Develop Reference

readObject() doesn't read an array

I'm trying to create a client-server program where a client sends an array with two objects inside of it to the server. The first object contains just a string. The second object is a shape that the user chooses. The user can choose between 4 different shapes.
Rectangle
Square
Triangle
Rombus
So in totale there are 5 classes. Form, Rectangle, Square, Triangle and Rombus. Each shape class inherits from a superclass called "FormaObj". After the client has sent the array to the server, the server has to understand what kind of object the client has sent(Rectangle, Square etc.) and calculate the area and perimeter of that shape.
So let's say for example that i want to send a rectangle to the server.
ClientFormeThread2 co;
FormaObj f[];
FormaObj forma;
RettangoloObjThread r;
QuadratoObjThread q;
TriangoloObjThread t;
RomboObjThread ro;
public ClientFormeForm2() {
initComponents();
co = new ClientFormeThread2();
f = new FormaObj[2];
}
private void btnRettangoloActionPerformed(java.awt.event.ActionEvent evt) {
try {
String nome = "Rettangolo";
//Creating the Obj form
FormaObj forma = new FormaObj(nome);
int base = Integer.parseInt(JOptionPane.showInputDialog("Inserire il valore della base"));
//Asking the user the insert the value of the base and the height of the rectangle
int altezza = Integer.parseInt(JOptionPane.showInputDialog("Inserire il valore dell'altezza"));
//Creating the object rectangle
RettangoloObjThread r = new RettangoloObjThread(base, altezza, nome);
f[0] = forma; //Putting the first object form inside the array
f[1] = r; //Putting the second object rectangle inside the array
co.comunicaFormaRettangolo(f); //Sending the array to the server
r = co.getRettangolo();
atxVisualizza.setText("Rettangolo" + "\n" + "Base: " + r.getLato1()+ "\n" + "Altezza: " +
r.getLato2() + "\n" + "Area: " + r.getArea() + "\n" + "Perimetro: " + r.getPerimetro());
}catch(ClassNotFoundException ex) {
Logger.getLogger(ClientFormeForm2.class.getName()).log(Level.SEVERE, null, ex);
}
That's what's inside co.comunicaFormaRettangolo(f); //Sending the array to the server
public ClientFormeThread2(){
try{
clientSocket = new Socket("localhost", 8123);
OutputStream o = clientSocket.getOutputStream();
InputStream i = clientSocket.getInputStream();
outOggetto = new ObjectOutputStream(o);
inOggetto = new ObjectInputStream(i);
System.out.println("Client Attivo");
}catch (IOException e) {
System.out.println(e.getMessage());
}
}
public void comunicaFormaRettangolo(FormaObj[] forma) throws ClassNotFoundException {
try {
f = forma;
outOggetto.writeObject(f);
outOggetto.flush();
r =(RettangoloObjThread)inOggetto.readObject();
int Area = r.getArea();
System.out.println(Area);
} catch (IOException ex) {
}
After the server receives the array, it reads what's inside of it.
public class ServerFormeThread2 extends Thread{
Socket clientDaServire;
int NClient;
FormaObj f[];
FormaObj forma;
RettangoloObjThread r;
QuadratoObjThread q;
TriangoloObjThread t;
RomboObjThread ro;
ObjectInputStream inOggetto;
ObjectOutputStream outOggetto;
public ServerFormeThread2(Socket clientDaServire, int NClient) {
this.clientDaServire = clientDaServire;
this.NClient = NClient;
}
public void run(){
try{
OutputStream os = clientDaServire.getOutputStream();
InputStream ois = clientDaServire.getInputStream();
outOggetto = new ObjectOutputStream(os);
inOggetto = new ObjectInputStream(ois);
f = (FormaObj[]) inOggetto.readObject(); //Reading the array
String NomeForma = f[0].getMessaggio(); //here i basically get the name of the shape.
while(!NomeForma.equals("Disconnetti")){
if(NomeForma.equals("Rettangolo")){ //checks whether the value of "NomeForma" equals"Rectangle"
r = (RettangoloObjThread) f[1]; //it reads the rectangle that has been stored inside the array
r.calcolaAreaRettangolo(); //here it calculates the area
r.calcolaPerimetroRettangolo(); //and here the perimeter
outOggetto.writeObject(r); //and here i only send the object rectangle back to the client because that's what i actually need
outOggetto.flush();
}
f = (FormaObj[]) inOggetto.readObject(); // i continue listening for other arrays containing
shapes that the client might send
NomeForma = f[0].getMessaggio();
}
outOggetto.writeObject(f);
outOggetto.flush();
outOggetto.close();
}catch(Exception e){
e.printStackTrace();
}
The Problem
The first time that an object is sent to the server everything works. So the client receives back the object rectangle and it displays the area and the perimeter on an TextArea. But when i try to send a second array containing another rectangle, the server doesn't read it. The whole program just freezes and i can't do anything apart from closing the server. No error appears. Down below i put the code for the classes "RettangoloObjThread" and "FormaObj"
RettangoloObjThread
import java.io.Serializable;
public class RettangoloObjThread extends FormaObj implements Serializable {
private int lato1;
private int lato2;
private int Area;
private int Perimetro;
public RettangoloObjThread(int lato1, int lato2, String nomeForma) {
super(nomeForma);
this.lato1 = lato1;
this.lato2 = lato2;
this.Area = 0;
this.Perimetro = 0;
}
public int getLato1() {
return lato1;
}
public void setLato1(int lato1) {
this.lato1 = lato1;
}
public int getLato2() {
return lato2;
}
public void setLato2(int lato2) {
this.lato2 = lato2;
}
public int getArea() {
return Area;
}
public void setArea(int Area) {
this.Area = Area;
}
public int getPerimetro() {
return Perimetro;
}
public void setPerimetro(int Perimetro) {
this.Perimetro = Perimetro;
}
public void calcolaAreaRettangolo(){
Area = lato1 * lato2;
}
public void calcolaPerimetroRettangolo(){
Perimetro = (lato1 + lato2)*2;
}
}
FormaObj
import java.io.Serializable;
public class FormaObj implements Serializable{
private String messaggio;
public FormaObj(String messaggio) {
this.messaggio = messaggio;
}
public String getMessaggio() {
return messaggio;
}
public void setMessaggio(String messaggio) {
this.messaggio = messaggio;
}

If your application is frozen, it means that the problem is in the thread deadlock, or an infinite loop is running somewhere, or something is considered very long-determined by the debugger.
It is also possible that your application simply threw an exception, but it was not logged because it was not handled properly.
You can track the problem yourself if you run the applications in debug mode and set breakpoints on the desired lines.
To format the code, use Ctrl+Alt+L
It will be more convenient this way.
Be careful with input streams, as they can only be used once.
In any case, running the app in debug mode will help you solve the problem and gain some experience.

I managed to solve the problem by adding writeUnshared() instead of the normal write()

Interactive Brokers API - Executing multiple trades

I'm trying to create a program for an API to place multiple trades at once, and then get prices for the stocks, and then rebalance every so often. I used a tutorial from online to get some of this code, and made a few tweaks.
However, when I run the code, it often connects and will place an order if I restart IB TWS. But if I go to run the code again it does not work, or show any indication that it will connect. Can anyone help me figure out how to keep the connection going, so that I can run the main.java file, and it will execute multiple trades and then end the connection? Do I need to change the client id number in either the code, or the settings of TWS?
There are three files:
Ordermanagement.java:
package SendMarketOrder;
//import statements//
class OrderManagement extends Thread implements EWrapper{
private EClientSocket client = null; //IB API client Socket Object
private Stock stock = new Stock();
private Order order = new Order();
private int orderId;
private double limitprice;
private String Ticker;
//method to create connection class. It's the constructor
public OrderManagement() throws InterruptedException, ClassNotFoundException, SQLException {
// Create a new EClientSocket object
System.out.println("////////////// Creating a Connection ////////////");
client = new EClientSocket(this); //Creation of a socket to connect
//connect to the TWS Demo
client.eConnect(null,7497,1);
try {
Thread.sleep(3000); //waits 3 seconds for user to accept
while (!(client.isConnected()));
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("///////// Connected /////////");
}
public void sendMarketOrder(String cusip, String buyorSell, int shares) throws SQLException, ClassNotFoundException{
//New Order ID
orderId++;
order.m_action = buyorSell;
order.m_orderId = orderId;
order.m_orderType = "MKT";
order.m_totalQuantity = shares;
order.m_account = "DU33xxxxx"; //write own account
order.m_clientId = 1;
//Create a new contract
stock.createContract(cusip);
client.placeOrder(orderId, stock.contract, order);
//Show order in console
SimpleDateFormat time_formatter = new SimpleDateFormat("HH:mm:ss");
String current_time_str = time_formatter.format(System.currentTimeMillis());
System.out.println("////////////////////////////////////////////////\n" +
"#Limit Price: " + order.m_lmtPrice + "///////////////////////////\n" +
"#Client number: " + order.m_clientId + "///////////////////////////\n" +
"#OrderType: " + order.m_orderType + "///////////////////////////\n" +
"#Order Quantity: " + order.m_totalQuantity + "///////////////////////////\n" +
"#Account number: " + order.m_account + "///////////////////////////\n" +
"#Symbol: " + stock.contract.m_secId + "///////////////////////////\n" +
"///////////////////////////////////////"
);
}
Stock.java
public class Stock{
private int StockId; //we can identify the stock
private String Symbol; //Ticker
public Stock() { //default constructor
}
public Stock(int StockId, String Symbol) { //constructor
this.StockId = StockId;
this.Symbol = Symbol;
}
//getter and setters
public int getStockId() {
return StockId;
}
public String getSymbol() {
return Symbol;
}
Contract contract = new Contract ();
public void createContract(String cusip){
contract.m_secId = cusip;
contract.m_secIdType = "CUSIP";
contract.m_exchange = "SMART";
contract.m_secType = "STK";
contract.m_currency = "USD";
}
}
Main.java:
package SendMarketOrder;
import java.sql.SQLException;
public class Main {
public static void main(String[] args) throws InterruptedException, ClassNotFoundException, SQLException {
OrderManagement order = new OrderManagement();
order.sendMarketOrder("922908363","BUY", 100);
order.sendMarketOrder("92204A504","BUY", 50);
order.sendMarketOrder("92204A702","BUY", 100);
System.exit(0);
}
}
These are my current settings TWS settings if that helps:
Thanks in advance for the help!

I changed a few things around in the code and added comments.
package sendmarketorder;//usually lower case pkg names
public class Main {
//you throw a bunch of exceptions that are never encountered
public static void main(String[] args) {
//since there's a Thread.sleep in this class
//it will block until ready
OrderManagement order = new OrderManagement();
//obviously you need some logic to buy/sell
//you can use command line args here if you want
order.sendMarketOrder("922908363", "BUY", 100);
order.sendMarketOrder("92204A504", "BUY", 50);
order.sendMarketOrder("92204A702", "BUY", 100);
//the socket creates a reader thread so this will stop it.
//if you didn't have this line the non-daemon thread would keep a
//connection to TWS and that's why you couldn't reconnect
//System.exit(0);//use better exit logic
}
}
.
package sendmarketorder;
import com.ib.client.*;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Map;
//doesn't extend thread and if you implement EWrapper you have to implement all methods
//in API 9.72 you can extend DefaultWrapper and just override the methods you need
public class OrderManagement implements EWrapper{
private EClientSocket client = null; //IB API client Socket Object
private int orderId = -1;//use as flag to send orders
//private double limitprice;
//private String Ticker;
//keep track of all working orders
private Map<Integer, Order> workingOrders = new HashMap<>();
//method to create connection class. It's the constructor
public OrderManagement(){
// Create a new EClientSocket object
System.out.println("////////////// Creating a Connection ////////////");
client = new EClientSocket(this); //Creation of a socket to connect
//connect to the TWS Demo
client.eConnect(null, 7497, 123);//starts reader thread
try {
while (orderId < 0){ //not best practice but it works
System.out.println("waiting for orderId");
Thread.sleep(1000);
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("///////// Connected /////////");
}
public void sendMarketOrder(String cusip, String buyorSell, int shares) {
//make new stock and order for each stock
Stock stock = new Stock();
Order order = new Order();
//New Order ID, but get from API as you have to increment on every run for life
orderId++;
order.m_action = buyorSell;
order.m_orderId = orderId;
order.m_orderType = "MKT";
order.m_totalQuantity = shares;
//I don't think you're supposed to use these fields
//order.m_account = "DU33xxxxx"; //write own account
//order.m_clientId = 1;
//Create a new contract
stock.createContract(cusip);
//remember which orders are working
workingOrders.put(orderId, order);
client.placeOrder(orderId, stock.contract, order);
//Show order in console
SimpleDateFormat time_formatter = new SimpleDateFormat("HH:mm:ss");
String current_time_str = time_formatter.format(System.currentTimeMillis());
System.out.println("////////////////////////////////////////////////\n"
+ "#Limit Price: " + order.m_lmtPrice + "///////////////////////////\n"
+ "#Client number: " + order.m_clientId + "///////////////////////////\n"
+ "#OrderType: " + order.m_orderType + "///////////////////////////\n"
+ "#Order Quantity: " + order.m_totalQuantity + "///////////////////////////\n"
+ "#Account number: " + order.m_account + "///////////////////////////\n"
+ "#Symbol: " + stock.contract.m_secId + "///////////////////////////\n"
+ "///////////////////////////////////////"
);
}
//always impl the error callback so you know what's happening
#Override
public void error(int id, int errorCode, String errorMsg) {
System.out.println(id + " " + errorCode + " " + errorMsg);
}
#Override
public void nextValidId(int orderId) {
System.out.println("next order id "+orderId);
this.orderId = orderId;
}
#Override
public void orderStatus(int orderId, String status, int filled, int remaining, double avgFillPrice, int permId, int parentId, double lastFillPrice, int clientId, String whyHeld) {
//so you know it's been filled
System.out.println(EWrapperMsgGenerator.orderStatus(orderId, status, filled, remaining, avgFillPrice, permId, parentId, lastFillPrice, clientId, whyHeld));
//completely filled when remaining == 0, or possible to cancel order from TWS
if (remaining == 0 || status.equals("Cancelled")){
//remove from map, should always be there
if (workingOrders.remove(orderId) == null) System.out.println("not my order!");
}
//if map is empty then exit program as all orders have been filled
if (workingOrders.isEmpty()){
System.out.println("all done");
client.eDisconnect();//will stop reader thread
//now is when you stop the program, but since all
//non-daemon threads have finished, the jvm will close.
//System.exit(0);
}
}
//impl rest of interface...
}

Tomcat 7 Openshift web socket application | socket connection closing

Question is quite basic . I am following a tutorial on creating a chat application using tomcat7 . Everything works fine on localhost but as i deploy it on openshift it doesn't seem to be creating a socket connection .
link to the uploaded website is here : http://qabchat-survey987.rhcloud.com
Java Script file is given bellow which is responsible for sending and receiving messages between client and server
var sessionId = '';
// name of the client
var name = '';
// socket connection url and port
var socket_url = 'qabchat-survey987.rhcloud.com';
var port = '8443';
$(document).ready(function() {
$("#form_submit, #form_send_message").submit(function(e) {
e.preventDefault();
join();
});
});
var webSocket;
/**
* Connecting to socket
*/
function join() {
// Checking person name
if ($('#input_name').val().trim().length <= 0) {
alert('Enter your name');
} else {
name = $('#input_name').val().trim();
$('#prompt_name_container').fadeOut(1000, function() {
// opening socket connection
openSocket();
});
}
return false;
}
/**
* Will open the socket connection
*/
function openSocket() {
// Ensures only one connection is open at a time
if (webSocket !== undefined && webSocket.readyState !== WebSocket.CLOSED) {
return;
}
// Create a new instance of the websocket
webSocket = new WebSocket("ws://" + socket_url + ":" + port
+ "/qabchat/chat1?name=" + name);
/**
* Binds functions to the listeners for the websocket.
*/
webSocket.onopen = function(event) {
$('#message_container').fadeIn();
if (event.data === undefined)
return;
};
webSocket.onmessage = function(event) {
// parsing the json data
parseMessage(event.data);
};
webSocket.onclose = function(event) {
alert('Error! Connection is closed. Try connecting again.');
};
}
/**
* Sending the chat message to server
*/
function send() {
var message = $('#input_message').val();
if (message.trim().length > 0) {
sendMessageToServer('message', message);
} else {
alert('Please enter message to send!');
}
}
/**
* Closing the socket connection
*/
function closeSocket() {
webSocket.close();
$('#message_container').fadeOut(600, function() {
$('#prompt_name_container').fadeIn();
// clearing the name and session id
sessionId = '';
name = '';
// clear the ul li messages
$('#messages').html('');
$('p.online_count').hide();
});
}
/**
* Parsing the json message. The type of message is identified by 'flag' node
* value flag can be self, new, message, exit
*/
function parseMessage(message) {
var jObj = $.parseJSON(message);
// if the flag is 'self' message contains the session id
if (jObj.flag == 'self') {
sessionId = jObj.sessionId;
} else if (jObj.flag == 'new') {
// if the flag is 'new', a client joined the chat room
var new_name = 'You';
// number of people online
var online_count = jObj.onlineCount;
$('p.online_count').html(
'Hello, <span class="green">' + name + '</span>. <b>'
+ online_count + '</b> people online right now')
.fadeIn();
if (jObj.sessionId != sessionId) {
new_name = jObj.name;
}
var li = '<li class="new"><span class="name">' + new_name + '</span> '
+ jObj.message + '</li>';
$('#messages').append(li);
$('#input_message').val('');
ai
} else if (jObj.flag == 'message') {
// if the json flag is 'message', it means somebody sent the chat
// message
var from_name = 'You';
if (jObj.sessionId != sessionId) {
from_name = jObj.name;
}
var li = '<li><span class="name">' + from_name + '</span> '
+ jObj.message + '</li>';
// appending the chat message to list
appendChatMessage(li);
$('#input_message').val('');
} else if (jObj.flag == 'exit') {
// if the json flag is 'exit', it means somebody left the chat room
var li = '<li class="exit"><span class="name red">' + jObj.name
+ '</span> ' + jObj.message + '</li>';
var online_count = jObj.onlineCount;
$('p.online_count').html(
'Hello, <span class="green">' + name + '</span>. <b>'
+ online_count + '</b> people online right now');
appendChatMessage(li);
}
}
/**
* Appending the chat message to list
*/
function appendChatMessage(li) {
$('#messages').append(li);
// scrolling the list to bottom so that new message will be visible
$('#messages').scrollTop($('#messages').height());
}
/**
* Sending message to socket server message will be in json format
*/
function sendMessageToServer(flag, message) {
var json = '{""}';
// preparing json object
var myObject = new Object();
myObject.sessionId = sessionId;
myObject.message = message;
myObject.flag = flag;
// converting json object to json string
json = JSON.stringify(myObject);
// sending message to server
webSocket.send(json);
}
I have tried using 8000 port as well as using wss: instead of ws for the instance of websocket . Java file is given bellow :
#ServerEndpoint("/chat1")
public class SocketServer {
// set to store all the live sessions
private static final Set<Session> sessions = Collections
.synchronizedSet(new HashSet<Session>());
// Mapping between session and person name
private static final HashMap<String, String> nameSessionPair = new HashMap<String, String>();
private static final HashMap<String, String> SessionNamePair=new HashMap<String,String>();
private JSONUtils jsonUtils = new JSONUtils();
// Getting query params
public static Map<String, String> getQueryMap(String query) {
Map<String, String> map = Maps.newHashMap();
if (query != null) {
String[] params = query.split("&");
for (String param : params) {
String[] nameval = param.split("=");
map.put(nameval[0], nameval[1]);
}
}
return map;
}
/**
* Called when a socket connection opened
* */
#OnOpen
public void onOpen(Session session) {
System.out.println(session.getId() + " has opened a connection");
Map<String, String> queryParams = getQueryMap(session.getQueryString());
String name = "";
if (queryParams.containsKey("name")) {
// Getting client name via query param
name = queryParams.get("name");
try {
name = URLDecoder.decode(name, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
// Mapping client name and session id
nameSessionPair.put(session.getId(), name);
SessionNamePair.put(name, session.getId());
}
// Adding session to session list
sessions.add(session);
try {
// Sending session id to the client that just connected
session.getBasicRemote().sendText(
jsonUtils.getClientDetailsJson(session.getId(),
"Your session details"));
} catch (IOException e) {
e.printStackTrace();
}
// Notifying all the clients about new person joined
sendMessageToAll(session.getId(), name, " joined conversation!", true,
false);
}
/**
* method called when new message received from any client
*
* #param message
* JSON message from client
* */
#OnMessage
public void onMessage(String message, Session session) {
System.out.println("Message from " + session.getId() + ": " + message);
String msg = null;
// Parsing the json and getting message
try {
JSONObject jObj = new JSONObject(message);
msg = jObj.getString("message");
} catch (JSONException e) {
e.printStackTrace();
}
// Sending the message to all clients
sendMessageToAll(session.getId(), nameSessionPair.get(session.getId()),
msg, false, false);
}
/**
* Method called when a connection is closed
* */
#OnClose
public void onClose(Session session) {
System.out.println("Session " + session.getId() + " has ended");
// Getting the client name that exited
String name = nameSessionPair.get(session.getId());
// removing the session from sessions list
sessions.remove(session);
// Notifying all the clients about person exit
sendMessageToAll(session.getId(), name, " left conversation!", false,
true);
}
/**
* Method to send message to all clients
*
* #param sessionId
* #param message
* message to be sent to clients
* #param isNewClient
* flag to identify that message is about new person joined
* #param isExit
* flag to identify that a person left the conversation
* */
private void sendMessageToAll(String sessionId, String name,
String message, boolean isNewClient, boolean isExit) {
// Looping through all the sessions and sending the message individually
for (Session s : sessions) {
String json = null;
// Checking if the message is about new client joined
if (isNewClient) {
json = jsonUtils.getNewClientJson(sessionId, name, message,
sessions.size());
} else if (isExit) {
// Checking if the person left the conversation
json = jsonUtils.getClientExitJson(sessionId, name, message,
sessions.size());
} else {
// Normal chat conversation message
json = jsonUtils
.getSendAllMessageJson(sessionId, name, message);
}
try {
System.out.println("Sending Message To: " + sessionId + ", "
+ json + SessionNamePair.get(name));
s.getBasicRemote().sendText(json);
} catch (IOException e) {
System.out.println("error in sending. " + s.getId() + ", "
+ e.getMessage());
e.printStackTrace();
}
}
}
}
I can not seem to figure out why the code is not working on openshift while it works just fine on localhost . Name of the main root directory of the project in openshift is qabchat.
I ran a simple test found out that after the onopen() function in javascript file , onclose() function is being called .

Java object LinkedList attribute: only receiving the first element on server-side using TCP

A little bit of context: the client is sending to the server a SOSPFPacket object (via TCP) that has various attributes, such as a Vector<LSA> lsaArray. The LSA itself has a LinkedList<LinkDescription> links attribute. In my test case, there are two messages being sent. In both messages, there is only one LSA in the vector. In the first message, the LSA has one LinkDescription, in the second, it has two. When I send a message, I increment the messageId.
The server receives both messages with proper ids, but in the second message, the links only contain one link instead of two. I'm clueless...
Here are the object implementations:
import java.io.*;
import java.util.Vector;
public class SOSPFPacket implements Serializable {
public final static short HELLO = 0;
public final static short LSU = 1;
public final static short OVER_BURDENED = 2;
public static int id = Integer.MIN_VALUE;
public String srcProcessIP;
public short srcProcessPort;
public String srcIP;
public String dstIP;
public short sospfType; //0 - HELLO, 1 - LinkState Update, 2 - Over Burdened
public String routerID;
public int messageId = id++;
public String neighborID; //neighbor's simulated IP address
public Vector<LSA> lsaArray = new Vector<>();
public String lsaInitiator = null;
}
import java.io.Serializable;
import java.util.LinkedList;
public class LSA implements Serializable {
public String linkStateID;
public int lsaSeqNumber = Integer.MIN_VALUE;
public LinkedList<LinkDescription> links = new LinkedList<LinkDescription>();
#Override
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append(linkStateID + ":").append(lsaSeqNumber + "\n");
for (LinkDescription ld : links) {
sb.append(ld);
}
sb.append("\n");
return sb.toString();
}
}
import java.io.Serializable;
public class LinkDescription implements Serializable {
public String linkID;
public int portNum;
public int tosMetrics;
public LinkDescription() {}
public LinkDescription(String linkID, int portNum, int tosMetrics) {
this.linkID = linkID;
this.portNum = portNum;
this.tosMetrics = tosMetrics;
}
public String toString() {
return linkID + "," + portNum + "," + tosMetrics;
}
}
To send the message, I do it via a Client.java thread implementing Runnable. Here are the relevant methods:
public void run() {
try {
_outputStream = new ObjectOutputStream(_clientSocket.getOutputStream());
sendMessage(SOSPFPacket.HELLO);
_inputStream = new ObjectInputStream(_clientSocket.getInputStream());
SOSPFPacket message = Util.receiveMessage(_inputStream);
if (message.sospfType == SOSPFPacket.OVER_BURDENED) {
System.out.println("Removing link with router " + message.srcIP + "...");
_router.removeLink(_remoteRouterIP);
return;
}
_remoteRouterDescription.setStatus(RouterStatus.TWO_WAY);
_router.addLinkDescriptionToDatabase(_remoteRouterDescription, _link.getWeight());
sendMessage(SOSPFPacket.HELLO);
message = Util.receiveMessage(_inputStream);
if (message.sospfType == SOSPFPacket.LSU) {
_router.synchronize(message.lsaArray);
}
_router.propagateSynchronization(message.lsaInitiator, message.srcIP);
} catch (IOException e) {
e.printStackTrace();
}
}
private void sendMessage(short messageType) {
try {
SOSPFPacket message = Util.makeMessage(_rd, _remoteRouterDescription, messageType, _router);
_outputStream.writeObject(message);
_outputStream.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
public class Util {
public static SOSPFPacket makeMessage(RouterDescription local, RouterDescription external, short messageType, Router rd) {
SOSPFPacket message = new SOSPFPacket();
message.srcProcessIP = local.getProcessIPAddress();
message.srcProcessPort = local.getProcessPortNumber();
message.srcIP = local.getSimulatedIPAddress();
message.dstIP = external.getSimulatedIPAddress();
message.sospfType = messageType;
message.routerID = local.getSimulatedIPAddress();
message.neighborID = external.getSimulatedIPAddress();
rd.getLsd().getStore().forEach((k, v) -> message.lsaArray.addElement(v));
message.lsaInitiator = messageType == SOSPFPacket.LSU ? message.srcIP : null;
return message;
}
public static SOSPFPacket receiveMessage(ObjectInputStream inputStream) {
SOSPFPacket receivedMessage = null;
try {
receivedMessage = (SOSPFPacket) inputStream.readObject();
String messageType;
switch (receivedMessage.sospfType) {
case SOSPFPacket.HELLO:
messageType = "HELLO";
break;
case SOSPFPacket.LSU:
messageType = "LINKSTATEUPDATE";
break;
case SOSPFPacket.OVER_BURDENED:
messageType = "OVER_BURDENED";
break;
default:
messageType = "UNKNOWN_STATE";
break;
}
System.out.println("received " + messageType + " from " + receivedMessage.srcIP + ";");
} catch (ClassNotFoundException e) {
System.out.println("No message received.");
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return receivedMessage;
}
}
And the server instantiates a private ClientServiceThread when it receives a new connection, which is in charge of receiving the message.
private class ClientServiceThread implements Runnable {
Socket _clientSocket;
Thread _runner;
ClientServiceThread(Socket s) {
_clientSocket = s;
_runner = new Thread(this);
}
public Thread getRunner() { return _runner; }
public void run() {
ObjectInputStream inputStream = null;
ObjectOutputStream outputStream = null;
try {
inputStream = new ObjectInputStream(_clientSocket.getInputStream());
outputStream = new ObjectOutputStream(_clientSocket.getOutputStream());
while (true) {
try {
SOSPFPacket receivedMessage = Util.receiveMessage(inputStream);
//some logic not relevant since the receivedMessage is already not correct
}
}
}
}
}
Again, all SOSPFPacket fields are correctly received, except for the Vector<LSA> lsaArray...
Edit: I also tried sending a third sendMessage(SOSPFPacket.HELLO) after _router.propagateSynchronization(message.lsaInitiator, message.srcIP);. This time, the message being sent contains two LSA, the first one having two LinkDescription, the second one having one. Both LSA are received by the server, but still, only the first LinkDescription is received in the first LSA. The message id is correct in all three messages.
If I run everything a second time (i.e. I create a new Client and a new ClientService Thread for the already running routers), only then does the server finally receive two LinkDescription in the first LSA.

Java sends references to objects that have already been serialized, to preserve the integrity of object graphs.
You should call ObjectOutputStream.reset() after each writeObject().
Or use ObjectOutputStream.writeUnshared(), but note that it still shares referenced objects, i.e. if you try to send a list with both added and changed element objects, it will send the new list and new element objects, but not the element objects which have been changed.

Finally figured it out. Somehow it seems like the problem was the following line of code in Util.makeMessage: rd.getLsd().getStore().forEach((k, v) -> message.lsaArray.addElement(v));. I replaced it with rd.getLsd().getStore().forEach((k, v) -> message.lsaArray.add(new LSA(v))); with the following LSA constructor:
public LSA(LSA lsa) {
linkStateID = lsa.linkStateID;
lsaSeqNumber = lsa.lsaSeqNumber;
links = new LinkedList<>();
for (LinkDescription ld : lsa.links) {
LinkDescription linkD = new LinkDescription();
linkD.linkID = ld.linkID;
linkD.portNum = ld.portNum;
linkD.tosMetrics = ld.tosMetrics;
links.add(linkD);
}
}
In other words, I needed to deep copy the object contained in my message.

Send object over udp in Java

I'm trying to send and object over udp by first serializing it and then deserializing it on the other end. I thought this would be trivial since I have sent other data over udp before and serialized stuff to the files etc.
I have debugged thing some time now and I keep getting EOFException on the receiving end. Packets arrive properly but somehow deserialization fails. I'm not sure if the mistake is in sender or receiver. I suppose the problem might be about the receiver not knowing the size of the packet.
Here is my sender class:
package com.machinedata.sensordata;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import android.content.Context;
import android.util.Log;
import com.machinedata.io.DataSerializer;
import com.machinedata.io.ManagerUdpPacket;
/**
* This class sends udp-packets. It is used to send driver's information to the manager tablet.
* #author tuomas
*
*/
public class UdpSender
{
private final int MANAGER_PORT = 1234;
private String ip = "192.168.11.50"; //tablet's IP
private DatagramSocket sock = null;
private InetAddress host;
private String mType;
private DataSerializer dataser;
public UdpSender(Context context)
{
try
{
sock = new DatagramSocket();
host = InetAddress.getByName(ip); //tabletin ip
}
catch(Exception e)
{
System.err.println("Exception alustettaessa senderia" + e);
}
dataser = new DataSerializer(context);
}
/**
* With this function we can send packets about our machine to the manager to
* see in the fleet-view.
*/
public void sendToManager(ManagerUdpPacket managerUdp)
{
//serialize
Log.v("sendudp", "Send a packet: " + managerUdp.getDriver());
//serialize
byte[] data = dataser.serializeManagerPacket(managerUdp);
//send
try
{
DatagramPacket dp = new DatagramPacket(data , data.length , host , MANAGER_PORT);
sock.send(dp);
}
catch(IOException e)
{
System.err.println("IOException senderissa " + e);
}
}
public void close()
{
sock.close();
}
}
Here is the serialization function:
/**
* Serializes packet to be sent over udp to the manager tablet.
*/
public byte[] serializeManagerPacket(ManagerUdpPacket mp)
{
try
{
ByteArrayOutputStream baos = new ByteArrayOutputStream(2048);
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(mp);
oos.close();
// get the byte array of the object
byte[] obj= baos.toByteArray();
baos.close();
return obj;
}
catch(Exception e) {
e.printStackTrace();
}
return null;
}
Packet receiver class
public class UdpReceiver {
private DatagramSocket clientSocket;
private byte[] receiveData;
private final int timeout = 1;
/**
* Create a receiver.
* #param port Port to receive from.
* #param signCount Number of signals in a packet
*/
public UdpReceiver(int port)
{
//receiveData = serializeManagerPacket(new ManagerUdpPacket("asd", new MachineData(1, 2, "asd", "modelName"), 1,2,3,4,5.0,null));
try{
clientSocket=new DatagramSocket(port);
clientSocket.setReceiveBufferSize(2048);
clientSocket.setSoTimeout(timeout);
}catch(SocketException e){
Log.e("ERR", "SocketException in UdpReceiver()");
}
}
public void close()
{
clientSocket.close();
}
/**
* Receive a data packet and split it into array.
* #param data Array to put data in, must be correct size
* #return True on successful read, false otherwise
*/
public ManagerUdpPacket receive()
{
//receive a packet
DatagramPacket recvPacket = new DatagramPacket(receiveData, receiveData.length);
try{
clientSocket.receive(recvPacket);
}catch(IOException e){
Log.e("ERR", "IOException in UdpReceiver.receive");
return null;
}
ManagerUdpPacket obj = deserializeManagerPacket(receiveData);
if (obj != null)
Log.v("udpPacket", "UDP saatu: " + obj.getDriver());
return obj;
}
/**
* Deserialize the udp-packet back to readable data.
* #param data
* #return
*/
public ManagerUdpPacket deserializeManagerPacket(byte[] data)
{
try
{
ObjectInputStream iStream = new ObjectInputStream(new ByteArrayInputStream(data));
ManagerUdpPacket obj = (ManagerUdpPacket) iStream.readObject();
iStream.close();
return obj;
}
catch(Exception e)
{
e.printStackTrace();
}
return null;
}
}
Thread which listens packets in receiving end:
dataStreamTask = new TimerTask()
{
public void run()
{
if (currentlyStreaming)
{
ManagerUdpPacket mp = udpReceiver.receive();
if(mp != null)
{
Log.v("log", "Paketti saatu! " + mp.getDriver());
}
//stop thread until next query
try {
synchronized(this){
this.wait(queryInterval);
}
} catch (InterruptedException e) {
Log.e("ERR", "InterruptedException in TimerTask.run");
}
}
}
And finally the class I'm sending over the UDP:
public class ManagerUdpPacket implements Serializable
{
private static final long serialVersionUID = 9169314425496496555L;
private Location gpsLocation;
private double totalFuelConsumption;
private long operationTime;
//workload distribution
private long idleTime = 0;
private long normalTime = 0;
private long fullTime = 0;
private int currentTaskId;
private String driverName;
String machineModelName = "";
String machineName = "";
int machineIconId = -1;
int machinePort = -1;
public ManagerUdpPacket(String driver, MachineData machine, int currentTaskId, long idleTime, long fullTime, long operationTime, double fuelConsumption, Location location)
{
driverName = driver;
this.currentTaskId = currentTaskId;
this.idleTime = idleTime;
this.fullTime = fullTime;
this.operationTime = operationTime;
this.totalFuelConsumption = fuelConsumption;
this.gpsLocation = location;
machineModelName = machine.getModelName();
machineName = machine.getName();
machineIconId = machine.getIconId();
machinePort = machine.getPort();
}
public String getDriver()
{
return driverName;
}
public int getCurrentTaskId()
{
return currentTaskId;
}
public long getIdleTime()
{
return idleTime;
}
public long getFullTime()
{
return fullTime;
}
public long getOperationTime()
{
return operationTime;
}
public double getTotalFuelConsumption()
{
return totalFuelConsumption;
}
public double getLocation()
{
return gpsLocation.getLatitude();
}
public String getMachineModelName()
{
return machineModelName;
}
public String getMachineName()
{
return machineName;
}
public int getMachineIconId()
{
return machineIconId;
}
public int getMachinePort()
{
return machinePort;
}
}
I tried to get the packet size from the size of the serialized packet or inserting arbitrary 2048 based on some examples on internet. Couldn't get it work though.

As far as i know the receive function returns the length of the bytes it received. But your buffer will be full:
Example:
int buffersize = 1024;
You send 8bytes over udp.
So your byte[] will be full with your 8 bytes but the rest of the 1024 will be 0.
save the size you get by the .receive() call and just save all values of your buffer to another byte[] and you should get your object.
For your example:
public ManagerUdpPacket receive()
{
int receivedBytes = 0;
//receive a packet
DatagramPacket recvPacket = new DatagramPacket(receiveData, receiveData.length);
try{
receivedBytes = clientSocket.receive(recvPacket);
}catch(IOException e){
Log.e("ERR", "IOException in UdpReceiver.receive");
return null;
}
byte[] myObject = new byte[receivedBytes];
for(int i = 0; i < receivedBytes; i++)
{
myObject[i] = receiveData[i];
}
ManagerUdpPacket obj = deserializeManagerPacket(myObject);
if (obj != null)
Log.v("udpPacket", "UDP saatu: " + obj.getDriver());
return obj;
}

When receiving data on UDP, always use java.net.DatagramSocket.getReceiveBufferSize();. This is the actual size of the platform or SP_RCVBUF for the socket. Since UDP is a datagram based protocol unlike TCP, which is streaming protocol, receiving buffers become critical for data sanity. Usually, receiving and sending buffers are equal in size, but you are not bothered while sending when using DatagramSocket.send(DatagramPacket), alternately, you can also use DatagramSocket.setSendBufferSize(DatagramSocket.getSendBufferSize()) for using the SO_SNDBUF option for this socket. Keep in mind, in UDP, if you use a SO_SNDBUF size greater than platform's, the packet can be discarded.