Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

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CautionThe main purpose of the assembly cache is to save you fromrepeatedly re-creating the assembly for the same type in thesame application session. Unfortunately, this seems to work onlyif you use the simplest XmlSerializer constructor, as shown here:XmlSerializer ser = new XmlSerializer(type);All other constructors—that is, those that can acceptnamespaces, type mapping, and attribute overrides—never lookinto the cache to find matching assemblies. The net effect of thisbehavior is that if you use, say, attribute overrides, as we didearlier, the assembly for the type is generated each time youcreate the constructor, even if the type is always the same.To work around this, use global instances of the XmlSerializerclass, one for each type you plan to work on. This workaround isnot strictly required if you use the simple constructor, but using aglobal serializer for each type results in slightly more efficientcode because you avoid any access to the cache, and not doingso will certainly result in significantly slower code. Generatingthe assembly pays for itself in a single serializing or deserializingoperation.Assembly CreationThe assembly is created from dynamically generated C# source code. The codecontains two classes whose names are hard-coded as XmlSerializationReader1 andXmlSerializationWriter1. The former class works like a tailor-made reader for the typebeing deserialized. The latter class is an ad hoc writer that dumps out to XML thecontents of the specified object instance. The classes are generated in theMicrosoft.Xml.Serialization.GeneratedAssembly namespace.The serializer's constructor uses an internal code-writer object to transform all typeinformation stored in XmlTypeMapping into C# source code. The C# source file, as wellas the assembly, are generated in a temporary folder—the path returned byPath.GetTempPath. Normally, the following temporary path is used:C:\Documents And Settings\[user name]\Local Settings\TempIf you monitor this folder with a tool like the one shown in Figure 11-5, you'll discoverwhat really happens when you call the XmlSerializer constructor.Figure 11-5: Unveiling the clandestine life of the temporary assembly.419
As you can see, the first file created is a C# source file whose name has been randomlygenerated. Next the serializer invokes the C# compiler, and the assembly is sooncreated! The files are cached in memory and deleted from disk immediately after havingbeen created. It's almost impossible to programmatically catch those files and make acopy for further perusal. The XML Serialization Notifier tool (XmlSerial_CS) shown inFigure 11-5 (and available in this book's sample files) uses the FileSystemWatcherclass to monitor file system events that take place in a given folder. The only trick I'vecome up with to get my hands on the serializer's internal files is dropping the deletepermission on the folder.Figure 11-6 shows the files generated using this trick for the serializer instance shownin Figure 11-5.Figure 11-6: The ILDASM view of the temporary assembly's contents.Serialization Writers and ReadersLet's take a brief look at what happens under the hood of the XmlSerialization-Readerand XmlSerializationWriter classes. The MSDN documentation touches on these twoclasses, which form the substrate of the classes contained in the temporary assembly.The XmlSerializationReader and XmlSerializationWriter classes are internal and are notintended to be used directly from user code. More interesting than the actual contentsof the classes is how the Serialize and Deserialize methods interact with them.Serializing to XMLThe Serialize method first gets a reference to the class-specific type writer. An instanceof the XmlSerializationWriter1 class is returned by the TempAssembly class thatrepresents the temporary assembly. Once the Serialize method holds a reference to theactual serialization writer, it calls the write method that outputs XML code to a textwriter.Deserializing from XMLAlthough a CanDeserialize method is provided, the Deserialize method never calls it. Ifthe type is not fully serializable, or if errors occurred somewhere along the way, theDeserialize method fails, throwing an exception.If no errors occur, the Deserialize method asks the temporary assembly to return areference to the reader object to be used. The reader object is simply an instance of theXmlSerializationReader1 class. The method that actually returns the object is one of theReadN_XXX methods, where N is the method index and XXX is the type.420
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Applied XML Programming for Microso
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services. Rainer Heller of Siemens
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IntroductionIt was about five years
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What Do I Need to Use This Book?Mos
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Part I: XML Core Classes in the .NE
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Related XML StandardsTable 1-1 list
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XMLDOM model (memory footprint and
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⋮A configuration section handler
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managed application, you must first
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Figure 1-1: Streams can be read and
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abstraction and explicitly indicate
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The XPath Query EngineXPath is a la
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Chapter 2: XML ReadersIn the Micros
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Table 2-1: Public Properties of the
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Table 2-3: Public Methods of the Xm
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Table 2-4: Types of Nodes in the Xm
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To produce these results, I created
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In particular, the XmlConvert class
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The method we create to do this is
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Consider the following attribute va
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An entity reference consists of the
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The NameTable ObjectOne of the secr
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End ClassByVal type As XmlNodeType)
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Fragments and Parser ContextThe con
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You can specify other settings for
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FullerAndrewSales ManagerLeverlingJ
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String[] m_headerValues;tokensbool
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get{if(m_readState != ReadState.Int
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}public override string this[string
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}}return false;The name of the attr
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dt.Columns.Add(col);}reader.MoveToE
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Readers and XML ReadersTo cap off o
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Chapter 3: XML Data ValidationOverv
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The XmlValidatingReader Programming
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The ValidationEventHandler EventThe
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Figure 3-1: The sample application
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document, no event is fired, but an
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valtype = "Auto.XDR";Figure 3-2 sho
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validator object for further proces
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);This method creates and adds a ne
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public XmlValidatingReader(Stream,
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XML InteroperabilityAs you can see,
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XSDs are more powerful than DTDs, a
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Compared to the DTD schema, this XD
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xmlns:z='#RowsetSchema'>This simple
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Figure 3-7: The XSD type hierarchy.
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Table 3-6: Mapping Between XSD and
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Table 3-7: Top-Level Elements for X
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The next step is to define a new sc
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Creating an XML Schema with Visual
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Figure 3-10: The graphical represen
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Open the XML readerXmlTextReader re
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Define the pattern for the contentX
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ody of the element. It is a simple
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determine the correct sequence and
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The root element can't be successfu
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Francesco Balena's Programming Visu
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}sw.Write(sb.ToString());sw.Close()
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What the XmlWriter Class Can't DoAl
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stream. Some working memory is free
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Table 4-5: Miscellaneous Writing Me
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If you want to get just the default
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else you might need that the writer
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By using the pubid argument (PUBLIC
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Figure 4-3: A dynamically created X
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This command executes normally, but
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"dinoe:isbn-0735618011");This code
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writer.WriteStartElement("element")
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}writer.WriteEndDocument();writer.C
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}}reader.Close();If in this code yo
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Figure 4-8: A PictureBox control di
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NoteThe entire source code for a sa
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Table 4-8: Public Methods of the Xm
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}Writer.WriteStartElement("xml");Wr
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Testing the XmlRecordsetWriter Clas
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Framework type and map each to an e
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}if (i % 2)writer.WriteNode(reader,
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Table 4-9: Methods of the XmlTextRe
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while(rw.Read()){switch(rw.NodeType
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if (m_reader.HasAttributes){// Cons
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Figure 4-14: The code can be used t
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}}rw.Writer.WriteStartElement(rw.Re
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Note The new keyword is C#-specific
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}The net effect of this code is tha
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.NET XML writers only ensure the we
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Part II: XML Data ManipulationChapt
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3JanetLeverlingWhen processed by an
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child elements when processing an X
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through the base class XmlNode. (Se
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Table 5-3: Events of the XmlDocumen
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Both XmlLinkedNode and XmlCharacter
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Figure 5-3: The XmlLinkedNode class
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Working with XML DocumentsTo be ful
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}}{if (n.NodeType == XmlNodeType.El
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While the secondary thread works, t
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Limitations of the XML DOM Eventing
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XML document is often overkill unle
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If you use a namespace, you might r
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Extending the XML DOMAlthough the .
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Table 5-6: Programming Interface of
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file changes, irrespective of the c
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Figure 5-7: The sample application
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Chapter 6: XML Query Language and N
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Figure 6-1: A sample XML tree in wh
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with the forward slash (/). The fol
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How XPointer Uses XPathAn XPointer
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the caller. Using SelectSingleNode
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StringBuilder sb = new StringBuilde
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Figure 6-4: The node set returned b
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A Better Way to Select a Single Nod
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3. Optionally, precompile the XPath
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Table 6-3: Properties of the XPathN
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the type. In addition, attributes a
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As you can see, several methods hav
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Setting Namespace InformationThe in
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string strX = (string) x;string str
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the navigator's author must careful
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⋮Notice that the sample file syst
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Table 6-10: Properties of the XPath
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supplies the underlying means to id
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• XSL Formatting Objects (XSL-FO)
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HTML," on page 299. In the meantime
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Table 7-2: XSLT Instructions for Da
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Table 7-4: XSLT Instructions for La
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In the first template, the context
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……⋮The expected target schema
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By the way, note that the version a
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The XslTransform ClassNow that we'v
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To avoid threading risks, be aware
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index of the style sheet contents.
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Table 7-7: Transform Method Overloa
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XSLT Output RecordsThe output of th
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Perform the transformation, record
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method, other attributes of interes
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Table 7-8: Methods of the XsltArgum
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the object's DataSetName property.
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s:rowbaseAfter you create the node
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features than the XslTransform clas
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Don't confuse the Internet Explorer
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Supported languages are C#, Visual
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double CalculateSubTotal(XPathNodeI
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profitable, because XML is a metala
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Chapter 8: XML and DatabasesOvervie
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Framework applications. SQLXML 3.0
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......The FOR XML AUTO mode always
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Figure 8-1: The client-side XML for
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lastname AS [Employee!1!Name]This s
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sql:field="FirstName" type="xsd:str
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to instantiate a COM object, query
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}// Process elementswhile(reader.Re
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(No context information specified)X
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}...The base class is for the most
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public override void Close(){m_data
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Synchronizing with a DataSet Object
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denote insertions, deletions, and u
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schema information to associate the
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This schema first defines a relatio
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that throughout the Updategram. The
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object for XML-driven updates, an A
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Table 8-2: Properties of the SqlXml
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Table 8-4: Methods of the SqlXmlCom
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This schema addresses a layout such
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database. If all goes well, the Dat
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Chapter 9: ADO.NET XML Data Seriali
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provided way to serialize ADO.NET o
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1DavolioNancy⋮106897⋮Basically,
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The element describes the body of
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Serializing to Valid XMLAs you can
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Table 9-3: The MappingType Enumerat
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⋮This syntax is simple and effect
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By using keyref and nested types, y
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Figure 9-6: An application that pas
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{}DataTable dt = CreateTempTable(dv
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dt = (DataTable) bf.Deserialize(sr.
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more valuable, because it automatic
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Loading DataSet Objects from XMLThe
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The XML source is read one node aft
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Figure 9-10: ReadXml correctly reco
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Figure 9-12: How Microsoft Visual S
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The reader tracks the current node
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}m_currentAttributeIndex = -1;When
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persistence, resort to the DiffGram
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......The root node can have up to
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object's tables. The data written o
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different blocks. Attributes in the
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Page 381 and 382: ...By design, the current DiffGram
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Page 395 and 396: 0As you can see, the class represen
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Page 427 and 428: A good source for learning about SO
Page 429 and 430: NoteSome programmers believe that .
Page 431 and 432: involved, you must use Web services
Page 433 and 434: handled by .NET Remoting; the user
Page 435 and 436: Figure 12-3: How .NET Remoting mars
Page 437 and 438: If you want to play with the transp
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Page 441 and 442: As we saw in Chapter 4, the XmlText
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Page 463 and 464: public class MyWebService : WebServ
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Page 467 and 468: Format of SOAP Messages for a Web M
Page 469 and 470: The SoapRpcMethod AttributeThe RPC
Page 471 and 472: If you compare this code with the r
Page 473 and 474: Figure 13-5: Processing a Web servi
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The machine.config file is an XML f
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Namespace="xmlnet/cs/0735618011")]p
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In situations in which the URL can'
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Const TheYear = 1997' Create the HT
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implementation does make a lot of s
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Mobile code allows you to send C# o
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Chapter 14: XML on the ClientOvervi
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accessible XML parser to consume th
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The following code shows a version
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NoteIn general, you can name the ou
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To create a hidden field, you can u
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To load assemblies from directories
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{}int size = 130;this.Columns.Add(m
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private void PrepareSortedDataView(
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Figure 14-3: An ASP.NET page that c
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var parser = new ActiveXObject("Mic
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"SERVER=localhost;DATABASE=northwin
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Chapter 15: .NET Framework Applicat
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Because we're focusing on applicati
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executable, ASP.NET application or
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NoteUser applications don't need to
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The myfile.config file contains the
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Some internal variablesXmlNodeList
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scratch or inherit from an existing
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Table 15-2: Predefined Section Hand
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The interface includes a single met
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NameValueCollection coll;coll = Con
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}if (configMenu != null)AddMenuTool
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}}menuTools.MenuItems.Add(index, mn
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Implementing the DataSet Section Ha
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AfterwordOverviewWhile writing this
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not an application-specific object.
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