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

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Creating a DataSet Section HandlerLet's look at a practical example of a new section handler namedDatasetSectionHandler. This section handler reads XML data from a configuration fileand stores it in a new DataSet object. The data must be laid out in a format that theReadXml method can successfully process. The typical format is the ADO.NET normalform that we examined in Chapter 9.Along with the custom section handler, let's write an application that can handleconfiguration data through a DataSet object. Suppose you have a Windows Formsapplication that can be extended with plug-in modules. We won't look at the details ofhow this could be done here; instead, we'll focus on how to effectively storeconfiguration data as XML. (In the section "Further Reading," on page 655, you'll find areference to a recent article that addresses this topic fully.) We'll analyze the plug-inengine for Windows Forms applications only, but the same pattern can be easilyapplied to Web Forms applications as well.Extending Windows Forms Application MenusThe sample application shown in Figure 15-2 allows users to add custom menu itemsbelow the first item on the Tools menu. Such menu items are linked to external plug-inmodules. In this context, a plug-in module is simply a class dynamically loaded from anassembly. More generally, the plug-in class will need to implement a particularinterface, or inherit from a given base class, because the application needs to have aconsistent way to call into any plug-in class. (For more information and a completeexample of extensible .NET Framework applications, check out the article referenced inthe section "Further Reading," on page 655. In our sample application, we'll limitourselves to creating a context-sensitive MessageBox call for each new registeredplug-in.Figure 15-2: A Windows Forms application that can be extended with plug-in modules thatintegrate with the menu.At loading, the sample application calls the following routine to set up the menu:private void SetupMenu(){// Access the menu config filestring path = "TypicalWinFormsApp/PlugIns";DataSet configMenu = (DataSet)ConfigurationSettings.GetConfig(path);// Add dynamic items to existing popup menus523
}if (configMenu != null)AddMenuToolsPlugIns(configMenu);The configuration settings—that is, the menu items to be added to the Tools menu—areread from the configuration file using the ConfigurationSettings class, as usual. Nothingin the preceding code reveals the presence of a custom section handler and acompletely custom XML schema for the settings. The only faint clue is the use of aDataSet object.After it has been successfully loaded from the configuration file, the DataSet object ispassed to a helper routine, AddMenuToolsPlugIns, which will modify the menu. We'llreturn to this point in the section "Invoking Plug-In Modules," on page 650; in themeantime, let's review the layout of the configuration file.The XML Layout of the Configuration SettingsThe data corresponding to plug-in modules is stored in a section group namedTypicalWinFormsApp. The actual section is named PlugIns. Each plug-in module isidentified by an assembly name, a class name, and display text. The display textconstitutes the caption of the menu item, whereas the assembly name and the classname provide for a dynamic method call. As mentioned, in a realworld scenario, youmight force the class to implement a particular interface so that it's clear to the callingapplication which methods are available for the object it is instantiating.Here is a sample configuration file for the application shown in Figure 15-2:Add new tool...MyToolsPlugInsMyPlugIn.AddNewToolSpecial tool...MyToolsPlugInsMyPlugIn.SpecialTool524
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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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If no match is found, ReadXml deduc
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Although this solution is clearly n
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The diffgr:error attribute on the r
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{}// Url is a form property that po
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...By design, the current DiffGram
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a DiffGram. To make DiffGrams reall
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Figure 10-8: The sample save-and-re
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dv.RowStateFilter = DataViewRowStat
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in the RowError property of the cor
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however, the verbosity of XML paten
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Chapter 11: XML SerializationOvervi
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0As you can see, the class represen
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ead-only properties; does not handl
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}public Employee(){m_ID = -1;}publi
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Methods of the XmlSerializer ClassT
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ns.Add("d", "urn:dino-e-xml");ns.Ad
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When designing classes destined to
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eferenced assembly and its properti
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The preceding code creates an attri
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}public string FirstName;public str
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XML as the type dictates. The attri
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create the XmlSerializer object. Ho
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command, the data flows into the se
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XmlAttributes changesFirstName = ne
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{if (emp.Territories == null)emp.Te
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{// Import type mapping information
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As you can see, the first file crea
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A good source for learning about SO
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NoteSome programmers believe that .
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involved, you must use Web services
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handled by .NET Remoting; the user
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Figure 12-3: How .NET Remoting mars
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If you want to play with the transp
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The query involves three tables—E
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As we saw in Chapter 4, the XmlText
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{// Propertiesprotected SalesDataPr
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We'll look more closely at channels
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server only when the client calls a
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Figure 12-5: The IIS application ma
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this little requirement is enough t
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typeof(ServiceSalesProvider),"tcp:/
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}The code in boldface demonstrates
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BinaryWriter writer = new BinaryWri
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Chapter 13: XML Web ServicesOvervie
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intSOAP is not magic—it is a simp
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public class MyWebService : WebServ
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effectively exposed over the Web, a
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Format of SOAP Messages for a Web M
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The SoapRpcMethod AttributeThe RPC
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If you compare this code with the r
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Figure 13-5: Processing a Web servi
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The machine.config file is an XML f
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Page 481 and 482: Const TheYear = 1997' Create the HT
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Page 485 and 486: Mobile code allows you to send C# o
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Page 489 and 490: accessible XML parser to consume th
Page 491 and 492: The following code shows a version
Page 493 and 494: NoteIn general, you can name the ou
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Page 501 and 502: private void PrepareSortedDataView(
Page 503 and 504: Figure 14-3: An ASP.NET page that c
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Page 509 and 510: Chapter 15: .NET Framework Applicat
Page 511 and 512: Because we're focusing on applicati
Page 513 and 514: executable, ASP.NET application or
Page 515 and 516: NoteUser applications don't need to
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Page 519 and 520: Some internal variablesXmlNodeList
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Page 523 and 524: Table 15-2: Predefined Section Hand
Page 525 and 526: The interface includes a single met
Page 527: NameValueCollection coll;coll = Con
Page 531 and 532: }}menuTools.MenuItems.Add(index, mn
Page 533 and 534: Implementing the DataSet Section Ha
Page 535 and 536: AfterwordOverviewWhile writing this
Page 537: not an application-specific object.
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