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

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