Serialising XML DOM

This topic explains how to serialise a DOM document and save it to a file.

Context

The XML Engine is based on the libxml2 library, which supports the serialisation of XML documents. This process converts a DOM tree into a format that can be saved to a file or transferred through a network connection.

This tutorial explains how to save an existing XML document to a file. To store the result in a buffer, use the SetOutput(RBuf8&) method instead of the SetOutputL(TDesC&) method used below.

Prerequisites

Before you start, you must:

understand the concepts of Document Object Model (DOM) and serialisation
understand the structure and classes of the XML DOM Engine component
have created an RXmlEngDocument (called myDoc in this example), either by parsing an XML file (as indicated in the XML DOM Parsing Tutorial) or by adding nodes to a new DOM tree.

Steps

If you have not done it earlier, call the XmlEnginePushL() method to open the XML library and put serialisation resources on the clean-up stack.
Example:
```
XmlEnginePushL();
```
Create an instance of the serialiser by calling its NewL() method.
The serialiser type is a member of the TXmlEngSerializerType enumeration.
Example:
```
CXmlEngSerializer* serializer = CXmlEngSerializer::NewL( ESerializerDefault );
```
Configure the serialiser by using the SetOutputL() and SetSerialisationOptions() methods.
You set the type of output (file, buffer, or stream) by choosing one of the SetOutput() or SetOuputL() methods.
Example:
```
_LIT( KOutputFile, "c:\\tutorial.xml" );
serializer->SetOutputL( KOutputFile );
```
The SetSerialisationOptions() function sets other serialisation options from the TXmlEngSerializationOptions class.
Example:
```
TXmlEngSerializationOptions options( TXmlEngSerializationOptions::KOptionIndent );
serializer->SetSerializationOptions( options );
```
Call the SerializeL() method to save your document to the tutorial.xml file.
Example:
```
TInt bytesWritten = serializer->SerializeL( myDoc );
```
Free your resources as necessary.
1. Close the XML library by calling the XmlPopAndClose() method. This method also removes the serialisation resources from the clean-up stack.
2. Perform any other clean-up operations.

Results

The data in the myDoc XML document is stored in the tutorial.xml file.