00001 /******************************************************************************* 00002 00003 @file ProtocolWriter.d 00004 00005 Copyright (C) 2004 Kris Bell 00006 00007 This software is provided 'as-is', without any express or implied 00008 warranty. In no event will the authors be held liable for damages 00009 of any kind arising from the use of this software. 00010 00011 Permission is hereby granted to anyone to use this software for any 00012 purpose, including commercial applications, and to alter it and/or 00013 redistribute it freely, subject to the following restrictions: 00014 00015 1. The origin of this software must not be misrepresented; you must 00016 not claim that you wrote the original software. If you use this 00017 software in a product, an acknowledgment within documentation of 00018 said product would be appreciated but is not required. 00019 00020 2. Altered source versions must be plainly marked as such, and must 00021 not be misrepresented as being the original software. 00022 00023 3. This notice may not be removed or altered from any distribution 00024 of the source. 00025 00026 00027 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 00028 00029 00030 @version Initial version, July 2004 00031 @author Kris 00032 00033 00034 *******************************************************************************/ 00035 00036 module mango.cluster.qos.socket.ProtocolWriter; 00037 00038 private import mango.io.model.IPickle; 00039 00040 private import mango.io.PickleWriter, 00041 mango.io.EndianWriter; 00042 00043 private import mango.cluster.model.IChannel; 00044 00045 /******************************************************************************* 00046 00047 Objects passed around a cluster are prefixed with a header, so the 00048 receiver can pick them apart correctly. This header consists of: 00049 00050 - the packet size, including the header (16 bits) 00051 - a command code (8 bits) 00052 - the length of the channel name (8 bits) 00053 - the channel name 00054 - the payload (an IPickle class) 00055 00056 Everything is written in Network order (big endian). 00057 00058 *******************************************************************************/ 00059 00060 class ProtocolWriter : PickleWriter 00061 { 00062 const ubyte Version = 0x01; 00063 00064 enum Command : ubyte {OK, Exception, Full, Locked, 00065 Add, Copy, Remove, Load, AddQueue, RemoveQueue}; 00066 00067 /*********************************************************************** 00068 00069 Construct a ProtocolWriter upon the given buffer. As 00070 Objects are serialized, their content is written to this 00071 buffer. The buffer content is then typically flushed to 00072 some external conduit, such as a file or socket. 00073 00074 Note that serialized data is always in Network order. 00075 00076 ***********************************************************************/ 00077 00078 this (IBuffer buffer) 00079 in { 00080 assert (buffer); 00081 } 00082 body 00083 { 00084 super (buffer); 00085 } 00086 00087 /*********************************************************************** 00088 00089 Flush the output 00090 00091 ***********************************************************************/ 00092 00093 override IWriter flush () 00094 { 00095 // remember the current buffer content 00096 uint content = buffer.readable (); 00097 00098 // flush pickled object(s) to output 00099 super.flush (); 00100 00101 // skip back in case we have to try this again 00102 buffer.skip (-content); 00103 00104 return this; 00105 } 00106 00107 /*********************************************************************** 00108 00109 ***********************************************************************/ 00110 00111 ProtocolWriter put (Command cmd, char[] channel, IPickle object = null, char[] element = null) 00112 { 00113 // reset the buffer first! 00114 buffer.clear (); 00115 ubyte[] content = cast(ubyte[]) buffer.getContent(); 00116 00117 super.put (cast(ushort) 0) 00118 .put (cast(ubyte) cmd) 00119 .put (cast(ubyte) Version) 00120 .put (channel) 00121 .put (element); 00122 00123 // is there a payload? 00124 if (object) 00125 super.freeze (object); 00126 00127 // go back and write the total number of bytes 00128 ushort size = buffer.getLimit; 00129 content[0] = size >> 8; 00130 content[1] = size & 0xff; 00131 return this; 00132 } 00133 00134 /*********************************************************************** 00135 00136 Write an exception message 00137 00138 ***********************************************************************/ 00139 00140 ProtocolWriter exception (char[] message) 00141 { 00142 put (ProtocolWriter.Command.Exception, message); 00143 return this; 00144 } 00145 00146 /*********************************************************************** 00147 00148 Write an "OK" confirmation 00149 00150 ***********************************************************************/ 00151 00152 ProtocolWriter success (char[] message = null) 00153 { 00154 put (ProtocolWriter.Command.OK, message); 00155 return this; 00156 } 00157 00158 /*********************************************************************** 00159 00160 Indicate something has filled up 00161 00162 ***********************************************************************/ 00163 00164 ProtocolWriter full (char[] message) 00165 { 00166 put (ProtocolWriter.Command.Full, message); 00167 return this; 00168 } 00169 00170 /*********************************************************************** 00171 00172 Write a serialized payload as constructed by the method 00173 ProtocolReader.getPacket() 00174 00175 ***********************************************************************/ 00176 00177 ProtocolWriter reply (ClusterContent content) 00178 { 00179 // reset the buffer first 00180 buffer.clear (); 00181 00182 // write the length ... 00183 super.put (cast(ushort) (content.length + ushort.sizeof + ubyte.sizeof + ubyte.sizeof)); 00184 00185 // and the ack ... 00186 super.put (cast(ubyte) ProtocolWriter.Command.OK); 00187 00188 // and the version ... 00189 super.put (cast(ubyte) Version); 00190 00191 // and the payload (which includes both channel & element) 00192 if (content.length) 00193 buffer.append (content); 00194 else 00195 // or filler for an empty channel & element ... 00196 super.put (cast(int) 0).put(cast(int) 0); 00197 00198 return this; 00199 } 00200 } 00201