diff --git a/src/gmio_core/internal/helper_task_iface.h b/src/gmio_core/internal/helper_task_iface.h
new file mode 100644
index 0000000..09acd44
--- /dev/null
+++ b/src/gmio_core/internal/helper_task_iface.h
@@ -0,0 +1,40 @@
+/****************************************************************************
+** GeomIO Library
+** Copyright FougSys (2 Mar. 2015)
+** contact@fougsys.fr
+**
+** This software is a reusable library whose purpose is to provide complete
+** I/O support for various CAD file formats (eg. STL)
+**
+** This software is governed by the CeCILL-B license under French law and
+** abiding by the rules of distribution of free software.  You can  use,
+** modify and/ or redistribute the software under the terms of the CeCILL-B
+** license as circulated by CEA, CNRS and INRIA at the following URL
+** "http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.html".
+****************************************************************************/
+
+#ifndef GMIO_INTERNAL_HELPER_TASK_IFACE_H
+#define GMIO_INTERNAL_HELPER_TASK_IFACE_H
+
+#include "../task_iface.h"
+
+#include <stddef.h>
+
+/*! Safe and convenient function for gmio_task_iface::is_stop_requested_func() */
+GMIO_INLINE gmio_bool_t gmio_task_iface_is_stop_requested(
+        const gmio_task_iface_t* itask)
+{
+    if (itask != NULL && itask->is_stop_requested_func != NULL)
+        return itask->is_stop_requested_func(itask->cookie);
+    return GMIO_FALSE;
+}
+
+/*! Safe and convenient function for gmio_task_iface::handle_progress_func() */
+GMIO_INLINE void gmio_task_iface_handle_progress(
+        const gmio_task_iface_t* itask, size_t value, size_t max_value)
+{
+    if (itask != NULL && itask->handle_progress_func != NULL)
+        itask->handle_progress_func(itask->cookie, value, max_value);
+}
+
+#endif /* GMIO_INTERNAL_HELPER_TASK_IFACE_H */
diff --git a/src/gmio_core/internal/helper_transfer.h b/src/gmio_core/internal/helper_transfer.h
index 8781e45..19d1b79 100644
--- a/src/gmio_core/internal/helper_transfer.h
+++ b/src/gmio_core/internal/helper_transfer.h
@@ -17,24 +17,27 @@
 #define GMIO_INTERNAL_HELPER_TRANSFER_H
 
 #include "../transfer.h"
+#include "helper_task_iface.h"
 
-#include <stddef.h>
-
-/*! Safe and convenient function for gmio_transfer::is_stop_requested_func() */
+/*! Safe and convenient function for gmio_task_iface::is_stop_requested_func()
+ *  through gmio_transfer::task_iface
+ */
 GMIO_INLINE gmio_bool_t gmio_transfer_is_stop_requested(
         const gmio_transfer_t* trsf)
 {
-    if (trsf != NULL && trsf->is_stop_requested_func != NULL)
-        return trsf->is_stop_requested_func(trsf->cookie);
+    if (trsf != NULL)
+        return gmio_task_iface_is_stop_requested(&trsf->task_iface);
     return GMIO_FALSE;
 }
 
-/*! Safe and convenient function for gmio_transfer::handle_progress_func() */
+/*! Safe and convenient function for gmio_task_iface::handle_progress_func()
+ *  through gmio_transfer::task_iface
+ */
 GMIO_INLINE void gmio_transfer_handle_progress(
         const gmio_transfer_t* trsf, size_t value, size_t max_value)
 {
-    if (trsf != NULL && trsf->handle_progress_func != NULL)
-        trsf->handle_progress_func(trsf->cookie, value, max_value);
+    if (trsf != NULL)
+        gmio_task_iface_handle_progress(&trsf->task_iface, value, max_value);
 }
 
 #endif /* GMIO_INTERNAL_HELPER_TRANSFER_H */
diff --git a/src/gmio_core/task_iface.h b/src/gmio_core/task_iface.h
new file mode 100644
index 0000000..8a85658
--- /dev/null
+++ b/src/gmio_core/task_iface.h
@@ -0,0 +1,51 @@
+/****************************************************************************
+** GeomIO Library
+** Copyright FougSys (2 Mar. 2015)
+** contact@fougsys.fr
+**
+** This software is a reusable library whose purpose is to provide complete
+** I/O support for various CAD file formats (eg. STL)
+**
+** This software is governed by the CeCILL-B license under French law and
+** abiding by the rules of distribution of free software.  You can  use,
+** modify and/ or redistribute the software under the terms of the CeCILL-B
+** license as circulated by CEA, CNRS and INRIA at the following URL
+** "http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.html".
+****************************************************************************/
+
+/*! \file task_iface.h
+ *  Declaration of gmio_task_iface
+ */
+
+#ifndef GMIO_TASK_IFACE_H
+#define GMIO_TASK_IFACE_H
+
+#include "global.h"
+
+struct gmio_task_iface
+{
+    /*! Optional opaque pointer on a user task object, passed as first
+     *  argument to hook functions */
+    void* cookie;
+
+    /*! Optional pointer on a function that says if the currently running
+     *  task must stop
+     *
+     *  If \c GMIO_TRUE is returned then the current task should abort as
+     *  soon as possible, otherwise it can continue execution.
+     */
+    gmio_bool_t (*is_stop_requested_func)(void* cookie);
+
+    /*! Optional pointer on a function that is called anytime some new progress
+     *  was done
+     *
+     *  \param cookie The cookie set inside the gmio_task_iface object
+     *  \param value Current value of the task progress (<= \p max_value )
+     *  \param max_value Maximum value of the task progress
+     */
+    void (*handle_progress_func)(void* cookie, size_t value, size_t max_value);
+};
+
+typedef struct gmio_task_iface gmio_task_iface_t;
+
+#endif /* GMIO_TASK_IFACE_H */
diff --git a/src/gmio_core/transfer.h b/src/gmio_core/transfer.h
index 6ad393d..8f591e8 100644
--- a/src/gmio_core/transfer.h
+++ b/src/gmio_core/transfer.h
@@ -23,36 +23,19 @@
 #include "buffer.h"
 #include "global.h"
 #include "stream.h"
+#include "task_iface.h"
 
 /*! Defines objects required for any transfer(read/write) operation */
 struct gmio_transfer
 {
-    /*! Optional opaque pointer on a user task object, passed as first
-     *  argument to hook functions */
-    void* cookie;
-
-    /*! Optional pointer on a function that says if the currently running
-     *  operation must stop
-     *
-     *  If \c GMIO_TRUE is returned then the current transfer should abort as
-     *  soon as possible, otherwise it can continue execution.
-     */
-    gmio_bool_t (*is_stop_requested_func)(void* cookie);
-
-    /*! Optional pointer on a function that is called anytime some progress
-     *  was done during transfer
-     *
-     *  \param cookie The cookie set inside the gmio_transfer object
-     *  \param value Current value of the transfer progress (<= \p max_value )
-     *  \param max_value Maximum value of the transfer progress
-     */
-    void (*handle_progress_func)(void* cookie, size_t value, size_t max_value);
-
     /*! The stream object to be used for I/O */
     gmio_stream_t stream;
 
-    /*! The memory buffer used by the transfer for stream operations */
+    /*! The memory block used by the transfer for stream buffering */
     gmio_buffer_t buffer;
+
+    /*! The interface object by which the transfer task can be controlled */
+    gmio_task_iface_t task_iface;
 };
 
 typedef struct gmio_transfer gmio_transfer_t;