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IIdentifierCreationService Interface

Provides a mechanism to create uniquely named identifiers throughout a specified range of activities.

Namespace:  System.Workflow.ComponentModel.Design
Assembly:  System.Workflow.ComponentModel (in System.Workflow.ComponentModel.dll)

'Declaration
Public Interface IIdentifierCreationService
'Usage
Dim instance As IIdentifierCreationService

IIdentifierCreationService provides a mechanism to create uniquely named identifiers throughout a range of activities.

The following example shows an implementation of the IIdentifierCreationService. This service ensures that each of the identifiers used within the current workflow is unique.

Friend NotInheritable Class IdentifierCreationService
    Implements IIdentifierCreationService
    Private serviceProvider As IServiceProvider = Nothing 

    Friend Sub New(ByVal serviceProvider As IServiceProvider)
        Me.serviceProvider = serviceProvider
    End Sub 

    Sub ValidateIdentifier(ByVal activity As Activity, ByVal identifier As String) Implements IIdentifierCreationService.ValidateIdentifier
        If identifier Is Nothing Then 
            Throw New ArgumentNullException("identifier")
        End If 
        If activity Is Nothing Then 
            Throw New ArgumentNullException("activity")
        End If 
        If activity.Name.ToLower().Equals(identifier.ToLower()) Then 
            Return 
        End If 
        Dim identifiers As New ArrayList()
        Dim rootActivity As Activity = GetRootActivity(activity)
        identifiers.AddRange(GetIdentifiersInCompositeActivity(CType(rootActivity, CompositeActivity)))
        identifiers.Sort()
        If identifiers.BinarySearch(identifier.ToLower(), StringComparer.OrdinalIgnoreCase) >= 0 Then 
            Throw New ArgumentException(String.Format("Duplicate Component Identifier 0}", identifier))
        End If 
    End Sub 

    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())
    End Function

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0
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