Arduino Ethernet Shield connection to socket server - sockets

Question

I'm using an ethernet shield for Arduino to connect it to a socket server (different computer) so that I can receive messages from it to activate some routine. Here is my code:
#include <Ethernet.h>
#include <SPI.h>
byte mac[] = { 0x90, 0xA2, 0xDA, 0x0F, 0x5A, 0x21 };
byte ip[] = { 192,168,1,11 }; //ip shield
byte server[] = { 192,168,1,7 }; // ip server
EthernetClient client;
String readString;
int ledPins[] = {19, 17, 2,3, 5, 6, 7, 8, 9}; // leds pins
int pinCount = 8;// number of leds
int const PINEYES = 9; //pin for different led
int const TIMERLEDS = 1000;
int const TIMERTOOFF= 3000;
//--------------------------------------------------------------------------
void setup() {
turnOffLeds();
Ethernet.begin(mac, ip);
Serial.begin(9600);
delay(1000);
Serial.println("connecting...");
if (client.connect(server, 1400)) {
Serial.println("connected");
client.println();
} else {
Serial.println("connection failed");
}
pinMode(PINEYES, OUTPUT);
int thisPin;
for (int thisPin = 0; thisPin < pinCount; thisPin++) {
pinMode(ledPins[thisPin], OUTPUT);
}
}
//--------------------------------------------------------------------------
void loop() {
if (client.available()) {
char c = client.read();
if (readString.length() < 30) {
if(c!='|')
readString.concat(c);
else {
client.flush();
//if (readString == "START_SENSATIONS") {
if (readString == "on") {
Serial.println("recebi");
client.stop();
turnOnMaya();
}
resetString();
}
}
Serial.println(readString);
}
if (!client.connected()) {
Serial.println();
Serial.println("disconnecting.");
client.stop();
for(;;)
;
}
}
//--------------------------------------------------------------------------
void turnOnMaya(){
turnOnLeds();
for (int thisPin = 0; thisPin < pinCount; thisPin++) {
delay(TIMERLEDS);
digitalWrite(ledPins[thisPin], LOW);
}
turnOnEyes();
delay(TIMERTOOFF);
turnOffLeds();
digitalWrite(PINEYES, LOW);
client.connect(server, 1400);
}
//--------------------------------------------------------------------------
void turnOnLeds(){
for (int thisPin = 0; thisPin < pinCount; thisPin++) {
digitalWrite(ledPins[thisPin], HIGH);
}
}
//--------------------------------------------------------------------------
void turnOffLeds(){
for (int thisPin = 0; thisPin < pinCount; thisPin++) {
digitalWrite(ledPins[thisPin], LOW);
}
}
//--------------------------------------------------------------------------
void turnOnEyes(){
digitalWrite(PINEYES, 255);
}
//--------------------------------------------------------------------------
void resetString() {
readString = "";
}
The problem is, when my server stops or is not available for some moments, I need my Arduino to keep on trying to connect to it until it is available again. But I can't make this work.
I tried this:
while(!client.available()){
Serial.println("connection failed, trying again...");
client.connect(server, 1400);
delay(1000);
}
But it doesn't work. It just prints "connection failed, trying again..." forever. How can I do this?
Thanks!

Answer 1

I'm assuming that the server in your PC is a normal java or c (or any other standard tcp server)
But your arduino client doesn't specify that it is TCP. So either change your server or the client(like in here - this uses wifi connection).
If your server is in java, it could be like this:
int port=9999;
try{
System.out.println("Starting server...");
ServerSocket ss=new ServerSocket(port);
Socket clientSocket=ss.accept();
System.out.println("Connection has been established...");
PrintWriter out=new PrintWriter(clientSocket.getOutputStream(),true);
BufferedReader br=new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
String inputLine;
System.out.println("Listening.....");
while((inputLine=br.readLine())!=null)
System.out.println(inputLine);
}catch(Exception e){System.out.println(e.getMessage());}