src/be/nikiroo/utils/serial/server/ConnectAction.java

   1 package be.nikiroo.utils.serial.server;
   2
   3 import java.io.BufferedReader;
   4 import java.io.IOException;
   5 import java.io.InputStreamReader;
   6 import java.io.OutputStreamWriter;
   7 import java.net.Socket;
   8
   9 import be.nikiroo.utils.Version;
  10 import be.nikiroo.utils.serial.Exporter;
  11 import be.nikiroo.utils.serial.Importer;
  12
  13 /**
  14  * Base class used for the client/server basic handling.
  15  * <p>
  16  * It represents a single action: a client is expected to only execute one
  17  * action, while a server is expected to execute one action for each client
  18  * action.
  19  *
  20  * @author niki
  21  */
  22 abstract class ConnectAction {
  23         private Socket s;
  24         private boolean server;
  25         private Version version;
  26         private Version clientVersion;
  27
  28         private Object lock = new Object();
  29         private BufferedReader in;
  30         private OutputStreamWriter out;
  31         private boolean contentToSend;
  32
  33         /**
  34          * Method that will be called when an action is performed on either the
  35          * client or server this {@link ConnectAction} represent.
  36          *
  37          * @param version
  38          *            the counter part version
  39          *
  40          * @throws Exception
  41          *             in case of I/O error
  42          */
  43         abstract protected void action(Version version) throws Exception;
  44
  45         /**
  46          * Method called when we negotiate the version with the client.
  47          * <p>
  48          * Thus, it is only called on the server.
  49          * <p>
  50          * Will return the actual server version by default.
  51          *
  52          * @param clientVersion
  53          *            the client version
  54          *
  55          * @return the version to send to the client
  56          */
  57         abstract protected Version negotiateVersion(Version clientVersion);
  58
  59         /**
  60          * Handler called when an unexpected error occurs in the code.
  61          *
  62          * @param e
  63          *            the exception that occurred
  64          */
  65         abstract protected void onError(Exception e);
  66
  67         /**
  68          * Create a new {@link ConnectAction}.
  69          *
  70          * @param s
  71          *            the socket to bind to
  72          * @param server
  73          *            TRUE for a server action, FALSE for a client action (will
  74          *            impact the process)
  75          * @param version
  76          *            the version of this client-or-server
  77          */
  78         protected ConnectAction(Socket s, boolean server, Version version) {
  79                 this.s = s;
  80                 this.server = server;
  81
  82                 if (version == null) {
  83                         this.version = new Version();
  84                 } else {
  85                         this.version = version;
  86                 }
  87
  88                 clientVersion = new Version();
  89         }
  90
  91         /**
  92          * The version of this client-or-server.
  93          *
  94          * @return the version
  95          */
  96         public Version getVersion() {
  97                 return version;
  98         }
  99
 100         /**
 101          * Actually start the process (this is synchronous).
 102          */
 103         public void connect() {
 104                 try {
 105                         in = new BufferedReader(new InputStreamReader(s.getInputStream(),
 106                                         "UTF-8"));
 107                         try {
 108                                 out = new OutputStreamWriter(s.getOutputStream(), "UTF-8");
 109                                 try {
 110                                         if (server) {
 111                                                 action(clientVersion);
 112                                         } else {
 113                                                 String v = sendString("VERSION " + version.toString());
 114                                                 if (v != null && v.startsWith("VERSION ")) {
 115                                                         v = v.substring("VERSION ".length());
 116                                                 }
 117
 118                                                 action(new Version(v));
 119                                         }
 120                                 } finally {
 121                                         out.close();
 122                                 }
 123                         } finally {
 124                                 in.close();
 125                         }
 126                 } catch (Exception e) {
 127                         onError(e);
 128                 } finally {
 129                         try {
 130                                 s.close();
 131                         } catch (Exception e) {
 132                                 onError(e);
 133                         }
 134                 }
 135         }
 136
 137         /**
 138          * Serialise and send the given object to the counter part (and, only for
 139          * client, return the deserialised answer -- the server will always receive
 140          * NULL).
 141          *
 142          * @param data
 143          *            the data to send
 144          *
 145          * @return the answer (which can be NULL) if this action is a client, always
 146          *         NULL if it is a server
 147          *
 148          * @throws IOException
 149          *             in case of I/O error
 150          * @throws NoSuchFieldException
 151          *             if the serialised data contains information about a field
 152          *             which does actually not exist in the class we know of
 153          * @throws NoSuchMethodException
 154          *             if a class described in the serialised data cannot be created
 155          *             because it is not compatible with this code
 156          * @throws ClassNotFoundException
 157          *             if a class described in the serialised data cannot be found
 158          */
 159         protected Object sendObject(Object data) throws IOException,
 160                         NoSuchFieldException, NoSuchMethodException, ClassNotFoundException {
 161                 synchronized (lock) {
 162                         String rep = sendString(new Exporter().append(data).toString(true));
 163                         if (rep != null) {
 164                                 return new Importer().read(rep).getValue();
 165                         }
 166
 167                         return null;
 168                 }
 169         }
 170
 171         /**
 172          * Reserved for the server: flush the data to the client and retrieve its
 173          * answer.
 174          * <p>
 175          * Also used internally for the client (only do something if there is
 176          * contentToSend).
 177          * <p>
 178          * Will only flush the data if there is contentToSend.
 179          *
 180          * @return the deserialised answer (which can actually be NULL)
 181          *
 182          * @throws IOException
 183          *             in case of I/O error
 184          * @throws NoSuchFieldException
 185          *             if the serialised data contains information about a field
 186          *             which does actually not exist in the class we know of
 187          * @throws NoSuchMethodException
 188          *             if a class described in the serialised data cannot be created
 189          *             because it is not compatible with this code
 190          * @throws ClassNotFoundException
 191          *             if a class described in the serialised data cannot be found
 192          * @throws java.lang.NullPointerException
 193          *             if the counter part has no data to send
 194          */
 195         protected Object recObject() throws IOException, NoSuchFieldException,
 196                         NoSuchMethodException, ClassNotFoundException,
 197                         java.lang.NullPointerException {
 198                 String str = recString();
 199                 if (str == null) {
 200                         throw new NullPointerException("No more data available");
 201                 }
 202
 203                 return new Importer().read(str).getValue();
 204         }
 205
 206         /**
 207          * Send the given string to the counter part (and, only for client, return
 208          * the answer -- the server will always receive NULL).
 209          *
 210          * @param line
 211          *            the data to send (we will add a line feed)
 212          *
 213          * @return the answer if this action is a client (without the added line
 214          *         feed), NULL if it is a server
 215          *
 216          * @throws IOException
 217          *             in case of I/O error
 218          */
 219         protected String sendString(String line) throws IOException {
 220                 synchronized (lock) {
 221                         out.write(line);
 222                         out.write("\n");
 223
 224                         if (server) {
 225                                 out.flush();
 226                                 return null;
 227                         }
 228
 229                         contentToSend = true;
 230                         return recString();
 231                 }
 232         }
 233
 234         /**
 235          * Reserved for the server (externally): flush the data to the client and
 236          * retrieve its answer.
 237          * <p>
 238          * Also used internally for the client (only do something if there is
 239          * contentToSend).
 240          * <p>
 241          * Will only flush the data if there is contentToSend.
 242          *
 243          * @return the answer (which can be NULL)
 244          *
 245          * @throws IOException
 246          *             in case of I/O error
 247          */
 248         protected String recString() throws IOException {
 249                 synchronized (lock) {
 250                         if (server || contentToSend) {
 251                                 if (contentToSend) {
 252                                         out.flush();
 253                                         contentToSend = false;
 254                                 }
 255
 256                                 String line = in.readLine();
 257                                 if (server && line != null && line.startsWith("VERSION ")) {
 258                                         // "VERSION client-version" (VERSION 1.0.0)
 259                                         Version clientVersion = new Version(
 260                                                         line.substring("VERSION ".length()));
 261                                         this.clientVersion = clientVersion;
 262                                         Version v = negotiateVersion(clientVersion);
 263                                         if (v == null) {
 264                                                 v = new Version();
 265                                         }
 266                                         sendString("VERSION " + v.toString());
 267
 268                                         line = in.readLine();
 269                                 }
 270
 271                                 return line;
 272                         }
 273
 274                         return null;
 275                 }
 276         }
 277 }