IHttpSessionState Interface

Definition

Namespace:

System.Web.SessionState

Assembly:

System.Web.dll

Defines the contract to implement a custom session-state container.

public interface class IHttpSessionState

public interface IHttpSessionState

type IHttpSessionState = interface

Public Interface IHttpSessionState

Derived

System.Web.SessionState.HttpSessionStateContainer

Examples

The following code example implements the IHttpSessionState interface to create a new session-state container class named MySessionState.

using System;
using System.Web;
using System.Web.SessionState;
using System.Collections;
using System.Collections.Specialized;
using System.Text;
using System.Threading;
using System.Globalization;

namespace Samples.AspNet.SessionState
{
  public sealed class MySessionState : IHttpSessionState
  {
    const int MAX_TIMEOUT = 24 * 60;  // Timeout cannot exceed 24 hours.

    string                      pId;
    ISessionStateItemCollection pSessionItems;
    HttpStaticObjectsCollection pStaticObjects;
    int                         pTimeout;
    bool                        pNewSession;
    HttpCookieMode              pCookieMode;
    SessionStateMode            pMode;
    bool                        pAbandon;
    bool                        pIsReadonly;

    public MySessionState(string                      id, 
                          ISessionStateItemCollection sessionItems,
                          HttpStaticObjectsCollection staticObjects,
                          int                         timeout,
                          bool                        newSession,
                          HttpCookieMode              cookieMode,
                          SessionStateMode            mode,
                          bool                        isReadonly)
    {
      pId            = id;   
      pSessionItems  = sessionItems;
      pStaticObjects = staticObjects;
      pTimeout       = timeout;    
      pNewSession    = newSession; 
      pCookieMode    = cookieMode;
      pMode          = mode;
      pIsReadonly    = isReadonly;
    }

    public int Timeout
    {
      get { return pTimeout; }
      set
      {
        if (value <= 0)
          throw new ArgumentException("Timeout value must be greater than zero.");

        if (value > MAX_TIMEOUT)
          throw new ArgumentException("Timout cannot be greater than " + MAX_TIMEOUT.ToString());

        pTimeout = value;
      }
    }

    public string SessionID
    {
      get { return pId; }
    }

    public bool IsNewSession
    {
      get { return pNewSession; }
    }

    public SessionStateMode Mode
    {
      get { return pMode; }
    }

    public bool IsCookieless
    {
      get { return CookieMode == HttpCookieMode.UseUri; }
    }

    public HttpCookieMode CookieMode
    {
      get { return pCookieMode; }
    }

    //
    // Abandon marks the session as abandoned. The IsAbandoned property is used by the
    // session state module to perform the abandon work during the ReleaseRequestState event.
    //
    public void Abandon()
    {
      pAbandon = true;
    }

    public bool IsAbandoned
    {
      get { return pAbandon; }
    }

    //
    // Session.LCID exists only to support legacy ASP compatibility. ASP.NET developers should use
    // Page.LCID instead.
    //
    public int LCID
    {
      get { return Thread.CurrentThread.CurrentCulture.LCID; }
      set { Thread.CurrentThread.CurrentCulture = CultureInfo.ReadOnly(new CultureInfo(value)); }
    }

    //
    // Session.CodePage exists only to support legacy ASP compatibility. ASP.NET developers should use
    // Response.ContentEncoding instead.
    //
    public int CodePage
    {
      get
      { 
        if (HttpContext.Current != null)
          return HttpContext.Current.Response.ContentEncoding.CodePage;
        else
          return Encoding.Default.CodePage;
      }
      set
      { 
        if (HttpContext.Current != null)
          HttpContext.Current.Response.ContentEncoding = Encoding.GetEncoding(value);
      }
    }

    public HttpStaticObjectsCollection StaticObjects
    {
      get { return pStaticObjects; }
    }

    public object this[string name]
    {
      get { return pSessionItems[name]; }
      set { pSessionItems[name] = value; }
    }

    public object this[int index]
    {
      get { return pSessionItems[index]; }
      set { pSessionItems[index] = value; }
    }

    public void Add(string name, object value)
    {
      pSessionItems[name] = value;        
    }

    public void Remove(string name)
    {
      pSessionItems.Remove(name);
    }

    public void RemoveAt(int index)
    {
      pSessionItems.RemoveAt(index);
    }

    public void Clear()
    {
      pSessionItems.Clear();
    }

    public void RemoveAll()
    {
        Clear();
    }

    public int Count
    {
      get { return pSessionItems.Count; }
    }

    public NameObjectCollectionBase.KeysCollection Keys
    {
      get { return pSessionItems.Keys; }
    }

    public IEnumerator GetEnumerator()
    {
      return pSessionItems.GetEnumerator();
    }

    public void CopyTo(Array items, int index)
    {
      foreach (object o in items)
        items.SetValue(o, index++);
    }

    public object SyncRoot
    {
        get { return this; }
    }

    public bool IsReadOnly
    {
      get { return pIsReadonly; }
    }

    public bool IsSynchronized
    {
      get { return false; }
    }
  }
}

Imports System.Web
Imports System.Web.SessionState
Imports System.Collections
Imports System.Collections.Specialized
Imports System.Text
Imports System.Threading
Imports System.Globalization

Namespace Samples.AspNet.SessionState

  Public NotInheritable Class MySessionState
    Implements IHttpSessionState
  
    Const MAX_TIMEOUT As Integer = 24 * 60  ' Timeout cannot exceed 24 hours.

    Dim pId            As String
    Dim pSessionItems  As ISessionStateItemCollection
    Dim pStaticObjects As HttpStaticObjectsCollection
    Dim pTimeout       As Integer
    Dim pNewSession    As Boolean
    Dim pCookieMode    As HttpCookieMode
    Dim pMode          As SessionStateMode
    Dim pAbandon       As Boolean
    Dim pIsReadonly    As Boolean

    Public Sub New(id            As String, _
                   sessionItems  As ISessionStateItemCollection, _
                   staticObjects As HttpStaticObjectsCollection, _
                   timeout       As Integer, _
                   newSession    As Boolean, _
                   cookieMode    As HttpCookieMode, _
                   mode          As SessionStateMode, _  
                   isReadonly As Boolean)
    
      pId            = id   
      pSessionItems  = sessionItems
      pStaticObjects = staticObjects
      pTimeout       = timeout    
      pNewSession    = newSession 
      pCookieMode    = cookieMode
      pMode          = mode
      pIsReadonly    = isReadonly
    End Sub


    Public Property Timeout As Integer Implements IHttpSessionState.Timeout
      Get
        Return pTimeout
      End Get
      Set
        If value <= 0 Then _
          Throw New ArgumentException("Timeout value must be greater than zero.")

        If value > MAX_TIMEOUT Then _
          Throw New ArgumentException("Timout cannot be greater than " & MAX_TIMEOUT.ToString())

        pTimeout = value
      End Set
    End Property


    Public ReadOnly Property SessionID As String Implements IHttpSessionState.SessionID
      Get
        Return pId
      End Get
    End Property


    Public ReadOnly Property IsNewSession As Boolean Implements IHttpSessionState.IsNewSession
      Get
        Return pNewSession
      End Get
    End Property


    Public ReadOnly Property Mode As SessionStateMode Implements IHttpSessionState.Mode    
      Get
        Return pMode
      End Get
    End Property


    Public ReadOnly Property IsCookieless As Boolean Implements IHttpSessionState.IsCookieLess    
      Get
        Return CookieMode = HttpCookieMode.UseUri
      End Get
    End Property


    Public ReadOnly Property CookieMode As HttpCookieMode Implements IHttpSessionState.CookieMode    
      Get
        Return pCookieMode
      End Get
    End Property


    '
    ' Abandon marks the session as abandoned. The IsAbandoned property is used by the
    ' session state module to perform the abandon work during the ReleaseRequestState event.
    '
    Public Sub Abandon() Implements IHttpSessionState.Abandon
      pAbandon = True
    End Sub

    Public ReadOnly Property IsAbandoned As Boolean  
      Get
        Return pAbandon
      End Get
    End Property

    '
        ' Session.LCID exists only to support legacy ASP compatibility. ASP.NET developers should use
    ' Page.LCID instead.
    '
    Public Property LCID As Integer Implements IHttpSessionState.LCID
      Get
        Return Thread.CurrentThread.CurrentCulture.LCID
      End Get
      Set
        Thread.CurrentThread.CurrentCulture = CultureInfo.ReadOnly(new CultureInfo(value))
      End Set
    End Property


    '
        ' Session.CodePage exists only to support legacy ASP compatibility. ASP.NET developers should use
    ' Response.ContentEncoding instead.
    '
    Public Property CodePage As Integer Implements IHttpSessionState.CodePage    
      Get
        If Not HttpContext.Current Is Nothing Then
          Return HttpContext.Current.Response.ContentEncoding.CodePage
        Else
          Return Encoding.Default.CodePage
        End If
      End Get
      Set       
        If Not HttpContext.Current Is Nothing Then _
          HttpContext.Current.Response.ContentEncoding = Encoding.GetEncoding(value)
      End Set
    End Property


    Public ReadOnly Property StaticObjects As HttpStaticObjectsCollection _
      Implements IHttpSessionState.StaticObjects
    
      Get
        Return pStaticObjects
      End Get
    End Property


    Public Property Item(name As String) As Object Implements IHttpSessionState.Item
      Get
        Return pSessionItems(name)
      End Get
      Set
        pSessionItems(name) = value
      End Set
    End Property


    Public Property Item(index As Integer) As Object Implements IHttpSessionState.Item    
      Get
        Return pSessionItems(index)
      End Get
      Set
        pSessionItems(index) = value
      End Set
    End Property
        

    Public Sub Add(name As String, value As Object) Implements IHttpSessionState.Add    
      pSessionItems(name) = value        
    End Sub


    Public Sub Remove(name As String) Implements IHttpSessionState.Remove    
      pSessionItems.Remove(name)
    End Sub


    Public Sub RemoveAt(index As Integer) Implements IHttpSessionState.RemoveAt    
      pSessionItems.RemoveAt(index)
    End Sub


    Public Sub Clear() Implements IHttpSessionState.Clear 
      pSessionItems.Clear()
    End Sub

    Public Sub RemoveAll() Implements IHttpSessionState.RemoveAll
        Clear()
    End Sub



    Public ReadOnly Property Count As Integer Implements IHttpSessionState.Count    
      Get
        Return pSessionItems.Count
      End Get
    End Property



    Public ReadOnly Property Keys As NameObjectCollectionBase.KeysCollection _
      Implements IHttpSessionState.Keys
    
      Get
        Return pSessionItems.Keys
      End Get
    End Property


    Public Function GetEnumerator() As IEnumerator Implements IHttpSessionState.GetEnumerator
        Return pSessionItems.GetEnumerator()
    End Function


    Public Sub CopyTo(items As Array, index As Integer) Implements IHttpSessionState.CopyTo    
      For Each o As Object In items
        items.SetValue(o, index)
        index += 1
      Next
    End Sub


    Public ReadOnly Property SyncRoot As Object Implements IHttpSessionState.SyncRoot    
        Get
          Return Me
       End Get
    End Property


    Public ReadOnly Property IsReadOnly As Boolean Implements IHttpSessionState.IsReadOnly    
      Get
        Return pIsReadonly
      End Get
    End Property


    Public ReadOnly Property IsSynchronized As Boolean Implements IHttpSessionState.IsSynchronized    
      Get
        Return False
      End Get
    End Property
  End Class
End Namespace

Remarks

A session-state container provides access to the session-state values and related information for the current session. Session information included in a session-state container is exposed to application code through the HttpSessionState class using the Session property. The HttpSessionState class is a wrapper class for a session-state container.

The ASP.NET implementation of a session-state container is the HttpSessionStateContainer class. At the beginning of a request, during the AcquireRequestState event, the SessionStateModule creates and populates an HttpSessionStateContainer object and assigns it to the current HttpContext. At the end of a request, during the ReleaseRequestState event, the SessionStateModule retrieves the HttpSessionStateContainer object from the current HttpContext and performs any required session work, such as writing the session values to the session store, or abandoning the session. If the request is abruptly terminated, such as through a redirect, the SessionStateModule performs the same cleanup by calling the EndRequest method.

To create a custom session-state container, create a class that implements the IHttpSessionState interface. If you are creating your own custom session-state container, you must also replace the SessionStateModule with your own custom module. Your custom module will create an instance of your custom session-state container and add it to the current HttpContext using the AddHttpSessionStateToContext method. An example of a custom session-state module is included in the SessionStateUtility class overview.

Properties

CodePage	Gets or sets the code-page identifier for the current session.
CookieMode	Gets a value that indicates whether the application is configured for cookieless sessions.
Count	Gets the number of items in the session-state item collection.
IsCookieless	Gets a value indicating whether the session ID is embedded in the URL or stored in an HTTP cookie.
IsNewSession	Gets a value indicating whether the session was created with the current request.
IsReadOnly	Gets a value indicating whether the session is read-only.
IsSynchronized	Gets a value indicating whether access to the collection of session-state values is synchronized (thread safe).
Item[Int32]	Gets or sets a session-state item value by numerical index.
Item[String]	Gets or sets a session-state item value by name.
Keys	Gets a collection of the keys for all values stored in the session-state item collection.
LCID	Gets or sets the locale identifier (LCID) of the current session.
Mode	Gets the current session-state mode.
SessionID	Gets the unique session identifier for the session.
StaticObjects	Gets a collection of objects declared by <object Runat="Server" Scope="Session"/> tags within the ASP.NET application file Global.asax.
SyncRoot	Gets an object that can be used to synchronize access to the collection of session-state values.
Timeout	Gets or sets the time-out period (in minutes) allowed between requests before the session-state provider terminates the session.

Methods

Abandon()	Ends the current session.
Add(String, Object)	Adds a new item to the session-state collection.
Clear()	Clears all values from the session-state item collection.
CopyTo(Array, Int32)	Copies the collection of session-state item values to a one-dimensional array, starting at the specified index in the array.
GetEnumerator()	Returns an enumerator that can be used to read all the session-state item values in the current session.
Remove(String)	Deletes an item from the session-state item collection.
RemoveAll()	Clears all values from the session-state item collection.
RemoveAt(Int32)	Deletes an item at a specified index from the session-state item collection.

See also

• ASP.NET Session State Overview