/** Send a CONNECT_MEDIATOR packet to the BackEnd to check if it is reachable */
private boolean ping(int cnt) throws ICPException {
// Try first with the current transport address, then with the various backup addresses
for (int i = -1; i < backEndAddresses.length; i++) {
if (i >= 0) {
// Set the mediator address to a new address..
String addr = backEndAddresses[i];
int colonPos = addr.indexOf(':');
String host = addr.substring(0, colonPos);
String port = addr.substring(colonPos + 1, addr.length());
mediatorTA = new JICPAddress(host, port, myMediatorID, "");
}
try {
myLogger.log(
Logger.FINE,
"Ping " + mediatorTA.getHost() + ":" + mediatorTA.getPort() + "(" + cnt + ")...");
JICPPacket pkt =
new JICPPacket(JICPProtocol.CONNECT_MEDIATOR_TYPE, JICPProtocol.DEFAULT_INFO, null);
pkt = deliver(pkt);
if (pkt.getType() == JICPProtocol.ERROR_TYPE) {
// Communication OK, but there was a JICP error.
String errorMsg = new String(pkt.getData());
if (errorMsg.equals(JICPProtocol.NOT_FOUND_ERROR)) {
// Back-end not found: either the max disconnection time expired server side or there
// was a fault and restart
// --> Try to recreate the Back-end
myLogger.log(
Logger.WARNING,
"Communication OK, but Back-end no longer present. Try to recreate it");
if (myConnectionListener != null) {
myConnectionListener.handleConnectionEvent(ConnectionListener.BE_NOT_FOUND, null);
}
try {
createBackEnd();
} catch (IMTPException imtpe) {
myLogger.log(Logger.WARNING, "Error re-creating the Back-end.");
return false;
}
} else {
// Generic JICP error. No need to go on
throw new ICPException("JICP error. " + errorMsg);
}
}
return true;
} catch (IOException ioe) {
// Ignore it, and try the next address...
myLogger.log(Logger.FINE, "Ping KO", ioe);
}
}
// No address succeeded.
return false;
}
/**
* Dispatch a serialized command to the BackEnd and get back a serialized response. Mutual
* exclusion with itself to preserve dispatching order
*/
public synchronized byte[] dispatch(byte[] payload, boolean flush) throws ICPException {
// Note that we don't even try to dispatch packets while the
// device is not reachable to preserve dispatching order.
// If dispatching succeeded in fact this command would overcome
// any postponed command waiting to be flushed.
if (myDisconnectionManager.isReachable()) {
// The following check preserves dispatching order when the
// device has just reconnected but flushing has not started yet
if (waitingForFlush && !flush) {
throw new ICPException("Upsetting dispatching order");
}
waitingForFlush = false;
int sid = outCnt;
outCnt = (outCnt + 1) & 0x0f;
myLogger.log(Logger.FINE, "Issuing outgoing command " + sid);
try {
JICPPacket pkt =
new JICPPacket(JICPProtocol.COMMAND_TYPE, JICPProtocol.DEFAULT_INFO, payload);
pkt.setSessionID((byte) sid);
pkt = deliver(pkt);
myLogger.log(Logger.FINE, "Response received " + pkt.getSessionID());
if (pkt.getType() == JICPProtocol.ERROR_TYPE) {
// Communication OK, but there was a JICP error on the peer
throw new ICPException(new String(pkt.getData()));
}
return pkt.getData();
} catch (IOException ioe) {
// Can't reach the BackEnd. Assume we are unreachable
myLogger.log(Logger.WARNING, "IOException on output connection", ioe);
myDisconnectionManager.setUnreachable(false);
throw new ICPException("Dispatching error.", ioe);
}
} else {
throw new ICPException("Unreachable");
}
}
public void run() {
if (cnt == 0) {
// Give precedence to the Thread that is creating the BackEnd
Thread.yield();
// In the meanwhile load the ConnectionListener if any
try {
myConnectionListener =
(ConnectionListener)
Class.forName(props.getProperty("connection-listener")).newInstance();
} catch (Exception e) {
// Just ignore it
}
}
myId = cnt++;
myLogger.log(Logger.INFO, "IM-" + myId + " started");
// Prepare an initial dummy response
JICPPacket rsp = new JICPPacket(JICPProtocol.RESPONSE_TYPE, JICPProtocol.DEFAULT_INFO, null);
while (active) {
try {
// Prepare the connection for next incoming command
refreshConnection();
myDisconnectionManager.waitUntilReachable();
// Deliver the response to the previous incoming command and wait for the next one
// If we are delivering the response to an exit command, set active to false to avoid an
// annoying stack trace
// (due to the fact that the back-end will close the connection instead of sending further
// commands) and exit
if (this == terminator) {
active = false;
}
JICPPacket cmd = deliver(rsp, myConnection);
myKeepAliveManager.update();
if (cmd.getType() == JICPProtocol.KEEP_ALIVE_TYPE) {
// Keep-alive
if (myLogger.isLoggable(Logger.FINER)) {
myLogger.log(Logger.FINER, "Keep-alive received");
}
rsp = new JICPPacket(JICPProtocol.RESPONSE_TYPE, JICPProtocol.OK_INFO, null);
} else {
// Command
byte sid = cmd.getSessionID();
if (sid == lastSid) {
myLogger.log(Logger.WARNING, "Duplicated command received " + sid);
rsp = lastResponse;
} else {
myLogger.log(Logger.FINE, "Incoming command received " + sid);
byte[] rspData = mySkel.handleCommand(cmd.getData());
myLogger.log(Logger.FINE, "Incoming command served " + sid);
rsp = new JICPPacket(JICPProtocol.RESPONSE_TYPE, JICPProtocol.DEFAULT_INFO, rspData);
rsp.setSessionID(sid);
lastSid = sid;
lastResponse = rsp;
}
}
} catch (Exception e) {
if (active) {
myLogger.log(Logger.WARNING, "Exception on input connection", e);
// Note that the boolean value passed to setUnreachable() only indicates if the
// unreachability was detected by a missing keep-alive
myDisconnectionManager.setUnreachable(false);
}
}
}
myLogger.log(Logger.INFO, "IM-" + myId + " terminated");
}
/**
* Send the CREATE_MEDIATOR command with the necessary parameter in order to create the BackEnd in
* the fixed network. Executed - at bootstrap time by the thread that creates the
* FrontEndContainer. - To re-attach to the platform after a fault of the BackEnd
*/
private synchronized void createBackEnd() throws IMTPException {
StringBuffer sb = BackEndStub.encodeCreateMediatorRequest(props);
if (myMediatorID != null) {
// This is a request to re-create my expired back-end
BackEndStub.appendProp(sb, JICPProtocol.MEDIATOR_ID_KEY, myMediatorID);
BackEndStub.appendProp(sb, "outcnt", String.valueOf(outCnt));
BackEndStub.appendProp(sb, "lastsid", String.valueOf(lastSid));
}
JICPPacket pkt =
new JICPPacket(
JICPProtocol.CREATE_MEDIATOR_TYPE,
JICPProtocol.DEFAULT_INFO,
null,
sb.toString().getBytes());
// Try first with the current transport address, then with the various backup addresses
for (int i = -1; i < backEndAddresses.length; i++) {
if (i >= 0) {
// Set the mediator address to a new address..
String addr = backEndAddresses[i];
int colonPos = addr.indexOf(':');
String host = addr.substring(0, colonPos);
String port = addr.substring(colonPos + 1, addr.length());
mediatorTA = new JICPAddress(host, port, myMediatorID, "");
}
try {
HTTPClientConnection hc = (HTTPClientConnection) getConnection(mediatorTA);
myLogger.log(
Logger.INFO,
"Creating BackEnd on "
+ hc.getProtocol()
+ mediatorTA.getHost()
+ ":"
+ mediatorTA.getPort());
pkt = deliver(pkt);
String replyMsg = new String(pkt.getData());
if (pkt.getType() != JICPProtocol.ERROR_TYPE) {
// BackEnd creation successful
BackEndStub.parseCreateMediatorResponse(replyMsg, props);
myMediatorID = props.getProperty(JICPProtocol.MEDIATOR_ID_KEY);
// Complete the mediator address with the mediator ID
mediatorTA =
new JICPAddress(mediatorTA.getHost(), mediatorTA.getPort(), myMediatorID, null);
myDisconnectionManager.setReachable();
myKeepAliveManager.update();
myLogger.log(Logger.INFO, "BackEnd OK. Mediator ID is " + myMediatorID);
return;
} else {
myLogger.log(Logger.WARNING, "Mediator error: " + replyMsg);
}
} catch (IOException ioe) {
// Ignore it, and try the next address...
myLogger.log(Logger.WARNING, "Connection error", ioe);
}
}
// No address succeeded!
throw new IMTPException("Error creating the BackEnd.");
}