Schema Validation with Oracle JDeveloper – XDK 11g

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JDeveloper built-in schema validation

Oracle JDeveloper 11g has built-in support for XML schema validation. If an XML document includes a reference to an XML schema, the XML document may be validated with the XML schema using the built-in feature. An XML schema may be specified in an XML document using the xsi:noNamespaceSchemaLocation attribute or the xsi:namespaceSchemaLocation attribute. Before we discuss when to use which attribute, we need to define the target namespace. A schema is a collection of type definitions and element declarations whose names belong to a particular namespace called a target namespace. Thus, a target namespace distinguishes between type definitions and element declarations from different collections. An XML schema doesn’t need to have a target namespace. If the XML schema has a target namespace, specify the schema’s location in an XML document using the xsi:namespaceSchemaLocation attribute. If the XML schema does not have a target namespace, specify the schema location using the xsi:noNamespaceSchemaLocation attribute. The xsi:noNamespaceSchemaLocation and xsi:namespaceSchemaLocation attributes are a hint to the processor about the location of an XML schema document. The example XML schema document that we shall create is catalog.xsd and is listed here:

<?xml version="1.0" encoding="utf-8"?>
<xsd:schema >
<xsd:element name="catalog"type="catalogType"/>
<xsd:complexType name="catalogType">
<xsd:sequence>
<xsd:element ref="journal" minOccurs="0"maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
<xsd:element name="journal" type="journalType"/>
<xsd:complexType name="journalType">
<xsd:sequence>
<xsd:element ref="article" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="title" type="xsd:string"/>
<xsd:attribute name="publisher" type="xsd:string"/>
<xsd:attribute name="edition" type="xsd:string"/>
</xsd:complexType>
<xsd:element name="article" type="articleType"/>
<xsd:complexType name="articleType">
<xsd:sequence>
<xsd:element name="title" type="xsd:string"/>
<xsd:element name="author" type="xsd:string"/>
</xsd:sequence>
<xsd:attribute name="section" type="xsd:string"/>
</xsd:complexType>
</xsd:schema>

The XML document instance that we shall generate from the schema is catalog.xml and is listed as follows:

<?xml version="1.0" encoding="utf-8"?>
<catalog>
<journal title="Oracle Magazine" publisher="Oracle
Publishing" edition="September-October 2008">
<article section="Features">
<title>Share 2.0</title>
<author>Alan Joch</author>
</article>
</journal>
<journal title="Oracle Magazine" publisher="Oracle
Publishing" edition="March-April 2008">
<article section="Oracle Developer">
<title>Declarative Data Filtering</title>
<author>Steve Muench</author>
</article>
</journal></catalog>

Specify the XML schema location in the XML document using the following attribute declaration:

xsi:noNamespaceSchemaLocation="catalog.xsd"

The XML schema may be in any directory. The example XML document does not include any namespace elements. Therefore, the schema is specified with the xsi:noNamespaceSchemaLocation attribute in the root element catalog. The XML schema may be specified with a relative URL, or a file, or an HTTP URL. The xsi:noNamespaceSchemaLocation attribute we added specifies the relative path to the XML schema document catalog.xsd. To validate the XML document with the XML schema, right-click on the XML document and select Validate XML

.

The XML document gets validated with the XML schema and the output indicates that the XML document does not have any validation errors.

To demonstrate validation errors, add a non-valid element to the XML document. As an example, add the following element to the catalog element after the first journal element:

<article></article>

To validate the modified XML document, right-click on the XML document and select Validate XML. The output indicates validation errors. All the elements after the non-valid element become non-valid. For example, the journal element is valid as a subelement of the catalog element, but because the second journal element is after the non-valid article element, the journal element also becomes non-valid as indicated in the validation output.

XDK 11g also provides a schema validation-specific API known as XSDValidator to validate an XML document with an XML schema. The choice of validation method depends on the additional functionality required in the validation application. XSDValidator is suitable for validation if all that is required is schema validation.

Setting the environment

Create an application (SchemaValidation, for example) and a project (SchemaValidation, for example) in JDeveloper. To create an application and a project select File | New. In the New Gallery window, select Categories | General and Items | Generic Application. Click on OK. In the Create Generic Application window, specify an Application Name and click on Next. In the Name your Generic project window, specify a Project Name and click on Finish. An application and a project get created. Next, add some XDK 11g JAR files to the project classpath. Select the project node in Application Navigator, and select Tools | Project Properties. In the Project Properties window, select Libraries and Classpath. Click on the Add Library button to add a library. In the Add Library window, select the Oracle XML Parser v2 library and click on the OK button. The Oracle XML Parser v2 library gets added to the project Libraries. Select the Add JAR/Directory button to add JAR file xml.jar from the C:OracleMiddlewarejdevelopermodulesoracle.xdk_11.1.1 directory.

First, create an XML document and an XML schema in JDeveloper. To create an XML document, select File | New. In the New Gallery window select Categories | General | XML. In the Items listed select XML Document, and click on the OK button.

In the Create XML File wizard, specify the XML file name, catalog.xml, and click on the OK button. An XML document gets added to the SchemaValidation project in Application Navigator. To add an XML schema, select File | New, and General | XML in the New Gallery window. Select XML schema in the Items listed. Click on the OK button.

An XML schema document gets added to SchemaValidation project.

The example XML document, catalog.xml, consists of a journal catalog. Copy the XML document to the catalog.xml file in the JDeveloper project.

The example XML document does not specify the location of the XML schema document to which the XML document must conform to, because we will be setting the XML schema document in the schema validation application. If the XML schema document is specified in the XML document and the schema validation application, the schema document set in the schema validation application is used.

Next, copy the example XML schema document, catalog.xsd to catalog.xsd in the JDeveloper project Schema Validation.

Each XML schema is required to be in the XML schema namespace http://www.w3.org/2001/XMLSchema. The XML schema namespace is specified with a namespace declaration in the root element, schema, of the XML schema. A namespace declaration is of the format >

Next, we will create Java classes for schema validation. Select File | New and subsequently Categories | General and Items | Java Class in the New Gallery window to create a Java class for schema validation. Click on the OK button. In the Create Java Class window specify a Class Name, XMLSchemaValidator, and a package name, schemavalidation, and click on the OK button. A Java class gets added to the SchemaValidation project. Similarly, add Java classes, DOMValidator and SAXValidator. The schema validation applications are shown in the Application Navigator.

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