diff --git a/ContentDirectory.py b/ContentDirectory.py
index d94633e..1f61acc 100644
--- a/ContentDirectory.py
+++ b/ContentDirectory.py
@@ -33,37 +33,44 @@ class ContentDirectoryControl(UPnPPublisher, dict):
     """This class implements the CDS actions over SOAP."""
 
     def getnextID(self):
-	ret = str(self.nextID)
-	self.nextID += 1
-	return ret
+        ret = str(self.nextID)
+        self.nextID += 1
+        return ret
 
     def addContainer(self, parent, title, klass = Container, **kwargs):
-	ret = self.addItem(parent, klass, title, **kwargs)
-	self.children[ret] = []
-	return ret
+        ret = self.addItem(parent, klass, title, **kwargs)
+        self.children[ret] = []
+        return ret
 
     def addItem(self, parent, klass, *args, **kwargs):
-	assert isinstance(self[parent], Container)
-	nid = self.getnextID()
-	i = klass(nid, parent, *args, **kwargs)
-	self.children[parent].append(i)
-	self[i.id] = i
-	return i.id
+        assert isinstance(self[parent], Container)
+        nid = self.getnextID()
+        i = klass(nid, parent, *args, **kwargs)
+        self.children[parent].append(i)
+        self[i.id] = i
+        return i.id
 
     def getchildren(self, item):
-	assert isinstance(self[item], Container)
-	return self.children[item][:]
+        assert isinstance(self[item], Container)
+        return self.children[item][:]
 
     def __init__(self, title, *args):
-	super(ContentDirectoryControl, self).__init__(*args)
-	fakeparent = '-1'
-	self.nextID = 0
-	self.children = { fakeparent: []}
-	self[fakeparent] = Container(None, '-1', 'fake')
-	root = self.addContainer(fakeparent, title)
-	assert root == '0'
-	del self[fakeparent]
-	del self.children[fakeparent]
+        super(ContentDirectoryControl, self).__init__(*args)
+        fakeparent = '-1'
+        self.nextID = 0
+        self.children = { fakeparent: []}
+        self.needupdate = False
+        self.updateId = 0
+        self[fakeparent] = Container(None, '-1', 'fake')
+        root = self.addContainer(fakeparent, title)
+        assert root == '0'
+        del self[fakeparent]
+        del self.children[fakeparent]
+
+    def doupdate(self):
+        if self.needupdate:
+            self.needupdate += 1
+            self.needupdate = False
 
     # Required actions
 
@@ -71,20 +78,21 @@ class ContentDirectoryControl(UPnPPublisher, dict):
         """Required: Return the searching capabilities supported by the device."""
 
         log.msg('GetSearchCapabilities()')
-	return { 'SearchCapabilitiesResponse': { 'SearchCaps': '' }}
+        return { 'SearchCapabilitiesResponse': { 'SearchCaps': '' }}
 
     def soap_GetSortCapabilities(self, *args, **kwargs):
         """Required: Return the CSV list of meta-data tags that can be used in
         sortCriteria."""
 
         log.msg('GetSortCapabilities()')
-	return { 'SortCapabilitiesResponse': { 'SortCaps': '' }}
+        return { 'SortCapabilitiesResponse': { 'SortCaps': '' }}
         
     def soap_GetSystemUpdateID(self, *args, **kwargs):
         """Required: Return the current value of state variable SystemUpdateID."""
 
         log.msg('GetSystemUpdateID()')
-	return { 'SystemUpdateIdResponse': { 'Id': 5 }}
+        self.needupdate = True
+        return { 'SystemUpdateIdResponse': { 'Id': self.updateId }}
 
     BrowseFlags = ('BrowseMetaData', 'BrowseDirectChildren')
 
@@ -94,8 +102,8 @@ class ContentDirectoryControl(UPnPPublisher, dict):
 
         (ObjectID, BrowseFlag, Filter, StartingIndex, RequestedCount,
          SortCriteria) = args
-	StartingIndex = int(StartingIndex)
-	RequestedCount = int(RequestedCount)
+        StartingIndex = int(StartingIndex)
+        RequestedCount = int(RequestedCount)
 
         log.msg('Browse(ObjectID=%s, BrowseFlags=%s, Filter=%s, '
                 'StartingIndex=%s RequestedCount=%s SortCriteria=%s)' %
@@ -103,14 +111,14 @@ class ContentDirectoryControl(UPnPPublisher, dict):
                  `RequestedCount`, `SortCriteria`))
 
         didl = DIDLElement()
-	result = {}
+        result = {}
 
         try:
-	    if BrowseFlag == 'BrowseDirectChildren':
-		ch = self.getchildren(ObjectID)[StartingIndex: StartingIndex + RequestedCount]
-		filter(lambda x, s = self, d = didl: d.addItem(s[x.id]) and None, ch)
-	    else:
-		didl.addItem(self[ObjectID])
+            if BrowseFlag == 'BrowseDirectChildren':
+                ch = self.getchildren(ObjectID)[StartingIndex: StartingIndex + RequestedCount]
+                filter(lambda x, s = self, d = didl: d.addItem(s[x.id]) and None, ch)
+            else:
+                didl.addItem(self[ObjectID])
 
             result = {'BrowseResponse': {'Result': didl.toString() ,
                                          'NumberReturned': didl.numItems(),
@@ -217,5 +225,5 @@ class ContentDirectoryServer(resource.Resource):
     def __init__(self, title):
         resource.Resource.__init__(self)
         self.putChild('scpd.xml', static.File('content-directory-scpd.xml'))
-	self.control = ContentDirectoryControl(title)
+        self.control = ContentDirectoryControl(title)
         self.putChild('control', self.control)