Beginning XML with C# 7

Transcription

1 Beginning XML with C# 7 XML Processing and Data Access for C# Developers Second Edition Bipin Joshi

2 Beginning XML with C# 7: XML Processing and Data Access for C# Developers Bipin Joshi 301 Pitruchhaya, Thane, India ISBN-13 (pbk): ISBN-13 (electronic): Library of Congress Control Number: Copyright 2017 by Bipin Joshi This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Cover image by Freepik ( Managing Director: Welmoed Spahr Editorial Director: Todd Green Acquisitions Editor: Steve Anglin Development Editor: Matthew Moodie Technical Reviewer: Michael Thomas Coordinating Editor: Mark Powers Copy Editor: Kezia Endsley Distributed to the book trade worldwide by Springer Science+Business Media New York, 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax (201) , orders-ny@springer-sbm.com, or visit Apress Media, LLC is a California LLC and the sole member (owner) is Springer Science + Business Media Finance Inc (SSBM Finance Inc). SSBM Finance Inc is a Delaware corporation. For information on translations, please rights@apress.com, or visit rights-permissions. Apress titles may be purchased in bulk for academic, corporate, or promotional use. ebook versions and licenses are also available for most titles. For more information, reference our Print and ebook Bulk Sales web page at Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the book's product page, located at For more detailed information, please visit Printed on acid-free paper

3 This work is dedicated to Lord Shiva, who, I believe, resides in each one of us as pure consciousness.

4 Contents About the Author...xvii About the Technical Reviewer...xix Introduction...xxi Chapter 1: Introducing XML and the.net Framework... 1 What Is XML?... 1 Benefits of XML... 2 XML-Driven Applications... 3 Rules of XML Grammar... 5 Markup Is Case Sensitive... 6 A Document Must Have One and Only One Root Element... 6 A Start Tag Must Have an End Tag... 6 Start and End Tags Must Be Properly Nested... 7 Attribute Values Must Be Enclosed in Quotes... 7 DTD and XML Schema... 7 Parsing XML Documents... 8 XSLT... 9 XPath The.NET Framework NET Framework and XML Assemblies and Namespaces The Classic XML Parsing Model of the.net Framework The LINQ-Based Parsing Model of the.net Framework NET Configuration Files v

5 ADO.NET ASP.NET Web Forms Server Controls XML Serialization Web Services, WCF Services, and Web API XML Documentation XAML Markup SQL Server XML Features Working with Visual Studio Creating Windows Forms Applications Creating Class Libraries Summary Chapter 2: Manipulating XML Documents Using the Document Object Model Using the DOM Parser Knowing When to Use DOM A Sample XML Document Opening an Existing XML Document for Parsing Navigating Through an XML Document Looking for Specific Elements and Nodes Retrieving Specific Elements Using the GetElementsByTagName() Method Retrieving Specific Elements Using the GetElementById() Method Selecting Specific Nodes Using the SelectNodes() Method Selecting a Single Specific Node Using the SelectSingleNode() Method Modifying XML Documents Navigating Between Various Nodes Modifying Existing Content Deleting Existing Content Adding New Content Using Helper Methods Dealing with Whitespace vi

6 Dealing with Namespaces Understanding Events of the XmlDocument Class Summary Chapter 3: Reading and Writing XML Documents What Are XML Readers and Writers? When to Use Readers and Writers Reader Classes The XmlTextReader Class The XmlValidatingReader Class The XmlNodeReader Class Reading XML Documents Using XmlTextReader Opening XML Documents Reading Attributes, Elements, and Values Improving Performance by Using Name Tables Dealing with Namespaces Moving Between Elements The ReadSubTree() Method The ReadToDescendant() Method The ReadToFollowing() Method The ReadToNextSibling() Method The Skip() Method Moving Between Attributes Reading Content The ReadInnerXml() Method The ReadOuterXml() Method The ReadString() Method Writing XML Documents Using XmlTextWriter Exporting Columns As Elements Exporting Columns As Attributes Specifying Character Encoding vii

7 Formatting the Output Including Namespace Support Dealing with Nontextual Data Serializing Data Deserializing Data Summary Chapter 4: Accessing XML Documents Using the XPath Data Model Overview of XPath Location Path Axis Node Tests Predicates Putting It All Together...87 XPath Functions The XPath Data Model Creating XPathNavigator Navigating an XML Document Using XPathNavigator Selecting Nodes Navigating Between Attributes Retrieving Inner and Outer XML Getting an XmlReader from XPathNavigator Getting an XmlWriter from XPathNavigator Editing XML Documents with the XPathNavigator Class Summary Chapter 5: Validating XML Documents Providing Structure for XML Documents Document Type Definition (DTD) XML Data Reduced (XDR) Schema XML Schema Definition (XSD) Schema Creating Structure for an XML Document viii

8 The Structure of Employees.xml Creating the DTD Creating the XML Schema Creating Schemas by Using the Schema Object Model (SOM) The Core SOM Classes Creating an XML Schema Using the SOM Attaching the DTD and XML Schemas to XML Documents Inline DTDs External DTDs Inline XML Schema External XML Schema Adding Frequently Used Schemas to the Schema Cache Using XmlReader to Validate XML Documents Using XmlDocument to Validate XML Documents Using XPathNavigator to Validate XML Documents Specifying XML Schema via Code Summary Chapter 6: Transforming XML with XSLT Overview of XSLT Applying Templates Using <xsl:apply-templates> Branching Using <xsl:if> Branching Using <xsl:choose> and <xsl:when> Transforming Elements and Attributes The XslCompiledTransform Class Performing Transformations Using XslCompiledTransform Passing Arguments to a Transformation Using Script Blocks in an XSLT Style Sheet Using Extension Objects Compiling XSLT Style Sheets Summary ix

9 Chapter 7: XML in ADO.NET Overview of ADO.NET Architecture Connected Data Access Disconnected Data Access ADO.NET Data Providers ADO.NET Classes XML and Connected Data Access Using the ExecuteXmlReader() Method XML and Disconnected Data Access Understanding DataSet Understanding DataAdapter Working with DataSet and DataAdapter Saving DataSet Contents As XML Reading XML Data into DataSet Generating Menus Dynamically Based On an XML File Reading Only the Schema Information Creating a Typed DataSet Using Visual Studio to Create a Typed DataSet Using the xsd.exe Tool to Create a Typed DataSet Summary Chapter 8: XML Serialization Understanding the Flavors of Serialization Classes Involved in the XML Serialization Serializing and Deserializing Objects Using XmlSerializer Handling Events Raised During Deserialization Serializing and Deserializing Complex Types Serialization and Inheritance Customizing the Serialized XML x

10 Serializing and Deserializing Objects Using DataContractSerializer Customizing the Serialized XML Serializing and Deserializing Objects Using SoapFormatter Customizing SOAP Serialization Summary Chapter 9: XML in Web Services What Are Web Services? Creating and Consuming Web Services Creating a Web Service Creating a Proxy for a Web Service Creating a Form That Calls the Web Methods Understanding SOAP Using SOAP Headers Customizing the XML Serialization Understanding the WSDL Document The Messages The Type Definitions The Port Types The Binding The Service A Summary of WSDL Summary Chapter 10: XML in WCF and Web API Operations Based Services vs. Resource Based Services Understanding WCF Vocabulary Creating and Consuming a WCF Service Creating the Service Hosting the Service Consuming the Service Testing the Host and Client xi

11 Hosting a WCF Service in IIS Understanding the Role of XML in WCF Services Using XmlSerializer Instead of DataContractSerializer Understanding REST Services Creating a REST Service Using WCF Creating a Client That Consumes the EmployeeManager REST Service Creating a REST Service Using Web API Creating a Client That Consumes the EmployeeManager Web API Service Using XmlSerializer Instead of DataContractSerializer Summary Chapter 11: XML in SQL Server Using XML Extensions to the SELECT Statement The FOR XML Clause Using OPENXML Using SQLXML Features The SQLXML Managed Classes The XML Data Type Creating a Table with an XML Column Inserting, Modifying, and Deleting XML Data Methods of the XML Data Type XML Data Modification Language (XML DML) XQuery Support in the XML Data Type Summary Chapter 12: XML in.net Framework Using XAML to Define the WPF User Interface Displaying XML Data in a WPF Application Using XML in ASP.NET XML and ASP.NET The XML Data Source Control xii

12 Working with Site Maps Using a SiteMapPath Control Using a SiteMapDataSource Control Using the XML Control Using the.net Framework Configuration System Structure of the web.config File Web.config Inheritance Using Web.config for Common Configuration Tasks Storing and Retrieving Application Configuration Settings Storing and Retrieving Database Connection Strings Using Forms Authentication Configuring Session State Displaying Custom Error Pages Documenting Code with XML Comments Creating a Class Library Using Sandcastle Help File Builder to Generate Help Files Summary Chapter 13: Working with LINQ to XML Overview of LINQ Working with LINQ Queries Classic XML Technologies vs. LINQ to XML Working with XML Fragments Visual Construction of XML Trees Ease in Namespace Handling Renaming XML Nodes Static Methods to Load XML Whitespace Handling XML Transformation When to Use LINQ to XML LINQ to XML Class Hierarchy xiii

13 Opening an Existing XML Document for Parsing Navigating Through an XML Tree Looking for Specific Elements and Attributes Retrieving Specific Elements Using the Descendants() Method Searching on the Basis of Attribute Values Modifying XML Data Loading the XML Document Navigating Between Various Nodes Adding New Content Modifying Existing Content Deleting Existing Content Saving the Modified XML Tree to a File Displaying Employee Details Events of the XElement Class Dealing with Whitespace Dealing with Namespaces Specifying Namespaces While Constructing Elements Validating XML Documents Transforming XML Trees Changing the Shape of an XML Tree Projecting a New Type Summary Appendix A: Creating a Custom XmlReader and XmlWriter Creating a Custom XmlReader Inheriting from XmlReader Creating the TableReader Class Using the TableReader Class xiv

14 Creating a Custom XmlWriter Inheriting from XmlWriter Creating the RssWriter Class Using the RssWriter Class Summary Appendix B: Resources W3C Web Site for XML Specifications W3C Web Site for XML Schema Specifications W3C Web Site for XPath-Related Information W3C Web Site for XSL-Related Information W3C Web Site for SOAP Specifications System.Xml Reference NET/ASP.NET/WCF/Web API Wikipedia XML Section Author s Web Site on.net and Web Development XML Notepad XML Editor Sandcastle Help File Builder SQLXML Programming Index xv

15 About the Author Bipin Joshi is a software consultant, trainer, author, and yoga mentor who writes about seemingly unrelated topics: software development and yoga! He conducts online training courses to help developers learn ASP.NET and web technologies better and faster. Currently his focus is ASP.NET, ASP.NET Core, C#, JavaScript frameworks, and design/architectural patterns. More details about his training courses are available at Bipin has been programming since 1995 and has worked with the.net Framework since its inception. He is a published author and has authored or co-authored more than 10 books and numerous articles on.net technologies. He regularly writes about ASP.NET and other cutting-edge web technologies on his web site at Bipin is a Microsoft Most Valuable Professional (MVP) and a former Microsoft Certified Trainer (MCT). Having embraced the yoga way of life, he enjoys the intoxicating presence of God and writes about yoga on his web site at Bipin has also penned a few books on yoga and teaches yoga and meditation to selected individuals. He can be reached through his web sites. xvii

16 About the Technical Reviewer Michael Thomas has worked in software development for more than 20 years as an individual contributor, team lead, program manager, and vice president of engineering. Michael has more than 10 years of experience working with mobile devices. His current focus is in the medical sector, using mobile devices to accelerate information transfer between patients and health care providers. xix

17 Introduction The Internet has brought a huge difference in the way we develop and use software applications. Applications have become more complex and distributed, connecting heterogeneous systems. With such a radical change, the role of XML is highly significant. XML has already established itself as a standard way of data encoding and transfer. In spite of the popularity of formats such as JSON (JavaScript Object Notation), XML is still being used in a wide range of applications, including enterprise applications. XML comes with a family of technologies such as XSLT, XPath, and XSD, that provide a fuller support for transforming, querying, and validating the underlying data. No wonder that Microsoft s.net Framework provides such a strong support for XML. Data access, raw parsing, serialization, configuration, code documentation, and services are some of the examples where the.net Framework harnesses the power and flexibility of XML. The.NET Framework comes with a plethora of classes that allow you to work with XML data. This book demystifies XML and allied technologies. Reading and writing XML data, using DOM, ADO.NET integration with XML, SQL Server XML features, applying XSLT style sheets, SOAP, use of XML in services (ASMX/ WCF/Web API), and configuration systems are some of the topics that this book explores in detail. Neat and concise examples scattered throughout the book will help you understand the practical use of the topic under consideration. The book can also act as a handy reference when developers go on the job. Who Is This Book For? This book is for developers who are familiar with the.net Framework and want to dive deep into the XML features of.net. This book will not teach you XML manipulation using non-microsoft tools. All the examples in this book are presented in C#, and hence working knowledge of C# is assumed. In some chapters, familiarity with LINQ, ADO.NET, and SQL Server is necessary, although I have provided a brief overview along with the respective topics. Software Required In order to work with the examples presented in this book, you need the following software: Visual Studio 2017: I used the Professional Edition of the product but for most of the examples you can also use the Community Edition..NET Framework 4.7 and C# 7: I used.net Framework 4.7 to build the examples discussed in this book. The examples and code fragments are written using C# 7. SQL Server with Northwind sample database: In the examples that rely on a database, I used SQL Server 2012 Developer Edition. You may also use some later version of the product if you so wish. Throughout the book we use data from the Northwind sample database. So, you need it ready in the SQL Server. You can download the required scripts from Microsoft s official web site. xxi

18 Introduction SQLXML 4.0 SP1: In the examples that discuss SQLXML programming, you need SQLXML 4.0 SP1 installed on your machine. It can be downloaded from Microsoft s official web site. Sandcastle Help File Builder (SHFB): In the examples that discuss XML code commenting, you need SHFB to generate the documentation. You can download it from its GitHub page. Browser: In the examples that require a web browser, I used Firefox. But any other browser should also work. Structure of This Book The book is divided into 13 chapters and two appendices. Chapters 1 to 4 talk about navigating, reading, and writing XML documents by using classes from the System.Xml namespace. In these chapters, you learn to use classes such as XmlDocument, XmlReader, XmlWriter, and XPathNavigator. Manipulating XML data is just one part of the story. Often you need to validate and transform it so that it becomes acceptable to your system. Chapters 5 and 6 deal with XML document validation and XSLT transformations, respectively. The.NET Framework technologies themselves use XML in many ways. This is often under the hood, but for any XML developer, knowing where this occurs is essential. To that end, Chapters 7 to 10 cover topics such as ADO.NET integration with XML, XML serialization, and ASMX/WCF/Web API services. Microsoft has not limited the use of XML only to areas such as ADO.NET, serialization, and services. SQL Server incorporates many XML-related features. These features are discussed in Chapter 11. Although this topic isn t strictly one of the XML features of.net Framework, many developers will find it useful, because many real-world projects developed using the.net Framework use SQL Server as a datastore. Chapter 12 covers many other areas where the.net Framework uses XML. Some of them include XAML, ASP.NET server controls, XML configuration files, and XML comments. Language Integrated Query (LINQ) includes what is known as LINQ to XML. It can be used to handle XML data in LINQ-style. Chapter 13 is dedicated to this programming model. Here, you will learn about core LINQ to XML features, including parsing and loading XML trees the LINQ to XML way and validating and projecting XML data. Finally, the two appendices supplement what you learned throughout the book by providing some more information and resources. Downloading the Source Code The complete source code for the book is available for download at the book s companion web site. Visit and go to this book s information page. You can then download the source code from the Source Code/Downloads section. Contacting the Author You can reach me via my web site at You can also follow me on various social networking sites (visit my web site for the links). xxii