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HierarchicalDataSourceControl Class

Provides a base class for data source controls that represent hierarchical data.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

'Declaration
<BindableAttribute(False)> _
Public MustInherit Class HierarchicalDataSourceControl _
	Inherits Control _
	Implements IHierarchicalDataSource
<asp:HierarchicalDataSourceControl />

The HierarchicalDataSourceControl type exposes the following members.

  NameDescription
Protected methodHierarchicalDataSourceControlInitializes a new instance of the HierarchicalDataSourceControl class.
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  NameDescription
Protected propertyAdapterGets the browser-specific adapter for the control. (Inherited from Control.)
Public propertyAppRelativeTemplateSourceDirectoryGets or sets the application-relative virtual directory of the Page or UserControl object that contains this control. (Inherited from Control.)
Public propertyBindingContainerInfrastructure. Gets the control that contains this control's data binding. (Inherited from Control.)
Protected propertyChildControlsCreatedGets a value that indicates whether the server control's child controls have been created. (Inherited from Control.)
Public propertyClientIDGets the server control identifier generated by ASP.NET. (Overrides Control.ClientID.)
Public propertyClientIDModeThis property is not used for data source controls. (Overrides Control.ClientIDMode.)
Protected propertyClientIDSeparatorGets a character value representing the separator character used in the ClientID property. (Inherited from Control.)
Protected propertyContextGets the HttpContext object associated with the server control for the current Web request. (Inherited from Control.)
Public propertyControlsGets a ControlCollection object that represents the child controls for a specified server control in the UI hierarchy. (Overrides Control.Controls.)
Public propertyDataItemContainerGets a reference to the naming container if the naming container implements IDataItemContainer. (Inherited from Control.)
Public propertyDataKeysContainerGets a reference to the naming container if the naming container implements IDataKeysControl. (Inherited from Control.)
Protected propertyDesignModeGets a value indicating whether a control is being used on a design surface. (Inherited from Control.)
Public propertyEnableThemingGets a value indicating whether this control supports themes. (Overrides Control.EnableTheming.)
Public propertyEnableViewStateGets or sets a value indicating whether the server control persists its view state, and the view state of any child controls it contains, to the requesting client. (Inherited from Control.)
Protected propertyEventsGets a list of event handler delegates for the control. This property is read-only. (Inherited from Control.)
Protected propertyHasChildViewStateGets a value indicating whether the current server control's child controls have any saved view-state settings. (Inherited from Control.)
Public propertyIDGets or sets the programmatic identifier assigned to the server control. (Inherited from Control.)
Protected propertyIdSeparatorInfrastructure. Gets the character used to separate control identifiers. (Inherited from Control.)
Protected propertyIsChildControlStateClearedGets a value indicating whether controls contained within this control have control state. (Inherited from Control.)
Protected propertyIsTrackingViewStateGets a value that indicates whether the server control is saving changes to its view state. (Inherited from Control.)
Protected propertyIsViewStateEnabledGets a value indicating whether view state is enabled for this control. (Inherited from Control.)
Protected propertyLoadViewStateByIDGets a value indicating whether the control participates in loading its view state by ID instead of index. (Inherited from Control.)
Public propertyNamingContainerGets a reference to the server control's naming container, which creates a unique namespace for differentiating between server controls with the same Control.ID property value. (Inherited from Control.)
Public propertyPageGets a reference to the Page instance that contains the server control. (Inherited from Control.)
Public propertyParentGets a reference to the server control's parent control in the page control hierarchy. (Inherited from Control.)
Public propertyRenderingCompatibilityGets a value that specifies the ASP.NET version that rendered HTML will be compatible with. (Inherited from Control.)
Public propertySiteGets information about the container that hosts the current control when rendered on a design surface. (Inherited from Control.)
Public propertySkinIDGets or sets the skin to apply to the HierarchicalDataSourceControl control. (Overrides Control.SkinID.)
Public propertyTemplateControlGets or sets a reference to the template that contains this control. (Inherited from Control.)
Public propertyTemplateSourceDirectoryGets the virtual directory of the Page or UserControl that contains the current server control. (Inherited from Control.)
Public propertyUniqueIDGets the unique, hierarchically qualified identifier for the server control. (Inherited from Control.)
Protected propertyViewStateGets a dictionary of state information that allows you to save and restore the view state of a server control across multiple requests for the same page. (Inherited from Control.)
Protected propertyViewStateIgnoresCaseGets a value that indicates whether the StateBag object is case-insensitive. (Inherited from Control.)
Public propertyViewStateModeGets or sets the view-state mode of this control. (Inherited from Control.)
Public propertyVisibleGets or sets a value indicating whether the control is visually displayed. (Overrides Control.Visible.)
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  NameDescription
Protected methodAddedControlCalled after a child control is added to the Controls collection of the Control object. (Inherited from Control.)
Protected methodAddParsedSubObjectNotifies the server control that an element, either XML or HTML, was parsed, and adds the element to the server control's ControlCollection object. (Inherited from Control.)
Public methodApplyStyleSheetSkinApplies the style properties that are defined in the page style sheet to the control. (Overrides Control.ApplyStyleSheetSkin(Page).)
Protected methodBuildProfileTreeInfrastructure. Gathers information about the server control and delivers it to the Trace property to be displayed when tracing is enabled for the page. (Inherited from Control.)
Protected methodClearCachedClientIDInfrastructure. Sets the cached ClientID value to Nothing. (Inherited from Control.)
Protected methodClearChildControlStateDeletes the control-state information for the server control's child controls. (Inherited from Control.)
Protected methodClearChildStateDeletes the view-state and control-state information for all the server control's child controls. (Inherited from Control.)
Protected methodClearChildViewStateDeletes the view-state information for all the server control's child controls. (Inherited from Control.)
Protected methodClearEffectiveClientIDModeInfrastructure. Sets the ClientIDMode property of the current control instance and of any child controls to Inherit. (Inherited from Control.)
Protected methodCreateChildControlsCalled by the ASP.NET page framework to notify server controls that use composition-based implementation to create any child controls they contain in preparation for posting back or rendering. (Inherited from Control.)
Protected methodCreateControlCollectionCreates a new ControlCollection object to hold the child controls (both literal and server) of the server control. (Overrides Control.CreateControlCollection.)
Public methodDataBindBinds a data source to the invoked server control and all its child controls. (Inherited from Control.)
Protected methodDataBind(Boolean)Binds a data source to the invoked server control and all its child controls with an option to raise the DataBinding event. (Inherited from Control.)
Protected methodDataBindChildrenBinds a data source to the server control's child controls. (Inherited from Control.)
Public methodDisposeEnables a server control to perform final clean up before it is released from memory. (Inherited from Control.)
Protected methodEnsureChildControlsDetermines whether the server control contains child controls. If it does not, it creates child controls. (Inherited from Control.)
Protected methodEnsureIDCreates an identifier for controls that do not have an identifier assigned. (Inherited from Control.)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodFindControl(String)Searches the current naming container for a server control with the specified id parameter. (Overrides Control.FindControl(String).)
Protected methodFindControl(String, Int32)Infrastructure. Searches the current naming container for a server control with the specified id and an integer, specified in the pathOffset parameter, which aids in the search. You should not override this version of the FindControl method. (Inherited from Control.)
Public methodFocusSets input focus to the control. (Overrides Control.Focus.)
Protected methodGetDesignModeStateInfrastructure. Gets design-time data for a control. (Inherited from Control.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Protected methodGetHierarchicalViewGets the view helper object for the IHierarchicalDataSource interface for the specified path.
Public methodGetRouteUrl(Object)Gets the URL that corresponds to a set of route parameters. (Inherited from Control.)
Public methodGetRouteUrl(RouteValueDictionary)Gets the URL that corresponds to a set of route parameters. (Inherited from Control.)
Public methodGetRouteUrl(String, Object)Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control.)
Public methodGetRouteUrl(String, RouteValueDictionary)Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodGetUniqueIDRelativeToReturns the prefixed portion of the UniqueID property of the specified control. (Inherited from Control.)
Public methodHasControlsDetermines if the server control contains any child controls. (Overrides Control.HasControls.)
Protected methodHasEventsReturns a value indicating whether events are registered for the control or any child controls. (Inherited from Control.)
Protected methodIsLiteralContentInfrastructure. Determines if the server control holds only literal content. (Inherited from Control.)
Protected methodLoadControlStateRestores control-state information from a previous page request that was saved by the SaveControlState method. (Inherited from Control.)
Protected methodLoadViewStateRestores view-state information from a previous page request that was saved by the SaveViewState method. (Inherited from Control.)
Protected methodMapPathSecureRetrieves the physical path that a virtual path, either absolute or relative, maps to. (Inherited from Control.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodOnBubbleEventDetermines whether the event for the server control is passed up the page's UI server control hierarchy. (Inherited from Control.)
Protected methodOnDataBindingRaises the DataBinding event. (Inherited from Control.)
Protected methodOnDataSourceChangedRaises the DataSourceChanged event.
Protected methodOnInitRaises the Init event. (Inherited from Control.)
Protected methodOnLoadRaises the Load event. (Inherited from Control.)
Protected methodOnPreRenderRaises the PreRender event. (Inherited from Control.)
Protected methodOnUnloadRaises the Unload event. (Inherited from Control.)
Protected methodOpenFileGets a Stream used to read a file. (Inherited from Control.)
Protected methodRaiseBubbleEventAssigns any sources of the event and its information to the control's parent. (Inherited from Control.)
Protected methodRemovedControlCalled after a child control is removed from the Controls collection of the Control object. (Inherited from Control.)
Protected methodRenderSends server control content to a provided HtmlTextWriter object, which writes the content to be rendered on the client. (Inherited from Control.)
Protected methodRenderChildrenOutputs the content of a server control's children to a provided HtmlTextWriter object, which writes the content to be rendered on the client. (Inherited from Control.)
Public methodRenderControl(HtmlTextWriter)Outputs server control content to a provided HtmlTextWriter object and stores tracing information about the control if tracing is enabled. (Overrides Control.RenderControl(HtmlTextWriter).)
Protected methodRenderControl(HtmlTextWriter, ControlAdapter)Outputs server control content to a provided HtmlTextWriter object using a provided ControlAdapter object. (Inherited from Control.)
Protected methodResolveAdapterGets the control adapter responsible for rendering the specified control. (Inherited from Control.)
Public methodResolveClientUrlGets a URL that can be used by the browser. (Inherited from Control.)
Public methodResolveUrlConverts a URL into one that is usable on the requesting client. (Inherited from Control.)
Protected methodSaveControlStateSaves any server control state changes that have occurred since the time the page was posted back to the server. (Inherited from Control.)
Protected methodSaveViewStateSaves any server control view-state changes that have occurred since the time the page was posted back to the server. (Inherited from Control.)
Protected methodSetDesignModeStateSets design-time data for a control. (Inherited from Control.)
Public methodSetRenderMethodDelegateInfrastructure. Assigns an event handler delegate to render the server control and its content into its parent control. (Inherited from Control.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Protected methodTrackViewStateCauses tracking of view-state changes to the server control so they can be stored in the server control's StateBag object. This object is accessible through the Control.ViewState property. (Inherited from Control.)
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  NameDescription
Public eventDataBindingOccurs when the server control binds to a data source. (Inherited from Control.)
Public eventDisposedOccurs when a server control is released from memory, which is the last stage of the server control lifecycle when an ASP.NET page is requested. (Inherited from Control.)
Public eventInitOccurs when the server control is initialized, which is the first step in its lifecycle. (Inherited from Control.)
Public eventLoadOccurs when the server control is loaded into the Page object. (Inherited from Control.)
Public eventPreRenderOccurs after the Control object is loaded but prior to rendering. (Inherited from Control.)
Public eventUnloadOccurs when the server control is unloaded from memory. (Inherited from Control.)
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  NameDescription
Public Extension MethodFindDataSourceControlReturns the data source that is associated with the data control for the specified control. (Defined by DynamicDataExtensions.)
Public Extension MethodFindFieldTemplateReturns the field template for the specified column in the specified control's naming container. (Defined by DynamicDataExtensions.)
Public Extension MethodFindMetaTableReturns the metatable object for the containing data control. (Defined by DynamicDataExtensions.)
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  NameDescription
Explicit interface implemetationPrivate propertyIControlBuilderAccessor.ControlBuilderFor a description of this member, see IControlBuilderAccessor.ControlBuilder. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.GetDesignModeStateFor a description of this member, see IControlDesignerAccessor.GetDesignModeState. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.SetDesignModeStateFor a description of this member, see IControlDesignerAccessor.SetDesignModeState. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.SetOwnerControlInfrastructure. For a description of this member, see IControlDesignerAccessor.SetOwnerControl. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIControlDesignerAccessor.UserDataFor a description of this member, see IControlDesignerAccessor.UserData. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIDataBindingsAccessor.DataBindingsFor a description of this member, see IDataBindingsAccessor.DataBindings. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIDataBindingsAccessor.HasDataBindingsFor a description of this member, see IDataBindingsAccessor.HasDataBindings. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIExpressionsAccessor.ExpressionsFor a description of this member, see IExpressionsAccessor.Expressions. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIExpressionsAccessor.HasExpressionsFor a description of this member, see IExpressionsAccessor.HasExpressions. (Inherited from Control.)
Explicit interface implemetationPrivate eventIHierarchicalDataSource.DataSourceChangedInfrastructure. Occurs when the HierarchicalDataSourceControl has changed in some way that affects data-bound controls.
Explicit interface implemetationPrivate methodIHierarchicalDataSource.GetHierarchicalViewInfrastructure. Gets the view helper object for the IHierarchicalDataSource interface for the specified path.
Explicit interface implemetationPrivate methodIParserAccessor.AddParsedSubObjectFor a description of this member, see IParserAccessor.AddParsedSubObject. (Inherited from Control.)
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ASP.NET supports a controls data-binding architecture that enables Web server controls to bind to data and present it in a consistent fashion. Web server controls that bind to data are called data-bound controls, and the classes that facilitate binding are called data source controls. Data source controls can represent any data source: a file, a stream, a relational database, a business object, and so on. Data source controls present data in a consistent way to data-bound controls, regardless of the source or format of the underlying data.

Data source controls that represent hierarchical data derive from the HierarchicalDataSourceControl class, while data source controls that represent lists or tables of data derive from the DataSourceControl class. The HierarchicalDataSourceControl class is the base implementation of the IHierarchicalDataSource interface, which defines a single method to retrieve hierarchical data source view objects associated with the data source control, GetHierarchicalView.

You can think of a data source control as the combination of the HierarchicalDataSourceControl object and its associated views on the underlying data, called data source view objects. While data source controls that represent tabular data are typically associated with only one named view, the HierarchicalDataSourceControl class supports a data source view for each level of hierarchical data that the data source control represents. The level of hierarchical data is identified by a unique hierarchical path, passed to the GetHierarchicalView method in the viewPath parameter. Each HierarchicalDataSourceView object defines the capabilities of a data source control for the hierarchical level represented, and performs operations such as insert, update, delete, and sort.

Web server controls that derive from the HierarchicalDataBoundControl class, such as TreeView, use hierarchical data source controls to bind to hierarchical data.

Data source controls are implemented as controls to enable declarative persistence and to optionally permit participation in state management. Data source controls have no visual rendering, and therefore do not support themes.

The following code example demonstrates how to extend the abstract HierarchicalDataSourceControl class and the HierarchicalDataSourceView class, and implement the IHierarchicalEnumerable and IHierarchyData interfaces to create a hierarchical data source control that retrieves file system information. The FileSystemDataSource control enables Web server controls to bind to FileSystemInfo objects and display basic file system information. The FileSystemDataSource class in the example provides the implementation of the GetHierarchicalView method, which retrieves a FileSystemDataSourceView object. The FileSystemDataSourceView object retrieves the data from the underlying data storage, in this case the file system information on the Web server. For security purposes, file system information is displayed only if the data source control is being used in a localhost, authenticated scenario, and only starts with the virtual directory that the Web Forms page using the data source control resides in. Finally, two classes that implement IHierarchicalEnumerable and IHierarchyData are provided to wrap the FileSystemInfo objects that FileSystemDataSource uses.


Imports System
Imports System.Collections
Imports System.IO
Imports System.Runtime.InteropServices
Imports System.Security.Permissions
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet

    Public Class FileSystemDataSource
        Inherits HierarchicalDataSourceControl

        Public Sub New()
        End Sub

        Private view As FileSystemDataSourceView = Nothing

        Protected Overrides Function GetHierarchicalView( _
            ByVal viewPath As String) As HierarchicalDataSourceView

            view = New FileSystemDataSourceView(viewPath)
            Return view
        End Function

    End Class
    Public Class FileSystemDataSourceView
        Inherits HierarchicalDataSourceView

        Private _viewPath As String

        Public Sub New(ByVal viewPath As String)
            Dim currentRequest As HttpRequest = HttpContext.Current.Request
            If viewPath = "" Then
                _viewPath = currentRequest.MapPath(currentRequest.ApplicationPath)
            Else
                _viewPath = Path.Combine(currentRequest.MapPath(currentRequest.ApplicationPath), viewPath)
            End If
        End Sub 'New


        ' Starting with the rootNode, recursively build a list of
        ' FileSystemInfo nodes, create FileSystemHierarchyData
        ' objects, add them all to the FileSystemHierarchicalEnumerable,
        ' and return the list.
        Public Overrides Function [Select]() As IHierarchicalEnumerable
            Dim currentRequest As HttpRequest = HttpContext.Current.Request

            ' SECURITY: There are many security issues that can be raised
            ' SECURITY: by exposing the file system structure of a Web server
            ' SECURITY: to an anonymous user in a limited trust scenario such as
            ' SECURITY: a Web page served on an intranet or the Internet.
            ' SECURITY: For this reason, the FileSystemDataSource only
            ' SECURITY: shows data when the HttpRequest is received
            ' SECURITY: from a local Web server. In addition, the data source
            ' SECURITY: does not display data to anonymous users.
            If currentRequest.IsAuthenticated AndAlso _
                (currentRequest.UserHostAddress = "127.0.0.1" OrElse _
                 currentRequest.UserHostAddress = "::1") Then

                Dim rootDirectory As New DirectoryInfo(_viewPath)

                Dim fshe As New FileSystemHierarchicalEnumerable()

                Dim fsi As FileSystemInfo
                For Each fsi In rootDirectory.GetFileSystemInfos()
                    fshe.Add(New FileSystemHierarchyData(fsi))
                Next fsi
                Return fshe
            Else
                Throw New NotSupportedException( _
                    "The FileSystemDataSource only " + _
                    "presents data in an authenticated, localhost context.")
            End If
        End Function 'Select
    End Class 'FileSystemDataSourceView

    Public Class FileSystemHierarchicalEnumerable
        Inherits ArrayList
        Implements IHierarchicalEnumerable

        Public Sub New()
        End Sub


        Public Overridable Function GetHierarchyData( _
            ByVal enumeratedItem As Object) As IHierarchyData _
            Implements IHierarchicalEnumerable.GetHierarchyData

            Return CType(enumeratedItem, IHierarchyData)
        End Function

    End Class


    Public Class FileSystemHierarchyData
        Implements IHierarchyData

        Public Sub New(ByVal obj As FileSystemInfo)
            fileSystemObject = obj
        End Sub

        Private fileSystemObject As FileSystemInfo = Nothing

        Public Overrides Function ToString() As String
            Return fileSystemObject.Name
        End Function

        ' IHierarchyData implementation.
        Public Overridable ReadOnly Property HasChildren() As Boolean _
         Implements IHierarchyData.HasChildren
            Get
                If GetType(DirectoryInfo) Is fileSystemObject.GetType() Then
                    Dim temp As DirectoryInfo = _
                        CType(fileSystemObject, DirectoryInfo)
                    Return temp.GetFileSystemInfos().Length > 0
                Else
                    Return False
                End If
            End Get
        End Property
        ' DirectoryInfo returns the OriginalPath, while FileInfo returns
        ' a fully qualified path.

        Public Overridable ReadOnly Property Path() As String _
         Implements IHierarchyData.Path
            Get
                Return fileSystemObject.ToString()
            End Get
        End Property

        Public Overridable ReadOnly Property Item() As Object _
         Implements IHierarchyData.Item
            Get
                Return fileSystemObject
            End Get
        End Property

        Public Overridable ReadOnly Property Type() As String _
         Implements IHierarchyData.Type
            Get
                Return "FileSystemData"
            End Get
        End Property

        Public Overridable Function GetChildren() _
            As IHierarchicalEnumerable _
            Implements IHierarchyData.GetChildren

            Dim children As New FileSystemHierarchicalEnumerable()

            If GetType(DirectoryInfo) Is fileSystemObject.GetType() Then
                Dim temp As DirectoryInfo = _
                    CType(fileSystemObject, DirectoryInfo)
                Dim fsi As FileSystemInfo
                For Each fsi In temp.GetFileSystemInfos()
                    children.Add(New FileSystemHierarchyData(fsi))
                Next fsi
            End If
            Return children
        End Function 'GetChildren


        Public Overridable Function GetParent() As IHierarchyData _
         Implements IHierarchyData.GetParent
            Dim parentContainer As New FileSystemHierarchicalEnumerable()

            If GetType(DirectoryInfo) Is fileSystemObject.GetType() Then
                Dim temp As DirectoryInfo = _
                    CType(fileSystemObject, DirectoryInfo)
                Return New FileSystemHierarchyData(temp.Parent)
            ElseIf GetType(FileInfo) Is fileSystemObject.GetType() Then
                Dim temp As FileInfo = CType(fileSystemObject, FileInfo)
                Return New FileSystemHierarchyData(temp.Directory)
            End If
            ' If FileSystemObj is any other kind of FileSystemInfo, ignore it.
            Return Nothing
        End Function 'GetParent
    End Class 'FileSystemHierarchyData
End Namespace


The following code example demonstrates how to declaratively bind a TreeView control to file system data using the FileSystemDataSource example.


<%@ Page Language="VB" %>
<%@ Register Tagprefix="aspSample" Namespace="Samples.AspNet" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
    <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
        <form id="form1" runat="server">

            <asp:treeview
                id="TreeView1"
                runat="server"
                datasourceid="FileSystemDataSource1" />            

            <aspSample:filesystemdatasource
                id = "FileSystemDataSource1"
                runat = "server" />            

        </form>
    </body>
</html>


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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