Developing an Object Oriented Business Component Using WCF and Visual Studio 2008 - Understanding the WCF Business Component: Source Code for Business Logic
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To enable applications to utilize the services of WCF Service, an interface must be defined. The client accesses business objects and executes the methods which are defined in this interface.
“IProductService” is an interface defined exclusively for the above purpose. It contains all the methods which are accessible to the client. It is defined as follows:
<ServiceContract()> _
Public Interface IProductService
<OperationContract()> _
Function GetProductInfo(ByVal ProductID As Integer) As Product
<OperationContract()> _
Function GetProductsLookup() As DataTable
<OperationContract()> _
Function GetProductsList() As Products
<OperationContract()> _
Sub Add(ByVal p_Product As Product)
<OperationContract()> _
Sub Update(ByVal p_Product As Product)
<OperationContract()> _
Sub Delete(ByVal p_Product As Product)
<OperationContract(name:="DeleteProductByID")> _
Sub Delete(ByVal p_ProductID As Integer)
End Interface
The above is simply an interface, which always contain abstract methods (or methods without any code). It has to be implemented using another class to make it a concrete class. “ProductFactoryService” is the class which implements the structure defined in the “IProductService” interface and it is defined as follows:
Imports System.Data
Imports System.Data.SqlClient
Public Class ProductFactoryService
Implements IProductService
Public Function GetProductInfo(ByVal ProductID As Integer) As Product Implements IProductService.GetProductInfo
Dim dr As DataRow = DBHelper.getRow("SELECT ProductID, ProductName, UnitPrice, UnitsInStock, UnitsOnOrder FROM dbo.Products WHERE ProductID=" & ProductID)
If dr Is Nothing Then
Return Nothing
Else
Return New Product With {.ProductID = dr("ProductID"), .ProductName = dr("ProductName") & "", .UnitPrice = dr("UnitPrice") & "", .UnitsInStock = dr("UnitsInStock") & "", .UnitsOnOrder = dr("UnitsOnOrder") & ""}
End If
End Function
Public Function GetProductsLookup() As System.Data.DataTable Implements IProductService.GetProductsLookup
Return DBHelper.getDataTable("SELECT ProductID, ProductID + ' - ' + ProductName AS ProductName FROM dbo.Products")
End Function
Public Function GetProductsList() As Products Implements IProductService.GetProductsList
Dim clnProducts As New Products
For Each dr As DataRow In DBHelper.getDataTable("SELECT ProductID, ProductName, UnitPrice, UnitsInStock, UnitsOnOrder FROM dbo.Products").Rows
clnProducts.Add(New Product With {.ProductID = dr("ProductID"), .ProductName = dr("ProductName") & "", .UnitPrice = dr("UnitPrice") & "", .UnitsInStock = dr("UnitsInStock") & "", .UnitsOnOrder = dr("UnitsOnOrder") & ""})
Next
Return clnProducts
End Function
Public Sub Add(ByVal p_Product As Product) Implements IProductService.Add
DBHelper.SQLExecute("INSERT INTO dbo.Products(ProductName, UnitPrice, UnitsInStock, UnitsOnOrder) VALUES ('" & p_Product.ProductName & "'," & p_Product.UnitPrice & "," & p_Product.UnitsInStock & "," & p_Product.UnitsOnOrder & ")")
End Sub
Public Sub Delete(ByVal p_Product As Product) Implements IProductService.Delete
Me.Delete(p_Product.ProductID)
End Sub
Public Sub Update(ByVal p_Product As Product) Implements IProductService.Update
DBHelper.SQLExecute("UPDATE dbo.Products SET ProductName='" & p_Product.ProductName & "', UnitPrice=" & p_Product.UnitPrice & ", UnitsInStock=" & p_Product.UnitsInStock & ", UnitsOnOrder=" & p_Product.UnitsOnOrder & " WHERE ProductID=" & p_Product.ProductID)
End Sub
Public Sub Delete(ByVal p_ProductID As Integer) Implements IProductService.Delete
DBHelper.SQLExecute("DELETE FROM dbo.Products WHERE ProductID = " & p_ProductID)
End Sub
End Class
You can observe that, each operation (or method) in the above class works with a utility class named “DBHelper,” which is a common gateway for data access.
Next: Understanding the WCF Business Component: Source Code for “DBHelper” >>
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