Developing COM Add-ins with Phillip Stiefel

Want to extend Access's development environment with powerful custom tools? COM add-ins might be just what you need.

In this Access Europe presentation, former MVP Philipp Stiefel demonstrates how to create COM add-ins for Microsoft Access using modern development tools. Drawing from his experience building commercial add-ins like Ivercy and Find & Replace, Philipp walks through the fundamentals of COM interfaces, implementation patterns, and best practices for add-in development.

Whether you're looking to enhance your development workflow or create tools for other Access developers, this comprehensive overview provides practical insights into building professional COM add-ins.

Why Use COM Add-ins?

Key Benefits

Enhance the Access development environment with custom tools
Leverage powerful programming environments beyond VBA
Seamlessly integrate into the Access UI
Optionally extend functionality to other Office applications
Access APIs not available through standard VBA declarations

Primary Use Cases

Developer productivity tools
Enhanced development environment features
Cross-Office application integration
Complex functionality requiring compiled code

Technical Foundation

COM Basics

Binary interface standard built into Windows
Programming language independent
Foundation for Office object libraries
Requires compiled objects (DLLs/EXEs)
Cannot be implemented directly in VBA

Required Interfaces

IDTExtensibility2 - Core add-in interface
IRibbonExtensibility - Optional ribbon support
Custom interfaces for specific functionality

Implementation Details

Essential Methods

OnConnection - Called when add-in loads
OnDisconnection - Called during shutdown
OnStartupComplete - After host app initializes
GetCustomUI - Returns ribbon XML (if implementing ribbon)

Registration Requirements

COM class registration in Windows Registry
Add-in registration in Office application
Can be per-user (HKCU) or machine-wide (HKLM)
Registration scripts simplify deployment

Development Best Practices

Environment Setup

Use modern development tools (Visual Studio, TwinBASIC)
Reference required type libraries
Consider late binding for Office automation
Implement proper debugging support

Design Considerations

Plan for both 32-bit and 64-bit compatibility
Handle loading/unloading gracefully
Implement proper error handling
Consider cross-Office compatibility if needed

Debugging and Testing

Key Tips

Use "Attach to Process" for live debugging
Add diagnostic message boxes during development
Test with other add-ins disabled
Verify registration settings

Conclusion

COM add-ins provide a powerful way to extend Access's development environment beyond what's possible with traditional Access add-ins. While the initial setup requires more technical knowledge than VBA-based solutions, the benefits of compiled code, advanced APIs, and cross-Office compatibility make them invaluable for serious Access developers.

Recording

The full recording is available on YouTube:

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Interact directly with presenters during Q&A sessions
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Share your own experiences and challenges
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Participate in group discussions

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