SessionIDManager.Validate Method (String)

 

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

Parameters

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
      Try
        Dim testGuid As Guid = New Guid(id)

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

      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.

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

.NET Framework
Available since 2.0
Return to top
Show: