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/**

 * Defines the generic APIs for processing transformation instructions,

 * and performing a transformation from source to result. These interfaces have no

 * dependencies on SAX or the DOM standard, and try to make as few assumptions as

 * possible about the details of the source and result of a transformation. It

 * achieves this by defining {@link javax.xml.transform.Source} and

 * {@link javax.xml.transform.Result} interfaces.

 *

 * <p>

 * To provide concrete classes for the user, the API defines specializations

 * of the interfaces found at the root level. These interfaces are found in

 * {@link javax.xml.transform.sax}, {@link javax.xml.transform.dom},

 * {@link javax.xml.transform.stax}, and {@link javax.xml.transform.stream}.

 *

 *

 * <h2>Creating Objects</h2>

 *

 * <p>

 * The API allows a concrete {@link javax.xml.transform.TransformerFactory}

 * object to be created from the static function

 * {@link javax.xml.transform.TransformerFactory#newInstance}.

 *

 *

 * <h2>Specification of Inputs and Outputs</h2>

 *

 * <p>

 * This API defines two interface objects called {@link javax.xml.transform.Source}

 * and {@link javax.xml.transform.Result}. In order to pass Source and Result

 * objects to the interfaces, concrete classes must be used. The following concrete

 * representations are defined for each of these objects:

 * {@link javax.xml.transform.stream.StreamSource} and

 * {@link javax.xml.transform.stream.StreamResult},

 * {@link javax.xml.transform.stax.StAXSource} and

 * {@link javax.xml.transform.stax.StAXResult}, and

 * {@link javax.xml.transform.sax.SAXSource} and

 * {@link javax.xml.transform.sax.SAXResult}, and

 * {@link javax.xml.transform.dom.DOMSource} and

 * {@link javax.xml.transform.dom.DOMResult}. Each of these objects defines a

 * FEATURE string (which is in the form of a URL), which can be passed into

 * {@link javax.xml.transform.TransformerFactory#getFeature} to see if the given

 * type of Source or Result object is supported. For instance, to test if a

 * DOMSource and a StreamResult is supported, you can apply the following test.

 *

 * <pre>

 * <code>

 * TransformerFactory tfactory = TransformerFactory.newInstance();

 * if (tfactory.getFeature(DOMSource.FEATURE) &&

 *     tfactory.getFeature(StreamResult.FEATURE)) {

 *     ...

 * }

 * </code>

 * </pre>

 *

 *

 * <h2><a id="qname-delimiter">Qualified Name Representation</a></h2>

 *

 * <p>

 * <a href="http://www.w3.org/TR/REC-xml-names">Namespaces</a> present something

 * of a problem area when dealing with XML objects. Qualified Names appear in XML

 * markup as prefixed names. But the prefixes themselves do not hold identity.

 * Rather, it is the URIs that they contextually map to that hold the identity.

 * Therefore, when passing a Qualified Name like "xyz:foo" among Java programs,

 * one must provide a means to map "xyz" to a namespace.

 *

 * <p>

 * One solution has been to create a "QName" object that holds the namespace URI,

 * as well as the prefix and local name, but this is not always an optimal solution,

 * as when, for example, you want to use unique strings as keys in a dictionary

 * object. Not having a string representation also makes it difficult to specify

 * a namespaced identity outside the context of an XML document.

 *

 * <p>

 * In order to pass namespaced values to transformations, for instance when setting

 * a property or a parameter on a {@link javax.xml.transform.Transformer} object,

 * this specification defines that a String "qname" object parameter be passed as

 * two-part string, the namespace URI enclosed in curly braces ({}), followed by

 * the local name. If the qname has a null URI, then the String object only

 * contains the local name. An application can safely check for a non-null URI by

 * testing to see if the first character of the name is a '{' character.

 *

 * <p>

 * For example, if a URI and local name were obtained from an element defined with

 * <xyz:foo xmlns:xyz="http://xyz.foo.com/yada/baz.html"/>, then the

 * Qualified Name would be "{http://xyz.foo.com/yada/baz.html}foo". Note that the

 * prefix is lost.

 *

 *

 * <h2>Result Tree Serialization</h2>

 *

 * <p>

 * Serialization of the result tree to a stream can be controlled with the

 * {@link javax.xml.transform.Transformer#setOutputProperties} and the

 * {@link javax.xml.transform.Transformer#setOutputProperty} methods.

 * These properties only apply to stream results, they have no effect when

 * the result is a DOM tree or SAX event stream.

 *

 * <p>

 * Strings that match the <a href="http://www.w3.org/TR/xslt#output">XSLT

 * specification for xsl:output attributes</a> can be referenced from the

 * {@link javax.xml.transform.OutputKeys} class. Other strings can be

 * specified as well.

 * If the transformer does not recognize an output key, a

 * {@link java.lang.IllegalArgumentException} is thrown, unless the key name

 * is <a href="#qname-delimiter">namespace qualified</a>. Output key names

 * that are namespace qualified are always allowed, although they may be

 * ignored by some implementations.

 *

 * <p>

 * If all that is desired is the simple identity transformation of a

 * source to a result, then {@link javax.xml.transform.TransformerFactory}

 * provides a

 * {@link javax.xml.transform.TransformerFactory#newTransformer()} method

 * with no arguments. This method creates a Transformer that effectively copies

 * the source to the result. This method may be used to create a DOM from SAX

 * events or to create an XML or HTML stream from a DOM or SAX events.

 *

 * <h2>Exceptions and Error Reporting</h2>

 *

 * <p>

 * The transformation API throw three types of specialized exceptions. A

 * {@link javax.xml.transform.TransformerFactoryConfigurationError} is parallel to

 * the {@link javax.xml.parsers.FactoryConfigurationError}, and is thrown

 * when a configuration problem with the TransformerFactory exists. This error

 * will typically be thrown when the transformation factory class specified with

 * the "javax.xml.transform.TransformerFactory" system property cannot be found or

 * instantiated.

 *

 * <p>

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

 * may be thrown if for any reason a Transformer can not be created. A

 * TransformerConfigurationException may be thrown if there is a syntax error in

 * the transformation instructions, for example when

 * {@link javax.xml.transform.TransformerFactory#newTransformer} is

 * called.

 *

 * <p>

 * {@link javax.xml.transform.TransformerException} is a general

 * exception that occurs during the course of a transformation. A transformer

 * exception may wrap another exception, and if any of the

 * {@link javax.xml.transform.TransformerException#printStackTrace()}

 * methods are called on it, it will produce a list of stack dumps, starting from

 * the most recent. The transformer exception also provides a

 * {@link javax.xml.transform.SourceLocator} object which indicates where

 * in the source tree or transformation instructions the error occurred.

 * {@link javax.xml.transform.TransformerException#getMessageAndLocation()}

 * may be called to get an error message with location info, and

 * {@link javax.xml.transform.TransformerException#getLocationAsString()}

 * may be called to get just the location string.

 *

 * <p>

 * Transformation warnings and errors are sent to an

 * {@link javax.xml.transform.ErrorListener}, at which point the application may

 * decide to report the error or warning, and may decide to throw an

 * <code>Exception</code> for a non-fatal error. The <code>ErrorListener</code>

 * may be set via {@link javax.xml.transform.TransformerFactory#setErrorListener}

 * for reporting errors that have to do with syntax errors in the transformation

 * instructions, or via {@link javax.xml.transform.Transformer#setErrorListener}

 * to report errors that occur during the transformation. The <code>ErrorListener</code>

 * on both objects will always be valid and non-<code>null</code>, whether set by

 * the application or a default implementation provided by the processor.

 * The default implementation provided by the processor will report all warnings

 * and errors to <code>System.err</code> and does not throw any <code>Exception</code>s.

 * Applications are <em>strongly</em> encouraged to register and use

 * <code>ErrorListener</code>s that insure proper behavior for warnings and

 * errors.

 *

 *

 * <h2>Resolution of URIs within a transformation</h2>

 *

 * <p>

 * The API provides a way for URIs referenced from within the stylesheet

 * instructions or within the transformation to be resolved by the calling

 * application. This can be done by creating a class that implements the

 * {@link javax.xml.transform.URIResolver} interface, with its one method,

 * {@link javax.xml.transform.URIResolver#resolve}, and use this class to

 * set the URI resolution for the transformation instructions or transformation

 * with {@link javax.xml.transform.TransformerFactory#setURIResolver} or

 * {@link javax.xml.transform.Transformer#setURIResolver}. The

 * <code>URIResolver.resolve</code> method takes two String arguments, the URI

 * found in the stylesheet instructions or built as part of the transformation

 * process, and the base URI against which the first argument will be made absolute

 * if the absolute URI is required.

 * The returned {@link javax.xml.transform.Source} object must be usable by

 * the transformer, as specified in its implemented features.

 *

 * @since 1.5

 */

package javax.xml.transform;