Appendix B. ADO.NET XML Extensions

Microsoft defines two namespaces for configuring DataSet schema files: codegen ( urn:schemas-microsoft-com:xml-msprop ) and msdata ( urn:schemas-microsoft-com:xml-msdata ). These namespaces extend the XSD format, allowing it to represent additional database-specific properties and allowing you to configure how typed DataSets are generated. In addition, the diffgr , or DiffGram namespace ( urn:schemas-microsoft-com:xml-diffgram-v1 ), defines attributes that provide a way for XML documents to track DataSet changes and row insertions and deletions.

The structure of the XSD file for a DataSet is as follows :

 <?xml version="1.0" encoding="utf-8"?> <xs:schema id="   DataSetName   ">   <xs:element name="   DataSetName   " >     <xs:complexType>       <xs:choice maxOccurs="unbounded">         <xs:element name="   DataTableName   " >           <xs:complexType>             <xs:sequence>               <xs:element name="   FieldName   " />           </xs:complexType>         </xs:element>       </xs:choice>     </xs:complexType>     <xs:unique name="   ConstraintName   " />     <xs:keyref name="   RelationName   " />   </xs:element> </xs:schema> 

The structure of the DiffGram format is shown next . All DiffGrams contains three sections: the current data, the original data, and any errors.

 <?xml version="1.0"?> <diffgr:diffgram          xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"         xmlns:diffgr="urn:schemas-microsoft-com:xml-diffgram-v1"         xmlns:xsd="http://www.w3.org/2001/XMLSchema">   <!-- Data goes here. Changed rows are flagged. -->   <diffgr:before>      <!-- Contains the original data. -->   </diffgr:before>   <diffgr:errors>      <!-- Contains error information. -->   </diffgr:errors> </diffgr:diffgram> 

For specific examples that show how you can create a typed DataSet and refine its schema, refer to Chapter 4. For an introduction to the DiffGram format and XML serialization with the DataSet , refer to Chapter 7.



ADO. NET in a Nutshell
ADO.NET in a Nutshell
ISBN: 0596003617
EAN: 2147483647
Year: 2005
Pages: 415

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