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Versioning WCF Project

2012-05-31T03:04:00.001-07:00

In this article I will be explaining Contract versioning in WCF.

Once the service is developed and rolled over to production, any changes in contracts should be backwards compatible so that existing clients are not affected when changes are deployed. We will explore the effects of changes in Data Contract and Service contracts and try to adopt a versioning strategy depending on the scenario.

I will explain further by examples

WCF Service:-

Contract:-

<ServiceContract(Namespace:="http://Microsoft.ServiceModel.10.00.00.01")>

Public Interface IService1

    <OperationContract()>

    Function GetData(ByVal value As Integer) As String

End Interface

Implementation:-

Public Class Service1

    Implements IService1

    Public Function GetData(ByVal value As Integer) As String Implements IService1.GetData

        Return String.Format("You entered: {0}", value)

    End Function

End Class

Web config:-

   <endpoint address="Demo1" binding="basicHttpBinding" contract="Service1.IService1"/>

Client 1:-

app.config:-

<endpoint address="http://localhost:51085/Service1.svc" binding="basicHttpBinding"

   bindingConfiguration="BasicHttpBinding_IService1" contract="ServiceReference1.IService1"

   name="BasicHttpBinding_IService1" />

Client class:-

  Sub Main()

        Dim serviceObj As New ServiceReference1.Service1Client

        Console.WriteLine(serviceObj.GetData(2).ToString())

        Console.ReadLine()

  End Sub

Now let’s assume we have 10 clients who are consuming the service, in the same manner as above.20 more clients are interested in consuming our service or some of our existing clients need more functionality or modify some function. We have to keep version of this, since all other clients can continue using the old service and we do can keep track of changes.

We can version our service by using date or build number in namespace. Example:-

WCF Service:-

Contract:-

<ServiceContract(Namespace:="http://Microsoft.ServiceModel. 10.00.00.01")>

Public Interface IService1

    <OperationContract()>

    Function GetData(ByVal value As Integer) As String

End Interface

<ServiceContract(Namespace:="http://Microsoft.ServiceModel. 10.00.00.02")>

Public Interface IService2

    Inherits IService1

    <OperationContract()>

    Function GetValue(ByVal value As Integer) As String

End Interface

Implementation:-

Public Class Service1

   Implements IService2

    Public Function GetData(ByVal value As Integer) As String Implements IService1.GetData

        Return String.Format("You entered: {0}", value)

    End Function

    Public Function GetValue(value As Integer) As String Implements IService2.GetValue

        Return String.Format("You entered: {0}", value)

    End Function

End Class

Web config:-

<endpoint address="ep1" binding="basicHttpBinding" contract="Service1.IService1"/>

<endpoint address="ep2" binding="basicHttpBinding" contract="Service1.IService2"/>

Client 2:-

app.config:-

<endpoint address="http://localhost:51085/Service1.svc" binding="basicHttpBinding"

  bindingConfiguration="BasicHttpBinding_IService2" contract="ServiceReference1.IService2"

                name="BasicHttpBinding_IService2" />

Client class:-

  Sub Main()

   Dim serviceObj As New ServiceReference1.Service2Client

        Console.WriteLine(serviceObj.GetData(5).ToString())

        Console.WriteLine(serviceObj.GetValue(10).ToString())

        Console.ReadLine()

  End Sub

Now all the existing client without any changes they can continue using the service as well as our new clients can use the new functionality by consuming the new endpoints.

Our service WSDL will have these namespaces like this.

Fault Contract in WCF

2012-04-16T06:44:00.001-07:00

Exceptions are technology specific. Hence they cannot cross service boundaries. Soap represent standard for errors.WCF can transfer error from service to client through faults. If the error is a fault Exception then all the details are transferred else only generic fault.

i.e. InternalServiceFault

we can use either [ServiceBehavior] or to enable Fault.

Example:-

behavior>

serviceBehaviors>

You can throw a Soap Fault using the FaultException class

You can specify the fault code and reason when you create it. All this details will be traveled to the client side.

Example:-

Throw New FaultException(Of FaultExceptionClass)(New FaultExceptionClass)

At the client side we can use the try catch block to catch this faultException

Example:- Catch ex As FaultException(Of FaultService.FaultExceptionClass)

Console.WriteLine("Fault value " + ex.Detail.m_Reason)

Console.WriteLine("Fault value " + ex.Detail.m_InnerReason)

Example:-

Client Side Code:-

Imports System.ServiceModel

Module Module1

'''

''' Main class

'''

Sub Main()

Try

' Create Service Proxy

Dim ser As New FaultService.Service1Client

' Call the service

Console.WriteLine(ser.GetData(1))

Console.ReadLine()

' Handle Fault Error

Catch ex As FaultException(Of FaultService.FaultExceptionClass)

' Two Property exposed by the FaultExceptionClass Class.

Console.WriteLine("Fault value " + ex.Detail.m_Reason)

Console.WriteLine("Fault value " + ex.Detail.m_InnerReason)

Console.ReadLine()

' Handle all other generic error.

Catch ex As Exception

Console.WriteLine(ex.Message)

Console.ReadLine()

End Try

End Sub

End Module

Server Side Code:-

'''

''' This Class wil have fault property exposed to client.

'''

<DataContract()>

Public Class FaultExceptionClass

Implements IDisposable

<DataMember()>

Private m_Reason As String

Public Property Reason() As String

Get

Return m_Reason

End Get

Set(ByVal value As String)

m_Reason = value

End Set

End Property

<DataMember()>

Private m_InnerReason As String

Public Property InnerReason() As String

Get

Return m_InnerReason

End Get

Set(ByVal value As String)

m_InnerReason = value

End Set

End Property

' Service Interface

<ServiceContract()>

Public Interface IService1

' use FaultContract type to Specify Fault Type.

<FaultContract(GetType(FaultExceptionClass))>

<OperationContract()>

Function GetData(ByVal value As Integer) As String

End Interface

' Class that implement IService1 Interface

Public Class Service1

Implements IService1

Public Sub New()

End Sub

' Function which throws fault exceptions.

Public Function GetData(ByVal value As Integer) As String Implements IService1.GetData

Try

Throw New FaultException(Of FaultExceptionClass)(New FaultExceptionClass)

Catch ex As Exception

Using objError As New FaultExceptionClass

objError.Reason = "Message"

objError.InnerReason = "InnerException"

Throw (New FaultException(Of FaultExceptionClass)(objError, "Data Error"))

End Using

End Try

Return String.Format("You entered: {0}", value)

End Function

End Class

<_!--Change in WebConfig-->

<_!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->

<_!-- 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 -->

behavior>

serviceBehaviors>

behaviors>

How to handle error and result in Diagnostics.process

2012-03-20T22:55:00.000-07:00

Diagnostics.process provides access to local and remote processes and enables you to start and stop local system processes.

The Process component is a useful tool for starting, stopping, controlling, and monitoring applications. Using the Process component, you can obtain a list of the processes that are running, or you can start a new process. A Process component is used to access system processes

If you start any Process by Diagnostics.process object then to get the error in that process you have to raise ErrorDataReceived event. Below I have written a simple example.

' Create instance of Process class

Dim m_Process As New Process

m_Process.StartInfo.FileName = = "cmd.exe"

m_Process.StartInfo.Arguments = "c:\test.bat"

' UseShellExecute should be False for RedirectStandardError and RedirectStandardOutput Properity

m_Process.StartInfo.UseShellExecute = False

' RedirectStandardError has to be true to handle ErrorDataReceived Event.

m_Process.StartInfo.RedirectStandardError = True

' RedirectStandardOutput has to be true to handle OutputDataReceived Event.

m_Process.StartInfo.RedirectStandardOutput = True

' This will hide the console window

m_Process.StartInfo.CreateNoWindow = True

' Start the Process

m_Process.Start()

' Wait for the process to complete

m_Process.WaitForExit()

' Handle error in ErrorHandler function

AddHandler m_Process.ErrorDataReceived, AddressOf ErrorHandler

' Get status of deployment from DataHandler

AddHandler m_Process.OutputDataReceived, AddressOf DataHandler

' Raise the events

m_Process.BeginErrorReadLine()

m_Process.BeginOutputReadLine()

' Wait for the method to execute

m_Process.WaitForExit()

' Handle the value

MessageBox.Show(DeploymentError)

MessageBox.Show(DeploymentStatus)

Private Sub ErrorHandler(ByVal sender As Object, ByVal e As DataReceivedEventArgs)

DeploymentError = DeploymentError + e.Data

End Sub

Private Sub DataHandler(ByVal sender As Object, ByVal e As DataReceivedEventArgs)

DeploymentStatus = DeploymentStatus + e.Data

End Sub

How to get the location of software installed in server machine.

2012-03-19T07:13:00.002-07:00

You can check the Registry Key for the Software installed location. You can do this by your VB code and run the exe you want in that location.

I will explain you this with a small example.

Imports Microsoft.Win32

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

'Enter the Software name you are searching for like SOFTWARE\Microsoft\Microsoft SQL Server

Using sqlServerKey As RegistryKey = Registry.LocalMachine.OpenSubKey("SOFTWARE\Microsoft\Microsoft SQL Server")

For Each subKeyName As String In sqlServerKey.GetSubKeyNames()

' Get the subFolder

If subKeyName.StartsWith("100") Then

Using instanceKey As RegistryKey = sqlServerKey.OpenSubKey(subKeyName)

' Get the subFolder

Dim path As String = instanceKey.OpenSubKey("DTS").OpenSubKey("Setup").GetValue("SQLPath")

' Enter the exe name you wants.

path = path + "Binn\DTExec.exe"

MessageBox.Show(path)

End Using

End If

End Using

End Sub

End Class

Events in .net with example

2012-03-18T23:31:00.000-07:00

An event is a message sent by an object to signal the occurrence of an action. The action could be caused by user interaction, such as a mouse click, or it could be triggered by some other program logic. The object that raises the event is called the event sender. The object that captures the event and responds to it is called the event receiver.
In event communication, the event sender class does not know which object or method will receive (handle) the events it raises. What is needed is an intermediary (or pointer-like mechanism) between the source and the receiver. The .NET Framework defines a special type (Delegate) that provides the functionality of a function pointer.

The Observer pattern is one of the most well known patterns used in software engineering. This pattern states that a non-determined number of business entities – called subscribers – are interested in a change of state of another business entity – called publisher – and that the publisher does not care who these subscribers are or what and why they are concerned with its change of state.

Let me explain you this by small example.

Public Class FrmCar

' Declare GetCarDetails Delegate

Public Delegate Sub GetCarDetails(ByVal Sender As Object, ByVal e As GetCarEventArgs)

Private Sub BtnShowDetails_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnShowDetails.Click

' Instance of Interface ICarDetails

Dim CarDetails As ICarDetails

Dim CarImplementation As CarDetailsImplementation

' According to the selected value in combobox. Value in switch case will execute.

Select Case Convert.ToString(cmbCar.SelectedItem.ToString())

Case "Maruthi"

' Assigning maruti_swift class to ICarDetails interface object.

CarDetails = New maruti_swift()

' initializing CarDetailsImplementation class object and sending the interface object as parameter.

CarImplementation = New CarDetailsImplementation(CarDetails)

' Registering the maruti swift car values.

CarDetails.RegisterCar("maruti swift", "2010", "Red")

Case "Hyundai"

' Assigning maruti_swift class to ICarDetails interface object.

CarDetails = New hyundai_santro()

' initializing CarDetailsImplementation class object and sending the interface object as parameter.

CarImplementation = New CarDetailsImplementation(CarDetails)

' Registering the hyundai santro car values.

CarDetails.RegisterCar("hyundai santro", "2011", "Black")

Case "Skoda"

' Assigning maruti_swift class to ICarDetails interface object.

CarDetails = New skoda_fabia()

' initializing CarDetailsImplementation class object and sending the interface object as parameter.

CarImplementation = New CarDetailsImplementation(CarDetails)

' Registering the skoda fabia car values.

CarDetails.RegisterCar("skoda fabia", "2012", "White")

Case Else

' Null handling

CarDetails = New NullHandler()

CarImplementation = New CarDetailsImplementation(CarDetails)

End Select

End Sub

End Class

Public Class CarDetailsImplementation

''' Constructor of class where NewCar event is handled.

Public Sub New(ByVal obj As ICarDetails)

AddHandler obj.NewCar, AddressOf ImplementCar

End Sub

''' In ImplementCar function the logic of the particular class is implemented

Private Sub ImplementCar(ByVal Sender As Object, ByVal e As GetCarEventArgs)

MessageBox.Show("Car Info: Name :- " + e.CarName + " Model No. :- " + e.Model + " Color:- " + e.Color)

End Sub

End Class

''' Maruti swift Car is Register with its value and NewCar event is raised.

''' The Raise event will call CarDetailsImplementation class and their the logic is implemented.

Public Class maruti_swift

Implements ICarDetails

Public Event NewCar(ByVal Sender As Object, ByVal e As GetCarEventArgs) Implements ICarDetails.NewCar

Public Sub onNewCar(ByVal e As GetCarEventArgs) Implements ICarDetails.onNewCar

RaiseEvent NewCar(Me, e)

End Sub

Public Sub RegisterCar(ByVal CarName As String, ByVal Model As String, ByVal Color As String) Implements ICarDetails.RegisterCar

Dim e As New GetCarEventArgs(CarName, Model, Color)

onNewCar(e)

End Sub

End Class

''' Skoda Fabia Car is Register with its value and NewCar event is raised.

''' The Raise event will call CarDetailsImplementation class and their the logic is implemented.

Public Class skoda_fabia

Implements ICarDetails

Public Event NewCar(ByVal Sender As Object, ByVal e As GetCarEventArgs) Implements ICarDetails.NewCar

Public Sub onNewCar(ByVal e As GetCarEventArgs) Implements ICarDetails.onNewCar

RaiseEvent NewCar(Me, e)

End Sub

Public Sub RegisterCar(ByVal CarName As String, ByVal Model As String, ByVal Color As String) Implements ICarDetails.RegisterCar

Dim e As New GetCarEventArgs(CarName, Model, Color)

onNewCar(e)

End Sub

End Class

''' Hyundai Santro Car is Register with its value and NewCar event is raised.

''' The Raise event will call CarDetailsImplementation class and their the logic is implemented.

Public Class hyundai_santro

Implements ICarDetails

Public Event NewCar(ByVal Sender As Object, ByVal e As GetCarEventArgs) Implements ICarDetails.NewCar

Public Sub onNewCar(ByVal e As GetCarEventArgs) Implements ICarDetails.onNewCar

RaiseEvent NewCar(Me, e)

End Sub

Public Sub RegisterCar(ByVal CarName As String, ByVal Model As String, ByVal Color As String) Implements ICarDetails.RegisterCar

Dim e As New GetCarEventArgs(CarName, Model, Color)

onNewCar(e)

End Sub

End Class

''' Null handling.

Public Class NullHandler

Implements ICarDetails

Public Event NewCar(ByVal Sender As Object, ByVal e As GetCarEventArgs) Implements ICarDetails.NewCar

Public Sub onNewCar(ByVal e As GetCarEventArgs) Implements ICarDetails.onNewCar

End Sub

Public Sub RegisterCar(ByVal CarName As String, ByVal Model As String, ByVal Color As String) Implements ICarDetails.RegisterCar

End Sub

End Class

Difference between Static Polymorphis and Dynamic Polymorphism

2012-03-18T10:02:00.000-07:00

What is Static Polymorphism?

What is Compile time Polymorphism?

What is Early binding?

What is Dynamic Polymorphism?

What is Runtime time Polymorphism?

What is Late binding?

These are most confusing questions, these things you use when you write code daily. But unless you prepare for interview, if someone ask you then you will be confused with this concepts.

In this small article, I will explain you what is static polymorphism and dynamic polymorphism?

Polymorphism means one name many forms.

Below Image will give you basic idea of static polymorphism and dynamic polymorphism.

Static Polymorphism: - Static Polymorphism means Compile time polymorphism or Early binding.

Method Overloading is an example of Static Polymorphism, where method name is same with different parameters and implementation.

Example:-

Public NotInheritable Class ErrorHandling

Public Shared Sub WriteErrorToDB(ByVal CustomMessage As String)

MessageBox.Show(CustomMessage)

End Sub

Public Shared Sub WriteErrorToDB(ByVal CustomMessage As String, ByVal ExceptionMessage As String)

MessageBox.Show(CustomMessage + " And also " + ExceptionMessage)

End Sub

End Class

Public Class Form3

Private Sub Form3_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

Try

' Some logic

' Failed Case

' Case where ex.message is not empty

Throw New ApplicationException("Your Code had got failed.")

' Case where ex.message is empty

' Throw New ApplicationException("")

Catch ex As Exception

If Convert.ToString(ex.Message) = "" Then

' Case where ex.message is empty

ErrorHandling.WriteErrorToDB("Their is some logic error in your form3. Please check it.")

Else

' Case where ex.message is not empty

ErrorHandling.WriteErrorToDB("Their is some logic error in your form3. Please check it.", ex.Message.ToString())

End If

End Try

End Sub

End Class

Dynamic polymorphism: – Dynamic polymorphism means Runtime time polymorphism or Late binding.

Method Overriding is an example of Dynamic Polymorphism, where the base class method is overridden by override keyword and its implementation is also changed.

Example:-

' Base class of cars which defines certain property of car which all car should have.

' So all its property will be Overridable

Public MustInherit Class Car

Public Overridable Sub CarProp()

MessageBox.Show("Car has four tyres")

End Sub

End Class

' A car from Maruti manufacturer, it should be inherited from Car.

Public Class Maruti

Inherits Car

Public Overrides Sub CarProp()

MessageBox.Show("Maruti has four tyres")

End Sub

End Class

' A car from Hyundai manufacturer, it should be inherited from Car.

Public Class Hyundai

Inherits Car

Public Overrides Sub CarProp()

MessageBox.Show("Hyundai has four tyres")

End Sub

End Class

Public Class Form4

Private Sub Form4_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

' Instance of Car has been created, but at runtime values are assigned to it.

Dim objCar As Car

objCar = New Hyundai

objCar.CarProp()

objCar = New Maruti

objCar.CarProp()

End Sub

End Class

Overriding the ToString Method

2012-03-18T08:42:00.000-07:00

Every class and object includes the ToString method. By default, this returns a string containing the name of your custom class or structure. By overriding this method, you can return more meaningful, human-readable information about your objects.

Every object gets the ToString method, which returns a string representation of that object. For example, all variables of type int have a ToString method, which enables them to return their contents as a string.

All classes and structures are based upon the Object class, so every such item that you define automatically inherits the ToString method

Lets us look into one simple example.

'''

''' Class which do some kind of calculation.

''' This class has overrided ToString method

'''

Public Class Calculate

' Private property which will be used inside this class

Private m_OutPutValue As Integer

Private Property OutPutValue() As Integer

Get

Return m_OutPutValue

End Get

Set(ByVal value As Integer)

m_OutPutValue = value

End Set

End Property

' Public constructor of the class.

' In this constructor we set the value of outputValue property

Public Sub New(ByVal x As Integer, ByVal y As Integer)

OutPutValue = x + y

End Sub

' Tostring method has been overrides to return the OutputValue as string.

Public Overrides Function ToString() As String

' Logic of this calculate class.

' Return the value as string.

Return Me.OutPutValue.ToString()

End Function

End Class

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

' Instance of Calculate Class is created

Dim obj As New Calculate(30, 20)

' Here obj.tostring will return the, value of calculate class, instead of class name.

MessageBox.Show(obj.ToString())

End Sub

End Class

Delegates with Example

2012-03-16T00:06:00.000-07:00

In this article I will to share with you, what is Delegates with a small example?

Well we can define Delegates as a type safe “Function Pointer” which holds references to static or instance methods. Delegates are used to call methods dynamically at runtime.

Example:-

Public Class MyAccount

' Delegates Declaration

Public Delegate Function CalVariables(ByVal x As Double, ByVal y As Double) As Double

' Shared Function in class which can be call without creating object of this class.

' This Class use Delegates as Parameter.

Public Shared Function Calculate(ByVal c As CalVariables, ByVal x As Double, ByVal y As Double, ByVal z As Double)

Return c(x, y) + z

End Function

End Class

Public Class Form1

'''

''' On Button click, selected value of combo box is taken in Switch case.

''' If the user had selected Add then the delegates function will add x and y.

''' If the user had selected subtract then the delegate function will subtract x and y.

''' And so on...

'''

Private Sub BtnShowDetails_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnShowDetails.Click

Select Case Convert.ToString(cmbCar.SelectedItem.ToString())

Case "Add"

Dim AddValue As New MyAccount.CalVariables(AddressOf AddValues)

' MyAccount.Calculate will call Calculate in MyAccount class first.

' Then c(x, y) will call the AddValues function.

MessageBox.Show(Convert.ToString(MyAccount.Calculate(AddValue, 5, 5, 5)))

Case "Subtract"

Dim subtractValue As New MyAccount.CalVariables(AddressOf subtractValues)

' MyAccount.Calculate will call Calculate in MyAccount class first.

' Then c(x, y) will call the subtractValues function.

MessageBox.Show(Convert.ToString(MyAccount.Calculate(subtractValue, 5, 5, 5)))

Case "Multiply"

Dim MultiplyValue As New MyAccount.CalVariables(AddressOf MultiplyValues)

' MyAccount.Calculate will call Calculate in MyAccount class first.

' Then c(x, y) will call the MultiplyValues function.

MessageBox.Show(Convert.ToString(MyAccount.Calculate(MultiplyValue, 5, 5, 5)))

Case "Divide"

Dim DivideValue As New MyAccount.CalVariables(AddressOf DivideValues)

' MyAccount.Calculate will call Calculate in MyAccount class first.

' Then c(x, y) will call the DivideValues function.

MessageBox.Show(Convert.ToString(MyAccount.Calculate(DivideValue, 5, 5, 5)))

End Select

End Sub

' Function To Add x and y

Private Function AddValues(ByVal x As Double, ByVal y As Double) As Double

Return x + y

End Function

' Function To Subtract x and y

Private Function subtractValues(ByVal x As Double, ByVal y As Double) As Double

Return x - y

End Function

' Function To Multiply x and y

Private Function MultiplyValues(ByVal x As Double, ByVal y As Double) As Double

Return x * y

End Function

' Function To Divide x and y

Private Function DivideValues(ByVal x As Double, ByVal y As Double) As Double

Return x / y

End Function

End Class

In MyAccount Class I have declared Delegate.

Public Delegate Function CalVariables(ByVal x As Double, ByVal y As Double) As Double

CalVariables is a shared function where CalVariables Delegates is used as Parameter.

In Form1 on Button click, selected value of combo box is taken in Switch case.

If the user had selected Add then,

Our delegates is addressed to AddValues Function.

Dim AddValue As New MyAccount.CalVariables(AddressOf AddValues)

MessageBox.Show(Convert.ToString(MyAccount.Calculate(AddValue, 5, 5, 5)))

Will be executed.

On calling MyAccount.Calculate(AddValue, 5, 5, 5)), Calculate method is called and

From there on c(x, y) + z; it calls to AddValues function.

This is a small basic example of .NET delegates as a powerful mechanism to perform dynamic method invocation.

How to get IPAddress Of networked System in C#.net

2008-09-19T05:44:00.000-07:00

How to get IPAddress Of networked System in C#.net.
I am doing one project in C#.net. Where I wants to get all the IP Address & Domain Name in my Network using C# code.