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 4. Derivative works are permitted, but they must carry this notice 00027 in full and credit the original source. 00028 00029 00030 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 00031 00032 00033 @version Initial version, July 2004 00034 @author Kris 00035 00036 00037 *******************************************************************************/ 00038 00039 module mango.cluster.qos.socket.ProtocolWriter; 00040 00041 private import mango.io.model.IPickle; 00042 00043 private import mango.io.PickleWriter, 00044 mango.io.EndianWriter; 00045 00046 private import mango.cluster.model.IChannel; 00047 00048 /******************************************************************************* 00049 00050 Objects passed around a cluster are prefixed with a header, so the 00051 receiver can pick them apart correctly. This header consists of: 00052 00053 - the packet size, including the header (16 bits) 00054 - a command code (8 bits) 00055 - the length of the channel name (8 bits) 00056 - the channel name 00057 - the payload (an IPickle class) 00058 00059 Everything is written in Network order (big endian). 00060 00061 *******************************************************************************/ 00062 00063 class ProtocolWriter : PickleWriter 00064 { 00065 const ubyte Version = 0x01; 00066 00067 enum Command : ubyte {OK, Exception, Full, Locked, 00068 Add, Copy, Remove, Load, AddQueue, RemoveQueue}; 00069 00070 /*********************************************************************** 00071 00072 Construct a ProtocolWriter upon the given buffer. As 00073 Objects are serialized, their content is written to this 00074 buffer. The buffer content is then typically flushed to 00075 some external conduit, such as a file or socket. 00076 00077 Note that serialized data is always in Network order. 00078 00079 ***********************************************************************/ 00080 00081 this (IBuffer buffer) 00082 in { 00083 assert (buffer); 00084 } 00085 body 00086 { 00087 super (buffer); 00088 } 00089 00090 /*********************************************************************** 00091 00092 Flush the output 00093 00094 ***********************************************************************/ 00095 00096 override IWriter flush () 00097 { 00098 // remember the current buffer content 00099 uint content = buffer.readable (); 00100 00101 // flush pickled object(s) to output 00102 super.flush (); 00103 00104 // skip back in case we have to try this again 00105 buffer.skip (-content); 00106 00107 return this; 00108 } 00109 00110 /*********************************************************************** 00111 00112 ***********************************************************************/ 00113 00114 ProtocolWriter put (Command cmd, char[] channel, IPickle object = null, char[] element = null) 00115 { 00116 // reset the buffer first! 00117 buffer.clear (); 00118 ubyte[] content = cast(ubyte[]) buffer.getContent(); 00119 00120 super.put (cast(ushort) 0) 00121 .put (cast(ubyte) cmd) 00122 .put (cast(ubyte) Version) 00123 .put (channel) 00124 .put (element); 00125 00126 // is there a payload? 00127 if (object) 00128 super.freeze (object); 00129 00130 // go back and write the total number of bytes 00131 ushort size = buffer.getLimit; 00132 content[0] = size >> 8; 00133 content[1] = size & 0xff; 00134 return this; 00135 } 00136 00137 /*********************************************************************** 00138 00139 Write an exception message 00140 00141 ***********************************************************************/ 00142 00143 ProtocolWriter exception (char[] message) 00144 { 00145 put (ProtocolWriter.Command.Exception, message); 00146 return this; 00147 } 00148 00149 /*********************************************************************** 00150 00151 Write an "OK" confirmation 00152 00153 ***********************************************************************/ 00154 00155 ProtocolWriter success (char[] message = null) 00156 { 00157 put (ProtocolWriter.Command.OK, message); 00158 return this; 00159 } 00160 00161 /*********************************************************************** 00162 00163 Indicate something has filled up 00164 00165 ***********************************************************************/ 00166 00167 ProtocolWriter full (char[] message) 00168 { 00169 put (ProtocolWriter.Command.Full, message); 00170 return this; 00171 } 00172 00173 /*********************************************************************** 00174 00175 Write a serialized payload as constructed by the method 00176 ProtocolReader.getPacket() 00177 00178 ***********************************************************************/ 00179 00180 ProtocolWriter reply (ClusterContent content) 00181 { 00182 // reset the buffer first 00183 buffer.clear (); 00184 00185 // write the length ... 00186 super.put (cast(ushort) (content.length + ushort.sizeof + ubyte.sizeof + ubyte.sizeof)); 00187 00188 // and the ack ... 00189 super.put (cast(ubyte) ProtocolWriter.Command.OK); 00190 00191 // and the version ... 00192 super.put (cast(ubyte) Version); 00193 00194 // and the payload (which includes both channel & element) 00195 if (content.length) 00196 buffer.append (content); 00197 else 00198 // or filler for an empty channel & element ... 00199 super.put (cast(int) 0).put(cast(int) 0); 00200 00201 return this; 00202 } 00203 } 00204