What Is an ActiveX Component?
An ActiveX component is a software object based on Microsoft’s COM (Component Object Model) technology. It is designed to be reusable and interoperable within different Windows applications. Developers use ActiveX components to extend the functionality of programs without rewriting code.
These components are often written in programming languages like C++, Visual Basic, or Delphi, and they are typically delivered as .OCX (OLE Custom Control) or .DLL (Dynamic Link Library) files.
Key Features
- Reusability: Components can be reused across multiple applications.
- Interactivity: Often used to add interactive content (e.g., video players, charts).
- Scripting Integration: Can be controlled by scripting languages like VBScript or JavaScript.
- Inter-Application Communication: Applications can talk to each other using shared ActiveX objects.
Common Use Cases
| Use Case | Description |
|---|---|
| Web Applications | ActiveX controls were often embedded in Internet Explorer to enable interactive content like file uploaders or media players. |
| Office Automation | Word or Excel could be controlled programmatically via ActiveX to automate reports or data entry. |
| Custom UI Components | Developers could create buttons, calendars, or data grids and reuse them across multiple forms. |
| System Controls | Some ActiveX controls interface with system hardware (e.g., scanners or printers). |
Security Concerns
One major reason ActiveX has fallen out of favour is security:
- ActiveX controls have full access to the Windows system.
- Malicious or poorly coded controls can cause serious harm (e.g., data loss, system compromise).
- They are Windows-only and browser-specific (mainly Internet Explorer).
Because of these concerns:
- Modern browsers like Chrome, Firefox, and Edge do not support ActiveX.
- Microsoft is phasing out ActiveX support in newer Windows versions.
Modern Alternatives
Due to security risks and platform limitations, developers now use:
- JavaScript + HTML5
- Web Assembly
- .NET controls
- Browser APIs
Summary
| Attribute | Description |
|---|---|
| Technology | Based on COM (Component Object Model) |
| File Types | .OCX, .DLL |
| Platform | Windows only |
| Used In | Internet Explorer, Microsoft Office, Windows apps |
| Replaced By | HTML5, JavaScript, Web Assembly, .NET |