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XML Serialization Introduction

10/28/2009
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Serialization is the process of converting an object into a form that can be readily transported. For example, you can serialize an object and transport it over the Internet using HTTP between a client and a server. On the other end, deserialization reconstructs the object from the stream.
XML serialization serializes only the public fields and property values of an object into an XML stream. XML serialization does not include type information. For example, if you have a Book object that exists in the Library namespace, there is no guarantee that it will be deserialized into an object of the same type.

Note   XML serialization does not convert methods, indexers, private fields, or read-only properties (except read-only collections). To serialize all an object's fields and properties, both public and private, use the BinaryFormatter instead of XML serialization.
The central class in XML serialization is the XmlSerializer class, and its most important methods are the Serialize and Deserialize methods. The XML stream generated by the XmlSerializer is compliant with the World Wide Web Consortium (www.w3.org) XML Schema definition language (XSD) 1.0 recommendation. Furthermore, the data types generated are compliant with the document titled "XML Schema Part 2: Datatypes."

The data in your objects is described using programming language constructs like classes, fields, properties, primitive types, arrays, and even embedded XML in the form of XmlElement or XmlAttribute objects. You have the option of creating your own classes, annotated with attributes, or using the XML Schema Definition tool to generate the classes based on an existing XML Schema.

If you have an XML Schema, you can run the XML Schema Definition tool to produce a set of classes that are strongly typed to the schema and annotated with attributes. When an instance of such a class is serialized, the generated XML adheres to the XML Schema. Provided with such a class, you can program against an easily manipulated object model while being assured that the generated XML conforms to the XML schema. This is an alternative to using other classes in the .NET Framework, such as the XmlReader and XmlWriter classes, to parse and write an XML stream. Those classes allow you to parse any XML stream. In contrast, use the XmlSerializer when the XML stream is expected to conform to a known XML Schema.

Attributes control the XML stream generated by the XmlSerializer class, allowing you to set the XML namespace, element name, attribute name, and so on, of the XML stream.

The XmlSerializer class can further serialize an object and generate an encoded SOAP XML stream. The generated XML adheres to section 5 of the World Wide Web Consortium document titled "Simple Object Access Protocol (SOAP) 1.1.".

The XmlSerializer class generates the SOAP messages created by, and passed to, XML Web services. To control the SOAP messages, you can apply attributes to the classes, return values, parameters, and fields found in an XML Web service file (.asmx). You can use both the attributes listed in "Attributes That Control XML Serialization" and "Attributes That Control Encoded SOAP Serialization" because an XML Web service can use either the literal or encoded SOAP style.