INFO: Example: Simple DCOM VB Client Talking to an MTS Component

MORE INFORMATION

• Limit the exercise to producing the samples on a single development computer running Windows NT with the Windows NT Options Pack until the instructions direct otherwise.
• Apply Microsoft Visual Basic 5.0 with Visual Studio Service Pack 3 on the development computer before producing this sample.

ActiveX DLL Project

   '***** BEGIN PASTE FOR "cls_calculator" class in
   '***** the FourFunction project***

   Public Function Add(num1 As Double, num2 As Double) As Double
      Add = num1 + num2
   End Function
   Public Function Subtract(num1 As Double, num2 As Double) As Double
      Subtract = num1 - num2
   End Function
   Public Function Multiply(num1 As Double, num2 As Double) As Double
      Multiply = num1 * num2
   End Function
   Public Function Divide(num1 As Double, num2 As Double) As Double
      If num2 = 0 Then
         Divide = 0
      Else
         Divide = num1 / num2
      End If
   End Function

   '***** END PASTE FOR "cls_calculator" class in the FourFunction
   '***** project***
				

Standard EXE Project

1. Open a new instance of Visual Basic, create a new Standard EXE project type, and name this project MTSCalcClient.
2. Place four command buttons on Form1.
3. Change the Caption Property to Add, Subtract, Multiply, and Divide.
4. Name the command buttons cmdAdd, cmdSubtract, cmdMultiply, and cmdDivide.
5. Add a TextBox on Form1, name it txtOperand1, place a label control next to this text box, and set the caption to Operand1.
6. Add a TextBox on Form1, name it txtOperand2, place a label control next to this text box, and change set the caption to Operand2.
7. Add a TextBox on Form1, name it txtResult place a label control next to this text box, and set the caption to Result.
8. In the code window of Form1 past the following code:

      '*************** BEGIN PASTE FOR MTSCalcClient Client ***************
   
      Dim obj_MTSCalc As Object
      Private Sub cmdAdd_Click()
         CheckInput txtOperand1, txtOperand2
         txtResult = CStr(obj_MTSCalc.Add(CDbl(txtOperand1),
         CDbl(txtOperand2)))
      End Sub
   
      Private Sub cmdDivide_Click()
         CheckInput txtOperand1, txtOperand2
         txtResult = CStr(obj_MTSCalc.Divide(CDbl(txtOperand1),
         CDbl(txtOperand2)))
      End Sub
   
      Private Sub cmdMultiply_Click()
         CheckInput txtOperand1, txtOperand2
         txtResult = CStr(obj_MTSCalc.Multiply(CDbl(txtOperand1),
         CDbl(txtOperand2)))
      End Sub
   
      Private Sub cmdSubtract_Click()
         CheckInput txtOperand1, txtOperand2
         txtResult = CStr(obj_MTSCalc.Subtract(CDbl(txtOperand1),
         CDbl(txtOperand2)))
      End Sub
   
      Private Sub Form_Load()
         Set obj_MTSCalc = CreateObject("FourFunction.cls_Calculator")
      End Sub
   
      Sub CheckInput(num1 As TextBox, num2 As TextBox)
   
         If IsNumeric(num1.Text) And IsNumeric(num2.Text) Then
   
         Else
            num1.Text = 0
            num2.Text = 0
         End If
   
      End Sub
   
      '*************** END PASTE FOR MTSCalcClient Client ***************
   						

Test Your Progress

1. Run the FourFunctionDLL project and minimize it.
2. Run the MTSCalcClient project and check that the calculator runs.
3. If the Calculator functions, move on to the next step. If it does not, troubleshoot appropriately.
4. Stop the MTSCalcClient project.
5. Stop the FourFunctionDLL project.
6. In the FourFunctionDLL project properties dialog box verify that the following values are set on the General tab:

         Threading Model = "Apartment Threaded"
         Unattended Execution = Checked
   						

7. Click the Component tab. In the Remote Server frame, set the Remote Server Files box to True.
8. Click OK.
9. Save the project.
10. Create a directory named C:\MyFourFunctionClient and save the MTSCalcClient project to this directory.

Create FourFunctionDemo Package

1. Create a directory named C:\MyFourFunctionDemo.
2. On the File menu, click Make FourFunction.dll, and specify that it be saved in the C:\MyFourFunctionDemo directory.
3. Start Transaction Server Explorer and expand the folders until you see My Computer. Expand the folders again until you see Packages Installed.
4. Right-click Packages Installed and click New.
5. Name the new package FourFunctionDemo.
6. Leave the Package Identity as Interactive User.
7. Click Finish.
8. Right-click the Components folder and click New.
9. Click the Install New Component(s) button.
10. Click the Add Files button, locate the C:\My FourFunctionDemo folder, and click FourFunction.dll.
11. Make sure that the components folder of the FourFunctionDemo package is open and that the FourFunction.cls_calculator ball with the green "X" mark is visible on the desktop.
12. Start the MTSCalcClient project and observe that the ball is now spinning. This indicates that the object has been started on the server computer. (Which, in this first case, is the same computer where these two components have been developed.)
13. Operate the functions of the calculator. All the logic is now being executed on the "server" (which currently is the development computer running MTS.)

Create a Setup Program