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

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XSDs are more powerful than DTDs, and more important, they recently achieved W3Crecommendation status, so they are a standard too.So when should you use DTDs instead of XSDs, and under what circumstances willDTDs give you a better trade-off? Compatibility and legacy code are the only possibleanswers to these questions. Especially if your application handles complex DTDs,porting them to an XSD can be costly and is in no way an easy task. There is no officialand totally reliable tool to automatically convert DTDs to schemas. On the W3C Website (www.w3.org), you'll find a conversion tool available for download, but I wouldn'ttrust it to do the job unsupervised and then take the output as a trustworthy result.Converting DTDs to schemas is no simple matter—in fact, it can be as complex astranslating spoken languages. Translating from English to Italian, for example, requiresa reengineering of the entire text, not just an adaptation of individual words andsentences. So design is deeply involved. When converting DTDs to schemas, youshould also consider rearchitecting tags into types and perhaps rearchitecting the wayyou expose data in light of the new features.Certainly XSDs provide you with more functions than DTDs can. For one thing,schemas are all written in XML and don't require you to learn a new language. If youlook at our basic DTD example in this context, you might not be scared by its unusualformat. As you move from textbook examples and enter the tough real world, thecomplexity of an inflexible language like DTD becomes more apparent.XSDs provide you with a finer level of control over the cardinality of the tags and theattribute types. In addition, XSDs can be used to set up a system of schema inheritancein which more complex types are built atop existing ones.All in all, if you currently have a huge, complex DTD, probably the best thing you can dois continue working with it while you carefully plan a migration to XSDs. DTDs andXSDs are both renowned standards, but especially if you are exchanging data betweenheterogeneous platforms, you're more likely to find a DTD-compliant parser than anXSD-compliant one. This situation will change over time, but not anytime soon. Checkthe supported functions for the XML parsers available on the target platform carefullybefore you drop DTDs.Using XDR SchemasAs mentioned, XML-Data Reduced (XDR) schema validation is the result of a Microsoftimplementation of an early draft of what today is XSDs. XDR was implemented for thefirst time in the version of MSXML that shipped with Microsoft Internet Explorer 5.0,back in the spring of 1999.In the XDR schema specification, you'll find almost all of the ideas that characterizeXSDs today. The main reason for XDR support in the .NET Framework is backwardcompatibility with existing MSXML-based applications. To enable these applications toupgrade properly to the .NET Framework, XDR support has been retained intact. Youwill not find XDR support anywhere else outside the Microsoft Windows platform,however.If you have used Microsoft ActiveX Data Objects (ADO), and in particular the library'sability to persist the contents of a Recordset object to XML, you are probably a veteranof XDR. In fact, the XML schema used to persist ADO 2.x Recordset objects to XML issimply XDR.81
Overview of XDR SchemasThe example XML document data_dtd.xml used to demonstrate DTDs containsinformation about the modules in which a given class is articulated. The following listingshows the XDR schema that provides a full description of the class:82
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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
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
Page 74 and 75: document, no event is fired, but an
Page 76 and 77: valtype = "Auto.XDR";Figure 3-2 sho
Page 78 and 79: validator object for further proces
Page 80 and 81: );This method creates and adds a ne
Page 82 and 83: public XmlValidatingReader(Stream,
Page 84 and 85: XML InteroperabilityAs you can see,
Page 88 and 89: Compared to the DTD schema, this XD
Page 90 and 91: xmlns:z='#RowsetSchema'>This simple
Page 93 and 94: Figure 3-7: The XSD type hierarchy.
Page 95 and 96: Table 3-6: Mapping Between XSD and
Page 97 and 98: Table 3-7: Top-Level Elements for X
Page 99 and 100: The next step is to define a new sc
Page 101 and 102: Creating an XML Schema with Visual
Page 103 and 104: Figure 3-10: The graphical represen
Page 105 and 106: Open the XML readerXmlTextReader re
Page 107 and 108: Define the pattern for the contentX
Page 109 and 110: ody of the element. It is a simple
Page 111 and 112: determine the correct sequence and
Page 113 and 114: The root element can't be successfu
Page 115 and 116: Francesco Balena's Programming Visu
Page 117 and 118: }sw.Write(sb.ToString());sw.Close()
Page 119 and 120: What the XmlWriter Class Can't DoAl
Page 121 and 122: stream. Some working memory is free
Page 123 and 124: Table 4-5: Miscellaneous Writing Me
Page 125 and 126: If you want to get just the default
Page 127 and 128: else you might need that the writer
Page 129 and 130: By using the pubid argument (PUBLIC
Page 131 and 132: Figure 4-3: A dynamically created X
Page 133 and 134: This command executes normally, but
Page 135 and 136: "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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