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

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As a result, the page first executes the client-side script associated with the HTMLbutton and fills the control with the XML data. Next the browser posts the page back tothe server as the submit button type mandates. This behavior is undesired for a coupleof reasons. First, it produces an unneeded round-trip to the Web server. Second, theround-trip cancels the changes to the user interface that have been made on the clientand that constitute the core of our efforts and our main reason for building and using amanaged control. On the other hand, the Windows Forms control is not a server-sidecontrol and does not have access to the ViewState property to control its state whenthe page posts back.This problem has a simple workaround: don't use the tag to insert abutton that is expected to interact with the managed control through client-side scriptcode. Instead, use the tag and explicitly set the type attribute to button, asshown in the following code:Also, don't set the runat attribute; if you do, the onclick attribute will be mistaken forserver-side code to be executed. In this way, the browser executes the associatedclient-side script code and refreshes the page accordingly, but no postback occurs.Using Hidden Fields and SQL QueriesDespite the fact that the tag is the official way of defining XML data islands withInternet Explorer, a hidden field is probably a better solution. With a hidden field,Internet Explorer doesn't preprocess the XML data into a COM-based XML DOMobject. This feature is welcome if you are going to process the XML data using scriptcode. No parsing is needed if you only plan to pass the XML data island to a managedcontrol, however. Using a hidden field or a hidden tag is a valid approach to insertingXML data in the body of an HTML page.The following code illustrates how to create a hidden field that contains dynamicallygenerated XML data. The data is the output you get from the XML normal form of aDataSet object. In this sample code, the DataSet object is obtained by running a queryagainst the Customers table in the Northwind database.private void Page_Load(object sender, EventArgs e){if (!IsPostBack){string xmldata = GetDataAsXml();RegisterHiddenField("xml", xmldata);}}private string GetDataAsXml(){SqlDataAdapter adapter = new SqlDataAdapter("SELECT customerid, companyname, contactname,contacttitle, city, country FROM customers",501
"SERVER=localhost;DATABASE=northwind;UID=sa;");DataSet ds = new DataSet();adapter.Fill(ds);return ds.GetXml();}Figure 14-5 shows the sample page in action.Figure 14-5: The sample page now shows filtered data from the Customers table. The XMLdata has been carried using a hidden field.NoteAnother key technique you can use to refresh the page using clientsidedata leverages DHTML. Although this approach can beeffective and powerful, it doesn't combine well with managed code.DHTML refers to the page object model and is designed forscripting. The page object model is exposed as a suite of COMobjects, and driving it from within managed code is certainlypossible but not particularly easy.ConclusionUsing XML data islands to import sensitive data into HTML pages is a technique thatdeserves further investigation. Creating XML data islands is easier with ASP.NET butwas not rocket science even prior to the advent of the .NET Framework. Accessing thecontents of a data island on the client is still based on Javascript code, and therefore isnot a feature that has been affected by the .NET Framework. So what's the problemwith using XML and the .NET Framework on the client?The .NET Framework classes provide a far richer object model that has a lot to offer interms of XML data manipulation, as we saw in Chapter 8, Chapter 9, and Chapter 10.Exploiting this bounty of functions on the client is possible thanks to the browserdeployableWindows Forms controls that we examined in this chapter. Code that usesXML and the .NET Framework on the client, although based on ASP.NET code, is notInternet-oriented because it imposes two key restrictions on the client environment: the502
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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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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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Page 485 and 486: Mobile code allows you to send C# o
Page 487 and 488: Chapter 14: XML on the ClientOvervi
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
Page 495 and 496: To create a hidden field, you can u
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Page 499 and 500: {}int size = 130;this.Columns.Add(m
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
Page 517 and 518: The myfile.config file contains the
Page 519 and 520: Some internal variablesXmlNodeList
Page 521 and 522: scratch or inherit from an existing
Page 523 and 524: Table 15-2: Predefined Section Hand
Page 525 and 526: The interface includes a single met
Page 527 and 528: NameValueCollection coll;coll = Con
Page 529 and 530: }if (configMenu != null)AddMenuTool
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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