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SessionIDManager.Validate Method

Gets a value indicating whether a session identifier is valid.

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

Public Overridable Function Validate ( _
	id As String _
) As Boolean
Dim instance As SessionIDManager 
Dim id As String 
Dim returnValue As Boolean 

returnValue = instance.Validate(id)


Type: System.String

The session identifier to validate.

Return Value

Type: System.Boolean
true if the session identifier is valid; otherwise, false.



This method is not intended to be called from application code.

The Validate method verifies that the supplied id is a 24-character string consisting of lowercase characters from a to z and numbers from 0 to 5 and that the maximum length of the session ID does not exceed 80 characters.

The GetSessionID method calls the Validate method when retrieving a session identifier from an HTTP request, to ensure that the supplied session identifier is properly formatted.

Notes to Inheritors:

You can supply a custom session identifier to be used by ASP.NET session state by creating a class that inherits the SessionIDManager class and overriding the CreateSessionID and Validate methods with your own custom implementation. Even when you create a custom session identifier, the session ID is limited to 80 characters by the SessionIDManager class.

The following code example shows a class that inherits the SessionIDManager class and overrides the CreateSessionID and Validate methods with methods that supply and validate a Guid as the SessionID.

Imports System
Imports System.Configuration
Imports System.Web.Configuration
Imports System.Web
Imports System.Web.SessionState

Namespace Samples.AspNet.Session

  Public Class GuidSessionIDManager
    Inherits SessionIDManager

    Public Overrides Function CreateSessionID(context As HttpContext) As String 
      Return Guid.NewGuid().ToString()
    End Function 

    Public Overrides Function Validate(id As String) As Boolean 
        Dim testGuid As Guid = New Guid(id)

        If id = testGuid.ToString() Then _
          Return True 

      End Try 

      Return False 
    End Function 

  End Class 

End Namespace

To use the custom class demonstrated in this example, replace the SessionID HTTP module in your Web.config file with your custom class, as shown in the following example.

  <remove name="SessionID" />
  <add name="SessionID"
       type="Samples.AspNet.Session.GuidSessionIDManager" />

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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, 2.0