XML Schema Design Patterns
Sang Shin Michle Garoche www.javapassion.com Learning is fun!
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Agenda
Popular XML Schema Design Patterns > Russian Doll > Salami Slice > Venetian Blind > Garden of Eden NetBeans Support on XML Schema Design Patterns
Popular XML Schema Design Patterns
Popular XML Schema Design Patterns
Russian Doll Salami Slice Venetian Blind Garden of Eden
Popular XML Schema Design Patterns
The patterns vary according to the number of their global elements or types.
You can conveniently classify the four most common patterns according to two criteria, namely:
> Ease of use for instance developers > Ease of reuse for schema developers
Russian Doll
Russian Doll
The Russian Doll design contains only one single global element. All the other elements are local. You nest element declarations within a single global declaration
Example: Russian Doll
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://schemas.sun.com/point/russiandoll" xmlns:tns="http://schemas.sun.com/point/russiandoll" elementFormDefault="qualified"> <xsd:element name="Line"> <xsd:complexType> <xsd:sequence> <xsd:element name="PointA"> <xsd:complexType> <xsd:attribute name="x" type="xsd:integer"/> <xsd:attribute name="y" type="xsd:integer"/> </xsd:complexType> </xsd:element> <xsd:element name="PointB"> <xsd:complexType> <xsd:attribute name="x" type="xsd:integer"/> <xsd:attribute name="y" type="xsd:integer"/> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:schema>
Global element
Advantages & Disadvantages
Advantages
> Contains only one valid root element. > Could reduce the complexity of namespace > Easy to use from instance developer's point of view
Disadvantages
> Reuse of elements is limited not easy to use from
schema developer's point of view > Supports single-file schema only
Usage
Russian Doll is the simplest and easiest pattern to use by instance developers. However, if its elements or types are intended for reuse, Russian Doll is not suitable for schema developers.
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Salami Slice
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Salami Slice
All the elements in the Salami Slice design are global. No nesting of element declarations is required and you can reuse the declarations throughout the schema. You must define all the elements within the global namespace.
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Example: Salami Slice
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://schemas.sun.com/point/salami" xmlns:tns="http://schemas.sun.com/point/salami" xmlns="http://schemas.sun.com/point/salami" elementFormDefault="qualified"> <xsd:element name="PointA"> <xsd:complexType> <xsd:attribute name="x" type="xsd:integer"/> <xsd:attribute name="y" type="xsd:integer"/> </xsd:complexType> </xsd:element> <xsd:element name="PointB"> <xsd:complexType> <xsd:attribute name="x" type="xsd:integer"/> <xsd:attribute name="y" type="xsd:integer"/> </xsd:complexType> </xsd:element> <xsd:element name="Line"> <xsd:complexType> <xsd:sequence> <xsd:element ref="PointA"/> <xsd:element ref="PointB"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:schema>
Global elements
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Advantages & Disadvantages
Advantages
> Contains all reusable elements (from schema
designer's standpoint) > Supports reuse of elements from other documents.
Disadvantages
> Exposes the complexity in namespace.
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Venetian Blind
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Venetian Blind
The Venetian Blind design contains only one global element. All the other elements are local. You nest element declarations within a single global declaration by means of named complex types and element groups. You can reuse those types and groups throughout the schema and must define only the root element within the global namespace.
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Example: Venetian Blind
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://schemas.sun.com/point/venetianblind" xmlns:tns="http://schemas.sun.com/point/venetianblind" xmlns="http://schemas.sun.com/point/venetianblind" elementFormDefault="qualified"> <xsd:complexType name="PointType"> <xsd:attribute name="x" type="xsd:integer"/> <xsd:attribute name="y" type="xsd:integer"/> </xsd:complexType> <xsd:element name="Line"> <xsd:complexType> <xsd:sequence> <xsd:element name="PointA" type="PointType"/> <xsd:element name="PointB" type="PointType"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:schema>
Global element
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Advantages & Disadvantages
Advantages
> Contains only one single root element. > Allows reuse for all the types and the single global
element. > Allows multiple files
Disadvantages
> Limits encapsulation by exposing types.
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Usage
Because it has only one single root element and all its types are reusable, Venetian Blind is suitable for use by both instance developers and schema developers.
> Venetian Blind is considered as an extension of
Russian Doll, in which all the types are defined globally.
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Garden of Eden
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Garden of Eden
You define all the elements and types in the global namespace and refer to the elements as required.
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Example: Garden of Eden
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://schemas.sun.com/point/gardenofeden" xmlns="http://schemas.sun.com/point/gardenofeden" elementFormDefault="qualified"> <xsd:complexType name="PointType"> <xsd:attribute name="x" type="xsd:integer"/> <xsd:attribute name="y" type="xsd:integer"/> </xsd:complexType> <xsd:complexType name="LineType"> <xsd:sequence> <xsd:element ref="PointA"/> <xsd:element ref="PointB"/> </xsd:sequence> </xsd:complexType> <xsd:element name="PointA" type="PointType"/> <xsd:element name="PointB" type="PointType"/> <xsd:element name="Line" type="LineType"/> </xsd:schema>
Global elements
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Advantages & Disadvantages
Advantages
> Allows reuse of both elements and types. > Allows multiple files.
Disadvantages
> Contains many potential root elements. > Limits encapsulation by exposing types. > Is difficult to read and understand.
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NetBeans Support on XML Schema Design Patterns
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NetBeans XML Schema Design Support
Lets you choose a design pattern by letting you choose
> Scheme of Creating global element > Scheme of Creating type
Creating global element
> Create a single global element > Create Multiple global elements
Creating type
> Create Type(s) > Do not Create Type(s)
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NetBeans XML Schema Design Support
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Thank you!
Sang Shin Michle Garoche http://www.javapassion.com Learning is fun!
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