diff --git a/owlps-positioning/Makefile b/owlps-positioning/Makefile
index b5f3cf7..f6815ba 100644
--- a/owlps-positioning/Makefile
+++ b/owlps-positioning/Makefile
@@ -23,7 +23,7 @@ TARGET = owlps-positioning
 HEADER = owlps-positioning.hh
 OBJ = posutil.o point3d.o referencepoint.o waypoint.o building.o \
 			area.o wifidevice.o accesspoint.o mobile.o measurement.o \
-			calibrationmeasurement.o request.o inputcsv.o
+			calibrationmeasurement.o request.o inputcsv.o stock.o
 
 all: $(TARGET)
 
@@ -33,6 +33,7 @@ all: $(TARGET)
 	$(GXX) $(GXXFLAGS) -c $<
 
 posutil.o: posutil.hh
+stock.o: stock.hh
 point3d.o: point3d.hh
 referencepoint.o : referencepoint.hh point3d.o
 waypoint.o: waypoint.hh point3d.o building.o
@@ -44,7 +45,7 @@ mobile.o: mobile.hh wifidevice.o
 measurement.o: measurement.hh accesspoint.o
 calibrationmeasurement.o: calibrationmeasurement.hh measurement.o referencepoint.o
 request.o: request.hh measurement.o
-inputcsv.o: inputcsv.hh inputmedium.hh request.o
+inputcsv.o: inputcsv.hh inputmedium.hh request.o stock.o
 #libowlps-positioning.o: libowlps-positioning.hh
 #positioning.o: point.hh referencepoint.hh accesspoint.hh area.hh measurement.hh libowlps-positioning.hh
 #server.o: server.hh positioning.hh point.hh measurement.hh treatment.hh libowlps-positioning.hh
diff --git a/owlps-positioning/TODO b/owlps-positioning/TODO
index 1deae6e..5651c3c 100644
--- a/owlps-positioning/TODO
+++ b/owlps-positioning/TODO
@@ -16,7 +16,8 @@
    Utiliser '\n' plutôt que endl lorsque le vidage du tampon n'est pas
    nécessaire.
 
-- Measurement : corriger le calcul de moyenne.
+- Measurement
+   Vérifier le calcul de moyenne (a priori OK).
 
 - Revoir le diagramme UML
    ° Associations : devraient êtres représentées par des attributs
@@ -31,6 +32,7 @@
 
 - Accesseurs par références ?
    getref_mon_attribut() (cf. l'ancien clientinfo.hh)
+   −> Accesseur en lecture : retourne une référence constante.
 
 - C++ en action
    Espaces de noms ? 109
diff --git a/owlps-positioning/accesspoint.hh b/owlps-positioning/accesspoint.hh
index 9fbb9d7..3f525df 100644
--- a/owlps-positioning/accesspoint.hh
+++ b/owlps-positioning/accesspoint.hh
@@ -18,9 +18,9 @@ public:
               const Point3D &_coordinates,
               const unsigned int &_frequency = AP_DEFAULT_CHANNEL):
     WifiDevice(wd), coordinates(_coordinates), frequency(_frequency) {}
-  AccessPoint(const Point3D &_coordinates,
-              const std::string &_ip_addr,
-              const std::string &_mac_addr,
+  AccessPoint(const Point3D &_coordinates = Point3D(),
+              const std::string &_ip_addr = "",
+              const std::string &_mac_addr = "",
               const float &_antenna_gain = AP_DEFAULT_ANTENNA_GAIN,
               const float &_trx_power = WIFIDEVICE_DEFAULT_TRX_POWER,
               const unsigned int &_frequency = AP_DEFAULT_CHANNEL):
diff --git a/owlps-positioning/inputcsv.cc b/owlps-positioning/inputcsv.cc
index 02815cc..beaf862 100644
--- a/owlps-positioning/inputcsv.cc
+++ b/owlps-positioning/inputcsv.cc
@@ -1,5 +1,6 @@
 #include "inputcsv.hh"
 #include "posutil.hh"
+#include "stock.hh"
 
 #include <stdint.h>
 
@@ -72,9 +73,10 @@ const Request& InputCSV::get_next_request()
       return current_request ;
     }
 
-  // FIXME! We need to search for the mobile corresponding to the read
-  // MAC address and set the mobile pointer in the Request.
-  //current_request.set_mobile(NULL) ;
+  // If the mobile did not exist, we create it
+  if (Stock::get_mobile(*ti).get_mac_addr().size() == 0)
+    Stock::getw_mobile(*ti).set_mac_addr(*ti) ;
+  current_request.set_mobile(&Stock::get_mobile(*ti)) ;
 
   // Read Timestamp field
   if (++ti == tok.end())
@@ -157,6 +159,11 @@ const Request& InputCSV::get_next_request()
           return current_request ;
         }
 
+      // If the AP did not exist, we create it
+      if (Stock::get_ap(mac_ap).get_mac_addr().size() == 0)
+        Stock::getw_ap(mac_ap).set_mac_addr(mac_ap) ;
+      measurements[mac_ap].set_ap(&Stock::get_ap(mac_ap)) ;
+
       // Adding value
       measurements[mac_ap].add_ss(ss) ;
     }
diff --git a/owlps-positioning/mobile.hh b/owlps-positioning/mobile.hh
index 3569fe1..8762c3c 100644
--- a/owlps-positioning/mobile.hh
+++ b/owlps-positioning/mobile.hh
@@ -10,8 +10,8 @@
 class Mobile: public WifiDevice
 {
 public:
-  Mobile(const std::string &_ip_addr,
-         const std::string &_mac_addr,
+  Mobile(const std::string &_ip_addr = "",
+         const std::string &_mac_addr = "",
          const float &_antenna_gain = MOBILE_DEFAULT_ANTENNA_GAIN,
          const float &_trx_power = WIFIDEVICE_DEFAULT_TRX_POWER):
     WifiDevice(_ip_addr, _mac_addr, _antenna_gain, _trx_power) {}
diff --git a/owlps-positioning/stock.cc b/owlps-positioning/stock.cc
new file mode 100644
index 0000000..0d07d02
--- /dev/null
+++ b/owlps-positioning/stock.cc
@@ -0,0 +1,12 @@
+#include "stock.hh"
+
+using namespace std ;
+using std::tr1::unordered_map ;
+
+
+
+unordered_map<string, Mobile> Stock::mobiles =
+  unordered_map<string, Mobile>() ;
+
+unordered_map<string, AccessPoint> Stock::aps =
+  unordered_map<string, AccessPoint>() ;
diff --git a/owlps-positioning/stock.hh b/owlps-positioning/stock.hh
new file mode 100644
index 0000000..774fcf2
--- /dev/null
+++ b/owlps-positioning/stock.hh
@@ -0,0 +1,52 @@
+#ifndef _OWLPS_POSITIONING_STOCK_HH_
+#define _OWLPS_POSITIONING_STOCK_HH_
+
+#include "mobile.hh"
+#include "accesspoint.hh"
+
+#include <unordered_map>
+
+class Stock
+{
+private:
+  static std::tr1::unordered_map<std::string, Mobile> mobiles ;
+  static std::tr1::unordered_map<std::string, AccessPoint> aps ;
+
+public:
+  static const Mobile& get_mobile(const std::string &mac) ;
+  static Mobile& getw_mobile(const std::string &mac) ;
+  static const AccessPoint& get_ap(const std::string &mac) ;
+  static AccessPoint& getw_ap(const std::string &mac) ;
+} ;
+
+
+
+/*** Accesseurs lecture ***/
+
+
+inline const Mobile& Stock::get_mobile(const std::string &mac)
+{
+  return mobiles[mac] ;
+}
+
+
+inline Mobile& Stock::getw_mobile(const std::string &mac)
+{
+  return mobiles[mac] ;
+}
+
+
+inline const AccessPoint& Stock::get_ap(const std::string &mac)
+{
+  return aps[mac] ;
+}
+
+
+inline AccessPoint& Stock::getw_ap(const std::string &mac)
+{
+  return aps[mac] ;
+}
+
+
+
+#endif // _OWLPS_POSITIONING_STOCK_HH_
diff --git a/owlps-positioning/wifidevice.hh b/owlps-positioning/wifidevice.hh
index c75b646..e8af829 100644
--- a/owlps-positioning/wifidevice.hh
+++ b/owlps-positioning/wifidevice.hh
@@ -18,8 +18,8 @@ protected:
   float trx_power ; // Transmit power in dBm
 
 public:
-  WifiDevice(const std::string &_ip_addr,
-             const std::string &_mac_addr,
+  WifiDevice(const std::string &_ip_addr = "",
+             const std::string &_mac_addr = "",
              const float &_antenna_gain = WIFIDEVICE_DEFAULT_ANTENNA_GAIN,
              const float &_trx_power = WIFIDEVICE_DEFAULT_TRX_POWER) ;
   WifiDevice(const WifiDevice &wd) ;