diff --git a/api.h b/api.h
index b6ee1f4..041181b 100644
--- a/api.h
+++ b/api.h
@@ -2,26 +2,31 @@
 #include <WiFiClientSecure.h>
 #include "config.h"
 
-WiFiClientSecure api;
+class OsemApi {
+  protected:
+  WiFiClientSecure client;
 
-bool postMeasurement(String m, String sensorID) {
-  //telnet.print("Connecting to API.. ");
-  if (!api.connect(API_ENDPOINT, 443)) {
-    //telnet.println("connection failed");
-    return false;
+  public:
+  bool postMeasurement(String m, String sensorID) {
+    //telnet.print("Connecting to API.. ");
+    if (!client.connect(API_ENDPOINT, 443)) {
+      //telnet.println("connection failed");
+      return false;
+    }
+    
+    if (!client.verify(API_FINGERPRINT, API_ENDPOINT)) {
+      Serial.println("certificate doesn't match");
+      return false;
+    }
+  
+    String url = "/boxes/" + String(ID_BOX) + "/" + sensorID;
+    // TODO: add actual measurement to post
+    client.print(String("POST ") + url + " HTTP/1.1\r\n" +
+                 "Host: " + API_ENDPOINT + "\r\n" +
+                 "User-Agent: mobile-sensebox-esp8266\r\n" +
+                 "Connection: close\r\n\r\n");
+  
+    return true;
   }
-  if (api.verify(API_FINGERPRINT, API_ENDPOINT)) {
-    //telnet.println("certificate matches");
-  } else {
-    //telnet.println("certificate doesn't match");
-    return false;
-  }
-
-  String url = "/boxes/" + String(ID_BOX) + "/" + sensorID;
-  api.print(String("POST ") + url + " HTTP/1.1\r\n" +
-               "Host: " + API_ENDPOINT + "\r\n" +
-               "User-Agent: mobile-sensebox-esp8266\r\n" +
-               "Connection: close\r\n\r\n");
+};
 
-  return true;
-}
diff --git a/gps.h b/gps.h
index e5ddff9..70df806 100644
--- a/gps.h
+++ b/gps.h
@@ -3,51 +3,71 @@
 #include <Time.h>
 #include "config.h"
 
-/* GPS */
-TinyGPSPlus gps;
-// allocate the maximum buffer size, so we can reduce the Serial polling interval to a minimum
-//SoftwareSerial gpsSerial(GPS_RX_PIN, GPS_TX_PIN, false, 27*49);
-
-void pollGPS() {
-  while (Serial.available() > 0)
-    gps.encode(Serial.read());  
-}
-
-bool updateLocation() {
-  // abort if the GPS device does not push valid data  within one update cycle
-  static const unsigned int timeout = 2 * GPS_INTERVAL;
-  unsigned long start = millis();
+class Gps {
+  protected:
+  TinyGPSPlus gps;
   
-  do {
-    pollGPS();
-    if (millis() - start > timeout) return false;
-  } while (!gps.location.isUpdated());
-  return true;
-}
-
-bool updateTime() {
-  // abort if the GPS device does not push valid data  within one update cycle
-  static const unsigned int timeout = 2 * GPS_INTERVAL;
-  unsigned long start = millis();
+  public:
+  void begin() {
+    Serial.begin(GPS_BAUD);
+  }
   
-  do {
-    pollGPS();
-    if (millis() - start > timeout) return false;
-  } while ( !(gps.date.isUpdated() && gps.time.isUpdated()) );
+  /** 
+   * parse all available bytes from the Serial input
+   * should be called frequently to avoid buffer overflows
+   */
+  void pollGPS() {
+    while (Serial.available() > 0)
+      gps.encode(Serial.read());  
+  }
 
-  // in case we didnt timeout, resync the local clock
-  setTime(gps.time.hour(), gps.time.minute(), gps.time.second(),
-    gps.date.day(), gps.date.month(), gps.date.year());
+  /**
+   * poll until we have a valid location.
+   * retries at most once, returns success state
+   */
+  bool updateLocation() {
+    // abort if the GPS device does not push valid data  within one update cycle
+    static const unsigned int timeout = 2 * GPS_INTERVAL;
+    unsigned long start = millis();
+    
+    do {
+      pollGPS();
+      if (millis() - start > timeout) return false;
+    } while (!gps.location.isUpdated()); // TODO: check if is valid?
+    return true;
+  }
+  
+  /**
+   * poll until we have a valid date & time.
+   * retries at most once, returns success state
+   */
+  bool updateTime() {
+    // abort if the GPS device does not push valid data  within one update cycle
+    static const unsigned int timeout = 2 * GPS_INTERVAL;
+    unsigned long start = millis();
 
-  return true;
-}
+    // TODO: check if is valid?
+    do {
+      pollGPS();
+      if (millis() - start > timeout) return false;
+    } while ( !(gps.date.isUpdated() && gps.time.isUpdated()) );
+  
+    // in case we didnt timeout, resync the local clock (Time.h)
+    setTime(gps.time.hour(), gps.time.minute(), gps.time.second(),
+      gps.date.day(), gps.date.month(), gps.date.year());
+  
+    return true;
+  }
 
+  /**
+   * return an iso8266 formatted datestring with the current time
+   */
+  static char* getISODate() {
+    // TODO: check why we need to allocate that much storage for a 20 character string for Serial printing??
+    char result[100] = { 0 };
+    sprintf(result, "%04d-%02d-%02d-T%02d:%02d:%02dZ",
+      year(), month(), day(), hour(), minute(), second());
+    return result;
+  }
+};
 
-/* UTILS */
-static char* getISODate() {
-  // TODO: check why we need to allocate that much storage for a 20 character string for Serial printing??
-  char result[100] = { 0 };
-  sprintf(result, "%04d-%02d-%02d-T%02d:%02d:%02dZ",
-    year(), month(), day(), hour(), minute(), second());
-  return result;
-}
diff --git a/mobile-sensebox.ino b/mobile-sensebox.ino
index a882e92..d4b848d 100644
--- a/mobile-sensebox.ino
+++ b/mobile-sensebox.ino
@@ -9,41 +9,57 @@
 
 //TelnetPrint telnet = TelnetPrint();
 Storage storage = Storage();
+Wifi wifi = Wifi();
+OsemApi api = OsemApi();
+Gps gps = Gps();
 
 /* UTILS */
-void printState(WifiState wifi) {
+void printState(WifiState wifiState) {
   DEBUG_OUT.print("homeAvailable: ");
-  DEBUG_OUT.println(wifi.homeAvailable);
+  DEBUG_OUT.println(wifiState.homeAvailable);
   DEBUG_OUT.print("numNetworks: ");
-  DEBUG_OUT.println(wifi.numNetworks);
+  DEBUG_OUT.println(wifiState.numNetworks);
   DEBUG_OUT.print("numUnencrypted: ");
-  DEBUG_OUT.println(wifi.numUnencrypted);
+  DEBUG_OUT.println(wifiState.numUnencrypted);
 
   DEBUG_OUT.print("lat: ");
   //DEBUG_OUT.print(gps.location.lat(), 6);
   DEBUG_OUT.print(" lng: ");
   //DEBUG_OUT.println(gps.location.lng(), 6);
 
-  DEBUG_OUT.println(getISODate());
+  DEBUG_OUT.println(gps.getISODate());
   DEBUG_OUT.println("");
 }
 
+bool storeMeasurement(float lat, float lng, float value, char* timeStamp, char* sensorID) {
+  Measurement m;
+  m.lat = lat;
+  m.lng = lng;
+  m.value = value;
+  strcpy(m.timeStamp, timeStamp);
+  strcpy(m.sensorID, sensorID);
+
+  return storage.add(m);
+}
+
 
 /* MAIN ENTRY POINTS */
 void setup() {
-  //Serial.begin(9600); // GPS reciever
   DEBUG_OUT.begin(115200);
 
-  WiFi.mode(WIFI_STA);
+  size_t bytesFree = storage.begin();
+  //gps.begin();
+  wifi.begin();
+  
   //connectWifi(WIFI_SSID, WIFI_PASS);
 
-  //delay(5000); // DEBUG: oportunity to connect to network logger
+  //delay(5000); // DEBUG oportunity to connect to network logger
 
   // wait until we got a first fix from GPS, and thus an initial time
   /*DEBUG_OUT.print("Getting GPS fix..");
-  while (!updateLocation()) { DEBUG_OUT.print("."); }
+  while (!gps.updateLocation()) { DEBUG_OUT.print("."); }
   DEBUG_OUT.print(" done! ");*/
-  DEBUG_OUT.println(getISODate());
+  DEBUG_OUT.println(gps.getISODate());
 
   DEBUG_OUT.println("Setup done!\n");
   DEBUG_OUT.println("WiFi MAC            WiFi IP");
@@ -52,50 +68,43 @@ void setup() {
   DEBUG_OUT.println(WiFi.localIP());
   
   DEBUG_OUT.print("SPIFF bytes free: ");
-  DEBUG_OUT.println(storage.begin());
+  DEBUG_OUT.println(bytesFree);
   
-  digitalWrite(D9, HIGH); // DEBUG: integrated  led? doesnt work
+  digitalWrite(D9, HIGH); // DEBUG: integrated led? doesnt work
 }
 
 void loop() {
   //pollGPS();
   //DEBUG_OUT.pollClients();
-  WifiState wifi = scanWifi(WIFI_SSID);
+  WifiState wifiState = wifi.scanWifi(WIFI_SSID);
+  char* dateString = gps.getISODate();
 
   // TODO: take other measurements (average them?)
 /*
-  if(!updateLocation()) DEBUG_OUT.println("GPS timed out (location)");
-  if(!updateTime()) DEBUG_OUT.println("GPS timed out (time)");
+  if(!gps.updateLocation()) DEBUG_OUT.println("GPS timed out (location)");
+  if(!gps.updateTime()) DEBUG_OUT.println("GPS timed out (time)");
 */
-  // TODO: write measurements to file
-
-  // TODO: connect to wifi, if available & not connected yet
-    // then upload local data, clean up
 
-  printState(wifi);
+  // write measurements to file
+  if (storeMeasurement(51.2, 7.89, wifiState.numNetworks, dateString, "12341234123412341234123412341234")) {
+    DEBUG_OUT.print("measurement stored! storage size: ");
+  } else {
+    DEBUG_OUT.print("measurement store failed! storage size: ");
+  }
+  DEBUG_OUT.println(storage.size());
 
-  // recall all previous measurements
+  // TODO: connect to wifi, if available & not connected yet
+    // then upload local data, remove from storage
+    
+  // DEBUG: recall all previous measurements
   while (storage.size()) {
     String measure = storage.pop();
+    //api.postMeasurement(measure.substring(0, 31), measure.substring(32));
     DEBUG_OUT.println("popped a measurement: ");
     DEBUG_OUT.println(measure.substring(0, 31)); // size of sensorID
     DEBUG_OUT.println(measure.substring(32));    // skip the newline char
   }
 
-  // store new measurement
-  Measurement testMeasure;
-  testMeasure.lat = 51.2;
-  testMeasure.lng = 7.89;
-  testMeasure.value = wifi.numNetworks;
-  strcpy(testMeasure.timeStamp, getISODate());
-  strcpy(testMeasure.sensorID, "123457812345678123456781234567");
-  
-  if (storage.add(testMeasure)) {
-    DEBUG_OUT.print("measurement stored! storage size: ");
-  } else {
-    DEBUG_OUT.print("measurement store failed! storage size: ");
-  }
-  DEBUG_OUT.println(storage.size());
-  
-  delay(2000);
+  printState(wifiState);
 }
+
diff --git a/wifi.h b/wifi.h
index 3809689..fbc1524 100644
--- a/wifi.h
+++ b/wifi.h
@@ -2,46 +2,53 @@
 #include <ESP8266WiFi.h>
 #include "config.h"
 
-/* WIFI */
 struct WifiState {
   bool homeAvailable;
   unsigned int numNetworks;
   unsigned int numUnencrypted;
 };
 
-// TODO: filter duplicate SSIDs!
-WifiState scanWifi(String homeSSID) {
-  WifiState state;
-  state.homeAvailable = false;
-  state.numNetworks = WiFi.scanNetworks(false, false);
-  state.numUnencrypted = 0;
-
-  for (unsigned int i = 0; i < state.numNetworks; i++) {
-    if (WiFi.encryptionType(i) == ENC_TYPE_NONE)
-      ++state.numUnencrypted;
-
-    if (WiFi.SSID(i) == homeSSID)
-      state.homeAvailable = true;
+class Wifi {
+  public:
+  void begin() {
+    WiFi.mode(WIFI_STA);
   }
-
-  return state;
-}
-
-bool connectWifi(const char* ssid, const char* pass) {
-  static const unsigned int timeout = 10000; // abort after 10 secs
-  unsigned long start = millis();
-
-  WiFi.disconnect();
-  WiFi.begin(ssid, pass);
-  //telnet.print("Connecting to WiFi.");
-  while (WiFi.status() != WL_CONNECTED && millis() - start < timeout) {
-    delay(200);
-    //telnet.print(".");
+  
+  WifiState scanWifi(String homeSSID) {
+    // TODO: filter duplicate SSIDs!
+    WifiState state;
+    state.homeAvailable = false;
+    state.numNetworks = WiFi.scanNetworks(false, false);
+    state.numUnencrypted = 0;
+  
+    for (unsigned int i = 0; i < state.numNetworks; i++) {
+      if (WiFi.encryptionType(i) == ENC_TYPE_NONE)
+        ++state.numUnencrypted;
+  
+      if (WiFi.SSID(i) == homeSSID)
+        state.homeAvailable = true;
+    }
+  
+    return state;
   }
-  if (WiFi.status() == WL_CONNECTED) {
-    //telnet.println("connected!");
-    return true;
+  
+  bool connectWifi(const char* ssid, const char* pass) {
+    static const unsigned int timeout = 10000; // abort after 10 secs
+    unsigned long start = millis();
+  
+    WiFi.disconnect();
+    WiFi.begin(ssid, pass);
+    //telnet.print("Connecting to WiFi.");
+    while (WiFi.status() != WL_CONNECTED && millis() - start < timeout) {
+      delay(200);
+      //telnet.print(".");
+    }
+    if (WiFi.status() == WL_CONNECTED) {
+      //telnet.println("connected!");
+      return true;
+    }
+    //telnet.println(" timeout");
+    return false;
   }
-  //telnet.println(" timeout");
-  return false;
-}
+};
+