET

In Chapter 8, I start to move away from the realm of the System.Xml namespace of classes, to explore thebroader picture of how XML is used in NET specifically from ADO.NET, the data access technology ofchoice

Chapter 8 looks at the role of XML in ADO.NET 2.0 and highlights the new XML related features ofADO.NET I cover the capabilities of the DataSet and DataTable classes, including reading and writingXML, and programmatically accessing or changing its XML representation I highlight how to synchro-nize DataSets with XmlDataDocuments and why you would do so I also cover the creation of stronglytyped DataSets and their advantages Finally, I take a glimpse at how to access some of the new XMLfeatures available in SQL Server 2005 from ADO.NET

XML Data Display

The XML support in ASP.NET provides excellent support for storing, retrieving and rendering XML

I start with looking at the new web.sitemap file that allows you to store the hierarchy of a Web site andleverage that to drive the navigation structure of a Web site Then, I go on to discuss the features of newXML data controls such as XmlDataSource, TreeView, and GridView for consuming and displayingnative XML directly in the browser Finally, I also introduce the new ASP.NET 2.0 script callback featurefor retrieving XML data directly from the browser without refreshing the page

SQL Server 2005 XML Integration

With the release of SQL Server 2005, XML support just got better and SQL Server 2005 provides powerfulXML query and data modification capabilities over XML data To start with, I introduce the new XMLfeatures of SQL Server 2005 including the FOR XML clause enhancements, XQuery support, and theXML data type Then I go on to discuss the execution of FOR XML queries from within ADO.NET bothsynchronously and asynchronously I also discuss the steps involved in working with typed and

untyped XML data type columns Finally, I illustrate how to retrieve XSD schemas from a typed columnusing ADO.NET and also focus on MARS and OPENXML() functions

Building an Airline Reservation System using ASP.NET 2.0 and SQL Server 2005

This case study ties together all the concepts including XML DOM, XML support in ADO.NET, XSLTfeatures in NET, XML data display, that have been covered so far in this book The focus of this casestudy is on incorporating these XML features in a real world airline reservations Web site and showcas-ing the best practices of using these XML features I also discuss the N-Tier design methodology andillustrate how to leverage that to create an extensible and flexible airline reservations system

XML Serialization

In Chapter 12, I look at serializing XML documents as XML data using the XmlSerializer class from theSystem.Xml.Serialization namespace More specifically, you create serializers, and then serialize and deseri-alize generic types, complex objects, properties, enumeration values, arrays and composite objects I alsolook at serializing and deserializing with nested objects, followed by formatting XML documents, XMLattributes, and text content Towards the end of the chapter, I discuss the steps involved in improving theserialization performance by pregenerating assemblies using the new XML serializer generator tool

Introduction

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ASP.NET 2.0 Configuration

In Chapter 14, I introduce the new configuration management API of ASP.NET 2.0 that enables users toprogrammatically build programs or scripts that create, read, and update settings in web.config andmachine.config files I also go on to discuss the new comprehensive admin tool that plugs into the exist-ing IIS Administration MMC, enabling an administrator to graphically read or change any setting withinour XML configuration files Throughout this chapter, I focus on the new configuration managementclasses, properties, and methods of the configuration API and also provide examples on how to usethem from your ASP.NET applications

Building a ShoppingAssistant using XML Web Services

This chapter is based on a case study named ShoppingAssistant, which provides one stop shopping forconsumers that want to find out information such as the products that are on sale, availability of prod-ucts in different stores, comparison of the price of the product across different stores and so on In thiscase study, I demonstrate how to leverage Web services in a real world Web application by using asyn-chronous Web service invocation capabilities in conjunction with other NET features such as XMLSerialization, FileSystemWatcher, and Timer component

What You Need to Use This Book

All of the examples in this book are ASP.NET samples The key requirements for running these tions are the NET Framework 2.0 and Microsoft Visual Studio 2005 You also need to have SQL Server

applica-2005 server along with the AdventureWorks sample database installed to make most of the sampleswork A few examples make use of SQL Server 2005 Express database

The SQL Server examples in this book utilize integrated security to connect to the SQL Server database,

so remember to enable integrated authentication in your SQL Server This will also require you to turn

on integrated Windows authentication (as well as impersonation depending on your configuration) inASP.NET Web sites

Tips, hints, tricks, and asides to the current discussion are offset and placed in italics like this.

As for styles in the text:

❑ We highlight new terms and important words when we introduce them.

❑ We show keyboard strokes like this: Ctrl+A

❑ We show file names, URLs, and code within the text like so: persistence.properties

Source Code

As you work through the examples in this book, you may choose either to type in all the code manually

or to use the source code files that accompany the book All of the source code used in this book is able for download at http://www.wrox.com Once at the site, simply locate the book’s title (either byusing the Search box or by using one of the title lists) and click the Download Code link on the book’sdetail page to obtain all the source code for the book

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Once you download the code, just decompress it with your favorite compression tool Alternately, youcan go to the main Wrox code download page at http://www.wrox.com/dynamic/books/

download.aspxto see the code available for this book and all other Wrox books

Errata

We make every effort to ensure that there are no errors in the text or in the code However, no one is perfect, and mistakes do occur If you find an error in one of our books, like a spelling mistake or faultypiece of code, we would be very grateful for your feedback By sending in errata you may save anotherreader hours of frustration and at the same time you will be helping us provide even higher qualityinformation

To find the errata page for this book, go to http://www.wrox.comand locate the title using the Searchbox or one of the title lists Then, on the book details page, click the Book Errata link On this page youcan view all errata that has been submitted for this book and posted by Wrox editors A complete booklist including links to each book’s errata is also available at www.wrox.com/misc-pages/booklist.shtml

Boxes like this one hold important, not-to-be forgotten information that is directly

relevant to the surrounding text.

Introduction

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If you don’t spot “your” error on the Book Errata page, go to www.wrox.com/contact/techsupport.shtmland complete the form there to send us the error you have found We’ll check the informationand, if appropriate, post a message to the book’s errata page and fix the problem in subsequent editions

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Professional ASP.NET 2.0 XML

Introduction to XML

Extensible Markup Language (XML) is a language defined by the World Wide Web Consortium(W3C, http://www.w3c.org), the body that sets the standards for the Web You can use XML tocreate your own elements, thus creating a customized markup language for your own use Inthis way, XML supersedes other markup languages such as Hypertext Markup Language(HTML); in HTML, all the elements you use are predefined — and there are not enough of them

In fact, XML is a metamarkup language because it lets you create your own markup languages.XML is the next logical step in developing the full potential of the Internet and the Web Just asHTML, HyperText Transfer Protocol (HTTP), and Web browsers paved the way for exciting newmethods of communications between networked computers and people, XML and its associatedtechnologies open new avenues of electronic communications between people and machines In thecase of XML, however, the promise is for both human-machine and machine-machine communica-tions, with XML as the “lowest-common-denominator” language that all other systems — propri-etary or open — can use

XML derives much of its strength in combination with the Web The Web provides a collection ofprotocols for moving data; XML represents a way to define that data The most immediate effecthas been a new way to look at the enterprise Instead of a tightly knit network of servers, theenterprise is now seen as encompassing not just our traditional networks but also the Web itself,with its global reach and scope XML has become the unquestionable standard for genericallymarking data to be shared As XML continues to grow in popularity, so too are the number ofways in which XML is being implemented XML can be used for a variety of purposes, from obvioustasks such as marking up simple data files and storing temporary data to more complex tasks such

as passing information from one program or process to another

XML finds several applications in business and, increasingly, in everyday life It provides a commondata format for companies that want to exchange documents It’s used by Web services to encodemessages and data in a platform-independent manner It’s even used to build Web sites, where itserves as a tool for cleanly separating content from appearance

This chapter is about XML as a language and its related technologies A comprehensive treatment ofthe subject could easily fill 300 pages or more, so this chapter attempts to strike a reasonable balancebetween detail and succinctness In the pages that follow, you learn about the different XML-relatedtechnologies and their usage But before that, take a brief look at XML itself.

A Primer on XML

XML is derived from the Standard Generalized Markup Language (SGML), a rich language used mostlyfor huge documentation projects The designers of XML drew heavily from SGML and were guided bythe lessons learned from HTML They produced a specification that was only about 20 percent the size

of the SGML specification, but nearly as powerful Although SGML is typically used by those who needthe power of an industrial-strength language, XML is intended for everyone

One of the great strengths of XML is the extensibility it brings to the table XML doesn’t have any tags of itsown and it doesn’t constrain you like other markup languages Instead, XML defines rules for developingsemantic tags of your own The tags you create form vocabularies that can be used to structure data intohierarchical trees of information You can think of XML as a metamarkup language that enables developers,companies, and even industries to create their own, specific markup languages

One of the most important concepts to grasp in XML is about content, not presentation The tags you create focus on organizing your data rather than displaying it XML isn’t used, for example, to indicate aparticular part of a document in a new paragraph or that another part should be bolded XML is used todevelop tags that indicate a particular piece of data is the author’s first name, another piece is the booktitle, and a third piece is the published year of the book

Self-Describing Data

As mentioned before, the most powerful feature of XML is that it doesn’t define any tags Creating yourown tags is what makes XML extensible; however, defining meaningful tags is up to you When creatingtags, it isn’t necessary to abbreviate or shorten your tag names It doesn’t make processing them anyfaster but it can make your XML documents more confusing or easier to understand Remember, devel-opers are going to be writing code against your XML documents On the one hand, you could certainlydefine tags like the following:

The second example is far more readable in human terms, and it also provides more functionality andversatility to nonhumans With this set of tags, applications can easily access the book’s title or authorname without splitting any strings or searching for spaces And, for developers writing code, searchingfor the author name in an XML document becomes much more natural when the name of the element istitle, for example, rather than H1

Indenting the tags in the previous example was done purely for readability and certainly isn’t necessary

in your XML documents You may find, however, when you create your own documents, indentation helps you to read them.

To process the previous XML data, no special editors are needed to create XML documents, although anumber of them are available And no breakthrough technology is involved Much of the attentionswirling around XML comes from its simplicity Specifically, interest in XML has grown because of theway XML simplifies the tasks of the developers who employ it in their designs Many of the tough taskssoftware developers have to do again and again over the years are now much easier to accomplish XMLalso makes it easier for components to communicate with each other because it provides a standardized,structured language recognized by the most popular platforms today In fact, in the NET platform,Microsoft has demonstrated how important XML is by using it as the underpinning of the entire platform

As you see in later chapters, NET relies heavily on XML and SOAP (Simple Object Access Protocol) in itsframework and base services to make development easier and more efficient

❑ The document contains one or more elements

❑ The document consists of exactly one root element (also known as the document element)

❑ The name of an element’s end tag matches the name defined in the start tag

❑ No attribute may appear more than once within an element

❑ Attribute values cannot contain a left-angle bracket (<)

❑ Elements delimited with start and end tags must nest properly within each other

Validity

First and foremost, a valid XML document must be well-formed before it can even think about being avalid XML document The well-formed requirement should be fairly straightforward, but the key thatmakes an XML document leap from well-formed to valid is slightly more difficult To be valid, an XMLdocument must be validated A document can be validated through a Document Type Definition (DTD), or

an XML Schema Definition (XSD) For the XML document to be valid, it must conform to the constraintsexpressed by the associated DTD or the XSD schema

3

Introduction to XML