| /* |
| * Copyright (c) 2003, 2013, 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 |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package com.sun.jdi.connect.spi; |
| |
| import java.io.IOException; |
| |
| /** |
| * A connection between a debugger and a target VM which it debugs. |
| * |
| * <p> A Connection represents a bi-directional communication channel |
| * between a debugger and a target VM. A Connection is created when |
| * {@link com.sun.jdi.connect.spi.TransportService TransportService} |
| * establishes a connection and successfully handshakes with a target |
| * VM. A TransportService implementation provides a reliable |
| * JDWP packet transportation service and consequently a Connection |
| * provides a reliable flow of JDWP packets between the debugger |
| * and the target VM. A Connection is stream oriented, that is, the |
| * JDWP packets written to a connection are read by the target VM |
| * in the order in which they were written. Similiarly packets written |
| * to a Connection by the target VM are read by the debugger in the |
| * order in which they were written. |
| * |
| * <p> A connection is either open or closed. It is open upon creation, |
| * and remains open until it is closed. Once closed, it remains closed, |
| * and any attempt to invoke an I/O operation upon it will cause a |
| * {@link ClosedConnectionException} to be thrown. A connection can |
| * be tested by invoking the {@link #isOpen isOpen} method. |
| * |
| * <p> A Connection is safe for access by multiple concurrent threads, |
| * although at most one thread may be reading and at most one thread may |
| * be writing at any given time. </p> |
| * |
| * @since 1.5 |
| */ |
| |
| @jdk.Exported |
| public abstract class Connection { |
| |
| /** |
| * Reads a packet from the target VM. |
| * |
| * <p> Attempts to read a JDWP packet from the target VM. |
| * A read operation may block indefinitely and only returns |
| * when it reads all bytes of a packet, or in the case of a |
| * transport service that is based on a stream-oriented |
| * communication protocol, the end of stream is encountered. |
| * |
| * <p> Reading a packet does not do any integrity checking on |
| * the packet aside from a check that the length of the packet |
| * (as indicated by the value of the <tt>length</tt> field, the |
| * first four bytes of the packet) is 11 or more bytes. |
| * If the value of the <tt>length</tt> value is less then 11 |
| * then an <tt>IOException</tt> is thrown. |
| * |
| * <p> Returns a byte array of a length equal to the length |
| * of the received packet, or a byte array of length 0 when an |
| * end of stream is encountered. If end of stream is encountered |
| * after some, but not all bytes of a packet, are read then it |
| * is considered an I/O error and an <tt>IOException</tt> is |
| * thrown. The first byte of the packet is stored in element |
| * <tt>0</tt> of the byte array, the second in element <tt>1</tt>, |
| * and so on. The bytes in the byte array are laid out as per the |
| * <a href="../../../../../../../../../technotes/guides/jpda/jdwp-spec.html"> |
| * JDWP specification</a>. That is, all fields in the packet |
| * are in big endian order as per the JDWP specification. |
| * |
| * <p> This method may be invoked at any time. If another thread has |
| * already initiated a {@link #readPacket readPacket} on this |
| * connection then the invocation of this method will block until the |
| * first operation is complete. </p> |
| * |
| * @return the packet read from the target VM |
| * |
| * @throws ClosedConnectionException |
| * If the connection is closed, or another thread closes |
| * the connection while the readPacket is in progress. |
| * |
| * @throws java.io.IOException |
| * If the length of the packet (as indictaed by the first |
| * 4 bytes) is less than 11 bytes, or an I/O error occurs. |
| * |
| * |
| */ |
| public abstract byte[] readPacket() throws IOException; |
| |
| /** |
| * Writes a packet to the target VM. |
| * |
| * <p> Attempts to write, or send, a JDWP packet to the target VM. |
| * A write operation only returns after writing the entire packet |
| * to the target VM. Writing the entire packet does not mean |
| * the entire packet has been transmitted to the target VM |
| * but rather that all bytes have been written to the |
| * transport service. A transport service based on a TCP/IP connection |
| * may, for example, buffer some or all of the packet before |
| * transmission on the network. |
| * |
| * <p> The byte array provided to this method should be laid out |
| * as per the <a |
| * href="../../../../../../../../../technotes/guides/jpda/jdwp-spec.html"> |
| * JDWP specification</a>. That is, all fields in the packet |
| * are in big endian order. The first byte, that is element |
| * <tt>pkt[0]</tt>, is the first byte of the <tt>length</tt> field. |
| * <tt>pkt[1]</tt> is the second byte of the <tt>length</tt> field, |
| * and so on. |
| * |
| * <p> Writing a packet does not do any integrity checking on |
| * the packet aside from checking the packet length. Checking |
| * the packet length requires checking that the value of the |
| * <tt>length</tt> field (as indicated by the first four bytes |
| * of the packet) is 11 or greater. Consequently the length of |
| * the byte array provided to this method, that is |
| * <tt>pkt.length</tt>, must be 11 or more, and must be equal |
| * or greater than the value of the <tt>length</tt> field. If the |
| * length of the byte array is greater than the value of |
| * the <tt>length</tt> field then all bytes from element |
| * <tt>pkt[length]</tt> onwards are ignored. In other words, |
| * any additional bytes that follow the packet in the byte |
| * array are ignored and will not be transmitted to the target |
| * VM. |
| * |
| * <p> A write operation may block or may complete immediately. |
| * The exact circumstances when an operation blocks depends on |
| * the transport service. In the case of a TCP/IP connection to |
| * the target VM, the writePacket method may block if there is |
| * network congestion or there is insufficient space to buffer |
| * the packet in the underlying network system. |
| * |
| * <p> This method may be invoked at any time. If another thread has |
| * already initiated a write operation upon this Connection then |
| * a subsequent invocation of this method will block until the first |
| * operation is complete. </p> |
| * |
| * @param pkt |
| * The packet to write to the target VM. |
| * |
| * @throws ClosedConnectionException |
| * If the connection is closed, or another thread closes |
| * the connection while the write operation is in progress. |
| * |
| * @throws java.io.IOException |
| * If an I/O error occurs. |
| * |
| * @throws IllegalArgumentException |
| * If the value of the <tt>length</tt> field is invalid, |
| * or the byte array is of insufficient length. |
| */ |
| public abstract void writePacket(byte pkt[]) throws IOException; |
| |
| /** |
| * Closes this connection. |
| * |
| * <p> If the connection is already closed then invoking this method |
| * has no effect. After a connection is closed, any further attempt |
| * calls to {@link #readPacket readPacket} or {@link #writePacket |
| * writePacket} will throw a {@link ClosedConnectionException}. |
| * |
| * <p> Any thread currently blocked in an I/O operation ({@link |
| * #readPacket readPacket} or {@link #writePacket writePacket}) |
| * will throw a {@link ClosedConnectionException}). |
| * |
| * <p> This method may be invoked at any time. If some other thread has |
| * already invoked it, however, then another invocation will block until |
| * the first invocation is complete, after which it will return without |
| * effect. </p> |
| * |
| * @throws java.io.IOException |
| * If an I/O error occurs |
| */ |
| public abstract void close() throws IOException; |
| |
| /** |
| * Tells whether or not this connection is open. </p> |
| * |
| * @return <tt>true</tt> if, and only if, this connection is open |
| */ |
| public abstract boolean isOpen(); |
| } |
