Upcoming Changes to System.Xml in .NET Framework 2.0 Beta 2

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We are in the process of locking down System.Xml for Beta 2 of the .NET Framework 2.0 and Visual Studio 2005. In the past few months we have received customer feedback about our feature set previewed in the Whidbey Alpha & Whidbey Beta 1 and this has guided our decision making process as to where to focus our energies to ensure a comprehensive feature set.

Below is the list of changes to System.Xml and subsidiary namespaces that have occurred between Beta 1 and Beta 2 of the .NET Framework 2.0 release.

ADDITIONS

XmlSchemaValidator

The XmlSchemaValidator class provides a push model API for W3C XML Schema validation. The primary scenario for using the XmlSchemaValidator is for validating an XML infoset in-place without having to serialize it as an XML document then reparse the document using a validating XML reader.

CHANGES

XmlReader

  • Added overloads to the static Create() method that take XmlParserContext
  • ReadValueAsXXX() methods renamed to ReadContentAsXXX(). Also reduced the number of ReadContentAsXXX() methods relative to the number of ReadValueAsXXX() methods in Whidbey beta 1.
  • Added ReadElementContentAsXXX() methods which are specific to obtaining the value of element nodes
  • Added methods for reading large streams of text or binary data embedded in an XML document in a streaming fashion

public virtual bool CanReadValueChunk { get; }

public virtual int ReadValueChunk (byte[] buffer, int startIndex, int count);

public virtual bool CanReadBinaryContent { get; }

public virtual int ReadContentAsBase64 (byte[] buffer, int startIndex, int count);

public virtual int ReadContentAsBinHex (byte[] buffer, int startIndex, int count);

public virtual int ReadElementContentAsBase64(byte[] buffer, int startIndex, int count);

public virtual int ReadElementContentAsBinHex(byte[] buffer, int startIndex, int count);

  • Added ReadToFollowing(string localname, string namespaceURI) which moves to the next occurrence of the named element in document order.

XmlReaderSettings

  • Added XmlSchemaValidationFlags enumeration to replace the following flags; IgnoreInlineSchema, IgnoreSchemaLocation, IgnoreValidationWarnings and IgnoreIdentityConstraints
  • Added existing ValidationType enumeration to replace to replace the following flags; DtdValidate and XsdValidate

XmlWriter

  • Reduced number of WriteValue() methods
  • Removed overloads of WriteStartElement and WriteStartAttribute that took an IXmlSchemaInfo parameter

XPathDocument

XPathNavigator and XPathEditableNavigator

  • The XPathEditableNavigator has been merged into the XPathNavigator, making it an editable XML cursor model API.
  • The XPathNavigator is the preferred API for exposing data as XML. This has been incorporated into the design guidelines for using XML in the .NET Framework

XmlDocument

  • The XPathNavigator returned by the CreateNavigator() method now allows one to edit the XmlDocument through the cursor model API.
  • The XmlDocument now supports XML schema validation of the entire subtree or partial validation of nodes in the document using the Validate() method
  • The following property added to XmlDocument

public XmlSchemaSet Schemas { get; set; }

  • The following property added to XmlNode

public virtual IXmlSchemaInfo SchemaInfo { get; }

XsltCommand

  • The XslTransform class was obsoleted in Whidbey Beta 1 and replaced by the System.Xml.Query.XsltCommand class.  In Beta 2, we decided to revamp the XsltCommand API in order to make migration from XslTransform simpler.  This effort also resulted in the renaming of the XsltCommand class to  System.Xml.Xsl.XslCompiledTransform.
  • XslCompiledTransform compiles XSLT to MSIL for significantly improved performance at the cost of increased (yet still small) compile times.
  • Supports the MSXML XSLT extension functions such as format-date, format-time etc.

Inference

  • This class has been renamed to XmlSchemaInference

XPathExpression -

  • Added static Compile() method enables one to compile an input string containing an XPath query into an XPathExpression object

REMOVALS

XmlArgumentList

To reduce the cost of churn caused by the obsoletion of XslTransform this class has been removed. In its place the XsltArgumentList from v1.1 can be used

XQueryCommand

Microsoft has decided not to ship a client side XQuery implementation in .NET Framework 2.0 as our customers expect us to ship an implementation that meets the following criteria:

  • Compliant with the W3C standards
  • Functionally addresses key scenarios

As a core platform component in Windows, they also expect us to ship a product that meets the high bar of not breaking their applications when future updates are released.  After talking to key customers and partners, we have determined it is important that we cross this high bar before shipping a full implementation of XQuery in the platform. 

The best estimates tell us that ETA for XQuery to become a W3C recommendation is end of 2005 which does not fit with the .NET Framework 2.0 product release cycle.

In the meantime, we are shipping a well-defined small subset of XQuery in SQL Server 2005 to query information stored natively as XML data type.  This will enable new customer scenarios in SQL Server for storing and retrieving semi-structured data.

In the NET Framework 2.0 RTM timeframe, we recommend that our customers continue to use XSLT and XPath on the client side to solve their key client side filtering and transformation scenarios.  With this in mind, we have made significant improvements to our client side story including:

  • Performance improvements - making the .NET Framework XSLT processor the best performing processor.
  • Functional improvements - improving the usability and feature set of the existing .NET Framework processor

Note: As a result of not shipping XQuery, XML Views using mapping and XQuery to query SQL Server 2005 and the XmlAdapter to perform updates that were originally previewed in the PDC Alpha release of .NET V2.0 have also been removed. These were removed in the Beta 1 release.