diff --git a/meshroom/core/desc.py b/meshroom/core/desc.py
index 3422a8b8..ce69601a 100755
--- a/meshroom/core/desc.py
+++ b/meshroom/core/desc.py
@@ -1,5 +1,7 @@
 from meshroom.common import BaseObject, Property, Variant
 from enum import Enum  # available by default in python3. For python2: "pip install enum34"
+import collections
+import os
 
 
 class Attribute(BaseObject):
@@ -23,6 +25,9 @@ class Attribute(BaseObject):
     isOutput = Property(bool, lambda self: self._isOutput, constant=True)
     isInput = Property(bool, lambda self: not self._isOutput, constant=True)
 
+    def validateValue(self, value):
+        return value
+
 
 class ListAttribute(Attribute):
     """ A list of Attributes """
@@ -35,6 +40,11 @@ class ListAttribute(Attribute):
 
     uid = Property(Variant, lambda self: self.elementDesc.uid, constant=True)
 
+    def validateValue(self, value):
+        if not (isinstance(value, collections.Iterable) and isinstance(value, basestring)):
+            raise ValueError('ListAttribute only supports iterable input values.')
+        return value
+
 
 class GroupAttribute(Attribute):
     """ A macro Attribute composed of several Attributes """
@@ -45,6 +55,11 @@ class GroupAttribute(Attribute):
         self.groupDesc = groupDesc
         super(GroupAttribute, self).__init__(label=label, description=description, value=None, uid=(), group=group)
 
+    def validateValue(self, value):
+        if not (isinstance(value, collections.Iterable) and isinstance(value, basestring)):
+            raise ValueError('GroupAttribute only supports iterable input values.')
+        return value
+
     def retrieveChildrenUids(self):
         allUids = []
         for desc in self.groupDesc.values():
@@ -68,6 +83,11 @@ class File(Attribute):
         super(File, self).__init__(label=label, description=description, value=value, uid=uid, group=group)
         self._isOutput = isOutput
 
+    def validateValue(self, value):
+        if not isinstance(value, basestring):
+            raise ValueError('File only supports string input: "{}".'.format(value))
+        return os.path.normpath(value).replace('\\', '/')
+
 
 class BoolParam(Param):
     """
@@ -75,6 +95,12 @@ class BoolParam(Param):
     def __init__(self, label, description, value, uid, group='allParams'):
         super(BoolParam, self).__init__(label=label, description=description, value=value, uid=uid, group=group)
 
+    def validateValue(self, value):
+        try:
+            return bool(value)
+        except:
+            raise ValueError('BoolParam only supports bool value.')
+
 
 class IntParam(Param):
     """
@@ -83,6 +109,12 @@ class IntParam(Param):
         self._range = range
         super(IntParam, self).__init__(label=label, description=description, value=value, uid=uid, group=group)
 
+    def validateValue(self, value):
+        try:
+            return int(value)
+        except:
+            raise ValueError('IntParam only supports int value.')
+
     range = Property(Variant, lambda self: self._range, constant=True)
 
 
@@ -93,6 +125,12 @@ class FloatParam(Param):
         self._range = range
         super(FloatParam, self).__init__(label=label, description=description, value=value, uid=uid, group=group)
 
+    def validateValue(self, value):
+        try:
+            return float(value)
+        except:
+            raise ValueError('FloatParam only supports float value.')
+
     range = Property(Variant, lambda self: self._range, constant=True)
 
 
@@ -105,6 +143,19 @@ class ChoiceParam(Param):
         self._joinChar = joinChar
         super(ChoiceParam, self).__init__(label=label, description=description, value=value, uid=uid, group=group)
 
+    def validateValue(self, value):
+        newValues = None
+        if self.exclusive:
+            newValues = [value]
+        else:
+            if not isinstance(value, collections.Iterable):
+                raise ValueError('Non exclusive ChoiceParam value "{}" should be iterable.'.format(value))
+            newValues = value
+        for newValue in newValues:
+            if newValue not in self.values:
+                raise ValueError('ChoiceParam value "{}" is not in "{}".'.format(newValue, str(self.values)))
+        return value
+
     values = Property(Variant, lambda self: self._values, constant=True)
     exclusive = Property(bool, lambda self: self._exclusive, constant=True)
     joinChar = Property(str, lambda self: self._joinChar, constant=True)
@@ -116,6 +167,11 @@ class StringParam(Param):
     def __init__(self, label, description, value, uid, group='allParams'):
         super(StringParam, self).__init__(label=label, description=description, value=value, uid=uid, group=group)
 
+    def validateValue(self, value):
+        if not isinstance(value, basestring):
+            raise ValueError('StringParam value "{}" should be a string.'.format(value))
+        return value
+
 
 class Level(Enum):
     NONE = 0
diff --git a/meshroom/core/graph.py b/meshroom/core/graph.py
index e6e15131..83c876d8 100644
--- a/meshroom/core/graph.py
+++ b/meshroom/core/graph.py
@@ -14,6 +14,7 @@ from collections import defaultdict
 from contextlib import contextmanager
 from enum import Enum  # available by default in python3. For python2: "pip install enum34"
 import logging
+import re
 
 from . import stats
 from . import desc
@@ -48,6 +49,7 @@ else:
     bytes = str
     basestring = basestring
 
+stringIsLinkRe = re.compile('^\{.+\}$')
 
 @contextmanager
 def GraphModification(graph):
@@ -143,7 +145,15 @@ class Attribute(BaseObject):
     def _set_value(self, value):
         if self._value == value:
             return
-        self._value = value
+
+        if isinstance(value, Attribute) or (isinstance(value, basestring) and stringIsLinkRe.match(value)):
+            # if we set a link to another attribute
+            self._value = value
+        else:
+            # if we set a new value, we use the attribute descriptor validator to check the validity of the value
+            # and apply some conversion if needed
+            convertedValue = self.desc.validateValue(value)
+            self._value = convertedValue
         # Request graph update when input parameter value is set
         # and parent node belongs to a graph
         # Output attributes value are set internally during the update process,