diff --git a/python/obitools3/dms/dms.pyx b/python/obitools3/dms/dms.pyx
index 345460e..e0de92e 100644
--- a/python/obitools3/dms/dms.pyx
+++ b/python/obitools3/dms/dms.pyx
@@ -51,6 +51,11 @@ cdef class DMS :
         """
         return __OBIDMS_COLUMN_CLASS__[obitype][1]
 
+    @staticmethod
+    cdef type get_view_class(bytes viewtype):
+        return __OBIDMS_VIEW_CLASS__[viewtype]
+        
+    
     def __init__(self, object dms_name) :
         '''
         Constructor of a obitools3.dms.DMS instance.
@@ -114,6 +119,18 @@ cdef class DMS :
         
         for v in p.glob("*.obiview"):
             yield str2bytes(v.stem)
+            
+    def values(self):
+        cdef bytes view_name
+        
+        for view_name in self.keys():
+            yield self.get_view(view_name)
+                
+    def items(self):
+        cdef bytes view_name
+        
+        for view_name in self.keys():
+            yield (view_name,self.get_view(view_name))
     
     def __contains__(self,key):
         cdef str key_s = tostr(key)
@@ -128,4 +145,21 @@ cdef class DMS :
     
     cpdef int view_count(self):
         return PyList_Size(list(self.keys()))
+    
+    def get_view(self):
+        raise NotImplemented
+    
+    def __len__(self):
+        return self.view_count()
+    
+    def __getitem__(self, object view_name):
+        return self.get_view(view_name)
+    
+    def __iter__(self):
+        return self.keys()
+    
+    cpdef bint is_view_writable(self, object view_name):
+        raise NotImplemented
+    
+        
     
\ No newline at end of file
diff --git a/python/obitools3/dms/view/view.pyx b/python/obitools3/dms/view/view.pyx
index 0852eb2..d1b6287 100644
--- a/python/obitools3/dms/view/view.pyx
+++ b/python/obitools3/dms/view/view.pyx
@@ -12,6 +12,8 @@ from ..capi.obiview cimport Alias_column_pair_p, \
                            
 from ..capi.obidmscolumn cimport OBIDMS_column_p
 
+from .dms  cimport __OBIDMS_VIEW_CLASS__
+
 from obitools3.utils cimport tobytes, \
                              bytes2str
                              
@@ -102,10 +104,10 @@ cdef class View :
         return view
         
     def close(self):
-        if (self._pointer != NULL 
-            and obi_save_and_close_view(self._pointer) < 0) :
-            raise Exception("Problem closing view %s" % 
-                            bytes2str(self.name))
+        if (self._pointer != NULL): 
+            if obi_save_and_close_view(self._pointer) < 0 :
+                raise Exception("Problem closing view %s" % 
+                                bytes2str(self.name))
 
     def __dealloc__(self):
         self.close()
@@ -238,7 +240,7 @@ cdef class View :
     # view type property getter
     @property
     def type(self):  # @ReservedAssignment
-        return bytes2str(self._pointer.infos.view_type)
+        return <bytes> self._pointer.infos.view_type
 
     # comments property getter
     @property
@@ -410,3 +412,15 @@ cdef class Line :
 #         return view_infos_d
 
 
+cdef register_view_class(bytes viewtype,
+                        type classe):
+    """
+    Each sub class of `dms.View` needs to be registered after its declaration
+    to declare its relationship with an `OBIType_t`
+    """
+    global __OBIDMS_VIEW_CLASS__
+
+    assert issubclass(classe,View)
+    
+    __OBIDMS_VIEW_CLASS__[viewtype]=classe
+