I have an Arduino Uno with Ethernet Shield. I have a problem with communication between server and arduino. Server is running on Socket.io version 1.0. I want to send data form arduino device. I dont now how to make the communication work. I read a lot about it. Is this solution right? I create Socket.io server and TCP server and then communication between them start. Could you please tell me what is the easiest way to create it when i want realtime communication. Thank you for your help. 
Basic client test code you can try to see if your hardware/network setup is ok.
//zoomkat 9-22-12
//simple client test
//for use with IDE 1.0.1
//with DNS, DHCP, and Host
//open serial monitor and send an e to test
//for use with W5100 based ethernet shields
//remove SD card if inserted
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
char serverName[] = "web.comporium.net"; // zoomkat's test web page server
EthernetClient client;
//////////////////////
void setup(){
if (Ethernet.begin(mac) == 0) {
Serial.println("Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
while(true);
}
Serial.begin(9600);
Serial.println("Better client test 9/22/12"); // so I can keep track of what is loaded
Serial.println("Send an e in serial monitor to test"); // what to do to test
}
void loop(){
// check for serial input
if (Serial.available() > 0) //if something in serial buffer
{
byte inChar; // sets inChar as a byte
inChar = Serial.read(); //gets byte from buffer
if(inChar == 'e') // checks to see byte is an e
{
sendGET(); // call sendGET function below when byte is an e
}
}
}
//////////////////////////
void sendGET() //client function to send/receive GET request data.
{
if (client.connect(serverName, 80)) { //starts client connection, checks for connection
Serial.println("connected");
client.println("GET /~shb/arduino.txt HTTP/1.1"); //download text
client.println("Host: web.comporium.net");
client.println("Connection: close"); //close 1.1 persistent connection
client.println(); //end of get request
}
else {
Serial.println("connection failed"); //error message if no client connect
Serial.println();
}
while(client.connected() && !client.available()) delay(1); //waits for data
while (client.connected() || client.available()) { //connected or data available
char c = client.read(); //gets byte from ethernet buffer
Serial.print(c); //prints byte to serial monitor
}
Serial.println();
Serial.println("disconnecting.");
Serial.println("==================");
Serial.println();
client.stop(); //stop client
}
My arduino print this message
Better client test 9/22/12
Send an e in serial monitor to test
connected
HTTP/1.1 404 Not Found
X-Powered-By: Express
Content-Type: text/html; charset=utf-8
Content-Length: 29
Date: Wed, 17 Sep 2014 17:08:56 GMT
Connection: close
Cannot GET /~shb/arduino.txt
disconnecting.
==================
Below is what is returned when the code I posted is used. It appears you changed the code i posted as it seems to have different return info. Either that, or you have some network setup you haven't explained.
Better client test 9/22/12
Send an e in serial monitor to test
connected
HTTP/1.1 200 OK
Date: Wed, 17 Sep 2014 22:30:57 GMT
Server: Apache/2.2.15 (CentOS)
Last-Modified: Sat, 13 Nov 2010 16:31:40 GMT
Accept-Ranges: bytes
Content-Length: 51
Connection: close
Content-Type: text/plain; charset=UTF-8
Woohoo! Your arduino ethernet client works!
zoomkat
disconnecting.
==================
I have server on 178.238.41.201:8080. On server is running Node.js and Socket.io . I send same data [date] form server to client.
Arduino code :
//zoomkat 9-22-12
//simple client test
//for use with IDE 1.0.1
//with DNS, DHCP, and Host
//open serial monitor and send an e to test
//for use with W5100 based ethernet shields
//remove SD card if inserted
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
//char serverName[] = "178,238,41,201"; // zoomkat's test web page serverbyte
byte serverName [] = { 178, 238, 41, 201 };
EthernetClient client;
//////////////////////
void setup(){
if (Ethernet.begin(mac) == 0) {
Serial.println("Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
while(true);
}
Serial.begin(9600);
Serial.println("Better client test 9/22/12"); // so I can keep track of what is loaded
Serial.println("Send an e in serial monitor to test"); // what to do to test
}
void loop(){
// check for serial input
if (Serial.available() > 0) //if something in serial buffer
{
byte inChar; // sets inChar as a byte
inChar = Serial.read(); //gets byte from buffer
if(inChar == 'e') // checks to see byte is an e
{
sendGET(); // call sendGET function below when byte is an e
}
}
}
//////////////////////////
void sendGET() //client function to send/receive GET request data.
{
if (client.connect(serverName, 8080)) { //starts client connection, checks for connection
Serial.println("connected");
client.println("GET /~shb/arduino.txt HTTP/1.1"); //download text
client.println("Host: web.comporium.net");
client.println("Connection: close"); //close 1.1 persistent connection
client.println(); //end of get request
}
else {
Serial.println("connection failed"); //error message if no client connect
Serial.println();
}
while(client.connected() && !client.available()) delay(1); //waits for data
while (client.connected() || client.available()) { //connected or data available
char c = client.read(); //gets byte from ethernet buffer
Serial.print(c); //prints byte to serial monitor
}
Serial.println();
Serial.println("disconnecting.");
Serial.println("==================");
Serial.println();
client.stop(); //stop client
}
and ARDUINO out:
Better client test 9/22/12
Send an e in serial monitor to test
connected
HTTP/1.1 404 Not Found
X-Powered-By: Express
Content-Type: text/html; charset=utf-8
Content-Length: 29
Date: Fri, 19 Sep 2014 19:02:04 GMT
Connection: closeCannot GET /~shb/arduino.txt
disconnecting.
It´s OK. Arduino return:
Better client test 9/22/12
Send an e in serial monitor to test
connected
HTTP/1.1 200 OK
X-Powered-By: Express
Accept-Ranges: bytes
Date: Fri, 19 Sep 2014 20:07:17 GMT
Cache-Control: public, max-age=0
Last-Modified: Thu, 18 Sep 2014 16:13:01 GMT
ETag: W/"p5yQkHxXDjtPmDBVRioE7Q=="
Content-Type: text/plain; charset=UTF-8
Content-Length: 29
Connection: closeit is okiz
:D:D:D:D:D:D:
disconnecting.
Arduino code modified
//zoomkat 9-22-12
//simple client test
//for use with IDE 1.0.1
//with DNS, DHCP, and Host
//open serial monitor and send an e to test
//for use with W5100 based ethernet shields
//remove SD card if inserted
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
byte serverName[] = { 178, 238, 41, 201 }; // zoomkat's test web page server
EthernetClient client;
//////////////////////
void setup(){
if (Ethernet.begin(mac) == 0) {
Serial.println("Failed to configure Ethernet using DHCP");
// no point in carrying on, so do nothing forevermore:
while(true);
}
Serial.begin(9600);
Serial.println("Better client test 9/22/12"); // so I can keep track of what is loaded
Serial.println("Send an e in serial monitor to test"); // what to do to test
}
void loop(){
// check for serial input
if (Serial.available() > 0) //if something in serial buffer
{
byte inChar; // sets inChar as a byte
inChar = Serial.read(); //gets byte from buffer
if(inChar == 'e') // checks to see byte is an e
{
sendGET(); // call sendGET function below when byte is an e
}
}
}
//////////////////////////
void sendGET() //client function to send/receive GET request data.
{
if (client.connect(serverName, 8080)) { //starts client connection, checks for connection
Serial.println("connected");
client.println("GET /arduino.txt HTTP/1.1"); //download text
client.println("Host: 178.238.41.201:8080");
client.println("Connection: close"); //close 1.1 persistent connection
client.println(); //end of get request
}
else {
Serial.println("connection failed"); //error message if no client connect
Serial.println();
}
while(client.connected() && !client.available()) delay(1); //waits for data
while (client.connected() || client.available()) { //connected or data available
char c = client.read(); //gets byte from ethernet buffer
Serial.print(c); //prints byte to serial monitor
}
Serial.println();
Serial.println("disconnecting.");
Serial.println("==================");
Serial.println();
client.stop(); //stop client
}
WHATS NEXT ?