XmlSerializer .NET Tutorial

XML was designed to be a technology for data exchange across heterogeneous systems. It can be easily transmitted between distributed components because of its platform independence and its simple, text-based, self-describing format. Yet these features hardly form the basis for a solid programming platform. Text-based data does not enforce type-safety rules. Programmers are much more enticed by object-oriented programming models, because each object is of a certain type, so the compiler can warn of potential type problems and data encapsulated by an object can be easily accessed. The ideal programming environment would use an object-oriented model to build the software but leverage the benefits of XML to communicate between distributed components, over the Internet or Message Queues for example.

Unfortunately the Microsoft platform lacked an easy, integrated way to transform objects in a program into XML documents and XML documents into objects. When it came to building XML-driven applications, developers could choose to bypass all type-safety and pass XML around in their systems, but in order to build a clean, object oriented architecture they had to invest time and resources into adding functionality to every class to save itself to XML. This functionality is referred to as serialization. The reverse operation, when an object is re-created from its serialized representation is called deserialization or XML data bindng. Figure 1 illustrates this process.

Figure 9.1: Xml serialization allows transforming objects to XML and vice versa. Object state is persisted to XML documents, which are well suited for storage or transmission. The XML documents can then be deserialized back into objects.

We will learn about using the .NET framework to serialize objects to an XML-based representation and then deserializing the XML back into objects. You will learn how to develop classes so their XML representation will map to a given XML format. This is a common problem in applications exchanging data through an XML-based format and the .NET Framework provides a powerful solution in the System.Xml.Serialization namespace.

Later in this book we will concentrate on XML Serialization in the context of more distributed applications where we communicate through an XML-based remote procedure call (RPC) protocol named SOAP.

Prerequisites

A basic understanding of two topics is required before we dive right into serialization. The two topics are:

• .NET Metadata Attributes
• XSD schemas.