Chapter 3: XML Schema

B4J tool works on a grammar definition using an XML Schema subset. In a nutshell, you have to declare all elements first, then all corresponding complex types. Complex types may not be embedded in one another, and have basically attributes and three possible contents:

text content
child elements in sequence (but same element may not appear twice at two non-successive different positions)
child elements in choice

Choices and sequences can not be mixed in the current version, and may never be in potential future releases.

Declaring allowed Vocaburary

First, declare all element names that appear in game data, starting with root element quizz. We don't consider attributes for now.
Each element declaration uses following syntax:

<xsd:element name="elementName" type="seq or ch or st"/>

type attribute is used in XML Schema to reference the corresponding complex type,

e.g. gmr:ElementName

The "gmr" prefix, associated with your game namespace "http://www.example.com/Guess_Me_Right", is always included in references (for complex types, attributes, etc...).

In this tutorial, we use an intermediate syntax: simply write type="seq" for sequences, type="ch" for choices, and type="s" for simple content elements (with text content).
Cheat: HERE is corresponding xml schema.

Generating Complex Types for Elements

ant addSchemaTypes

generates template complex types according to your previous declarations. Based on our conventions, each complex type has the same name as corresponding element, different only by first capital letter. THIS is the resulting file.

Adding attributes and children

You should now add attributes declarations, using following syntax:

<xsd:attribute name="attributeName" type="xsd:byte" />

Attribute name is free; for an attributeName attribute, an atAttributeName variable will contain decoded value, and an isAtAttributeNamePresent boolean will be available if it is an optional one.
Following table lists supported types with corresponding Java type:

XML Schema	Java
xsd:boolean	boolean
xsd:byte	byte
xsd:short	short
xsd:int	int
xsd:unsignedInt	int
xsd:long	long
xsd:float	int*
xsd:double	double
xsd:string	String (UTF-8)
mathFP:float	int (encoded with MathFP)
mathFP:radAngle	int (encoded with MathFP)
mathFP:cosRadAngle	int (encoded with MathFP)
mathFP:sinRadAngle	int (encoded with MathFP)
mathFP:minusCosRadAngle	int (encoded with MathFP)
mathFP:minusSinRadAngle	int (encoded with MathFP)
include:Id	byte
include:IdRef	byte
ignore:Id	None
ignore:IdRef	None

*: was int before mathFP:float was available, should become float.
Cheat: THIS is resulting file

Validate Complete Grammar and Data

Finally, your schema is now VALID! You can use it to validate your game data, using

ant validateData

but you should first check it is a valid XML Schema subset for B4J using

ant validateSchema

Go on to Chapter 4...
or back to Chapter 1 or Chapter 2.

Chapter 3: XML Schema

Declaring allowed Vocaburary

Generating Complex Types for Elements

Adding attributes and children

Validate Complete Grammar and Data

Next