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 * by Oracle in the LICENSE file that accompanied this code.

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 * This code is distributed in the hope that it will be useful, but WITHOUT

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

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package javax.xml;

/**

 * <p>Utility class to contain basic XML values as constants.

 *

 * @author Jeff Suttor

 * @see <a href="http://www.w3.org/TR/xml11/">Extensible Markup Language (XML) 1.1</a>

 * @see <a href="http://www.w3.org/TR/REC-xml">Extensible Markup Language (XML) 1.0 (Second Edition)</a>

 * @see <a href="http://www.w3.org/XML/xml-V10-2e-errata">XML 1.0 Second Edition Specification Errata</a>

 * @see <a href="http://www.w3.org/TR/xml-names11/">Namespaces in XML 1.1</a>

 * @see <a href="http://www.w3.org/TR/REC-xml-names">Namespaces in XML</a>

 * @see <a href="http://www.w3.org/TR/xmlschema-1/">XML Schema Part 1: Structures</a>

 * @since 1.5

 **/

public final class XMLConstants {

    /**

     * Private constructor to prevent instantiation.

     */

    private XMLConstants() {

    }

    /**

     * Namespace URI to use to represent that there is no Namespace.

     *

     * <p>Defined by the Namespace specification to be "".

     *

     * @see <a href="http://www.w3.org/TR/REC-xml-names/#defaulting">

     * Namespaces in XML, 5.2 Namespace Defaulting</a>

     */

    public static final String NULL_NS_URI = "";

    /**

     * Prefix to use to represent the default XML Namespace.

     *

     * <p>Defined by the XML specification to be "".

     *

     * @see <a

     * href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">

     * Namespaces in XML, 3. Qualified Names</a>

     */

    public static final String DEFAULT_NS_PREFIX = "";

    /**

     * The official XML Namespace name URI.

     *

     * <p>Defined by the XML specification to be

     * "{@code http://www.w3.org/XML/1998/namespace}".

     *

     * @see <a

     * href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">

     * Namespaces in XML, 3. Qualified Names</a>

     */

    public static final String XML_NS_URI =

        "http://www.w3.org/XML/1998/namespace";

    /**

     * The official XML Namespace prefix.

     *

     * <p>Defined by the XML specification to be "{@code xml}".

     *

     * @see <a

     * href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">

     * Namespaces in XML, 3. Qualified Names</a>

     */

    public static final String XML_NS_PREFIX = "xml";

    /**

     * The official XML attribute used for specifying XML Namespace

     * declarations, {@link #XMLNS_ATTRIBUTE

     * XMLConstants.XMLNS_ATTRIBUTE}, Namespace name URI.

     *

     * <p>Defined by the XML specification to be

     * "{@code http://www.w3.org/2000/xmlns/}".

     *

     * @see <a

     * href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">

     * Namespaces in XML, 3. Qualified Names</a>

     */

    public static final String XMLNS_ATTRIBUTE_NS_URI =

        "http://www.w3.org/2000/xmlns/";

    /**

     * The official XML attribute used for specifying XML Namespace

     * declarations.

     *

     * <p>It is <strong><em>NOT</em></strong> valid to use as a

     * prefix.  Defined by the XML specification to be

     * "{@code xmlns}".

     *

     * @see <a

     * href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">

     * Namespaces in XML, 3. Qualified Names</a>

     */

    public static final String XMLNS_ATTRIBUTE = "xmlns";

    /**

     * W3C XML Schema Namespace URI.

     *

     * <p>Defined to be "{@code http://www.w3.org/2001/XMLSchema}".

     *

     * @see <a href=

     *  "http://www.w3.org/TR/xmlschema-1/#Instance_Document_Constructions">

     *  XML Schema Part 1:

     *  Structures, 2.6 Schema-Related Markup in Documents Being Validated</a>

     */

    public static final String W3C_XML_SCHEMA_NS_URI =

        "http://www.w3.org/2001/XMLSchema";

    /**

     * W3C XML Schema Instance Namespace URI.

     *

     * <p>Defined to be "{@code http://www.w3.org/2001/XMLSchema-instance}".

     *

     * @see <a href=

     *  "http://www.w3.org/TR/xmlschema-1/#Instance_Document_Constructions">

     *  XML Schema Part 1:

     *  Structures, 2.6 Schema-Related Markup in Documents Being Validated</a>

     */

    public static final String W3C_XML_SCHEMA_INSTANCE_NS_URI =

        "http://www.w3.org/2001/XMLSchema-instance";

    /**

     * W3C XPath Datatype Namespace URI.

     *

     * <p>Defined to be "{@code http://www.w3.org/2003/11/xpath-datatypes}".

     *

     * @see <a href="http://www.w3.org/TR/xpath-datamodel">XQuery 1.0 and XPath 2.0 Data Model</a>

     */

    public static final String W3C_XPATH_DATATYPE_NS_URI = "http://www.w3.org/2003/11/xpath-datatypes";

    /**

     * XML Document Type Declaration Namespace URI as an arbitrary value.

     *

     * <p>Since not formally defined by any existing standard, arbitrarily define to be "{@code http://www.w3.org/TR/REC-xml}".

     */

    public static final String XML_DTD_NS_URI = "http://www.w3.org/TR/REC-xml";

        /**

         * RELAX NG Namespace URI.

         *

         * <p>Defined to be "{@code http://relaxng.org/ns/structure/1.0}".

         *

         * @see <a href="http://relaxng.org/spec-20011203.html">RELAX NG Specification</a>

         */

        public static final String RELAXNG_NS_URI = "http://relaxng.org/ns/structure/1.0";

        /**

         * Feature for secure processing.

         *

         * <ul>

         *   <li>

         *     {@code true} instructs the implementation to process XML securely.

         *     This may set limits on XML constructs to avoid conditions such as denial of service attacks.

         *   </li>

         *   <li>

         *     {@code false} instructs the implementation to process XML in accordance with the XML specifications

         *     ignoring security issues such as limits on XML constructs to avoid conditions such as denial of service attacks.

         *   </li>

         * </ul>

         */

        public static final String FEATURE_SECURE_PROCESSING = "http://javax.xml.XMLConstants/feature/secure-processing";

        /**

         * Property: accessExternalDTD

         *

         * <p>

         * Restrict access to external DTDs and external Entity References to the protocols specified.

         * If access is denied due to the restriction of this property, a runtime exception that

         * is specific to the context is thrown. In the case of {@link javax.xml.parsers.SAXParser}

         * for example, {@link org.xml.sax.SAXException} is thrown.

         *

         * <p>

         * <b>Value: </b> a list of protocols separated by comma. A protocol is the scheme portion of a

         * {@link java.net.URI}, or in the case of the JAR protocol, "jar" plus the scheme portion

         * separated by colon.

         * A scheme is defined as:

         *

         * <blockquote>

         * scheme = alpha *( alpha | digit | "+" | "-" | "." )<br>

         * where alpha = a-z and A-Z.<br><br>

         *

         * And the JAR protocol:<br>

         *

         * jar[:scheme]<br><br>

         *

         * Protocols including the keyword "jar" are case-insensitive. Any whitespaces as defined by

         * {@link java.lang.Character#isSpaceChar } in the value will be ignored.

         * Examples of protocols are file, http, jar:file.

         *

         * </blockquote>

         *

         *<p>

         * <b>Default value:</b> The default value is implementation specific and therefore not specified.

         * The following options are provided for consideration:

         * <blockquote>

         * <UL>

         *     <LI>an empty string to deny all access to external references;</LI>

         *     <LI>a specific protocol, such as file, to give permission to only the protocol;</LI>

         *     <LI>the keyword "all" to grant  permission to all protocols.</LI>

         * </UL><br>

         *      When FEATURE_SECURE_PROCESSING is enabled,  it is recommended that implementations

         *      restrict external connections by default, though this may cause problems for applications

         *      that process XML/XSD/XSL with external references.

         * </blockquote>

         *

         * <p>

         * <b>Granting all access:</b>  the keyword "all" grants permission to all protocols.

         *

         * <p>

         * <b>System Property:</b> The value of this property can be set or overridden by

         * system property {@code javax.xml.accessExternalDTD}.

         *

         *

         * <p>

         * <b>jaxp.properties:</b> This configuration file is in standard

         * {@link java.util.Properties} format and typically located in the {@code conf}

         * directory of the Java installation. If the file exists and the system

         * property is specified, its value will be used to override the default

         * of the property.

         *

         *

         * @since 1.7

         */

        public static final String ACCESS_EXTERNAL_DTD = "http://javax.xml.XMLConstants/property/accessExternalDTD";

        /**

         * <p>Property: accessExternalSchema</p>

         *

         * <p>

         * Restrict access to the protocols specified for external reference set by the

         * schemaLocation attribute, Import and Include element. If access is denied

         * due to the restriction of this property, a runtime exception that is specific

         * to the context is thrown. In the case of {@link javax.xml.validation.SchemaFactory}

         * for example, org.xml.sax.SAXException is thrown.

         *

         * <p>

         * <b>Value:</b> a list of protocols separated by comma. A protocol is the scheme portion of a

         * {@link java.net.URI}, or in the case of the JAR protocol, "jar" plus the scheme portion

         * separated by colon.

         * A scheme is defined as:

         *

         * <blockquote>

         * scheme = alpha *( alpha | digit | "+" | "-" | "." )<br>

         * where alpha = a-z and A-Z.<br><br>

         *

         * And the JAR protocol:<br>

         *

         * jar[:scheme]<br><br>

         *

         * Protocols including the keyword "jar" are case-insensitive. Any whitespaces as defined by

         * {@link java.lang.Character#isSpaceChar } in the value will be ignored.

         * Examples of protocols are file, http, jar:file.

         *

         * </blockquote>

         *

         * <p>

         * <b>Default value:</b> The default value is implementation specific and therefore not specified.

         * The following options are provided for consideration:

         * <blockquote>

         * <UL>

         *     <LI>an empty string to deny all access to external references;</LI>

         *     <LI>a specific protocol, such as file, to give permission to only the protocol;</LI>

         *     <LI>the keyword "all" to grant  permission to all protocols.</LI>

         * </UL><br>

         *      When FEATURE_SECURE_PROCESSING is enabled,  it is recommended that implementations

         *      restrict external connections by default, though this may cause problems for applications

         *      that process XML/XSD/XSL with external references.

         * </blockquote>

         *

         * <p>

         * <b>Granting all access:</b>  the keyword "all" grants permission to all protocols.

         *

         * <p>

         * <b>System Property:</b> The value of this property can be set or overridden by

         * system property {@code javax.xml.accessExternalSchema}

         *

         * <p>

         * <b>jaxp.properties:</b> This configuration file is in standard

         * {@link java.util.Properties} format and typically located in the {@code conf}

         * directory of the Java installation. If the file exists and the system

         * property is specified, its value will be used to override the default

         * of the property.

         *

         * @since 1.7

         */

        public static final String ACCESS_EXTERNAL_SCHEMA = "http://javax.xml.XMLConstants/property/accessExternalSchema";

        /**

         * Property: accessExternalStylesheet

         *

         * <p>

         * Restrict access to the protocols specified for external references set by the

         * stylesheet processing instruction, Import and Include element, and document function.

         * If access is denied due to the restriction of this property, a runtime exception

         * that is specific to the context is thrown. In the case of constructing new

         * {@link javax.xml.transform.Transformer} for example,

         * {@link javax.xml.transform.TransformerConfigurationException}

         * will be thrown by the {@link javax.xml.transform.TransformerFactory}.

         *

         * <p>

         * <b>Value:</b> a list of protocols separated by comma. A protocol is the scheme portion of a

         * {@link java.net.URI}, or in the case of the JAR protocol, "jar" plus the scheme portion

         * separated by colon.

         * A scheme is defined as:

         *

         * <blockquote>

         * scheme = alpha *( alpha | digit | "+" | "-" | "." )<br>

         * where alpha = a-z and A-Z.<br><br>

         *

         * And the JAR protocol:<br>

         *

         * jar[:scheme]<br><br>

         *

         * Protocols including the keyword "jar" are case-insensitive. Any whitespaces as defined by

         * {@link java.lang.Character#isSpaceChar } in the value will be ignored.

         * Examples of protocols are file, http, jar:file.

         *

         * </blockquote>

         *

         * <p>

         * <b>Default value:</b> The default value is implementation specific and therefore not specified.

         * The following options are provided for consideration:

         * <blockquote>

         * <UL>

         *     <LI>an empty string to deny all access to external references;</LI>

         *     <LI>a specific protocol, such as file, to give permission to only the protocol;</LI>

         *     <LI>the keyword "all" to grant  permission to all protocols.</LI>

         * </UL><br>

         *      When FEATURE_SECURE_PROCESSING is enabled,  it is recommended that implementations

         *      restrict external connections by default, though this may cause problems for applications

         *      that process XML/XSD/XSL with external references.

         * </blockquote>

         *

         * <p>

         * <b>Granting all access:</b>  the keyword "all" grants permission to all protocols.

         *

         * <p>

         * <b>System Property:</b> The value of this property can be set or overridden by

         * system property {@code javax.xml.accessExternalStylesheet}

         *

         * <p>

         * <b>jaxp.properties:</b> This configuration file is in standard

         * {@link java.util.Properties} format and typically located in the {@code conf}

         * directory of the Java installation. If the file exists and the system

         * property is specified, its value will be used to override the default

         * of the property.

         *

         * @since 1.7

         */

        public static final String ACCESS_EXTERNAL_STYLESHEET = "http://javax.xml.XMLConstants/property/accessExternalStylesheet";

        /**

         * Feature: useCatalog

         *

         * <p>

         * Instructs XML processors to use XML Catalogs to resolve entity references.

         * Catalogs may be set through JAXP factories, system properties, or

         * jaxp.properties by using the {@code javax.xml.catalog.files} property

         * defined in {@link javax.xml.catalog.CatalogFeatures}.

         * The following code enables Catalog on SAX parser:

         * <pre>{@code

         *      SAXParserFactory spf = SAXParserFactory.newInstance();

         *      spf.setFeature(XMLConstants.USE_CATALOG, true);

         *      SAXParser parser = spf.newSAXParser();

         *      parser.setProperty(CatalogFeatures.Feature.FILES.getPropertyName(), "catalog.xml");

         * }</pre>

         *

         * <p>

         * <b>Value:</b> a boolean. If the value is true, and a catalog is set,

         * the XML parser will resolve external references using

         * {@link javax.xml.catalog.CatalogResolver}. If the value is false,

         * XML Catalog is ignored even if one is set. The default value is true.

         *

         * <p>

         * <b>System Property:</b> The value of this property can be set or overridden by

         * system property {@code javax.xml.useCatalog}

         *

         * <p>

         * <b>jaxp.properties:</b> This configuration file is in standard

         * {@link java.util.Properties} format and typically located in the {@code conf}

         * directory of the Java installation. If the file exists and the system

         * property is specified, its value will be used to override the default

         * value of the property.

         *

         * @since 9

         */

        public static final String USE_CATALOG = "http://javax.xml.XMLConstants/feature/useCatalog";

}