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

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' Get the results as a XMLDOMSet xmldoc = xmlhttp.responseXml' Extract the XML-based image description from the responseimg = xmldoc.text' Store the results in a file named RAW_OUTPUT.XMLSet fso = CreateObject("Scripting.FileSystemObject")Set f = fso.CreateTextFile("raw_output.xml")f.Write imgf.Close' Extract the JPEG image from raw outputSet shell = CreateObject("WScript.Shell")shell.Run "jpegextractor.exe raw_output.xml image.jpg"This script first invokes the method and gets the results as an XML Document ObjectModel (XML DOM) object. The inner text of the document is saved to a local variableand then to a temporary file (raw_output.xml). Finally, a small managed utility(jpegextractor.exe) parses the XML stream, extracts and decodes the JPEG bits, andsaves them to a file. The result is a JPEG file representing the sales report for the yearyou specify.NoteThe jpegextractor.exe utility is available as source code in thisbook's sample files, along with the Web service, the scripts, and theclient applications discussed in this chapter..NET Remoting vs. Web ServicesWeb services were designed to overcome a few Web architecture problems—particularly in the area of component interoperability. Web services are key tools foraccessing otherwise inaccessible functionalities exposed over heterogeneous hardwareand software platforms.If we stopped our analysis here, the conclusion would be rather obvious: Web servicesare the first fundamental software development of the new millennium. Although Webservices will certainly represent a milestone in the history of computer programming,the more we design them and use them, the more we realize they have seriouslimitations. Subsequently, and perhaps unfortunately, using a Web service isn't alwaysthe best solution.Which Came First?I perceive the .NET Framework Web services as a special case of .NET Remoting, butone could argue for the opposite scenario as well. Putting Web services at the center ofthe interoperability universe and considering .NET Remoting as a platform-specific477
implementation does make a lot of sense. In general, the way you look at the newestMicrosoft remoting technologies depends on your individual perspective.If you look at interoperability from a .NET Framework–specific viewpoint, you willprobably agree with my perception and put Web services on a secondary plane. If yoursituation spans more vendors and more platforms, you'll recognize that theunquestionable similarity between the Web service API and the .NET Remoting APIstems from the fact that .NET Remoting has stolen some features from the Web servicespecification.So which came first, the .NET Remoting egg or the Web service chicken? If you'reconsidering .NET Remoting, you are looking at Microsoft's remoting technologiesmostly from a .NET Framework perspective. The key issue is slightly different, however.Instead of focusing on which technology came first, you should ask what eachtechnology can do for you. And your final choice should favor the technology that mostclosely meets your needs.When to Use .NET Remoting.NET Remoting is ideal for .NET-to-.NET communication. More exactly, it's beendesigned for precisely that purpose. As a .NET Framework–specific technology, .NETRemoting lets you use all common language runtime (CLR) types, detects and handleslocal calls differently, and distinguishes the atomic unit of processing at a differentlevel—the application domain (AppDomain) level instead of the process level. And.NET Remoting increases its performance by allowing the use of binary protocols.The Special Case of Win32/COMIf you need to set up communication between a .NET Framework application and aWin32 or COM application, you might consider an ad hoc DLL, a COM object, or even amemory mapped file as an alternative to using Web services. In this scenario, you can'tuse .NET Remoting because one of the applications is either a Win32 or a COMapplication—that is, a non-.NET-Framework application.When to Use Web ServicesWeb services are ideal in a couple of scenarios. First, they are the only safe way to goif your goal is targeting a non-Microsoft platform. If you have to access code running onLinux or want to make your .NET Framework component available to a Linux client, byall means, go for Web services. Second, you should use Web services when,irrespective of the involved platforms, the user requirements mandate that theapplication must be programmatically accessible through a URL.Web Service IssuesAs a software application that makes itself available only through Internet connections,a Web service is at risk of being, or becoming, a slow application. For this reason,optimization is more than ever a critical factor. Overall performance is affected mostlyby the network latency but also, in small part, by the format of the protocol being used.HTTP and SOAP are both based on text, and SOAP in particular is a quite verboseprotocol. This results in packets significantly larger than those typical of binary protocolssuch as Common Object Request Broker Architecture (CORBA) or even DistributedCOM (DCOM).When trying to improve the usability of a Web service (the area in which you shouldfocus your optimization efforts), you should address the following tasks:• Performing asynchronous calls478
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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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Page 433 and 434: handled by .NET Remoting; the user
Page 435 and 436: Figure 12-3: How .NET Remoting mars
Page 437 and 438: If you want to play with the transp
Page 439 and 440: The query involves three tables—E
Page 441 and 442: As we saw in Chapter 4, the XmlText
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Page 445 and 446: We'll look more closely at channels
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Page 449 and 450: Figure 12-5: The IIS application ma
Page 451 and 452: this little requirement is enough t
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Page 455 and 456: }The code in boldface demonstrates
Page 457 and 458: BinaryWriter writer = new BinaryWri
Page 459 and 460: Chapter 13: XML Web ServicesOvervie
Page 461 and 462: intSOAP is not magic—it is a simp
Page 463 and 464: public class MyWebService : WebServ
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Page 467 and 468: Format of SOAP Messages for a Web M
Page 469 and 470: The SoapRpcMethod AttributeThe RPC
Page 471 and 472: If you compare this code with the r
Page 473 and 474: Figure 13-5: Processing a Web servi
Page 475 and 476: The machine.config file is an XML f
Page 477 and 478: Namespace="xmlnet/cs/0735618011")]p
Page 479 and 480: In situations in which the URL can'
Page 481: Const TheYear = 1997' Create the HT
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
Page 497 and 498: To load assemblies from directories
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
Page 505 and 506: var parser = new ActiveXObject("Mic
Page 507 and 508: "SERVER=localhost;DATABASE=northwin
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
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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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