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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   * published by the Free Software Foundation.  Oracle designates this
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   *
   * 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
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   * You should have received a copy of the GNU General Public License version
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  package java.sql;
  
  /**
   * The interface used for the custom mapping of an SQL user-defined type (UDT) to
   * a class in the Java programming language. The class object for a class
   * implementing the <code>SQLData</code> interface will be entered in the
   * appropriate <code>Connection</code> object's type map along with the SQL
   * name of the UDT for which it is a custom mapping.
   * <P>
   * Typically, a <code>SQLData</code> implementation
   * will define a field for each attribute of an SQL structured type or a
   * single field for an SQL <code>DISTINCT</code> type. When the UDT is
   * retrieved from a data source with the <code>ResultSet.getObject</code>
   * method, it will be mapped as an instance of this class.  A programmer
   * can operate on this class instance just as on any other object in the
   * Java programming language and then store any changes made to it by
   * calling the <code>PreparedStatement.setObject</code> method,
   * which will map it back to the SQL type.
   * <p>
   * It is expected that the implementation of the class for a custom
   * mapping will be done by a tool.  In a typical implementation, the
   * programmer would simply supply the name of the SQL UDT, the name of
   * the class to which it is being mapped, and the names of the fields to
   * which each of the attributes of the UDT is to be mapped.  The tool will use
   * this information to implement the <code>SQLData.readSQL</code> and
   * <code>SQLData.writeSQL</code> methods.  The <code>readSQL</code> method
   * calls the appropriate <code>SQLInput</code> methods to read
   * each attribute from an <code>SQLInput</code> object, and the
   * <code>writeSQL</code> method calls <code>SQLOutput</code> methods
   * to write each attribute back to the data source via an
   * <code>SQLOutput</code> object.
   * <P>
   * An application programmer will not normally call <code>SQLData</code> methods
   * directly, and the <code>SQLInput</code> and <code>SQLOutput</code> methods
   * are called internally by <code>SQLData</code> methods, not by application code.
   *
   * @since 1.2
   */
  public interface SQLData {
  
   /**
    * Returns the fully-qualified
    * name of the SQL user-defined type that this object represents.
    * This method is called by the JDBC driver to get the name of the
    * UDT instance that is being mapped to this instance of
    * <code>SQLData</code>.
    *
    * @return the type name that was passed to the method <code>readSQL</code>
    *            when this object was constructed and populated
    * @exception SQLException if there is a database access error
    * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
    * this method
    * @since 1.2
    */
    String getSQLTypeName() throws SQLException;
  
   /**
    * Populates this object with data read from the database.
    * The implementation of the method must follow this protocol:
    * <UL>
    * <LI>It must read each of the attributes or elements of the SQL
    * type  from the given input stream.  This is done
    * by calling a method of the input stream to read each
    * item, in the order that they appear in the SQL definition
    * of the type.
    * <LI>The method <code>readSQL</code> then
    * assigns the data to appropriate fields or
    * elements (of this or other objects).
    * Specifically, it must call the appropriate <i>reader</i> method
    * (<code>SQLInput.readString</code>, <code>SQLInput.readBigDecimal</code>,
    * and so on) method(s) to do the following:
    * for a distinct type, read its single data element;
    * for a structured type, read a value for each attribute of the SQL type.
    * </UL>
    * The JDBC driver initializes the input stream with a type map
    * before calling this method, which is used by the appropriate
    * <code>SQLInput</code> reader method on the stream.
    *
    * @param stream the <code>SQLInput</code> object from which to read the data for
    * the value that is being custom mapped
    * @param typeName the SQL type name of the value on the data stream
    * @exception SQLException if there is a database access error
    * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
    * this method
    * @see SQLInput
    * @since 1.2
    */
    void readSQL (SQLInput stream, String typeName) throws SQLException;
  
    /**
    * Writes this object to the given SQL data stream, converting it back to
    * its SQL value in the data source.
    * The implementation of the method must follow this protocol:<BR>
    * It must write each of the attributes of the SQL type
    * to the given output stream.  This is done by calling a
    * method of the output stream to write each item, in the order that
    * they appear in the SQL definition of the type.
    * Specifically, it must call the appropriate <code>SQLOutput</code> writer
    * method(s) (<code>writeInt</code>, <code>writeString</code>, and so on)
    * to do the following: for a Distinct Type, write its single data element;
    * for a Structured Type, write a value for each attribute of the SQL type.
    *
    * @param stream the <code>SQLOutput</code> object to which to write the data for
    * the value that was custom mapped
    * @exception SQLException if there is a database access error
    * @exception SQLFeatureNotSupportedException if the JDBC driver does not support
    * this method
    * @see SQLOutput
    * @since 1.2
    */
    void writeSQL (SQLOutput stream) throws SQLException;
  }
  