Sub EnsureUniqueIdentifiers(ByVal parentActivity As CompositeActivity, ByVal childActivities As ICollection) Implements IIdentifierCreationService.EnsureUniqueIdentifiers

    If parentActivity Is Nothing Then
        Throw New ArgumentNullException("parentActivity")
    End If
    If childActivities Is Nothing Then
        Throw New ArgumentNullException("childActivities")
    End If
    Dim allActivities As New List(Of Activity)()

    Dim activities As New Queue(childActivities)
    While activities.Count > 0

        Dim activity As Activity = CType(activities.Dequeue(), Activity)
        If TypeOf activity Is CompositeActivity Then
            For Each child As Activity In CType(activity, CompositeActivity).Activities
                activities.Enqueue(child)
            Next
        End If

        'If we are moving activities, we need not regenerate their identifiers
        If CType(activity, IComponent).Site IsNot Nothing Then
            Continue While
        End If

        allActivities.Add(activity)
    End While

    ' get the root activity
    Dim rootActivity As CompositeActivity = CType(GetRootActivity(parentActivity), CompositeActivity)
    Dim identifiers As New ArrayList() ' all the identifiers in the workflow
    identifiers.AddRange(GetIdentifiersInCompositeActivity(rootActivity))

    For Each activity As Activity In allActivities

        Dim finalIdentifier As String = activity.Name

        ' now loop until we find a identifier that hasn't been used.
        Dim baseIdentifier As String = GetBaseIdentifier(activity)
        Dim index As Integer = 0

        identifiers.Sort()
        While finalIdentifier Is Nothing Or _
        finalIdentifier.Length = 0 Or _
        identifiers.BinarySearch(finalIdentifier.ToLower(), StringComparer.OrdinalIgnoreCase) >= 0
            finalIdentifier = String.Format("0}1}", baseIdentifier, ++index)
        End While

        ' add new identifier to collection 
        identifiers.Add(finalIdentifier)
        activity.Name = finalIdentifier
    Next
End Sub

Private Shared Function GetIdentifiersInCompositeActivity(ByVal CompositeActivity As CompositeActivity) As IList
    Dim identifiers As New ArrayList()
    If CompositeActivity IsNot Nothing Then
        identifiers.Add(CompositeActivity.Name)
        Dim allChildren As IList(Of Activity) = GetAllNestedActivities(CompositeActivity)
        For Each activity As Activity In allChildren
            identifiers.Add(activity.Name)
        Next
    End If

    Return ArrayList.ReadOnly(identifiers)
End Function

Private Shared Function GetBaseIdentifier(ByVal activity As Activity)
    Dim baseIdentifier As String = activity.GetType().Name
    Dim b As New StringBuilder(baseIdentifier.Length)
    For i As Integer = 0 To baseIdentifier.Length
        If Char.IsUpper(baseIdentifier(i)) And (i = 0 Or i = baseIdentifier.Length - 1 Or Char.IsUpper(baseIdentifier(i + 1))) Then
            b.Append(Char.ToLower(baseIdentifier(i)))
        Else
            b.Append(baseIdentifier.Substring(i))
            Exit For
        End If
    Next
    Return b.ToString()
End Function

Private Shared Function GetRootActivity(ByVal activity As Activity) As Activity
    If activity Is Nothing Then
        Throw New ArgumentException("activity")
    End If

    While activity.Parent IsNot Nothing
        activity = activity.Parent
    End While

    Return activity
End Function

Private Shared Function GetAllNestedActivities(ByVal compositeActivity As CompositeActivity) As Activity()

    If compositeActivity Is Nothing Then
        Throw New ArgumentNullException("compositeActivity")
    End If

    Dim nestedActivities As New ArrayList()
    Dim compositeActivities As New Queue()
    compositeActivities.Enqueue(compositeActivity)
    While compositeActivities.Count > 0

        Dim compositeActivity2 As CompositeActivity = CType(compositeActivities.Dequeue(), CompositeActivity)

        For Each activity As Activity In compositeActivity2.Activities
            nestedActivities.Add(activity)
            If activity Is compositeActivity Then
                compositeActivities.Enqueue(activity)
            End If
        Next

        For Each activity As Activity In compositeActivity2.EnabledActivities
            If Not nestedActivities.Contains(activity) Then
                nestedActivities.Add(activity)
                If (activity Is compositeActivity) Then
                    compositeActivities.Enqueue(activity)
                End If
            End If
        Next
    End While
    Return CType(nestedActivities.ToArray(GetType(Activity)), Activity())