Arduino pushing data via HTTP

LIBS = Ethernet Ethernet/utility String SPI

#include <SPI.h>
#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xDD };
byte ip[] = { 192,168,1, 42 };
byte gateway[] = { 192, 168, 1, 1};
byte subnet[] = { 255, 255, 255, 0 };

byte server[] = { 192, 168, 1, 2 };

// initialize the library instance:
Client client(server, 80);

const int postingInterval = 9000;   // delay between updates
long lastConnectionTime = 0;        // last time connected to the server
boolean lastConnected = false;      // state of the connection
long counter = 1;

String txtMsg="";

void sendData() {

  if (client.connect()) {
    Serial.println("connecting...");

    client.print("POST /input/ HTTP/1.1\n");

    client.print("Host: HOSTNAME\n");
    client.print("X-ApiKey: RANDOM_API_KEY\n");

    client.println("User-Agent: Arduino");
    client.println("Accept: text/html");
    client.print("Content-Length: ");
    client.println(txtMsg.length(), DEC);

    client.print("Content-Type: text/json\n");
    client.println("Connection: close\n");

    client.println(txtMsg);

    lastConnectionTime = millis();
    counter += 1;
    Serial.println("sent...");
  }
  else {
    Serial.println("connection failed");
    delay(1000);
  }
}

void setup()
{
  // start the Ethernet connection:
  Ethernet.begin(mac, ip);

  Serial.begin(9600);
  // delay for the ethernet to get up
  delay(1000);
}

void loop()
{
  // get the sensor data (using the sensor is the next step -- atm no real data)
  int sensorReading = 42;

  if(millis() - lastConnectionTime > postingInterval) {
    // disconnect old client
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();

    delay(1000);

    // the JSON message
    txtMsg = "[ value=";
    txtMsg += sensorReading;
    txtMsg += ", counter=";
    txtMsg += counter;
    txtMsg += "]";

    sendData();
  }

  lastConnected = client.connected();
}