Question

I have a WCF Service with wsHttpBindings and SSL enabled, but I’d like to enable WCF sessions.

After changing SessionMode to required

SessionMode:=SessionMode.Required

 I’m getting error described below. 

Contract requires Session, but Binding ‘WSHttpBinding’ doesn’t support
it or isn’t configured properly to support it.

Here’s my sample application.

App.config

  <?xml version="1.0" encoding="utf-8" ?>
    <configuration>

      <system.web>
        <compilation debug="true" />
      </system.web>
      <!-- When deploying the service library project, the content of the config file must be added to the host's 
      app.config file. System.Configuration does not support config files for libraries. -->
      <system.serviceModel>

        <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
        <client />
        <bindings>
          <wsHttpBinding>
            <binding name="NewBinding0" useDefaultWebProxy="false" allowCookies="true">
              <readerQuotas maxStringContentLength="10240" />
              <!--reliableSession enabled="true" /-->
              <security mode="Transport">
                <transport clientCredentialType="None" proxyCredentialType="None" >
                  <extendedProtectionPolicy policyEnforcement="Never" />
                </transport >
              </security>
            </binding>
          </wsHttpBinding>
        </bindings>
        <services>
          <service name="WcfServiceLib.TestService">
            <endpoint address="" binding="wsHttpBinding" bindingConfiguration="NewBinding0"
              contract="WcfServiceLib.ITestService">
              <identity>
                <servicePrincipalName value="Local Network" />
              </identity>
            </endpoint>
            <endpoint address="mex" binding="mexHttpsBinding" contract="IMetadataExchange" />
            <host>
              <baseAddresses>
                <add baseAddress="https://test/TestService.svc" />
              </baseAddresses>
            </host>
          </service>
        </services>

        <behaviors>
          <serviceBehaviors>
            <behavior>
              <!-- To avoid disclosing metadata information, 
              set the value below to false and remove the metadata endpoint above before deployment -->
              <serviceMetadata httpsGetEnabled="True"/>
              <!-- To receive exception details in faults for debugging purposes, 
              set the value below to true.  Set to false before deployment 
              to avoid disclosing exception information -->
              <serviceDebug includeExceptionDetailInFaults="False" />
            </behavior>
          </serviceBehaviors>
        </behaviors>
      </system.serviceModel>

    </configuration>

ITestService.vb

  <ServiceContract(SessionMode:=SessionMode.Required)>
    Public Interface ITestService

        <OperationContract(IsInitiating:=True, IsTerminating:=False)> _
        Function GetData(ByVal value As Integer) As String

    End Interface

TestService.vb

    <ServiceBehavior(InstanceContextMode:=InstanceContextMode.PerSession, _ 
    ReleaseServiceInstanceOnTransactionComplete:=False, _ 
    ConcurrencyMode:=ConcurrencyMode.Single)>
        Public Class TestService
            Implements ITestService

            Private _user As User

            <OperationBehavior(TransactionScopeRequired:=True)>
            Public Function GetData(ByVal value As Integer) As String _
 Implements ITestService.GetData

                If _user Is Nothing Then

                    _user = New User()
                    _user.userName = "User_" & value
                    _user.userPassword = "Pass_" & value

                    Return String.Format("You've entered: {0} , Username = {1} , Password = {2} ", _
                                         value, _user.userName, _user.userPassword)
                Else
                    Return String.Format("Username = {1} , Password = {2} ", _
                                    _user.userName, _user.userPassword)
                End If

            End Function

        End Class

I tried all possible solutions, I could find, but nothing helped.

Some advice to enable reliable sessions, but it doesn’t work with ssl (if only you have your custom binding), others advice to use http instead of https, but I’d like to enable Sessions with my current configurations, if it’s possible.

Is there any approach to achieve this?

Any kind of help is much appreciated.

Answer 1

If you want “sessions” with wsHttpBinding, you have to use either reliable messaging, or the security sessions. (source : how to enable WCF Session with wsHttpBidning with Transport only Security).

WSHttpBinding supports session but only if either security (SecureConversation) or reliable messaging are enabled.
If you are using transport security then it is not using WS-SecureConversation and WS-ReliableMessaging is turned off by default. Therefore the two protocols that WSHttpBinding uses for session are not available. You either need to use message security or turn on reliable session. (source : http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/57b3453e-e7e8-4875-ba23-3be4fff080ea/).

We’ve disallowed RM over Https in the standard bindings because the way to secure an RM session is to use a security session and Https does not provide session.

I found the msdn blurb about it here: http://msdn2.microsoft.com/en-us/library/ms733136.aspx
The blurb is “The only exception is when using HTTPS. The SSL session is not bound to the reliable session. This imposes a threat because sessions sharing a security context (the SSL session) are not protected from each other; this might or might not be a real threat depending on the application.”

However you can do it if you determine there is no threat. There is an RM over HTTPS sample via custom binding http://msdn2.microsoft.com/en-us/library/ms735116.aspx (source : http://social.msdn.microsoft.com/forums/en-US/wcf/thread/fb4e5e31-e9b0-4c24-856d-1c464bd0039c/).

To sum up your possibilities you can either :

1 – Keep wsHttpBinding, remove transport security and enable reliable messaging

  <wsHttpBinding>
    <binding name="bindingConfig">
      <reliableSession enabled="true" />
      <security mode="None"/>
    </binding>
  </wsHttpBinding>

But you loose the SSL layer and then part of your security.

2 – Keep wsHttpBinding, keep transport security and add message authentication

  <wsHttpBinding>
    <binding name="bindingConfig">
      <security mode="TransportWithMessageCredential">
        <message clientCredentialType="UserName"/>
      </security>
    </binding>
  </wsHttpBinding>

You get to keep your SSL security layer but your client will have to provide credentials (of any form) and even if you don’t validate them at the service side, fake ones must still be provided as WCF will reject any message not specifying credentials.

3 – Use a custom binding with reliable messaging and HTTPS transport

  <customBinding>
    <binding name="bindingConfig">
      <reliableSession/>
      <httpsTransport/>
    </binding>
  </customBinding>

I can’t see any downside to this except the threat explained in MSDN, and it depends on your application.

4 – Use other session providers
If your application is hotsed in IIS, you could set

<serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>

and depend on the

HttpContext.Current.Session

for your state.

Or implementing your own cookies.

PS : Note that for all those WCF configuration, I only tested service activation, not calls.

EDIT : As per user request, wsHttpBinding with TransportWithMessageCredential security mode implementing sessions (I’m not too familiar with VB.NET so pardon my syntax) :

Service code snippet :

<ServiceContract(SessionMode:=SessionMode.Required)>
Public Interface IService1

    <OperationContract()> _
    Sub SetSessionValue(ByVal value As Integer)

    <OperationContract()> _
    Function GetSessionValue() As Nullable(Of Integer)

End Interface

<ServiceBehavior(InstanceContextMode:=InstanceContextMode.PerSession, 
    ConcurrencyMode:=ConcurrencyMode.Single)>
Public Class Service1
    Implements IService1

    Private _sessionValue As Nullable(Of Integer)

    Public Sub SetSessionValue(ByVal value As Integer) Implements IService1.SetSessionValue
        _sessionValue = value
    End Sub

    Public Function GetSessionValue() As Nullable(Of Integer) Implements IService1.GetSessionValue
        Return _sessionValue
    End Function
End Class

Public Class MyUserNamePasswordValidator
    Inherits System.IdentityModel.Selectors.UserNamePasswordValidator

    Public Overrides Sub Validate(userName As String, password As String)
        ' Credential validation logic
        Return ' Accept anything
    End Sub

End Class

service Configuration snippet :

<system.serviceModel>
  <services>
    <service name="WcfService1.Service1" behaviorConfiguration="WcfService1.Service1Behavior">
      <endpoint address="" binding="wsHttpBinding" contract="WcfService1.IService1" bindingConfiguration="bindingConf"/>
      <endpoint address="mex" binding="mexHttpsBinding" contract="IMetadataExchange"/>
    </service>
  </services>
  <bindings>
    <wsHttpBinding>
      <binding name="bindingConf">
        <security mode="TransportWithMessageCredential">
          <message clientCredentialType="UserName"/>
        </security>
      </binding>
    </wsHttpBinding>
  </bindings>
  <behaviors>
    <serviceBehaviors>
      <behavior name="WcfService1.Service1Behavior">
        <serviceMetadata httpsGetEnabled="true"/>
        <serviceDebug includeExceptionDetailInFaults="false"/>
        <serviceCredentials>
          <userNameAuthentication 
            userNamePasswordValidationMode="Custom"
            customUserNamePasswordValidatorType="WcfService1.MyUserNamePasswordValidator, WcfService1"/>
        </serviceCredentials>
      </behavior>
    </serviceBehaviors>
  </behaviors>
</system.serviceModel>

Client test code snippet :

Imports System.Threading.Tasks

Module Module1

    Sub Main()
        Parallel.For(0, 10, Sub(i) Test(i))
        Console.ReadLine()
    End Sub

    Sub Test(ByVal i As Integer)
        Dim client As ServiceReference1.Service1Client
        client = New ServiceReference1.Service1Client()
        client.ClientCredentials.UserName.UserName = "login"
        client.ClientCredentials.UserName.Password = "password"
        Console.WriteLine("Session N° {0} : Value set to {0}", i)
        client.SetSessionValue(i)
        Dim response As Nullable(Of Integer)
        response = client.GetSessionValue()
        Console.WriteLine("Session N° {0} : Value returned : {0}", response)
        client.Close()
    End Sub

End Module