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

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makes coding significantly easier. In fact, programmers don't have to worry aboutpossible conflicts with other applications attempting to access the same port. Inaddition, dynamic port allocation also increases the overall level of flexibility becausethe particular communication port doesn't have to be hard-coded or persistedsomewhere as an application-specific argument. On the down side, systemadministrators don't usually agree to leave such a wide range of ports open to inboundtraffic because doing so could leave a major hole in security.NoteThe DCOM security model is based on the assumption thatdevelopers and administrators configure the security settingsproperly for each component. The net effect of this approach is thatthe same binary code works unchanged both in environments inwhich the security is of no concern (for example, on a local singlemachine) and in environments in which the code needs to beprocessed in a secure fashion (as in a fully distributed environment).DCOM Extensions for the InternetOver the years, DCOM has been extended to work around this security issue. Inparticular, the COM Internet Services (CIS) layer has given DCOM the capability towork over port 80 thanks to a new transportation protocol called TunnelingTransmission Control Protocol (TTCP). CIS works as an Internet Server ApplicationProgramming Interface (ISAPI) filter and requires Microsoft Internet InformationServices (IIS) 4.0 or later to run on the server machine. Basically, TTCP works byfooling the firewall. At the very beginning of each DCOM operation, TTCP shakeshands with the server, declaring its intention to use HTTP over port 80. If the firewallagrees, what follows is a traffic pattern of non-HTTP packets that are blissfully deliveredover port 80 of those firewalls that are lazy enough to accept binary packets overHTTP. All in all, CIS gives DCOM a good chance of entering through a window when itfinds that the front door is locked. This peculiarity also affects the way DCOMcomponents work. In fact, server components can't call back the client component tosink events or send notifications..NET Remoting to the RescueWhat's new and better with .NET Remoting? The advent of the .NET Frameworkpushed COM-related technology aside, and DCOM is no exception. The .NETFramework architecture for remoting arose completely redesigned, with two key goalsto pursue: allowing for seamless and location-independent coding while providing a fullyoperational way of interacting with restricted servers.NoteThe previous statement about the diminished status of COM-relatedtechnologies doesn't imply that existing COM components areobsolete in the new .NET world. On the contrary, the .NETFramework integrates seamlessly with COM components and theWin32 API through ad hoc interoperability mechanisms such asCOM Callable Wrappers (CCWs) and P/Invoke. By adopting a"leave-no-COM-object-behind" philosophy, the .NET Frameworkdesigners ensured the continued success of existing COM-relatedtechnologies even as developers migrate to the .NET Framework.The .NET Remoting classes allow for optimized and effective communication between.NET Framework applications. They don't offer even the possibility of being used in anyother scenario. For cross-platform scenarios in which heterogeneous environments are425
involved, you must use Web services. But if you need to set up communicationbetween two .NET Framework applications, nothing is better and more efficient than.NET Remoting.What Is .NET Remoting?The entire set of services that enable .NET Framework applications to communicatewith each other falls under the umbrella of .NET Remoting. Such applications canreside on the same computer, can work on different computers in the same LAN, andcan even be scattered across the world in heterogeneous networks but onhomogeneous platforms—that is, platforms that can host the common languageruntime (CLR) and access the .NET Framework.The .NET Remoting architecture enables you to use different transportation protocols,serialization formats, object lifetime schemes, and modes of object creation. In addition,programmers can directly plug into the flow of messages that each communicationoriginates and can hook up activities at various stages of the process.At a lower level of abstraction, however, the only thing .NET Remoting can do for you isenable communication and data exchange between different application domains(AppDomains).Application DomainsThe .NET Framework CLR provides a feature-rich execution environment for code.Within the CLR, code finds available services like garbage collection, security,versioning, and threading. Executable code must be loaded into the CLR to bemanaged while running, however.NoteCurrently, only the Microsoft Windows XP operating system isequipped with a CLR-aware program loader capable of running a.NET Framework executable within the context of a CLR instance.For compatibility with all non-XP Windows operating systems, all.NET Framework executables include a tailor-made stub programthat operating systems automatically launch when executables don'tmatch the current system platform. This stub passes the control toanother piece of code that instantiates the CLR and loads themanaged code into it. See the section "Further Reading," on page559, for additional resources on this topic.To run an application's code, the instance of the CLR must obtain a pointer to anAppDomain. AppDomains are separate units of processing that the CLR recognizes ina running process. All .NET Framework processes run at least one AppDomain—known as the default AppDomain—that is created during the CLR initialization. Anapplication can have additional AppDomains. Each AppDomain is independentlyconfigured and given personal settings for security, reference paths, and configurationfiles.AppDomains are separated and isolated from one another in a way that resemblesprocess separation in Win32. The CLR enforces isolation by preventing direct callsbetween objects residing in different AppDomains. From the CPU perspective,AppDomains are much more lightweight than Win32 processes and provide for a morelightweight mechanism of isolation between processing units. The .NET Frameworkprovides the remoting API as a tailor-made set of system services to access an objectthat resides in an external AppDomain. Figure 12-1 illustrates such an inter-AppDomaincommunication.426
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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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Page 381 and 382: ...By design, the current DiffGram
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Page 393 and 394: Chapter 11: XML SerializationOvervi
Page 395 and 396: 0As you can see, the class represen
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Page 421 and 422: {if (emp.Territories == null)emp.Te
Page 423 and 424: {// Import type mapping information
Page 425 and 426: As you can see, the first file crea
Page 427 and 428: A good source for learning about SO
Page 429: NoteSome programmers believe that .
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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
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Page 455 and 456: }The code in boldface demonstrates
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Page 459 and 460: Chapter 13: XML Web ServicesOvervie
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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
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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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