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

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The XPath Query EngineXPath is a language that allows you to navigate within XML documents. Think of XPathas a general-purpose query language for addressing, sorting, and filtering both theelements and the text of an XML document.The XPath notation is basically declarative. Any XPath expression is a path within theXML document that identifies the information with the given characteristics. The pathdefines a pattern, and the resulting selection includes all the nodes that match it. Theselection is expressed through a notation that emphasizes the hierarchical relationshipbetween the nodes. It works in much the same way files and folders work. For example,the XPath expression "book/publisher" means find the "publisher" element within the"book" element. The XPath navigation model works in the context of a hierarchy ofnodes in the XML document's tree. XPath makes use of a variation of theXmlDocument class, named XPathDocument.Running an XPath query is not actually different from executing a TransactSQL (T-SQL) query on SQL Server. Instead of getting back a collection of rows, a valid XPathexpression returns a collection of nodes. To scroll the returned nodes, you just use anXPath-customized version of a reader. We'll look at XPath in more detail in Chapter 6.ConclusionIn this chapter, we examined the building blocks of XML and explored the rationalebehind XML readers and writers—a new and innovative way to perform basicoperations on XML data sources. In the .NET Framework, XML readers introduce adatabase-like cursor model to navigate through data. The cursor model fallssomewhere between the well-known XMLDOM and SAX models. Not as expensive asXMLDOM and more programmer-friendly than SAX, the .NET Framework cursor modelpresents XML as just another data format you can work on using a familiar approach.As a developer, you are certainly familiar with I/O operations accomplished on a file ora database. Why should XML data sources be totally different? The node becomes justanother atomic element, along with the database row or the byte. Ad hoc methodsmake it possible for you to move through nodes in a straightforward, effective way.Readers and writers are not the only tools you can use to create XML-driven .NETapplications. Another group of classes work according to the specification of the W3CDOM. XSLT and XPath expressions are a pair of XML-related technologies that arepopular with developers and effective for arranging applications. In the .NETFramework, you find made-to-measure classes that make XML-to-XML transformationand query evaluation fast and easy.All the XML technologies introduced in this chapter will be covered in depth in thechapters that follow, beginning with XML readers in Chapter 2.Further ReadingThe W3C organization is currently working on a draft of the DOM Level 3 Core toinclude support for an abstract modeling schema and I/O serialization. Check out themost recent draft at http://www.w3.org/TR/2002/WD-DOM-Level3-ASLS-20020409. Theapproved standard—DOM Level 2 Core—is available at http://www.w3.org/TR/DOM-Level-2.Relevant information about XML standards is available from the W3C Web site, athttp://www.w3.org. If you want to learn more about the SAX specification, look at thenew Web site for the SAX project, at http://www.saxproject.org.19
A lot of useful developer-oriented documentation about XML is available on the Websites of the companies that support XML. In addition to the Microsoft Web site(http://msdn.microsoft.com/xml), check out the Intel Developer Services Web site(http://cedar.intel.com). In particular, you'll find an essential guide to XML in the .NETFramework: http://cedar.intel.com/media/pdf/dotnet/net_jumpstart.pdf.Finally, if you just want a good, all-encompassing book about XML programming, Iheartily recommend the Microsoft Press Core Reference book XML Programming(http://www.microsoft.com/mspress/books/4798.asp), by R. Allen Wyke, SultanRehman, and Brad Leupen (Microsoft Press, 2002). For a more general look into XMLas a unifying technology, Essential XML: Beyond Markup (Addison Wesley, 2000), byDon Box, Aaron Skonnard, and John Lam, is still one of the best books available.20
Page 2 and 3: Applied XML Programming for Microso
Page 4 and 5: services. Rainer Heller of Siemens
Page 6 and 7: IntroductionIt was about five years
Page 8 and 9: What Do I Need to Use This Book?Mos
Page 10 and 11: Part I: XML Core Classes in the .NE
Page 12 and 13: Related XML StandardsTable 1-1 list
Page 14 and 15: XMLDOM model (memory footprint and
Page 16 and 17: ⋮A configuration section handler
Page 18 and 19: managed application, you must first
Page 20 and 21: Figure 1-1: Streams can be read and
Page 22 and 23: abstraction and explicitly indicate
Page 26 and 27: Chapter 2: XML ReadersIn the Micros
Page 28 and 29: Table 2-1: Public Properties of the
Page 30 and 31: Table 2-3: Public Methods of the Xm
Page 32 and 33: Table 2-4: Types of Nodes in the Xm
Page 34 and 35: To produce these results, I created
Page 36 and 37: In particular, the XmlConvert class
Page 38 and 39: The method we create to do this is
Page 40 and 41: Consider the following attribute va
Page 42 and 43: An entity reference consists of the
Page 44 and 45: The NameTable ObjectOne of the secr
Page 46 and 47: End ClassByVal type As XmlNodeType)
Page 48 and 49: Fragments and Parser ContextThe con
Page 50 and 51: You can specify other settings for
Page 52 and 53: FullerAndrewSales ManagerLeverlingJ
Page 54 and 55: String[] m_headerValues;tokensbool
Page 56 and 57: get{if(m_readState != ReadState.Int
Page 58 and 59: }public override string this[string
Page 60 and 61: }}return false;The name of the attr
Page 62 and 63: dt.Columns.Add(col);}reader.MoveToE
Page 64 and 65: Readers and XML ReadersTo cap off o
Page 66 and 67: Chapter 3: XML Data ValidationOverv
Page 68 and 69: The XmlValidatingReader Programming
Page 70 and 71: The ValidationEventHandler EventThe
Page 72 and 73: 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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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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