Self Hosted WCF Service as Windows Service with custom Authentication

Download source MSMSystemServices.rar

Introduction

In this article, I want to demonstrate a very simple WCF Server / Client application but this demo application is intended to demonstrate about the Self hosted service. You may raise a question "what is self hoting ?". Let me explain in detail.

There are two ways to host a WCF Service; they are;

1. Hosting with IIS : The traditional way to host a WCF web service.

2. Self Hosting : An alternate way to host a service with no IIS.  

What is self hosting ?

Hosting a service inside a managed application is known as self-hosted service. A managed application either can be a Console Application, Windows Forms Application, WPF or Windows Service. Check out this link on MSDN for more details and check this MSDN link for sample code.

There is a detailed discussion on this asp.net forum regarding the differences between self-hosted and IIS hosted services.

Lets move to WCF;

WCF has two zones:

1. Services
2. Clients

1. Service

The basic steps to make a Service live.

1. Define a service contract
2. Implement a service contract
3. Host and run a service contract 

2. Clients 

WCF Clients is an application which can communicate with WCF Service operations as method. 

The dynamic WCF Client communication to the Service has three steps:

1. Create a WCF Client using channel factory class ( System.ServiceModel.ChannelFactory )
2. Configure a WCF Client
3. Use a WCF Client

In this article, I'm going to use Windows Service as managed application to host the WCF service.

• The source code contains Windows Service and Self Hosted WCF Service on Http.
• All examples are programmed in Visual Basic .Net, 
• Sample sends the requests / responses via Port 9090 over Http.
• Sample uses dynamic connection string using INI file and uses simple AES Cryptography for password encryption / decryption.
• Topics of hosting on Https is not covered.

After reading this article and studying the samples, you may get an idea to create self hosted web service with custom authentication on windows service.

Background

Recently, I had a requirement to host a service with authentication where I didn’t have IIS and the solution is to have self hosted WCF service which use custom user authentication and the clients can consume it dynamically using channel factory method.

Server Side

So, lets start with WCF Service. Create a WCF Service Library project and then add the below references and name the Project as MSMSystemService.

1. System.ServiceModel

2. System.IdentityModel

3. System.IdentityModel.Selectors

WCF Library Project

1. Add an Interface (IDataServices.vb) to the Project and define the Service Contract 

In this example, I had used the data class from MSMSystemService.DataModels.Academics.

Imports System
Imports System.ServiceModel
Imports MSMSystemService.DataModels.Academics

Namespace MSMServices

    <servicecontract()>
    Public Interface IDataServices

        ' TODO: Add your service operations here
        <operationcontract()>
        Function GetPupilData(ByVal lngStudentID As Long) As StudentInfo

    End Interface

End Namespace

2. Add a data class (DataServices.vb) and Implement the Service Contract  

In this example, the class DataServices returns the data from MSMSystemService.DataModels.Academics.StudentInfo data class.

Imports MSMSystemService.DataModels.Academics

Namespace MSMServices
    
    Public Class DataServices
        Implements IDataServices

        Public Function GetPupilData(ByVal lngStudentID As Long) As StudentInfo Implements IDataServices.GetPupilData

            Dim oStudent As New StudentInfo

            oStudent.StudentID = lngStudentID

            oStudent.Fill()

            Return oStudent

        End Function

    End Class

End Namespace

3. Custom Authentication

Add an new class (MSMServiceAuthentication.vb) and  Inherit the class System.IdentityModel.Selectors.UserNamePasswordValidator and implement Validate subroutine. There is a custom exception class (MSMSecurityException) demonstrated for managing custom security token validation faliure.

Add the below code to MSMServiceAuthentication.vb.

Imports System
Imports System.Security
Imports System.Security.Principal
Imports System.IdentityModel
Imports System.IdentityModel.Selectors

Namespace MSMServices

    Public Class MSMServiceAuthentication
        Inherits UserNamePasswordValidator

        Public Overrides Sub Validate(userName As String, password As String)

            If userName = "admin" And password = "admin" Then
                'OK
            Else
                Throw New MSMSecurityException()
            End If

        End Sub

    End Class

    Public Class MSMSecurityException
        Inherits Exception

        Public Sub New()
            MyBase.New("Invalid Security Token")
        End Sub

    End Class

End Namespace

The WCF service part is ready and the next job is to create an Managed Application which hosts the WCF service. In this case, Windows Service is going to act as a Managed Application.

Add an new Windows Service project (name it as MSMServiceController)  to MSMServiceController project and setup the ServiceName and Service Description properties as described below.

4. Windows Service 

Set Service Properties 

Open the Properties of the Service class MSMServiceController.vb and set "ServiceName" property to "MSMDataServices". 

Add Installer Class

Right click on Service class MSMServiceController.vb and select Add Installer.

Visual Studio will create an new class ProjectInstaller.vb with two components;

1. ProcessInstaller  (Rename as MSMProcessInstaller)

2. Service Installer. (Rename as MSMServiceInstaller)

Open ProjectInstaller.vb class and set the Properties of Service Installer.

Note: The values set in ServiceName and Description properties will be displayed on the Windows Service Management console once the Windows Service was installed.

Add the below code to windows service class. In this code, I have used a custom registry manager and custom INI file manager for reading the connection string from INI settings file.

Note: Developers can use the WSHttpBinding class instead of BasicHttpBinding for Https hosting over SSL .

Imports System
Imports System.ServiceProcess
Imports System.ComponentModel
Imports System.Configuration
Imports System.Configuration.Install
Imports System.ServiceModel
Imports System.ServiceModel.Description
Imports MSMSystemService.MSMServices
Imports MSMSystemService.Utilities


Public Class MSMServiceController

    Dim sBAddress As Uri 
    Dim oSelfHost As ServiceHost 'New ServiceHost(GetType(DataServices), sBAddress)

    Protected Overrides Sub OnStart(ByVal args() As String)

        Dim oSetting As New MSMSettingManager
        Dim oRegistry As New MSMRegistryManager
        Dim oWSHttpBind As New BasicHttpBinding
        Dim oSmb As ServiceMetadataBehavior
        Dim sFilename As String
        Dim sServiceURI As String

        ' Add code here to start your service. This method should set things
        ' in motion so your service can do its work.

        Try

            oRegistry.RegistryRootKey = SystemRegistryRoot.SystemLocalComputer
            oRegistry.RegistryKeyPath = "SOFTWARE\MSMServices\DataService"
            oRegistry.KeyName = "RootFolder"
            oRegistry.ReadKey()

            sFilename = oRegistry.keyValue
            oSetting.SettingsFileName = Replace(sFilename & "\MSMServices.ini", "\\", "\")

            oSetting.ApplicationName = "Service"
            oSetting.KeyName = "URI"
            sServiceURI = oSetting.ReadSettings()

            If Trim(sServiceURI) <> "" Then

                oWSHttpBind.Security.Mode = BasicHttpSecurityMode.TransportCredentialOnly
                oWSHttpBind.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic

                sBAddress = New Uri(sServiceURI)
                oSelfHost = New ServiceHost(GetType(DataServices), sBAddress)

                oSmb = oSelfHost.Description.Behaviors.Find(Of ServiceMetadataBehavior)()

                If (oSmb Is Nothing) Then

                    oSmb = New ServiceMetadataBehavior

                    oSmb.HttpGetEnabled = True

                    oSelfHost.Description.Behaviors.Add(oSmb)

                End If

                oSelfHost.AddServiceEndpoint(GetType(IMetadataExchange), MetadataExchangeBindings.CreateMexHttpBinding(), "mex")
                oSelfHost.AddServiceEndpoint(GetType(IDataServices), oWSHttpBind, sBAddress)

                oSelfHost.Credentials.UserNameAuthentication.UserNamePasswordValidationMode = ServiceModel.Security.UserNamePasswordValidationMode.Custom
                oSelfHost.Credentials.UserNameAuthentication.CustomUserNamePasswordValidator = New MSMServiceAuthentication()

                oSelfHost.Open()

            Else
                EventLog.WriteEntry("MSM Data Service Error: Invalid URI Specified", EventLogEntryType.Error, 10255)
            End If

        Catch ex As Exception
            EventLog.WriteEntry("MSM Data Service Error: " & ex.Message.ToString(), EventLogEntryType.Error, 10255)
        End Try

    End Sub

    Protected Overrides Sub OnStop()
        ' Add code here to perform any tear-down necessary to stop your service.

        If (oSelfHost IsNot Nothing) Then

            If oSelfHost.State = CommunicationState.Opened Then
                oSelfHost.Close()
            End If

        End If

    End Sub

End Class

Windows Service part is complete, next step is to compile and test the code.

Follow the below step to install and run the sample windows service.

1. Build the Solution and copy the compiled EXEs & Assemblies to a folder.

2. Run MSMServiceUtilities.exe to configure the dynamic URI and Database. 

   Note: Verify the port's availability before setting up the URI.

3. Click "Register Root" first and then click "Register Service".

Step 4: Use the below command from the folder to Install / uninstall the Windows Service;

Step 5: Start the installed Windows Service and verify the status in the Event Viewer

Service Status in Event Viewer

Client Side 

Create an new Windows Forms Application project and design a form with the required fields;

Add the below references to the project;

Imports System.Net.Security<br />
Imports System.ServiceModel

Add the service reference with user authentication;

This service reference will create WSDL references to our DataServices web service.

This sample client appilcation deploys BasicHttpBinding class for creating Http traffic over custom authentication using ChannelFactory method.

Note: Developers can make this client application more dynamic by reading URI from INI file.

Code of the Click event of Get button.  

Private Sub cmdGetStudent_Click(sender As Object, e As EventArgs) Handles cmdGetStudent.Click

    Dim oWSHttp As New WSHttpBinding 'For Https access
    Dim oBSHttp As New BasicHttpBinding 'For Http access
    Dim oDSClient As IDataServices
    Dim oURI As New Uri("http://192.168.1.92:9090/DataServices")
    Dim oDSStudent As New StudentInfo
    Dim oEndpoint As New EndpointAddress(oURI)

    If Trim(txtStudentID.Text) <> "" Then

        oBSHttp.Security.Mode = BasicHttpSecurityMode.TransportCredentialOnly
        oBSHttp.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic

        Dim oChFactory As New ChannelFactory(Of IDataServices)(oBSHttp, oEndpoint)

        oChFactory.Credentials.UserName.UserName = "admin"
        oChFactory.Credentials.UserName.Password = "admin"

        oDSClient = oChFactory.CreateChannel()

        oDSStudent = oDSClient.GetPupilData(Val(txtStudentID.Text))

        txtFirstname.Text = oDSStudent.FirstName
        txtMiddleName.Text = oDSStudent.MiddleName
        txtLastname.Text = oDSStudent.LastName
        txtGrnnumber.Text = oDSStudent.GRNNumber
        txtGender.Text = ""

        CType(oDSClient, IClientChannel).Close()

    End If

End Sub

Client side coding part is complete, you can test the application now.

Points of Interest

Implementting WCF webservice over HTTPS (SSL) greatly improves the security, maintainability, scalability, and stability of the application. 

Your feedback is always welcome.