By now most of you might have started using VS 2010 Beta 2. In this article we will see how to create a WCF service using Workflow 4.0 Beta 2. This article is based on a Beta version and could possibly change in the future. Assuming you have installed VS 2010 Beta 2, Open VS 2010 and create a Workflow project. Following are the activities provided:
The activities shown above are used to develop various categories of applications. In this article, we will see how to expose WCF service using Messaging activities provided by Workflow 4.0.
Step 1: Open VS 2010 and create a blank solution > name it as ‘WF40_CreatingWCF_Service’. In this solution, right click and add a new ‘WCF Workflow Application’, name it as ‘WCF_DataService’ as shown below:
Once you add this project, you will get the following Workflow in designer as shown below. This consists of the ‘Receive’ and ‘SendReply’ activities. These activities are present under namespace ‘System.ServiceModel.Activities’. The workflow is as shown below:
This WCF service has the extension ‘xamlx’. This is newly provided by .NET in VS 2010. The Receive Activity already defines ‘GetData’ operation for the WCF service. On opening the property of the Receive activity, you will see a UI as shown below:
- ‘ServiceContractName’ defines ‘IService’ service contract to be published by the WCF service.
- ‘CanCreateInstance’ defines activation for the WCF service.
- ‘Protection Level’ defines message protection e.g. Sign, EncryptedAnSign.
- ‘SerializationOption’ defines the default serialization for user defined classes from WCF service to consumer.
- ‘Content’ property defines the input values contained into the message when client application of WCF makes request message to WCF service.
Step 2: Right click on the ‘WCF_DataService’ and add the following class ‘clsDataAccess’ and write the following code in it:
C#
public class Employee
{
public int EmpNo { get; set; }
public string EmpName { get; set; }
public int Salary { get; set; }
public int DeptNo { get; set; }
}
public class clsDataAccess
{
public Employee[] GetAllEmployee()
{
Employee[] arrEmp = null;
SqlConnection Conn = new SqlConnection("Data Source=.;Initial Catalog=Company;Integrated Security=SSPI");
SqlCommand Cmd = new SqlCommand();
Conn.Open();
Cmd.Connection = Conn;
Cmd.CommandText = "Select * from Employee";
SqlDataReader Reader = Cmd.ExecuteReader();
DataTable DtEmp = new DataTable();
DtEmp.Load(Reader);
arrEmp = new Employee[DtEmp.Rows.Count];
int i = 0;
foreach (DataRow Dr in DtEmp.Rows)
{
arrEmp[i] = new Employee();
arrEmp[i].EmpNo = Convert.ToInt32(Dr["EmpNo"]);
arrEmp[i].EmpName = Dr["EmpName"].ToString();
arrEmp[i].Salary = Convert.ToInt32(Dr["Salary"]);
arrEmp[i].DeptNo = Convert.ToInt32(Dr["DeptNo"]);
i = i + 1;
}
return arrEmp;
}
}
VB.NET
Public Class Employee
Private privateEmpNo As Integer
Public Property EmpNo() As Integer
Get
Return privateEmpNo
End Get
Set(ByVal value As Integer)
privateEmpNo = value
End Set
End Property
Private privateEmpName As String
Public Property EmpName() As String
Get
Return privateEmpName
End Get
Set(ByVal value As String)
privateEmpName = value
End Set
End Property
Private privateSalary As Integer
Public Property Salary() As Integer
Get
Return privateSalary
End Get
Set(ByVal value As Integer)
privateSalary = value
End Set
End Property
Private privateDeptNo As Integer
Public Property DeptNo() As Integer
Get
Return privateDeptNo
End Get
Set(ByVal value As Integer)
privateDeptNo = value
End Set
End Property
End Class
Public Class clsDataAccess
Public Function GetAllEmployee() As Employee()
Dim arrEmp() As Employee = Nothing
Dim Conn As New SqlConnection("Data Source=.;Initial Catalog=Company;Integrated Security=SSPI")
Dim Cmd As New SqlCommand()
Conn.Open()
Cmd.Connection = Conn
Cmd.CommandText = "Select * from Employee"
Dim Reader As SqlDataReader = Cmd.ExecuteReader()
Dim DtEmp As New DataTable()
DtEmp.Load(Reader)
arrEmp = New Employee(DtEmp.Rows.Count - 1){}
Dim i As Integer = 0
For Each Dr As DataRow In DtEmp.Rows
arrEmp(i) = New Employee()
arrEmp(i).EmpNo = Convert.ToInt32(Dr("EmpNo"))
arrEmp(i).EmpName = Dr("EmpName").ToString()
arrEmp(i).Salary = Convert.ToInt32(Dr("Salary"))
arrEmp(i).DeptNo = Convert.ToInt32(Dr("DeptNo"))
i = i + 1
Next Dr
Return arrEmp
End Function
End Class
The above class contains the method ‘GetAllEmployee’ which returns an array of all employees of type ‘Employee’ class.
Step 3: Rename ‘Service1.xamx’ to ‘CService.xamlx’. Drag and drop the ‘InvokeMethod’ activity from ‘Primitives’ activity from the toolbox, right below the ‘ReceiveRequest’ activity. Change the OperationName of the ‘ReceiveRequest’ activity from ‘GetData’ to ‘GetAllEmp‘. From the lower left corner of the designer, you will find ‘Variables’ > click on it and add the following variable types:
(Note: All expression types in WF 4.0 accept code with VB Syntax)
‘objData’ is defined to make a call using the ‘InvokeMethod’ activity to the clsDataAccess’ class. ‘arrEmp’ is declared since it is the return type from the method.
Step 4: Set following properties of the ‘InvokeMethod’ activity:
|
Property Name
|
Value
|
|
MethodName
|
GetAllEmployee
|
|
TargetObject
|
objData
|
|
Result
|
arrEmp
|
Now the workflow will be as shown below:
Step 5: Right click on ‘CService.xamlx’ and click on ‘View In Browser’. The following output should be displayed:
Step 6: Build the project and publish it on IIS. (Note that the virtual directory is in the application pool configured for ASP.NET 4.0).
Now you can create a client application where you can consume this WCF service. The important thing here is that it uses ‘basicHttpBinding’ by default for communication (it is the default used in WCF 4.0). So if you want to have a secure communication, you must make changes in the Web.Config file.
Conclusion: VS2010 beta has provided codeless WCF exposure using WF 4.0. For the developer, it is now necessary to just design the Data access layer and business layer using WCF template (WF 4.0) which makes it easier to make the business logic distributable with less efforts. The entire source code of this article can be downloaded over here
This article has been editorially reviewed by Suprotim Agarwal.
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Mahesh Sabnis is a DotNetCurry author and a Microsoft MVP having over two decades of experience in IT education and development. He is a Microsoft Certified Trainer (MCT) since 2005 and has conducted various Corporate Training programs for .NET Technologies (all versions), and Front-end technologies like Angular and React. Follow him on twitter @
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