Microsoft KB Archive/170946

= How To Create and Use a Minimal ActiveX Component in VB =

Article ID: 170946

Article Last Modified on 7/1/2004

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APPLIES TO


 * Microsoft Visual Basic 5.0 Learning Edition
 * Microsoft Visual Basic 6.0 Learning Edition
 * Microsoft Visual Basic 5.0 Professional Edition
 * Microsoft Visual Basic 6.0 Professional Edition
 * Microsoft Visual Basic 5.0 Enterprise Edition
 * Microsoft Visual Basic 6.0 Enterprise Edition

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This article was previously published under Q170946



SUMMARY
Visual Basic versions 5.0 and later feature the ability to create ActiveX Components. This article illustrates how to create a minimal ActiveX Component and use it from a minimal Automation Controller. This article does not exercise the full functionality of ActiveX Components. It is intended to help you write your first ActiveX Component.



Step One: Create the Server
 Start a new project in Visual Basic. Choose either ActiveX EXE or ActiveX DLL. From the Project Menu, choose Add Module, then Module.  Type the following code in the General Declarations section of Module1: Sub Main NOTE: End Sub will be added automatically for you.   Add the following code to the General Declaration section of Class1: Public MyString As String

Public Function MyFunction As String MyFunction = "You never know what you're gonna get." End Function

Public Sub Class_Initialize MyString = "Life is like a box of chocolates."

End Sub

  In the Properties window for Class1, set the following property:    Property      Value Instancing   5 - MultiUse

 From the Project menu, choose Project1 Properties. Under the General Tab, choose Sub Main from Startup Object list and click OK.</li> Start the program by choosing Start from the Run menu or by pressing the F5 key.

You now have a complete (though limited) OLE automation server. Later, you can choose Make Project1 EXE or Make Project1 DLL from the File menu to create an ActiveX component that can be used without having to run the project. Now you're ready to automate your server.</li> Minimize Visual Basic.</li></ol>

Step Two: Create a Client to Access the Server
<ol> Start a second copy of Visual Basic. A new project (Project1) with a default form (Form1) is created.</li>  Add the following code to the appropriate events of Form1: ' In the General Declarations section: Private MyObj As Object

Private Sub Form_Load Set MyObj = CreateObject("Project1.Class1") End Sub

Private Sub Form_Click Print MyObj.MyString Print MyObj.MyFunction End Sub

Private Sub Form_Unload (Cancel As Integer) Set MyObj = Nothing End Sub

</li> Start the program by choosing Start from the Run menu or by pressing the F5 key.</li> Click Form1. The following text is output to Form1:

Life is like a box of chocolates.

You never know what you're gonna get.</li></ol>

When Form1 loads, it instantiates one copy of your ActiveX Component. On the click, it makes two OLE calls: One to retrieve the value of the MyString public variable and one to invoke the MyFunction public function.

When Form1 unloads, it destroys its created instance of the ActiveX Component. If this is the last instance in memory, the server process is removed from memory as well.

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