diff --git a/interfaces.py b/interfaces.py
index 50525f0..2cfd966 100644
--- a/interfaces.py
+++ b/interfaces.py
@@ -22,6 +22,7 @@ loops interface definitions.
 $Id$
 """
 
+from zope.interface import Interface
 from zope.app.container.interfaces import IOrderedContainer
 
 from zope.schema import TextLine
@@ -70,18 +71,18 @@ class ITask(IOrderedContainer):
             target resource types given.
         """
 
-    def allocateResource(resource, allocType=None):
+    def allocateResource(resource, allocType='standard'):
         """ Allocate resource to self. A special allocation type may be given.
         """
 
-    def createAndAllocateResource(resourceType='Resource', allocType='standard',
+    def createAndAllocateResource(resourceType=None, allocType='standard',
                                   container=None, name=None):
         """ Allocate resource to self. A special allocation type may be given.
-            Additional properties may be given as keyword parameters.
         """
 
-    def deallocateResource(resource):
-        """ Deallocate from self the resource allocated.
+    def deallocateResource(resource, allocTypes=None):
+        """ Deallocate from self the resource given. If no allocTypes
+            given all allocations to resource will be removed.
         """
 
     def allocatedUserIds():
@@ -89,9 +90,9 @@ class ITask(IOrderedContainer):
             Used by catalog index 'allocUserIds'.
         """
 
-    def getAllocType(resource):
-        """ Return the allocation type for the resource given. Raise a
-            ValueException if resource is not allocated to self.
+    def getAllocTypes(resource):
+        """ Return the allocation types with which the resource given
+            is allocated to self.
         """
 
     def getAllAllocTypes():
@@ -111,3 +112,9 @@ class IResource(IOrderedContainer):
             source task types given.
         """
 
+
+class IResourceConstraint(Interface):
+    """ A ResourceConstraint governs which Resource objects may be
+        allocated to a Task object.
+    """
+
diff --git a/resource.py b/resource.py
index a68387e..cf48443 100644
--- a/resource.py
+++ b/resource.py
@@ -24,6 +24,7 @@ $Id$
 
 from zope.interface import implements
 from zope.app.container.ordered import OrderedContainer
+from zope.app import zapi
 
 from interfaces import IResource
 
@@ -52,13 +53,23 @@ class Resource(OrderedContainer):
 
     # Helper methods:
 
-    def _updateAllocations(self, task, allocType):
+    def _addAllocation(self, task, allocType):
         #called by Task.allocateResource
         tList = self._allocations.get(allocType, [])
         tList.append(task)
         self._allocations[allocType] = tList
 
-    def _createResourceName(self):
+    def _removeAllocations(self, task, allocTypes):
+        #called by Task.deallocateResource
+        allocs = self._allocations
+        for at in allocTypes or allocs.keys():
+            if task in allocs[at]:
+                allocs[at].remove(task)
+
+    def _createResourceName(self, container=None):
         prefix = 'rsc'
-        last = max([ int(n[len(prefix):]) for n in self.__parent__.keys() ] or [1])
+        container = container or zapi.getParent(self)
+        last = max([ int(n[len(prefix):]) for n in container.keys() ] or [1])
         return prefix + str(last+1)
+
+        
\ No newline at end of file
diff --git a/task.py b/task.py
index edf4001..ba2e4c1 100644
--- a/task.py
+++ b/task.py
@@ -24,10 +24,11 @@ $Id$
 
 from zope.interface import implements
 from zope.app.container.ordered import OrderedContainer
+from zope.app import zapi
 
+from resource import Resource
 from interfaces import ITask
 
-
 class Task(OrderedContainer):
 
     implements(ITask)
@@ -54,9 +55,9 @@ class Task(OrderedContainer):
         task._parentTasks.append(self)
 
     def createSubtask(self, taskType=None, container=None, name=None):
-        container = container or self.__parent__
+        container = container or zapi.getParent(self)
         task = Task()
-        name = name or self._createTaskName()
+        name = name or task._createTaskName(container)
         container[name] = task
         self.assignSubtask(task)
         return task
@@ -65,37 +66,47 @@ class Task(OrderedContainer):
         self._subtasks.remove(task)
         task._parentTasks.remove(self)
 
-    # resources:
+    # resource allocations:
 
     def getAllocatedResources(self, allocTypes=None, resTypes=None):
         from sets import Set
         allocs = self._resourceAllocs
         res = Set()
-        for at in allocs.keys():
-            if allocTypes is None or at in allocTypes:
-                res.union_update(allocs[at])
+        for at in allocTypes or allocs.keys():
+            res.union_update(allocs[at])
+        if resTypes:
+            res = [ r for r in res if r in resTypes ]
         return tuple(res)
 
-    def allocateResource(self, resource, allocType=None):
-        allocType = allocType or 'standard'
+    def allocateResource(self, resource, allocType='standard'):
         allocs = self._resourceAllocs
         rList = allocs.get(allocType, [])
-        rList.append(resource)
+        if resource not in rList:
+            rList.append(resource)
         allocs[allocType] = rList
-        resource._updateAllocations(self, allocType)
+        resource._addAllocation(self, allocType)
 
-    def createAndAllocateResource(self, resourceType='Resource', allocType='standard',
-                                  container=None, id=None):
-        return None
+    def createAndAllocateResource(self, resourceType=None, allocType='standard',
+                                  container=None, name=None):
+        container = container or zapi.getParent(self)
+        resource = Resource()
+        name = name or resource._createResourceName(container)
+        container[name] = resource
+        self.allocateResource(resource, allocType)
+        return resource
 
-    def deallocateResource(self, resource):
-        pass
+    def deallocateResource(self, resource, allocTypes=None):
+        allocs = self._resourceAllocs
+        for at in allocTypes or allocs.keys():
+            if resource in allocs[at]:
+                allocs[at].remove(resource)
+        resource._removeAllocations(self, allocTypes)
 
     def allocatedUserIds(self):
         return ()
 
-    def getAllocType(self, resource):
-        return 'standard'
+    def getAllocTypes(self, resource):
+        return ('standard',)
 
     def getAllAllocTypes(self):
         return ('standard',)
@@ -103,7 +114,8 @@ class Task(OrderedContainer):
 
     # Helper methods:
 
-    def _createTaskName(self):
+    def _createTaskName(self, container=None):
         prefix = 'tsk'
-        last = max([ int(n[len(prefix):]) for n in self.__parent__.keys() ] or [1])
+        container = container or zapi.getParent(self)
+        last = max([ int(n[len(prefix):]) for n in container.keys() ] or [1])
         return prefix + str(last+1)
diff --git a/tests/test_resource.py b/tests/test_resource.py
index a9871be..929fcae 100755
--- a/tests/test_resource.py
+++ b/tests/test_resource.py
@@ -54,6 +54,14 @@ class Test(unittest.TestCase):
         t1.allocateResource(r1)
         self.assertEqual((t1,), r1.getTasksAllocatedTo())
 
+    def testDeallocateFromTask(self):
+        t1 = self.t1
+        r1 = self.r1
+        t1.allocateResource(r1)
+        self.assertEqual((t1,), r1.getTasksAllocatedTo())
+        t1.deallocateResource(r1)
+        self.assertEqual((), r1.getTasksAllocatedTo())
+
 
 def test_suite():
     return unittest.TestSuite((
diff --git a/tests/test_task.py b/tests/test_task.py
index 88b379a..e237a68 100755
--- a/tests/test_task.py
+++ b/tests/test_task.py
@@ -4,9 +4,11 @@ import unittest
 #from zope.testing.doctestunit import DocTestSuite
 from zope.interface.verify import verifyClass
 #from zope.app.tests.setup import placelessSetUp
+from zope.app.tests.setup import placefulSetUp
 #from zope.app.container.tests.test_icontainer import TestSampleContainer
 from zope.app.container.interfaces import IContained
 from zope.app.folder import Folder
+from zope.app import zapi
 
 from loops.task import Task
 from loops.interfaces import ITask
@@ -16,7 +18,8 @@ class TestTask(unittest.TestCase):
     "Test methods of the Task class."
 
     def setUp(self):
-        #placelessSetUp()
+#        placelessSetUp()
+        placefulSetUp()
         self.f1 = Folder()
         self.f1.__name__ = u'f1'
         self.t1 = Task()
@@ -35,8 +38,8 @@ class TestTask(unittest.TestCase):
         verifyClass(ITask, Task)
 
     def testContained(self):
-        self.assertEqual(u'tsk1', self.t1.__name__)
-        self.assertEqual(u'f1', self.t1.__parent__.__name__)
+        self.assertEqual(u'tsk1', zapi.name(self.t1))
+        self.assertEqual(u'f1', zapi.name(zapi.getParent(self.t1)))
 
     def testTitle(self):
         t = Task()
@@ -75,9 +78,9 @@ from loops.resource import Resource
 class TestTaskResource(unittest.TestCase):
     "Test methods of the Task class related to Resource allocations."
 
-
     def setUp(self):
         #placelessSetUp()
+        #placefulSetUp()
         self.f1 = Folder()
         self.f1.__name__ = u'f1'
         self.t1 = Task()
@@ -97,6 +100,20 @@ class TestTaskResource(unittest.TestCase):
         t1.allocateResource(r1)
         self.assertEqual((r1,), t1.getAllocatedResources())
 
+    def testDeallocateResource(self):
+        t1 = self.t1
+        r1 = self.r1
+        t1.allocateResource(r1)
+        self.assertEqual((r1,), t1.getAllocatedResources())
+        t1.deallocateResource(r1)
+        self.assertEqual((), t1.getAllocatedResources())
+
+    def testCreateAndAllocateResource(self):
+        t1 = self.t1
+        self.assertEqual((), t1.getAllocatedResources())
+        r1 = t1.createAndAllocateResource()
+        self.assertEqual((r1,), t1.getAllocatedResources())
+
 
 def test_suite():
     return unittest.TestSuite((