README

Mono Xml Serializer Generator Tool - README

genxs is a tool for generating custom XML serialization writers and readers for
classes.


* Usage
-----------------------------

The tool takes as input a configuration file which specifies several
information, such as the class for which to generate the reader and writer, the
name and namespace of the classes to generate, and a collection of hooks to
apply. Hooks are very useful, because with them you can eaily customize the
behavior of the serializer without needing to modify the generated file, so you
can safely regenerate it if the source class is modified.

To use the tool, run the following command:

	mono genxs.exe configurationFile [destinationFolder]

where:
 * configurationFile: the configuration file path
 * destinationFolder: the folder where to generate the files
	
NOTE: This tool only runs in the Mono runtime, since it uses some internal
classes not available in other runtimes.


* Configuration file format
-----------------------------

The configuration file is an xml document based on the following grammar
("?" means optional, "*" 0 or more):
	
	<configuration>
		<serializer class="name" assembly="name"> *
			<reader>name</reader> ?
			<writer>name</writer> ?
			<baseSerializer>name</baseSerializer> ? (2.0-only)
			<implementation>name</implementation> ? (2.0-only)
			<namespace>name</namespace> ?
			<namespaceImports> ?
				<namespaceImport>namespace</namespaceImport> *
			</namespaceImports>
			<outFileName>name</outFileName> ?
			<readerHooks> ?
				<hook ...> *
			</readerHooks>
			<writerHooks> ?
				<hook ...> *
			</writerHooks>
		</serializer>
	</configuration>

A configuration file can have multiple "serializer" elements, each of which
specifies the class for which to generate a serializer together with several
generation options. The source class is specified in the following attributes:

 * class: name of the class (including namespace).
 * assembly: assembly name. It can include the complete path.
 
Generation options are specified in child elements:

 * reader: name of the reader class.
 * writer: name of the writer class.
 * baseSerializer: 2.0 only. name of the base XML serializer class.
 * implementation: 2.0 only. name of the serializer implementation class.
 * namespace: namespace of the reader and writer classes.
 * namespaceImport: a list of namespaces to be added as namespace imports
   ("using" declarations in C#) on the top of the output source.
   It contains "namespaceImport" child elements which contains one namespace.
 * outFileName: name of the generated file.
 * readerHooks: a list of hooks to apply to the reader.
 * writerHooks: a list of hooks to apply to the writer.


* Specifying Hooks
-----------------------------

Using hooks you can customize the behavior of readers and writers.
A hook specification follows this grammar:

	<hook type="name">
		<select> ?
			<typeName>name</typeName> ?
			<typeAttribute>name</typeAttribute> *
			<typeMember>name</typeMember> ?
		</select>
		<replace>source code</replace> ?
		<insertBefore>source code</insertBefore> ?
		<insertAfter>source code</insertAfter> ?
	</hook>

The "type" attribute specifies the context in which the hook is applied. It can
be one of the following:

 * attributes: hook is applied where attributes are serialized/deserialized.
 * elements: hook is applied where elements are serialized/deserialized.
 * unknownAttribute: hook is applied where unknown attributes are processed.
 * unknownElement: hook is applied where unknown elements are processed.
 * member: hook is applied where a member is serialized/deserialized.
 * type: hook is applied for the whole type.

The "select" element specifies the classes and members to which the hook has
to be added. It can contain the following elements:

 * typeName: the class with that name will be selected (must include namespace)
 * typeAttribute: all classes which have that attribute applied will be
   selected (specify the full attribute class name, including namespace).
   Several attribute names can be specified.
 * typeMember: name of the class member for which the hook must be added.

The hook source code can be specified using any of the following elements:

 * replace: the provided source code will replace all serialization/deserialization
   operations in the hook context.
 * insertBefore: the source code will be added before the hook context.
 * insertAfter: the source code will be added after the hook context.

When writing the code for a hook you can use some special variables that are
defined during the code generation process. The variables are the following:

 * $TYPE: name of the class being generated, without namespace.
 * $FULLTYPE: full name of the class being generated, including namespace.
 * $OBJECT: the object being serialized or deserialized. When using a replace
   reader hook of type "type", the hook code must assign the deserialized object
   to this variable.
 * $ELEMENT: name of the element of the object being serialized/deserialized.
 * $NAMESPACE: namespace of the element of the object being 
   serialized/deserialized.
 * $MEMBER: name of the member being serialized/deserialized. Only valid in
   the "member" context.

* Hook examples
---------------------------------

The following example adds a call to a Validate method after the deserialization
of any object:

	<hook type="type">
		<insertAfter>System.Xml.Schema.XmlSchema.Validate$TYPE ($OBJECT);</insertAfter>
	</hook>
	
This example specifies the code to be used to deserialize the XmlSchema class:

	<hook type="type">
		<select>
			<typeName>System.Xml.Schema.XmlSchema</typeName>
		</select>
		<replace>$OBJECT = System.Xml.Schema.XmlSchema.Read (Reader, null);</replace>
	</hook>

That one specifies the code to be used to read XmlSchema instances:

	<hook type="type">
		<select>
			<typeName>System.Xml.Schema.XmlSchema</typeName>
		</select>
		<replace>$OBJECT.Write (Writer);</replace>
	</hook>

With this two hooks the serializer will print some information when serializing
the class "MyClass":

	<hook type="type">
		<select>
			<typeName>MyNamespace.MyClass</typeName>
		</select>
		<insertBefore>Console.WriteLine ("Serializing MyClass");</replace>
		<insertAfter>Console.WriteLine ("MyClass serialized");</insertAfter>
	</hook>
	<hook type="member">
		<select>
			<typeName>MyNamespace.MyClass</typeName>
		</select>
		<insertAfter>Console.WriteLine ("Serialized member $MEMBER");</insertAfter>
	</hook>
	
This hook writes an additional element for all types that have the custom
attribute "MyAttribute":

	<hook type="elements">
		<select>
			<typeAttribute>MyNamespace.MyAttribute</typeAttribute>
		</select>
		<insertAfter>
			Writer.WriteStartElement ("privateData");
			Writer.WriteString ($OBJECT.PrivateData);
			Writer.WriteEndElement ();
		</insertAfter>
	</hook>

* Configuration file example
---------------------------------

This is the configuration file used to generate the serializer for ServiceDescription:

<configuration>
	<serializer class="System.Web.Services.Description.ServiceDescription" assembly="System.Web.Services">
		<reader>ServiceDescriptionReaderBase</reader>
		<writer>ServiceDescriptionWriterBase</writer>
		<namespace>System.Web.Services.Description</namespace>
		<namespaceImports>
			<namespaceImport>System.Xml.Schema</namespaceImport>
		</namespaceImports>
		<outFileName>ServiceDescriptionSerializerBase.cs</outFileName>
		<readerHooks>
			<hook type="unknownElement">
				<select>
					<typeAttribute>System.Web.Services.Configuration.XmlFormatExtensionPointAttribute</typeAttribute>
				</select>
				<replace>ServiceDescription.ReadExtension (Reader, $OBJECT);</replace>
			</hook>
			<hook type="type">
				<select>
					<typeName>System.Xml.Schema.XmlSchema</typeName>
				</select>
				<replace>$OBJECT = XmlSchema.Read (Reader, null);</replace>
			</hook>
		</readerHooks>
		<writerHooks>
			<hook type="elements">
				<select>
					<typeAttribute>System.Web.Services.Configuration.XmlFormatExtensionPointAttribute</typeAttribute>
				</select>
				<insertBefore>ServiceDescription.WriteExtensions (Writer, $OBJECT);</insertBefore>
			</hook>
			<hook type="type">
				<select>
					<typeName>System.Xml.Schema.XmlSchema</typeName>
				</select>
				<replace>$OBJECT.Write (Writer);</replace>
			</hook>
		</writerHooks>
	</serializer>
</configuration>


-----------------
Lluis Sanchez Gual
lluis@ximian.com