System.Xml Namespace

The supported standards include:

• XML 1.0 - http://www.w3.org/TR/1998/REC-xml-19980210 - including DTD support.

• XML Namespaces - http://www.w3.org/TR/REC-xml-names/ - both stream level and DOM.

• XSD Schemas - http://www.w3.org/2001/XMLSchema

• XPath expressions - http://www.w3.org/TR/xpath

• XSLT transformations - http://www.w3.org/TR/xslt

• DOM Level 1 Core - http://www.w3.org/TR/REC-DOM-Level-1/

• DOM Level 2 Core - http://www.w3.org/TR/DOM-Level-2/

The .NET Framework 4.5, provides a set of asynchronous APIs for XmlReader and XmlWriter, which are based on the Visual Studio Asynchronous Programming model. These APIs provide the ability to process XML asynchronously. It is preferable to use these APIs to perform XML operations with Network IO where latency is noticeable. With these asynchronous APIs, you can write the asynchronous code similar to the synchronous one. Also, you can transit your existing synchronous code to asynchronously code easily.

The following is a list of best practices for using the asynchronous APIs:

1. Use the asynchronous APIs in applications where there is significant network stream latency. Avoid using the asynchronous APIs for memory stream or local file stream reads and writes. Also, the input Stream, XmlTextReader and XmlTextWriter should support asynchronous operations as well, otherwise threads will still be blocked by IO operations.

2. Using a mix synchronous and asynchronous function calls is not encouraged since you may forget the use the await keyword on API, or use a synchronous API where an asynchronous one is need.

3. Do not set the Async or Async flag to true if you do not intend to use an asynchronous API.

4. If you forget to specify the await keyword when calling an asynchronous API, you may receive either an expected result or an exception, which is non-deterministic.

5. When reading a large text node, XmlReader may only cache a partial text value and return the text node, so retrieving Value may be blocked by an IO operation. Use the GetValueAsync method to get the text value in asynchronous mode. You may also use ReadValueChunkAsync to read a large text block chunk-by-chunk.

6. When using XmlWriter, call FlushAsync before calling Close to avoid blocking an IO operation.

Classes

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	Class	Description
	NameTable	Implements a single-threaded XmlNameTable.
	UniqueId	A unique identifier optimized for Guids.
	XmlAttribute	Represents an attribute. Valid and default values for the attribute are defined in a document type definition (DTD) or schema.
	XmlAttributeCollection	Represents a collection of attributes that can be accessed by name or index.
	XmlBinaryReaderSession	Enables optimized strings to be managed in a dynamic way.
	XmlBinaryWriterSession	Enables using a dynamic dictionary to compress common strings that appear in a message and maintain state.
	XmlCDataSection	Represents a CDATA section.
	XmlCharacterData	Provides text manipulation methods that are used by several classes.
	XmlComment	Represents the content of an XML comment.
	XmlConvert	Encodes and decodes XML names and provides methods for converting between common language runtime types and XML Schema definition language (XSD) types. When converting data types the values returned are locale independent.
	XmlDataDocument	Obsolete. Allows structured data to be stored, retrieved, and manipulated through a relational DataSet.
	XmlDeclaration	Represents the XML declaration node <?xml version='1.0'...?>.
	XmlDictionary	Implements a dictionary used to optimize Windows Communication Foundation (WCF)'s XML reader/writer implementations.
	XmlDictionaryReader	An abstract class that the Windows Communication Foundation (WCF) derives from XmlReader to do serialization and deserialization.
	XmlDictionaryReaderQuotas	Contains configurable quota values for XmlDictionaryReaders.
	XmlDictionaryString	Represents an entry stored in a XmlDictionary.
	XmlDictionaryWriter	Represents an abstract class that Windows Communication Foundation (WCF) derives from XmlWriter to do serialization and deserialization.
	XmlDocument	Represents an XML document.
	XmlDocumentFragment	Represents a lightweight object that is useful for tree insert operations.
	XmlDocumentType	Represents the document type declaration.
	XmlElement	Represents an element.
	XmlEntity	Represents an entity declaration, such as <!ENTITY... >.
	XmlEntityReference	Represents an entity reference node.
	XmlException	Returns detailed information about the last exception.
	XmlImplementation	Defines the context for a set of XmlDocument objects.
	XmlLinkedNode	Gets the node immediately preceding or following this node.
	XmlNamedNodeMap	Represents a collection of nodes that can be accessed by name or index.
	XmlNamespaceManager	Resolves, adds, and removes namespaces to a collection and provides scope management for these namespaces.
	XmlNameTable	Table of atomized string objects.
	XmlNode	Represents a single node in the XML document.
	XmlNodeChangedEventArgs	Provides data for the NodeChanged, NodeChanging, NodeInserted, NodeInserting, NodeRemoved and NodeRemoving events.
	XmlNodeList	Represents an ordered collection of nodes.
	XmlNodeReader	Represents a reader that provides fast, non-cached forward only access to XML data in an XmlNode.
	XmlNotation	Represents a notation declaration, such as <!NOTATION... >.
	XmlParserContext	Provides all the context information required by the XmlReader to parse an XML fragment.
	XmlProcessingInstruction	Represents a processing instruction, which XML defines to keep processor-specific information in the text of the document.
	XmlQualifiedName	Represents an XML qualified name.
	XmlReader	Represents a reader that provides fast, noncached, forward-only access to XML data.
	XmlReaderSettings	Specifies a set of features to support on the XmlReader object created by the Create method.
	XmlResolver	Resolves external XML resources named by a Uniform Resource Identifier (URI).
	XmlSecureResolver	Helps to secure another implementation of XmlResolver by wrapping the XmlResolver object and restricting the resources that the underlying XmlResolver has access to.
	XmlSignificantWhitespace	Represents white space between markup in a mixed content node or white space within an xml:space= 'preserve' scope. This is also referred to as significant white space.
	XmlText	Represents the text content of an element or attribute.
	XmlTextReader	Represents a reader that provides fast, non-cached, forward-only access to XML data.
	XmlTextWriter	Represents a writer that provides a fast, non-cached, forward-only way of generating streams or files containing XML data that conforms to the W3C Extensible Markup Language (XML) 1.0 and the Namespaces in XML recommendations.
	XmlUrlResolver	Resolves external XML resources named by a Uniform Resource Identifier (URI).
	XmlValidatingReader	Obsolete. Represents a reader that provides document type definition (DTD), XML-Data Reduced (XDR) schema, and XML Schema definition language (XSD) validation.
	XmlWhitespace	Represents white space in element content.
	XmlWriter	Represents a writer that provides a fast, non-cached, forward-only means of generating streams or files containing XML data.
	XmlWriterSettings	Specifies a set of features to support on the XmlWriter object created by the XmlWriter.Create method.
	XmlXapResolver	Obsolete. The XmlXapResolver type is used to resolve resources in the Silverlight application’s XAP package.

Interfaces

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	Interface	Description
	IApplicationResourceStreamResolver	Obsolete. Represents an application resource stream resolver.
	IFragmentCapableXmlDictionaryWriter	Contains properties and methods that when implemented by a XmlDictionaryWriter, allows processing of XML fragments.
	IHasXmlNode	Enables a class to return an XmlNode from the current context or position.
	IStreamProvider	Represents an interface that can be implemented by classes providing streams.
	IXmlBinaryReaderInitializer	Provides methods for reinitializing a binary reader to read a new document.
	IXmlBinaryWriterInitializer	Specifies implementation requirements for XML binary writers that derive from this interface.
	IXmlDictionary	An interface that defines the contract that an Xml dictionary must implement to be used by XmlDictionaryReader and XmlDictionaryWriter implementations.
	IXmlLineInfo	Provides an interface to enable a class to return line and position information.
	IXmlMtomReaderInitializer	Specifies implementation requirements for XML MTOM readers that derive from this interface.
	IXmlMtomWriterInitializer	When implemented by an MTOM writer, this interface ensures initialization for an MTOM writer.
	IXmlNamespaceResolver	Provides read-only access to a set of prefix and namespace mappings.
	IXmlTextReaderInitializer	Specifies implementation requirements for XML text readers that derive from this interface.
	IXmlTextWriterInitializer	Specifies implementation requirements for XML text writers that derive from this interface.

Delegates

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	Delegate	Description
	OnXmlDictionaryReaderClose	delegate for a callback method when closing the reader.
	XmlNodeChangedEventHandler	Represents the method that handles NodeChanged, NodeChanging, NodeInserted, NodeInserting, NodeRemoved and NodeRemoving events.

Enumerations

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	Enumeration	Description
	ConformanceLevel	Specifies the amount of input or output checking that the created XmlReader and XmlWriter objects perform.
	DtdProcessing	Specifies the options for processing DTDs. The DtdProcessing enumeration is used by XmlReaderSettings.
	EntityHandling	Specifies how the XmlTextReader or XmlValidatingReader handle entities.
	Formatting	Specifies formatting options for the XmlTextWriter.
	NamespaceHandling	Specifies whether to remove duplicate namespace declarations in the XmlWriter.
	NewLineHandling	Specifies how to handle line breaks.
	ReadState	Specifies the state of the reader.
	ValidationType	Specifies the type of validation to perform.
	WhitespaceHandling	Specifies how white space is handled.
	WriteState	Specifies the state of the XmlWriter.
	XmlDateTimeSerializationMode	Specifies how to treat the time value when converting between string and DateTime.
	XmlDictionaryReaderQuotaTypes	Enumerates the configurable quota values for XmlDictionaryReaders.
	XmlNamespaceScope	Defines the namespace scope.
	XmlNodeChangedAction	Specifies the type of node change.
	XmlNodeOrder	Describes the document order of a node compared to a second node.
	XmlNodeType	Specifies the type of node.
	XmlOutputMethod	Specifies the method used to serialize the XmlWriter output.
	XmlSpace	Specifies the current xml:space scope.
	XmlTokenizedType	Represents the XML type for the string. This allows the string to be read as a particular XML type, for example a CDATA section type.