/*
 *  Operation.java
 *
 *  $Revision$ $Date$ 
 * 
 *  (c) Copyright 2001, 2002 Motorola, Inc.  ALL RIGHTS RESERVED.
 */
package javax.obex;

import java.lang.*;
import java.io.*;
import javax.microedition.io.*;
/**
 * The <code>Operation</code> interface provides ways to manipulate a single
 * OBEX PUT or GET operation.  The implementation of this interface sends
 * OBEX packets as they are built.  If during the operation the peer in the
 * operation ends the operation, an <code>IOException</code> is thrown on
 * the next read from the input stream, write to the output stream, or call to
 * <code>sendHeaders()</code>.
 * <P>
 * <STRONG>Definition of methods inherited from <code>ContentConnection</code></STRONG>
 * <P>
 * <code>getEncoding()</code> will always return <code>null</code>.
 * <BR><code>getLength()</code> will return the length specified by the OBEX Length
 * header or -1 if the OBEX Length header was not included.
 * <BR><code>getType()</code> will return the value specified in the OBEX Type
 * header or <code>null</code> if the OBEX Type header was not included.<BR>
 * <P>
 * <STRONG>How Headers are Handled</STRONG>
 * <P>
 * As headers are received, they may be retrieved through the
 * <code>getReceivedHeaders()</code> method.  If new headers are set during the
 * operation, the new headers will be sent during the next packet exchange.
 * <P>
 * <STRONG>PUT example</STRONG>
 * <P>
 * <PRE>
 * void putObjectViaOBEX(ClientSession conn, HeaderSet head, byte[] obj)
 *     throws IOException {
 *
 *     // Include the length header
 *     head.setHeader(head.LENGTH, new Long(obj.length));
 *
 *     // Initiate the PUT request
 *     Operation op = conn.put(head);
 *
 *     // Open the output stream to put the object to it
 *     DataOutputStream out = op.openDataOutputStream();
 *
 *     // Send the object to the server
 *     out.write(obj);
 *
 *     // End the transaction
 *     out.close();
 *     op.close();
 * }
 * </PRE>
 * <P>
 * <STRONG>GET example</STRONG>
 * <P>
 * <PRE>
 * byte[] getObjectViaOBEX(ClientSession conn, HeaderSet head) throws IOException {
 *
 *     // Send the initial GET request to the server
 *     Operation op = conn.get(head);
 *
 *     // Retrieve the length of the object being sent back
 *     int length = op.getLength();
 *
 *      // Create space for the object
 *      byte[] obj = new byte[length];
 *
 *     // Get the object from the input stream
 *     DataInputStream in = trans.openDataInputStream();
 *     in.read(obj);
 *
 *     // End the transaction
 *     in.close();
 *     op.close();
 *
 *     return obj;
 * }
 * </PRE>
 * <H3>Client PUT Operation Flow</H3>
 * For PUT operations, a call to <code>close()</code> the <code>OutputStream</code>
 * returned from <code>openOutputStream()</code> or <code>openDataOutputStream()</code>
 * will signal that the request is done.  (In OBEX terms, the End-Of-Body header should
 * be sent and the final bit in the request will be set.)  At this point, the
 * reply from the server may begin to be processed.  A call to
 * <code>getResponseCode()</code> will do an implicit close on the
 * <code>OutputStream</code> and therefore signal that the request is done.
 * <H3>Client GET Operation Flow</H3>
 * For GET operation, a call to <code>openInputStream()</code> or
 * <code>openDataInputStream()</code> will signal that the request is done.  (In OBEX
 * terms, the final bit in the request will be set.)  A call to
 * <code>getResponseCode()</code> will cause an implicit close on the
 * <code>InputStream</code>.  No further data may be read at this point.
 *
 * @version 1.0 February 11, 2002
 */
public interface Operation extends ContentConnection {

    /**
     * Sends an ABORT message to the server.  By calling this method, the
     * corresponding input and output streams will be closed along with this
     * object.  No headers are sent in the abort request.  This will end the
     * operation since <code>close()</code> will be called by this method.
     *
     * @exception IOException if the transaction has already ended or if an
     * OBEX server calls this method
     */
    public void abort() throws IOException;

    /**
     * Returns the headers that have been received during the operation.
     * Modifying the object returned has no effect on the headers that are
     * sent or retrieved.
     *
     * @return the headers received during this <code>Operation</code>
     *
     * @exception IOException if this <code>Operation</code> has been closed
     */
    public HeaderSet getReceivedHeaders() throws IOException;

    /**
     * Specifies the headers that should be sent in the next OBEX message that
     * is sent.
     *
     * @param headers the headers to send in the next message
     *
     * @exception IOException  if this <code>Operation</code> has been closed
     * or the transaction has ended and no further messages will be exchanged
     *
     * @exception IllegalArgumentException if <code>headers</code> was not created
     * by a call to <code>ServerRequestHandler.createHeaderSet()</code> or
     * <code>ClientSession.createHeaderSet()</code>
     *
     * @exception NullPointerException if <code>headers</code> if <code>null</code>
     */
    public void sendHeaders(HeaderSet headers) throws IOException;

    /**
     * Returns the response code received from the server.  Response codes
     * are defined in the <code>ResponseCodes</code> class.
     *
     * @see ResponseCodes
     *
     * @return the response code retrieved from the server
     *
     * @exception IOException if an error occurred in the transport layer during
     * the transaction; if this object was created by an OBEX server
     */
    public int getResponseCode() throws IOException;
}