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

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model designed for interprocess communication. Another facet of this model is .NETXML Web services. Although .NET XML Web services allow you to expose .NETFramework objects to any client that can use HTTP, .NET Remoting is optimized for.NET-to-.NET communication. Communication between the client and the remotableobject can take place using SOAP or binary payloads transported over HTTP or TCP..NET Remoting can transfer any serializable CLR types; it is not limited to XML SchemaDefinition (XSD) types or complex custom types as rendered by the .NET XMLserializer.This chapter illustrated the key features of the .NET Remoting system and showed youhow to set up a remotable object that exposes nontrivial functionalities. In particular,you learned how to expose JPEG images through XML documents. Of course, if thegoal of your distributed system is simply to create and return dynamic images, .NETRemoting might not be for you. But from a broader standpoint that encompasses Webservices, .NET Remoting not only makes sense, it is also compelling. The examplewe've constructed in this chapter has two aims. First, it demonstrates that .NETRemoting and Web services are just two remoting interfaces and that the same coreclass can outfit both. Second, it shows that to come up with truly efficient and effectivecode, you must always take the most appropriate route and create specialized codeinstead of pursuing the promises of code universality and platform independence.This chapter covered only the first side of remoting—.NET Remoting for CLR types. InChapter 13, we'll look at Web services—a truly interoperable infrastructure ideal forrolling up your functionalities and making them available to a potentially infinite set ofclients.Further ReadingAlthough this chapter touched on all the key aspects of the .NET Remoting technology,it revealed only the tip of the iceberg. Throughout the chapter, I've noted severalaspects of .NET Remoting whose coverage was simply beyond the scope of a bookabout XML. Principal among the resources that cover these topics in more detail is theMSDN .NET Framework documentation, but many other appropriate resources are alsoavailable.I mentioned that Windows XP and newer systems boast a modified loader that looksdirectly into the source Portable Executable (PE) file to find .NET Framework-specificmetadata. To understand the entire loading process of managed executables inWindows XP as well as in Windows 2000, I know just one resource: Jeffrey Richter'sexcellent book Applied Microsoft .NET Framework Programming (Microsoft Press,2002).In the October 2002 issue of MSDN Magazine, you can find an article of mine that, likethis chapter, attempts to explain the ABCs of .NET Remoting. In that article, you'll find adeeper discussion of architectural aspects—channels, formatters, and sink chains—than we've covered here.The internal engine that performs memory management for instances of remote objectsis the lease manager (LM). Jeff Prosise, in Chapter 15 of his book ProgrammingMicrosoft .NET (Microsoft Press, 2002), explains a lot about it.Finally, if you're just looking for a complete .NET Remoting book, here it is: Microsoft.NET Remoting, by Scott McLean, James Naftel, and Kim Williams (Microsoft Press,2002).453
Chapter 13: XML Web ServicesOverviewThe term Web service is relatively new, but the idea behind Web services has beenaround for a while. A Web service is an interface-less Web site designed forprogrammatic access. This means that instead of invoking URLs representing Webpages, you invoke URLs that represent methods on remote objects. Similarly, insteadof getting back colorful and animated HTML code, you get back XML Schema Definition(XSD) data types packed in XML messages. Aside from these higher-level differences,the underlying models for a Web site and a Web service are the same. In addition, anysecurity measure you can implement on a Web site can be duplicated in a Web service.To summarize, the Web service model is just another programming model running ontop of HTTP.A Web service is a software application that can be accessed over the Web by othersoftware. Web services are applicable in any type of Web environment, be it Internet,intranet, or extranet. All you need to locate and access a Web service is a URL. Intheory, a number of Internet-friendly protocols might be working through that URL. Inpractice, the protocol for everyday use of Web services is always HTTP.How is a Web service different from a remote procedure call (RPC) implementation ofdistributed interfaces? For the most part, a Web service is an RPC mechanism thatuses the Simple Object Access Protocol (SOAP) to support data interchange. Thisgeneral definition represents the gist of a Web service, but it focuses only on the corebehavior. A Web service is more than just a business object available over an HTTPaccessiblenetwork. A number of evolving industry standards are supported today,including the Universal Description, Discovery, and Integration (UDDI) standard and theWeb Services Description Language (WSDL); others, such as the Web ServicesSecurity (WS-Security) and the Global XML Web Services Architecture (GXA), will besupported soon. These industry standards contribute to setting up a full and powerfulenvironment for remote object-oriented access and programming.In this chapter, we'll look at implementing and programming Web services in theMicrosoft .NET Framework. We'll also take a look at the Web infrastructure that makesthese services available and at the functionalities you can obtain and publish. Todemonstrate the breakthrough that Web services represent in the software industry,we'll rewrite the .NET Remoting code example from Chapter 12 to make it work as aWeb service. In doing so, we'll also be able to examine the differences between the.NET Remoting and Web service architectures and determine in which scenarios eacharchitecture is suitable.The .NET Framework Infrastructure for Web ServicesAlthough Web services and the .NET Framework were introduced at roughly the sametime, there is no strict dependency between the two, and the presence of one does notnecessarily imply the presence of the other. The .NET Framework is simply one of theplatforms that support Web services and that provide effective tools and system classesto create and consume Web services. No one person invented Web services, but all thebig players in the IT arena are rapidly adopting and transforming the raw idea of"software callable by other software" into something that fits their respectivedevelopment platforms.Regardless of how a Web service is created—and whether it is vendor-specific orplatform-specific—the way in which a Web service is exposed to the public is the same.454
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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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Page 425 and 426: As you can see, the first file crea
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Page 429 and 430: NoteSome programmers believe that .
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Page 435 and 436: Figure 12-3: How .NET Remoting mars
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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 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 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
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Page 499 and 500: {}int size = 130;this.Columns.Add(m
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Page 503 and 504: Figure 14-3: An ASP.NET page that c
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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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