jaxp/src/share/classes/javax/xml/validation/package.html
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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
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+
+<!DOCTYPE html
+     PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+     "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+
+<html xmlns="http://www.w3.org/1999/xhtml">
+
+<head>
+  <title>javax.xml.validation</title>
+
+  <meta name="CVS"
+        content="$Id: package.html,v 1.2 2005/06/10 03:50:43 jeffsuttor Exp $" />
+  <meta name="AUTHOR"
+        content="Jeff.Suttor@Sun.com" />
+</head>
+	<body>
+		<p>
+		    This package provides an API for validation of XML documents.  <em>Validation</em> is the process of verifying
+		    that an XML document is an instance of a specified XML <em>schema</em>.  An XML schema defines the
+		    content model (also called a <em>grammar</em> or <em>vocabulary</em>) that its instance documents
+		    will represent.
+        </p>
+        <p>
+            There are a number of popular technologies available for creating an XML schema. Some of the most
+            popular include:
+		</p>
+            <ul>
+                <li><strong>Document Type Definition (DTD)</strong> - XML's built-in schema language.</li>
+                <li><strong><a href="http://www.w3.org/XML/Schema">W3C XML Schema (WXS)</a></strong> - an object-oriented XML schema
+                    language. WXS also provides a type system for constraining the character data of an XML document.
+                    WXS is maintained by the <a href="http://www.w3.org">World Wide Web Consortium (W3C)</a> and is a W3C
+                    Recommendation (that is, a ratified W3C standard specification).</li>
+                <li><strong><a href="http://www.relaxng.org">RELAX NG (RNG)</a></strong> - a pattern-based,
+                    user-friendly XML schema language. RNG schemas may also use types to constrain XML character data.
+                    RNG is maintained by the <a href="http://www.oasis-open.org">Organization for the Advancement of
+                    Structured Information Standards (OASIS)</a> and is both an OASIS and an
+                    <a href="http://www.iso.org">ISO (International Organization for Standardization)</a> standard.</li>
+                <li><strong><a href="http://www.schematron.com/">Schematron</a></strong> - a rules-based XML schema
+                language. Whereas DTD, WXS, and RNG are designed to express the structure of a content model,
+                Schematron is designed to enforce individual rules that are difficult or impossible to express
+                with other schema languages. Schematron is intended to supplement a schema written in
+                structural schema language such as the aforementioned. Schematron is in the process
+                of becoming an ISO standard.</li>
+            </ul>
+        <p>
+		    Previous versions of JAXP supported validation as a feature of an XML parser, represented by
+		    either a {@link javax.xml.parsers.SAXParser} or {@link javax.xml.parsers.DocumentBuilder} instance.
+        </p>
+        <p>
+		    The JAXP validation API decouples the validation of an instance document from the parsing of an
+		    XML document. This is advantageous for several reasons, some of which are:
+		</p>
+		    <ul>
+		        <li><strong>Support for additional schema langauges.</strong> As of JDK 1.5, the two most
+		        popular JAXP parser implementations, Crimson and Xerces, only support a subset of the available
+		        XML schema languages. The Validation API provides a standard mechanism through which applications
+		        may take of advantage of specialization validation libraries which support additional schema
+		        languages.</li>
+		        <li><strong>Easy runtime coupling of an XML instance and schema.</strong> Specifying the location
+		        of a schema to use for validation with JAXP parsers can be confusing. The Validation API makes this
+		        process simple (see <a href="#example-1">example</a> below).</li>
+          </ul>
+		<p>
+            <a name="example-1"><strong>Usage example</strong>.</a> The following example demonstrates validating
+            an XML document with the Validation API (for readability, some exception handling is not shown):
+		</p>
+            <pre>
+            
+    // parse an XML document into a DOM tree
+    DocumentBuilder parser = DocumentBuilderFactory.newInstance().newDocumentBuilder();
+    Document document = parser.parse(new File("instance.xml"));
+
+    // create a SchemaFactory capable of understanding WXS schemas
+    SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
+
+    // load a WXS schema, represented by a Schema instance
+    Source schemaFile = new StreamSource(new File("mySchema.xsd"));
+    Schema schema = factory.newSchema(schemaFile);
+
+    // create a Validator instance, which can be used to validate an instance document
+    Validator validator = schema.newValidator();
+
+    // validate the DOM tree
+    try {
+        validator.validate(new DOMSource(document));
+    } catch (SAXException e) {
+        // instance document is invalid!
+    }
+</pre>
+		<p>
+		    The JAXP parsing API has been integrated with the Validation API. Applications may create a {@link javax.xml.validation.Schema} with the validation API
+		    and associate it with a {@link javax.xml.parsers.DocumentBuilderFactory} or a {@link javax.xml.parsers.SAXParserFactory} instance
+		    by using the {@link javax.xml.parsers.DocumentBuilderFactory#setSchema(Schema)} and {@link javax.xml.parsers.SAXParserFactory#setSchema(Schema)}
+		    methods. <strong>You should not</strong> both set a schema and call <code>setValidating(true)</code> on a parser factory. The former technique
+		    will cause parsers to use the new validation API; the latter will cause parsers to use their own internal validation
+		    facilities. <strong>Turning on both of these options simultaneously will cause either redundant behavior or error conditions.</strong>
+        </p>
+	</body>
+</html>