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| <h1 xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0">Step 2: Define a Meta Model using XML Schema</h1> |
| <div class="section" title="Step 2: Define a Meta Model using XML Schema"> |
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| <h2 class="title" style="clear: both"> |
| <a name="xsd_tutorial_metamodel"/>Step 2: Define a Meta Model using XML Schema</h2> |
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| </div> |
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| <p>In case you are not going to use an existing XML Schema Definition, |
| you can create a new a new one like described below. These steps make use |
| of the Eclipse Web Tools Platform (WTP) to have fancy editors.</p> |
| <p>In Eclipse, click on <span class="emphasis"> |
| <em>"File", "New", "Other..."</em> |
| </span> |
| and choose <span class="emphasis"> |
| <em>"XML Schema"</em> |
| </span> from category "XML". Select |
| the project's "src" folder and specify a filename. Clicking on "finish" |
| creates an empty XSD file. It is important that the XSD file is located |
| somewhere within the project's classpath.</p> |
| <p>This XML Schema consists of two complex data types, which contain |
| some elements and attributes. "complex" in the XSD terminology means that |
| as opposed to simple data types that they can actually have sub-elements |
| and/or attributes. This example is too minimalistic to do anything |
| useful.</p> |
| <p>The complex Type <code class="classname">Wizard</code> contains the elements |
| <code class="classname">startpage</code> , <code class="classname">name</code> , |
| <code class="classname">welcometext</code> , and <code class="classname">choicepage</code> |
| . Except for <code class="classname">choicepage</code> all elements have to |
| contain strings, whereas the string of <code class="classname">startpage</code> |
| must be a valid id of any <code class="classname">ChoicePage</code> . The complex |
| type <code class="classname">ChoicePage</code> just contains an |
| <code class="classname">id</code> and a <code class="classname">name</code> . For Xpand it |
| does not make any difference if something is modeled as an XML-attribute |
| or XML-element. Just the datafield's type defines how Xpand treats the |
| value.</p> |
| <p>To get an overview how schemas can be used by the Xpand XSD Adapter, |
| see <a class="xref" href="xsd_reference_declare_xsd.html" title="How to declare XML Schemas">the section called “How to declare XML Schemas”</a> |
| </p> |
| <p>Internally, the Xpand XSD Adapter transforms the XSD model to an |
| Ecore model which Xpand can use like any other Ecore model. For more |
| information about that, see <a class="xref" href="xsd_reference_xsd2ecore.html" title="Behind the scenes: Transforming XSD to Ecore">the section called “Behind the scenes: Transforming XSD to Ecore”</a> |
| </p> |
| <div class="figure"> |
| <a name="xsd_tutorial_xsd_editor"/> |
| <p class="title"> |
| <b>Figure 4. WTP Schema Editor</b> |
| </p> |
| <div class="figure-contents"> |
| <div class="mediaobject"> |
| <img src="xsd_tutorial/xsd-editor.png" alt="WTP Schema Editor"/> |
| </div> |
| </div> |
| </div> |
| <br class="figure-break"/> |
| <pre class="programlisting"><?xml version="1.0" encoding="UTF-8"?> |
| <schema xmlns="http://www.w3.org/2001/XMLSchema" |
| targetNamespace="http://www.example.org/wizard" |
| xmlns:tns="http://www.example.org/wizard" |
| elementFormDefault="qualified"> |
| |
| <complexType name="Wizard"> |
| <sequence> |
| <element name="startpage" type="IDREF" /> |
| <element name="name" type="string" /> |
| <element name="welcometext" type="string" /> |
| <element name="choicepage" type="tns:ChoicePage" /> |
| </sequence> |
| </complexType> |
| |
| <complexType name="ChoicePage"> |
| <sequence> |
| <element name="title" type="string" /> |
| </sequence> |
| <attribute name="id" type="ID" /> |
| </complexType> |
| |
| <element name="wizard" type="tns:Wizard" /> |
| </schema></pre> |
| </div> |
| </body> |
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