hope you doing all well, i m using processing IDE to interact with arduinos chips scattered across the local network, so i did a client server architecture via ethernet, made sure each chips has its own unique and available ip adresse, when i tried to communicate with 3 chips it works well, but the moment i exceed 3 chips simultaniously i m getting a consistant connectException : connection refused from one of the chips, this is the server class i m using in processing :
import java.io.*;
import java.net.*;
import java.util.concurrent.*;
class ServerHandler implements Runnable {
private ServerSocket server;
private boolean serverRunning = true;
private String receivedMessage = null;
private int port;
private boolean isConfigserver;
private ExecutorService clientThreadPool;
private int clientCounter = 0;
public ServerHandler(int port, boolean isConfigserver) {
this.port = port;
this.isConfigserver = isConfigserver;
this.clientThreadPool = Executors.newCachedThreadPool();
}
@Override
public void run() {
try {
// Create a server socket to listen on the specified port
server = new ServerSocket(this.port);
println("Server is running on port : " + this.port);
while (serverRunning) {
try {
Socket client = server.accept(); // Accept incoming connections
clientCounter++;
println("Client connected: " + client.getInetAddress() + ", Total clients handled: " + clientCounter);
if (!isConfigserver) {
// Handle each client connection in a separate thread
ClientHandler clientHandler = new ClientHandler(client, selectedMode, Nombre_mesures);
clientThreadPool.submit(clientHandler);
} else {
BufferedReader reader = new BufferedReader(new InputStreamReader(client.getInputStream()));
String receivedData = reader.readLine();
if (receivedData != null) {
receivedData = receivedData.trim();
println("Received from Arduino about config: " + receivedData);
if (receivedData.equals("OK")) {
isReady = true;
//println("we are ready to go");
}
}
client.close();
println("Client connection closed after configuration");
}
} catch (IOException e) {
println("Error handling client connection: " + e.getMessage());
e.printStackTrace();
}
}
} catch (IOException e) {
println("Server error: " + e.getMessage());
e.printStackTrace();
}
}
public void stopServer() {
serverRunning = false;
if (server != null && !server.isClosed()) {
try {
server.close();
} catch (IOException e) {
println("Error closing server: " + e.getMessage());
e.printStackTrace();
}
}
clientThreadPool.shutdown();
}
private class ClientHandler implements Runnable {
private Socket client;
private String selectedMode;
private int Nombre_mesures;
private int counter_requete = 0;
public ClientHandler(Socket client, String selectedMode, int Nombre_mesures) {
this.client = client;
this.selectedMode = selectedMode;
this.Nombre_mesures = Nombre_mesures;
}
@Override
public void run() {
try {
println("Handling client: " + client.getInetAddress());
try (BufferedReader reader = new BufferedReader(new InputStreamReader(client.getInputStream()))) {
if (!mode_auto) {
while (counter_requete < Nombre_mesures) {
String receivedData = reader.readLine();
if (receivedData != null) {
receivedData = receivedData.trim();
println("Received from Arduino: " + receivedData);
// extractAndWriteData(receivedData, selectedMode, counter_requete);
counter_requete++;
println("Current request counter: " + counter_requete);
}
}
counter_requete = 0;
} else {
if (compteur_auto < Nombre_mesures * combinations1280.size() * gatewayList.size()) {
String receivedData = reader.readLine();
if (receivedData != null) {
receivedData = receivedData.trim();
println("Received from Arduino: " + receivedData);
extractAndWriteData(receivedData, selectedMode, counter_requete);
compteur_auto++;
ismesuredone = true;
delay(300);
// println("Automatic mode counter: " + compteur_auto);
}
}
}
} catch (IOException e) {
println("Error reading client data: " + e.getMessage());
e.printStackTrace();
} finally {
try {
client.close();
println("Client connection closed");
} catch (IOException e) {
println("Error closing client connection: " + e.getMessage());
e.printStackTrace();
}
}
} catch (Exception e) {
println("Unhandled exception: " + e.getMessage());
e.printStackTrace();
}
}
}
private void delay(int ms) {
try {
Thread.sleep(ms);
} catch (InterruptedException e) {
println("Delay interrupted: " + e.getMessage());
e.printStackTrace();
}
}
}
this server class runs in it own thread as a way to handle response from arduinos chips, as for how a connection is iniatialised, in the main code i do this :
for (int i = 0; i < gatewayList.size(); i++) {
int index = gatewayList.get(i);
int[] firstIP = ipAddresses.get(index);
String adress_GW = firstIP[0] + "." + firstIP[1] + "." + firstIP[2] + "." + firstIP[3];
// println(adress_GW);
int retryCount = 0;
int maxRetries = 5; // Limit the number of retries to avoid infinite loops
while (!isSent && retryCount < maxRetries) {
try {
myClient = new Client(this, adress_GW, 80);
if (myClient.active()) {
myClient.write(message);
isSent = true;
println("Message sent to " + adress_GW);
} else {
println("Client is not active, retrying...");
}
} catch (Exception e) {
println("Exception: " + e.getMessage() + ", retrying... (" + (retryCount + 1) + "/" + maxRetries + ")");
} finally {
retryCount++;
delay(200); // Delay before retrying
}
}
if (!isSent) {
println("Failed to send message to " + adress_GW + " after " + maxRetries + " retries.");
}
isSent = false;
}
where i send a message to each gateway, 3 of the 4 gateway got the message , but the last one consistanly give me this :
java.net.ConnectException: Connection refused: connect
at java.base/sun.nio.ch.Net.connect0(Native Method)
at java.base/sun.nio.ch.Net.connect(Net.java:579)
at java.base/sun.nio.ch.Net.connect(Net.java:568)
at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:593)
at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327)
at java.base/java.net.Socket.connect(Socket.java:633)
at java.base/java.net.Socket.connect(Socket.java:583)
at java.base/java.net.Socket.<init>(Socket.java:507)
at java.base/java.net.Socket.<init>(Socket.java:287)
at processing.net.Client.<init>(Unknown Source)
at G4P_interface.automatique_window_draw(G4P_interface.java:1335)
at jdk.internal.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at g4p_controls.GWindow.draw(Unknown Source)
at g4p_controls.GWindowAWT.draw(Unknown Source)
at processing.core.PApplet.handleDraw(PApplet.java:2094)
at processing.awt.PSurfaceAWT$9.callDraw(PSurfaceAWT.java:1386)
at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:356)
any suggestions why this occur ? why the connection was refused ?
i tried to add connection timeout, retry and further investigate the exception but didn’t find the reason this occured.
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