Скачать или смотреть Resolving Windows URI Scheme Registration for User-Installed Apps

Learn how to tackle the challenge of registering a Windows URI Scheme for applications installed only for the current user while avoiding registry permission issues.
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This video is based on the question https://stackoverflow.com/q/77044649/ asked by the user 'Andy' ( https://stackoverflow.com/u/22503808/ ) and on the answer https://stackoverflow.com/a/77055592/ provided by the user 'Rob Mensching' ( https://stackoverflow.com/u/23852/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Challenge: Windows URI Scheme Registration

If you're developing a .NET WinForms application, you've probably encountered the situation where your installer needs to register your application as a URI scheme in the Windows Registry. The problem arises primarily when your application can be installed either for all users or just for the current user. When attempting to register a URI scheme for a logged-in user, you may run into permissions issues — a significant roadblock in your development process.

The Problem Breakdown

Registry Permissions: When installed for a single user, the application tries to access the registry in a way that may require elevated permissions, resulting in failures.

User Conflicts: If multiple users are on the same machine and install your app for their individual accounts, managing their respective registry entries becomes complicated.

Application Accessibility: You need a solution that allows easy access across users without requiring global installation when unnecessary.

Proposed Solution: Navigating the Registry Basics

To effectively manage URI scheme registration, understanding the Windows registry structure and behavior is crucial.

Key Registry Paths

HKEY_CLASSES_ROOT (HKCR): This root merges two essential areas:

HKEY_LOCAL_MACHINE\Software\Classes (per-machine)

HKEY_CURRENT_USER\Software\Classes (per-user)

This means that while reading from HKCR is straightforward, writing to it may lead to complications depending on your permissions — especially for a per-user installation.

Writing Properly to the Registry

If you have control over whether you want to write to the per-machine or per-user keys, here's what you can do:

Identify the Target: Determine if the app should be registered for the current user or for all users.

Use Direct Paths: Instead of going through HKCR when writing, directly specify the HKEY_LOCAL_MACHINE\Software\Classes for all users and HKEY_CURRENT_USER\Software\Classes for the individual user.

Conditional Logic: Implement logic in your installer that checks whether the installation is for all users or just the current user, and write the registry entries accordingly.

Looking for Alternatives

In case per-user installation continues to be problematic or if you're looking for a more elegant solution, consider these alternatives:

Launcher Application: Create a launcher app installed for everyone that checks the existence of the secondary app’s installation for the logged-in user. This launcher could handle URI registration seamlessly based on conditions.

Documentation & Feedback: Provide clear documentation for user installation options and solicit feedback to improve user experience during installation.

Conclusion: A Balanced Approach

Balancing user-specific settings and installation integrity is crucial when working with Windows URI schemes. By understanding the registry's functionality, leveraging correct paths for installation, and considering alternative solutions like a launcher, you'll be able to navigate and resolve these challenges elegantly.

With thoughtful implementation, your application can deliver a user-friendly experience without running into restrictions or conflicts.