/*

 * Copyright 2005-2006 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

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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.getXMLReader().getContentHandler();

 *   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 writeable 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>

  * <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 writeable

   * 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 writeable 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 writeable 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 writeable 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 sourceClass The class of the source, or null.

   * If the class is null, a vendor specifc 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 writeable 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 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.