diff --git a/aqhome/data/storage.c b/aqhome/data/storage.c
index 9afa0fc..722a89a 100644
--- a/aqhome/data/storage.c
+++ b/aqhome/data/storage.c
@@ -39,16 +39,26 @@ static GWEN_BUFFER *_getDataFilePathForValueId(const AQH_STORAGE *sto, uint64_t
 
 
 /* ------------------------------------------------------------------------------------------------
- * implementations
+ * GWEN macros
  * ------------------------------------------------------------------------------------------------
  */
 
+GWEN_INHERIT_FUNCTIONS(AQH_STORAGE)
+
+
+
+/* ------------------------------------------------------------------------------------------------
+ * implementations
+ * ------------------------------------------------------------------------------------------------
+ */
 
 AQH_STORAGE *AQH_Storage_new(void)
 {
   AQH_STORAGE *sto;
 
   GWEN_NEW_OBJECT(AQH_STORAGE, sto);
+  GWEN_INHERIT_INIT(AQH_STORAGE, sto);
+
   sto->deviceList=AQH_Device_List_new();
   sto->valueList=AQH_Value_List_new();
   sto->dataFileList=AQH_DataFile_List_new();
@@ -61,6 +71,7 @@ AQH_STORAGE *AQH_Storage_new(void)
 void AQH_Storage_free(AQH_STORAGE *sto)
 {
   if (sto) {
+    GWEN_INHERIT_FINI(AQH_STORAGE, sto);
     AQH_DataFile_List_free(sto->dataFileList);
     AQH_Value_List_free(sto->valueList);
     AQH_Device_List_free(sto->deviceList);
@@ -194,6 +205,116 @@ void AQH_Storage_SubRuntimeFlags(AQH_STORAGE *sto, uint32_t flags)
 
 
 
+int AQH_Storage_WriteState(AQH_STORAGE *sto)
+{
+  int rv;
+
+  rv=AQH_Storage_WriteStateFile(sto, sto->stateFile);
+  if (rv<0) {
+    DBG_INFO(AQH_LOGDOMAIN, "here (%d)", rv);
+    return rv;
+  }
+  sto->runtimeFlags&=~AQH_STORAGE_RTFLAGS_MODIFIED;
+  return 0;
+}
+
+
+
+
+const char *AQH_Storage_GetDataFileFolder(const AQH_STORAGE *sto)
+{
+  return sto?sto->dataFileFolder:NULL;
+}
+
+
+
+void AQH_Storage_SetDataFileFolder(AQH_STORAGE *sto, const char *s)
+{
+  if (sto) {
+    free(sto->dataFileFolder);
+    sto->dataFileFolder=s?strdup(s):NULL;
+  }
+}
+
+
+
+AQH_STORAGE_INIT_FN AQH_Storage_SetInitFn(AQH_STORAGE *sto, AQH_STORAGE_INIT_FN fn)
+{
+  AQH_STORAGE_INIT_FN oldFn;
+
+  oldFn=sto->initFn;
+  sto->initFn=fn;
+  return oldFn;
+}
+
+
+
+AQH_STORAGE_FINI_FN AQH_Storage_SetFiniFn(AQH_STORAGE *sto, AQH_STORAGE_FINI_FN fn)
+{
+  AQH_STORAGE_FINI_FN oldFn;
+
+  oldFn=sto->finiFn;
+  sto->finiFn=fn;
+  return oldFn;
+}
+
+
+
+AQH_STORAGE_ADDDATAPOINT_FN AQH_Storage_SetAddDatapointFn(AQH_STORAGE *sto, AQH_STORAGE_ADDDATAPOINT_FN fn)
+{
+  AQH_STORAGE_ADDDATAPOINT_FN oldFn;
+
+  oldFn=sto->addDatapointFn;
+  sto->addDatapointFn=fn;
+  return oldFn;
+}
+
+
+
+AQH_STORAGE_GETDATAPOINTS_FN AQH_Storage_SetGetDatapointsFn(AQH_STORAGE *sto, AQH_STORAGE_GETDATAPOINTS_FN fn)
+{
+  AQH_STORAGE_GETDATAPOINTS_FN oldFn;
+
+  oldFn=sto->getDatapointsFn;
+  sto->getDatapointsFn=fn;
+  return oldFn;
+}
+
+
+
+AQH_STORAGE_GETFIRSTDATAPOINT_FN AQH_Storage_SetGetFirstDatapointFn(AQH_STORAGE *sto, AQH_STORAGE_GETFIRSTDATAPOINT_FN fn)
+{
+  AQH_STORAGE_GETFIRSTDATAPOINT_FN oldFn;
+
+  oldFn=sto->getFirstDatapointFn;
+  sto->getFirstDatapointFn=fn;
+  return oldFn;
+}
+
+
+
+AQH_STORAGE_GETLASTDATAPOINT_FN AQH_Storage_SetGetLastDatapointFn(AQH_STORAGE *sto, AQH_STORAGE_GETLASTDATAPOINT_FN fn)
+{
+  AQH_STORAGE_GETLASTDATAPOINT_FN oldFn;
+
+  oldFn=sto->getLastDatapointFn;
+  sto->getLastDatapointFn=fn;
+  return oldFn;
+}
+
+
+
+AQH_STORAGE_GETLASTNDATAPOINTS_FN AQH_Storage_SetGetLastNDatapointsFn(AQH_STORAGE *sto, AQH_STORAGE_GETLASTNDATAPOINTS_FN fn)
+{
+  AQH_STORAGE_GETLASTNDATAPOINTS_FN oldFn;
+
+  oldFn=sto->getLastNDatapointsFn;
+  sto->getLastNDatapointsFn=fn;
+  return oldFn;
+}
+
+
+
 int AQH_Storage_Init(AQH_STORAGE *sto)
 {
   int rv;
@@ -244,39 +365,6 @@ int AQH_Storage_Fini(AQH_STORAGE *sto)
 
 
 
-int AQH_Storage_WriteState(AQH_STORAGE *sto)
-{
-  int rv;
-
-  rv=AQH_Storage_WriteStateFile(sto, sto->stateFile);
-  if (rv<0) {
-    DBG_INFO(AQH_LOGDOMAIN, "here (%d)", rv);
-    return rv;
-  }
-  sto->runtimeFlags&=~AQH_STORAGE_RTFLAGS_MODIFIED;
-  return 0;
-}
-
-
-
-
-const char *AQH_Storage_GetDataFileFolder(const AQH_STORAGE *sto)
-{
-  return sto?sto->dataFileFolder:NULL;
-}
-
-
-
-void AQH_Storage_SetDataFileFolder(AQH_STORAGE *sto, const char *s)
-{
-  if (sto) {
-    free(sto->dataFileFolder);
-    sto->dataFileFolder=s?strdup(s):NULL;
-  }
-}
-
-
-
 int AQH_Storage_AddDatapoint(AQH_STORAGE *sto, uint64_t valueId, uint64_t timestamp, double dataPoint)
 {
   AQH_DATAFILE *df;
@@ -471,6 +559,34 @@ int AQH_Storage_GetLastDataPoint(AQH_STORAGE *sto, uint64_t valueId, uint64_t *p
 
 
 
+int AQH_Storage_GetFirstDataPoint(AQH_STORAGE *sto, uint64_t valueId, uint64_t *pTimestamp, double *pValue)
+{
+  AQH_DATAFILE *df;
+  uint64_t numEntries;
+  int rv;
+
+  df=_getDataFileByValueId(sto, valueId);
+  if (df==NULL) {
+    DBG_ERROR(AQH_LOGDOMAIN, "No file for value id %lu", (unsigned long int) valueId);
+    return GWEN_ERROR_INVALID;
+  }
+  numEntries=AQH_DataFile_GetNumberOfEntries(df);
+  if (numEntries<2) {
+    DBG_INFO(AQH_LOGDOMAIN, "No data entries in file");
+    return GWEN_ERROR_NO_DATA;
+  }
+
+  rv=AQH_DataFile_ReadRecord(df, 1, pTimestamp, pValue);
+  if (rv<0) {
+    DBG_INFO(AQH_LOGDOMAIN, "here (%d)", rv);
+    return rv;
+  }
+
+  return 0;
+}
+
+
+
 
 AQH_DATAFILE *_getDataFileByValueId(AQH_STORAGE *sto, uint64_t valueId)
 {
diff --git a/aqhome/data/storage.h b/aqhome/data/storage.h
index 3dff203..1382ade 100644
--- a/aqhome/data/storage.h
+++ b/aqhome/data/storage.h
@@ -12,6 +12,8 @@
 
 #include <aqhome/api.h>
 
+#include <gwenhywfar/inherit.h>
+
 
 
 #ifdef __cplusplus
@@ -20,6 +22,8 @@ extern "C" {
 
 
 typedef struct AQH_STORAGE AQH_STORAGE;
+GWEN_INHERIT_FUNCTION_LIB_DEFS(AQH_STORAGE, AQHOME_API)
+
 
 
 #ifdef __cplusplus
@@ -40,6 +44,17 @@ typedef struct AQH_STORAGE AQH_STORAGE;
 extern "C" {
 #endif
 
+typedef int (*AQH_STORAGE_INIT_FN)(AQH_STORAGE *sto);
+typedef int (*AQH_STORAGE_FINI_FN)(AQH_STORAGE *sto);
+
+typedef int (*AQH_STORAGE_ADDDATAPOINT_FN)(AQH_STORAGE *sto, uint64_t valueId, uint64_t timestamp, double dataPoint);
+typedef uint64_t *(*AQH_STORAGE_GETDATAPOINTS_FN)(AQH_STORAGE *sto, uint64_t valueId,
+						  uint64_t fromTime, uint64_t toTime,
+						  uint64_t maxArrayLen);
+typedef int (*AQH_STORAGE_GETFIRSTDATAPOINT_FN)(AQH_STORAGE *sto, uint64_t valueId, uint64_t *pTimestamp, double *pValue);
+typedef int (*AQH_STORAGE_GETLASTDATAPOINT_FN)(AQH_STORAGE *sto, uint64_t valueId, uint64_t *pTimestamp, double *pValue);
+typedef uint64_t *(*AQH_STORAGE_GETLASTNDATAPOINTS_FN)(AQH_STORAGE *sto, uint64_t valueId, uint64_t maxDataPointsRequested);
+
 
 
 /**
@@ -74,14 +89,23 @@ AQHOME_API int AQH_Storage_Fini(AQH_STORAGE *sto);
 
 AQHOME_API int AQH_Storage_WriteState(AQH_STORAGE *sto);
 
+
 AQHOME_API int AQH_Storage_AddDatapoint(AQH_STORAGE *sto, uint64_t valueId, uint64_t timestamp, double dataPoint);
 AQHOME_API uint64_t *AQH_Storage_GetDataPoints(AQH_STORAGE *sto, uint64_t valueId,
                                                uint64_t fromTime, uint64_t toTime,
                                                uint64_t maxArrayLen);
+AQHOME_API int AQH_Storage_GetFirstDataPoint(AQH_STORAGE *sto, uint64_t valueId, uint64_t *pTimestamp, double *pValue);
 AQHOME_API int AQH_Storage_GetLastDataPoint(AQH_STORAGE *sto, uint64_t valueId, uint64_t *pTimestamp, double *pValue);
 AQHOME_API uint64_t *AQH_Storage_GetLastNDataPoints(AQH_STORAGE *sto, uint64_t valueId, uint64_t maxDataPointsRequested);
 
 
+AQHOME_API AQH_STORAGE_INIT_FN AQH_Storage_SetInitFn(AQH_STORAGE *sto, AQH_STORAGE_INIT_FN fn);
+AQHOME_API AQH_STORAGE_FINI_FN AQH_Storage_SetFiniFn(AQH_STORAGE *sto, AQH_STORAGE_FINI_FN fn);
+AQHOME_API AQH_STORAGE_ADDDATAPOINT_FN AQH_Storage_SetAddDatapointFn(AQH_STORAGE *sto, AQH_STORAGE_ADDDATAPOINT_FN fn);
+AQHOME_API AQH_STORAGE_GETDATAPOINTS_FN AQH_Storage_SetGetDatapointsFn(AQH_STORAGE *sto, AQH_STORAGE_GETDATAPOINTS_FN fn);
+AQHOME_API AQH_STORAGE_GETFIRSTDATAPOINT_FN AQH_Storage_SetGetFirstDatapointFn(AQH_STORAGE *sto, AQH_STORAGE_GETFIRSTDATAPOINT_FN fn);
+AQHOME_API AQH_STORAGE_GETLASTDATAPOINT_FN AQH_Storage_SetGetLastDatapointFn(AQH_STORAGE *sto, AQH_STORAGE_GETLASTDATAPOINT_FN fn);
+AQHOME_API AQH_STORAGE_GETLASTNDATAPOINTS_FN AQH_Storage_SetGetLastNDatapointsFn(AQH_STORAGE *sto, AQH_STORAGE_GETLASTNDATAPOINTS_FN fn);
 
 
 #ifdef __cplusplus
diff --git a/aqhome/data/storage_p.h b/aqhome/data/storage_p.h
index 9c76b55..2ad7bc7 100644
--- a/aqhome/data/storage_p.h
+++ b/aqhome/data/storage_p.h
@@ -25,6 +25,8 @@
 
 
 struct AQH_STORAGE {
+  GWEN_INHERIT_ELEMENT(AQH_STORAGE)
+
   AQH_VALUE_LIST *valueList;
   AQH_DEVICE_LIST *deviceList;
 
@@ -37,6 +39,14 @@ struct AQH_STORAGE {
   AQH_DATAFILE_LIST *dataFileList;
 
   uint32_t runtimeFlags;
+
+  AQH_STORAGE_INIT_FN initFn;
+  AQH_STORAGE_FINI_FN finiFn;
+  AQH_STORAGE_ADDDATAPOINT_FN addDatapointFn;
+  AQH_STORAGE_GETDATAPOINTS_FN getDatapointsFn;
+  AQH_STORAGE_GETFIRSTDATAPOINT_FN getFirstDatapointFn;
+  AQH_STORAGE_GETLASTDATAPOINT_FN getLastDatapointFn;
+  AQH_STORAGE_GETLASTNDATAPOINTS_FN getLastNDatapointsFn;
 };