Understanding ActiveX Controls in Classic ASP Applications

Last Updated: Nov 14, 2025
6 min read
Legacy Archive
Legacy Guidance: This article preserves historical web development content. For modern .NET 8+ best practices, visit our Tutorials section.

Introduction

ActiveX controls were a cornerstone of early web development, allowing developers to embed rich, interactive components into web pages. In Classic ASP, these COM-based objects provided functionality beyond basic HTML, such as calendars, charts, and media players. While largely deprecated today, understanding ActiveX remains valuable for maintaining legacy systems.

What is ActiveX?

ActiveX is Microsoft's framework for reusable software components based on COM (Component Object Model). These controls can be embedded in web pages using the <OBJECT> tag, enabling client-side execution of complex logic. Unlike server-side ASP scripts, ActiveX runs on the client's machine, offering responsive interactions but introducing security challenges.

Common use cases included form validations, data visualizations, and system integrations that required native Windows capabilities.

Embedding ActiveX Controls in ASP Pages

To embed an ActiveX control, use the <OBJECT> tag with the control's CLSID (Class ID). Here's a basic example for a Microsoft Calendar Control:

Basic ActiveX Embedding 
<OBJECT ID="calendar1" 
     CLASSID="CLSID:8E27C92B-1264-101C-8A2F-040224009C02"
     CODEBASE="MSCAL.OCX#Version=7,0,0,6214"
     WIDTH=200 HEIGHT=200>
</OBJECT>

The CLASSID identifies the control, while CODEBASE specifies the download location if not installed.

Creating ActiveX Objects Server-Side in ASP

For server-side processing, instantiate COM objects using Server.CreateObject. This is safer than client-side embedding and runs within the ASP environment:

Server-Side ActiveX Creation 
<%
On Error Resume Next
Set objExcel = Server.CreateObject("Excel.Application")
If Err.Number <> 0 Then
    Response.Write "Excel not available: " & Err.Description
    Response.End
End If

objExcel.Visible = False
Set objWorkbook = objExcel.Workbooks.Add
' Process data...
objWorkbook.SaveAs "C:\temp\report.xls"
objExcel.Quit
Set objWorkbook = Nothing
Set objExcel = Nothing
%>

Always include error handling, as COM objects may not be registered on the server.

Complete ASP Page with ActiveX

Here's a full example generating a report using an ActiveX Excel object:

Complete ActiveX Report 
<HTML>
<HEAD><TITLE>ActiveX Report Generator</TITLE></HEAD>
<BODY>
    <H2>Sales Report</H2>
    <%
    Set objExcel = Server.CreateObject("Excel.Application")
    objExcel.Visible = False
    Set objWorkbook = objExcel.Workbooks.Add
    Set objSheet = objWorkbook.ActiveSheet
    
    objSheet.Cells(1,1).Value = "Product"
    objSheet.Cells(1,2).Value = "Sales"
    objSheet.Cells(2,1).Value = "Widget A"
    objSheet.Cells(2,2).Value = 1500
    
    objWorkbook.SaveAs Server.MapPath("report.xls")
    objExcel.Quit
    Set objSheet = Nothing
    Set objWorkbook = Nothing
    Set objExcel = Nothing
    %>
    <P>Report generated: <A HREF="report.xls">Download</A></P>
</BODY>
</HTML>

Accessing Properties and Methods

Once created, interact with the object's properties and methods like any VBScript variable:

ActiveX Property Access 
<%
Set objDict = Server.CreateObject("Scripting.Dictionary")
objDict.Add "Key1", "Value1"
objDict.Add "Key2", "Value2"

If objDict.Exists("Key1") Then
    Response.Write "Found: " & objDict("Key1")
End If

' Iterate
For Each key In objDict.Keys
    Response.Write key & " = " & objDict(key) & "<BR>"
Next
Set objDict = Nothing
%>

Security Considerations

ActiveX controls pose risks like arbitrary code execution. In ASP, prefer server-side instantiation to avoid client prompts. Always validate inputs and restrict permissions.

Secure ActiveX Usage 
<%
' Validate user input before processing
Dim safeInput
safeInput = Replace(Request.Form("data"), "<script>", "") ' Basic sanitization

On Error Resume Next
Set obj = Server.CreateObject("MySecure.Control")
If Err.Number <> 0 Then
    Response.Write "Control unavailable."
    Response.End
End If

obj.Process safeInput
Response.Write obj.Result
Set obj = Nothing
%>

Migrating to ASP.NET

In ASP.NET, replace ActiveX with managed alternatives like Chart controls or third-party libraries:

ASP.NET Chart Alternative 
<%@ Register Assembly="System.Web.DataVisualization" Namespace="System.Web.UI.DataVisualization.Charting" TagPrefix="asp" %>

<asp:Chart ID="Chart1" runat="server" Width="400px">
    <Series>
        <asp:Series Name="Sales" ChartType="Column">
            <Points>
                <asp:DataPoint XValue="Widget A" YValues="1500" />
            </Points>
        </asp:Series>
    </Series>
</asp:Chart>

Code-behind:

ASP.NET Code-Behind 
protected void Page_Load(object sender, EventArgs e)
{
    // Data binding logic
    Chart1.DataBind();
}

Best Practices for ActiveX in Legacy Systems

  • Register controls on servers/clients using regsvr32.exe.
  • Use On Error Resume Next for graceful degradation.
  • Avoid client-side ActiveX; opt for server-side where possible.
  • Plan migrations to modern frameworks like Blazor or React.
  • Test cross-browser, though ActiveX is IE-only.
  • Document ProgIDs and dependencies for maintenance.

Example secure embedding with fallback:

Best Practices Example 
<OBJECT ID="ctrl1" 
     CLASSID="CLSID:YourControlCLSID"
     CODEBASE="yourcontrol.ocx#Version=1,0,0,0">
    <P>ActiveX not supported. <A HREF="fallback.html">Use alternative</A>.</P>
</OBJECT>

Conclusion

ActiveX controls powered innovative web experiences in the Classic ASP era but come with maintenance and security burdens today. By mastering their integration and planning migrations, you can sustain legacy applications while transitioning to robust .NET solutions.

Quick FAQ

What is an ActiveX control and when should I use it?

ActiveX controls are reusable COM components for embedding interactive features in web pages. Use them for legacy client-side functionality like calendars or charts, but prefer modern alternatives like JavaScript libraries for new projects.

How do I create an ActiveX object in Classic ASP?

Use Server.CreateObject('ProgID') in ASP to instantiate the control, e.g., Set obj = Server.CreateObject('Scripting.Dictionary'). Always handle errors with On Error Resume Next for compatibility.

Are ActiveX controls secure for modern web applications?

No, ActiveX has significant security risks due to its client-side execution model. Migrate to sandboxed alternatives like Web Components or Blazor for safer, cross-browser compatibility.

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