DataContractSerializer的那点事

在DataContractSerializer之前有XMLSerializer, 网上关于此的比较有：

http://www.danrigsby.com/blog/index.php/2008/03/07/xmlserializer-vs-datacontractserializer-serialization-in-wcf/

亮点在此: 10%的性能提升.

 

因为DataContractSerializer不支持一些xsd标签：

group, all, choice...

http://msdn.microsoft.com/zh-cn/library/ms733112.aspx

 

如果要使用DataContractSerializer就需要将XSD转为符合其标准的XSD. 有以下步骤：

1. convert xsd to a standard xsd.

2. use xsd2code to generate cs file.

3. add the cs file into a assembly project and build to a dll file.

4. use svcutil to generate xsd file via the dll,  command: svcutil.exe /t:metadata /dataContractOnly skd.dll

5. remove all ...specified element. since xsd2code will generate a ...specified element for value type element if its optional is true, to indicate the value was set or        not.       

    like:

          int Age{get;set;}

          int AgeSpecified{get;set}

    if AgeSpecified==false, even if we set Age=20, XMLserialize will also ignore Age, and Age not be serialized.

 

    but in step 4, the below element will be added into the Schame:

    <xs:element minOccurs="0" name="AgeSpecified" type="xs:boolean" />

    this addtional elements cost performance and let schame not very clear, that's why we need step5.

    xsl:   

    <xsl:template match="xs:element[substring(@name,string-length(@name)-8,9)='Specified']" priority="1"></xsl:template>
    <xsl:template match="xs:element[(@minOccurs='0') and not (@nillable='true')]">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
            <xsl:attribute name="nillable">true</xsl:attribute>
        </xsl:copy>

  Notice, we added nillable=true attribute on all value-type elements, let svcutil to generate nullable property, to represent the state of specified =false.

 

6. add emit default info, let svcutil generate the property with [System.Runtime.Serialization.DataMemberAttribute(EmitDefaultValue=false)]

    then DataContractSerializer will naver serialize the property when its value is default.

    http://msdn.microsoft.com/en-us/library/aa347792.aspx

    http://kb.cnblogs.com/a/1520121/

    XSL:

          <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
            <xs:annotation>
                <xs:appinfo>
                    <DefaultValue EmitDefaultValue="false" xmlns="http://schemas.microsoft.com/2003/10/Serialization/" />
                </xs:appinfo>
            </xs:annotation>
        </xsl:copy>

7. generate the cs file by xsd, use command svcutil ddkkd.cs /dconly *.xsd