/*
 * Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation. Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.sql;

import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;

import javax.xml.transform.Result;
import javax.xml.transform.Source;

/**
 * The mapping in the JavaTM programming language for the SQL XML type.
 * XML is a built-in type that stores an XML value
 * as a column value in a row of a database table.
 * By default drivers implement an SQLXML object as
 * a logical pointer to the XML data
 * rather than the data itself.
 * An SQLXML object is valid for the duration of the transaction in which it was created.
 * <p>
 * The SQLXML interface provides methods for accessing the XML value
 * as a String, a Reader or Writer, or as a Stream. The XML value
 * may also be accessed through a Source or set as a Result, which
 * are used with XML Parser APIs such as DOM, SAX, and StAX, as
 * well as with XSLT transforms and XPath evaluations.
 * <p>
 * Methods in the interfaces ResultSet, CallableStatement, and PreparedStatement,
 * such as getSQLXML allow a programmer to access an XML value.
 * In addition, this interface has methods for updating an XML value.
 * <p>
 * The XML value of the SQLXML instance may be obtained as a BinaryStream using
 * <pre>
 * SQLXML sqlxml = resultSet.getSQLXML(column);
 * InputStream binaryStream = sqlxml.getBinaryStream();
 * </pre>
 * For example, to parse an XML value with a DOM parser:
 * <pre>
 * DocumentBuilder parser = DocumentBuilderFactory.newInstance().newDocumentBuilder();
 * Document result = parser.parse(binaryStream);
 * </pre>
 * or to parse an XML value with a SAX parser to your handler:
 * <pre>
 * SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
 * parser.parse(binaryStream, myHandler);
 * </pre>
 * or to parse an XML value with a StAX parser:
 * <pre>
 * XMLInputFactory factory = XMLInputFactory.newInstance();
 * XMLStreamReader streamReader = factory.createXMLStreamReader(binaryStream);
 * </pre>
 * <p>
 * Because databases may use an optimized representation for the XML,
 * accessing the value through getSource() and
 * setResult() can lead to improved processing performance
 * without serializing to a stream representation and parsing the XML.
 * <p>
 * For example, to obtain a DOM Document Node:
 * <pre>
 * DOMSource domSource = sqlxml.getSource(DOMSource.class);
 * Document document = (Document) domSource.getNode();
 * </pre>
 * or to set the value to a DOM Document Node to myNode:
 * <pre>
 * DOMResult domResult = sqlxml.setResult(DOMResult.class);
 * domResult.setNode(myNode);
 * </pre>
 * or, to send SAX events to your handler:
 * <pre>
 * SAXSource saxSource = sqlxml.getSource(SAXSource.class);
 * XMLReader xmlReader = saxSource.getXMLReader();
 * xmlReader.setContentHandler(myHandler);
 * xmlReader.parse(saxSource.getInputSource());
 * </pre>
 * or, to set the result value from SAX events:
 * <pre>
 * SAXResult saxResult = sqlxml.setResult(SAXResult.class);
 * ContentHandler contentHandler = saxResult.getHandler();
 * contentHandler.startDocument();
 * // set the XML elements and attributes into the result
 * contentHandler.endDocument();
 * </pre>
 * or, to obtain StAX events:
 * <pre>
 * StAXSource staxSource = sqlxml.getSource(StAXSource.class);
 * XMLStreamReader streamReader = staxSource.getXMLStreamReader();
 * </pre>
 * or, to set the result value from StAX events:
 * <pre>
 * StAXResult staxResult = sqlxml.setResult(StAXResult.class);
 * XMLStreamWriter streamWriter = staxResult.getXMLStreamWriter();
 * </pre>
 * or, to perform XSLT transformations on the XML value using the XSLT in xsltFile
 * output to file resultFile:
 * <pre>
 * File xsltFile = new File("a.xslt");
 * File myFile = new File("result.xml");
 * Transformer xslt = TransformerFactory.newInstance().newTransformer(new StreamSource(xsltFile));
 * Source source = sqlxml.getSource(null);
 * Result result = new StreamResult(myFile);
 * xslt.transform(source, result);
 * </pre>
 * or, to evaluate an XPath expression on the XML value:
 * <pre>
 * XPath xpath = XPathFactory.newInstance().newXPath();
 * DOMSource domSource = sqlxml.getSource(DOMSource.class);
 * Document document = (Document) domSource.getNode();
 * String expression = "/foo/@bar";
 * String barValue = xpath.evaluate(expression, document);
 * </pre>
 * To set the XML value to be the result of an XSLT transform:
 * <pre>
 * File sourceFile = new File("source.xml");
 * Transformer xslt = TransformerFactory.newInstance().newTransformer(new StreamSource(xsltFile));
 * Source streamSource = new StreamSource(sourceFile);
 * Result result = sqlxml.setResult(null);
 * xslt.transform(streamSource, result);
 * </pre>
 * Any Source can be transformed to a Result using the identity transform
 * specified by calling newTransformer():
 * <pre>
 * Transformer identity = TransformerFactory.newInstance().newTransformer();
 * Source source = sqlxml.getSource(null);
 * File myFile = new File("result.xml");
 * Result result = new StreamResult(myFile);
 * identity.transform(source, result);
 * </pre>
 * To write the contents of a Source to standard output:
 * <pre>
 * Transformer identity = TransformerFactory.newInstance().newTransformer();
 * Source source = sqlxml.getSource(null);
 * Result result = new StreamResult(System.out);
 * identity.transform(source, result);
 * </pre>
 * To create a DOMSource from a DOMResult:
 * <pre>
 * DOMSource domSource = new DOMSource(domResult.getNode());
 * </pre>
 * <p>
 * Incomplete or invalid XML values may cause an SQLException when
 * set or the exception may occur when execute() occurs. All streams
 * must be closed before execute() occurs or an SQLException will be thrown.
 * <p>
 * Reading and writing XML values to or from an SQLXML object can happen at most once.
 * The conceptual states of readable and not readable determine if one
 * of the reading APIs will return a value or throw an exception.
 * The conceptual states of writable and not writable determine if one
 * of the writing APIs will set a value or throw an exception.
 * <p>
 * The state moves from readable to not readable once free() or any of the
 * reading APIs are called: getBinaryStream(), getCharacterStream(), getSource(), and getString().
 * Implementations may also change the state to not writable when this occurs.
 * <p>
 * The state moves from writable to not writable once free() or any of the
 * writing APIs are called: setBinaryStream(), setCharacterStream(), setResult(), and setString().
 * Implementations may also change the state to not readable when this occurs.
 *
 * <p>
 * All methods on the <code>SQLXML</code> interface must be fully implemented if the
 * JDBC driver supports the data type.
 *
 * @see javax.xml.parsers
 * @see javax.xml.stream
 * @see javax.xml.transform
 * @see javax.xml.xpath
 * @since 1.6
 */
public interface SQLXML
{
 /**
 * This method closes this object and releases the resources that it held.
 * The SQL XML object becomes invalid and neither readable or writable
 * when this method is called.
 *
 * After <code>free</code> has been called, any attempt to invoke a
 * method other than <code>free</code> will result in a <code>SQLException</code>
 * being thrown. If <code>free</code> is called multiple times, the subsequent
 * calls to <code>free</code> are treated as a no-op.
 * @throws SQLException if there is an error freeing the XML value.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 void free() throws SQLException;

 /**
 * Retrieves the XML value designated by this SQLXML instance as a stream.
 * The bytes of the input stream are interpreted according to appendix F of the XML 1.0 specification.
 * The behavior of this method is the same as ResultSet.getBinaryStream()
 * when the designated column of the ResultSet has a type java.sql.Types of SQLXML.
 * <p>
 * The SQL XML object becomes not readable when this method is called and
 * may also become not writable depending on implementation.
 *
 * @return a stream containing the XML data.
 * @throws SQLException if there is an error processing the XML value.
 * An exception is thrown if the state is not readable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 InputStream getBinaryStream() throws SQLException;

 /**
 * Retrieves a stream that can be used to write the XML value that this SQLXML instance represents.
 * The stream begins at position 0.
 * The bytes of the stream are interpreted according to appendix F of the XML 1.0 specification
 * The behavior of this method is the same as ResultSet.updateBinaryStream()
 * when the designated column of the ResultSet has a type java.sql.Types of SQLXML.
 * <p>
 * The SQL XML object becomes not writable when this method is called and
 * may also become not readable depending on implementation.
 *
 * @return a stream to which data can be written.
 * @throws SQLException if there is an error processing the XML value.
 * An exception is thrown if the state is not writable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 OutputStream setBinaryStream() throws SQLException;

 /**
 * Retrieves the XML value designated by this SQLXML instance as a java.io.Reader object.
 * The format of this stream is defined by org.xml.sax.InputSource,
 * where the characters in the stream represent the unicode code points for
 * XML according to section 2 and appendix B of the XML 1.0 specification.
 * Although an encoding declaration other than unicode may be present,
 * the encoding of the stream is unicode.
 * The behavior of this method is the same as ResultSet.getCharacterStream()
 * when the designated column of the ResultSet has a type java.sql.Types of SQLXML.
 * <p>
 * The SQL XML object becomes not readable when this method is called and
 * may also become not writable depending on implementation.
 *
 * @return a stream containing the XML data.
 * @throws SQLException if there is an error processing the XML value.
 * The getCause() method of the exception may provide a more detailed exception, for example,
 * if the stream does not contain valid characters.
 * An exception is thrown if the state is not readable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 Reader getCharacterStream() throws SQLException;

 /**
 * Retrieves a stream to be used to write the XML value that this SQLXML instance represents.
 * The format of this stream is defined by org.xml.sax.InputSource,
 * where the characters in the stream represent the unicode code points for
 * XML according to section 2 and appendix B of the XML 1.0 specification.
 * Although an encoding declaration other than unicode may be present,
 * the encoding of the stream is unicode.
 * The behavior of this method is the same as ResultSet.updateCharacterStream()
 * when the designated column of the ResultSet has a type java.sql.Types of SQLXML.
 * <p>
 * The SQL XML object becomes not writable when this method is called and
 * may also become not readable depending on implementation.
 *
 * @return a stream to which data can be written.
 * @throws SQLException if there is an error processing the XML value.
 * The getCause() method of the exception may provide a more detailed exception, for example,
 * if the stream does not contain valid characters.
 * An exception is thrown if the state is not writable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 Writer setCharacterStream() throws SQLException;

 /**
 * Returns a string representation of the XML value designated by this SQLXML instance.
 * The format of this String is defined by org.xml.sax.InputSource,
 * where the characters in the stream represent the unicode code points for
 * XML according to section 2 and appendix B of the XML 1.0 specification.
 * Although an encoding declaration other than unicode may be present,
 * the encoding of the String is unicode.
 * The behavior of this method is the same as ResultSet.getString()
 * when the designated column of the ResultSet has a type java.sql.Types of SQLXML.
 * <p>
 * The SQL XML object becomes not readable when this method is called and
 * may also become not writable depending on implementation.
 *
 * @return a string representation of the XML value designated by this SQLXML instance.
 * @throws SQLException if there is an error processing the XML value.
 * The getCause() method of the exception may provide a more detailed exception, for example,
 * if the stream does not contain valid characters.
 * An exception is thrown if the state is not readable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 String getString() throws SQLException;

 /**
 * Sets the XML value designated by this SQLXML instance to the given String representation.
 * The format of this String is defined by org.xml.sax.InputSource,
 * where the characters in the stream represent the unicode code points for
 * XML according to section 2 and appendix B of the XML 1.0 specification.
 * Although an encoding declaration other than unicode may be present,
 * the encoding of the String is unicode.
 * The behavior of this method is the same as ResultSet.updateString()
 * when the designated column of the ResultSet has a type java.sql.Types of SQLXML.
 * <p>
 * The SQL XML object becomes not writable when this method is called and
 * may also become not readable depending on implementation.
 *
 * @param value the XML value
 * @throws SQLException if there is an error processing the XML value.
 * The getCause() method of the exception may provide a more detailed exception, for example,
 * if the stream does not contain valid characters.
 * An exception is thrown if the state is not writable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 void setString(String value) throws SQLException;

 /**
 * Returns a Source for reading the XML value designated by this SQLXML instance.
 * Sources are used as inputs to XML parsers and XSLT transformers.
 * <p>
 * Sources for XML parsers will have namespace processing on by default.
 * The systemID of the Source is implementation dependent.
 * <p>
 * The SQL XML object becomes not readable when this method is called and
 * may also become not writable depending on implementation.
 * <p>
 * Note that SAX is a callback architecture, so a returned
 * SAXSource should then be set with a content handler that will
 * receive the SAX events from parsing. The content handler
 * will receive callbacks based on the contents of the XML.
 * <pre>
 * SAXSource saxSource = sqlxml.getSource(SAXSource.class);
 * XMLReader xmlReader = saxSource.getXMLReader();
 * xmlReader.setContentHandler(myHandler);
 * xmlReader.parse(saxSource.getInputSource());
 * </pre>
 *
 * @param <T> the type of the class modeled by this Class object
 * @param sourceClass The class of the source, or null.
 * If the class is null, a vendor specific Source implementation will be returned.
 * The following classes are supported at a minimum:
 * <pre>
 * javax.xml.transform.dom.DOMSource - returns a DOMSource
 * javax.xml.transform.sax.SAXSource - returns a SAXSource
 * javax.xml.transform.stax.StAXSource - returns a StAXSource
 * javax.xml.transform.stream.StreamSource - returns a StreamSource
 * </pre>
 * @return a Source for reading the XML value.
 * @throws SQLException if there is an error processing the XML value
 * or if this feature is not supported.
 * The getCause() method of the exception may provide a more detailed exception, for example,
 * if an XML parser exception occurs.
 * An exception is thrown if the state is not readable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 <T extends Source> T getSource(Class<T> sourceClass) throws SQLException;

 /**
 * Returns a Result for setting the XML value designated by this SQLXML instance.
 * <p>
 * The systemID of the Result is implementation dependent.
 * <p>
 * The SQL XML object becomes not writable when this method is called and
 * may also become not readable depending on implementation.
 * <p>
 * Note that SAX is a callback architecture and the returned
 * SAXResult has a content handler assigned that will receive the
 * SAX events based on the contents of the XML. Call the content
 * handler with the contents of the XML document to assign the values.
 * <pre>
 * SAXResult saxResult = sqlxml.setResult(SAXResult.class);
 * ContentHandler contentHandler = saxResult.getXMLReader().getContentHandler();
 * contentHandler.startDocument();
 * // set the XML elements and attributes into the result
 * contentHandler.endDocument();
 * </pre>
 *
 * @param <T> the type of the class modeled by this Class object
 * @param resultClass The class of the result, or null.
 * If resultClass is null, a vendor specific Result implementation will be returned.
 * The following classes are supported at a minimum:
 * <pre>
 * javax.xml.transform.dom.DOMResult - returns a DOMResult
 * javax.xml.transform.sax.SAXResult - returns a SAXResult
 * javax.xml.transform.stax.StAXResult - returns a StAXResult
 * javax.xml.transform.stream.StreamResult - returns a StreamResult
 * </pre>
 * @return Returns a Result for setting the XML value.
 * @throws SQLException if there is an error processing the XML value
 * or if this feature is not supported.
 * The getCause() method of the exception may provide a more detailed exception, for example,
 * if an XML parser exception occurs.
 * An exception is thrown if the state is not writable.
 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.6
 */
 <T extends Result> T setResult(Class<T> resultClass) throws SQLException;

}