How do I create a "custom protocol" and map it to an application?

Question

How would one go about creating a "custom protocol?" I know you can create a URL protocol by adding a number of registry entries to HKEY_CLASSES_ROOT, but that seems to only work in a browser. I need for it to work in Windows Explorer also.

I know that I can write a client/server sort of interface, but I think that is overkill for my client's needs (and budget).

Long story short...

• A third-party application should call: tbwx:<row_id>
• My app should load and delete a record from the database.

It sounds fairly simple (or so I thought). Any ideas?

Thanks

Answer 1

You can create a custom protocol as long as you add a URL Protocol value of type REG_SZ to a class's key. It doesn't need an actual value, just needs to be present. Here's a simple example of an "Echo Protocol" I just created which works in Windows Explorer.

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\echo]
"URL Protocol"=""
@="Echo Protocol"

[HKEY_CLASSES_ROOT\echo\shell]

[HKEY_CLASSES_ROOT\echo\shell\open]

[HKEY_CLASSES_ROOT\echo\shell\open\command]
@="C:\\WINDOWS\\SYSTEM32\\CMD.EXE /Q /C (echo %1) && pause"

Then if you type in Windows Explorer (or Run menu) for the path:

It should even work from a browser as well, you'll just need to confirm like any other protocol:

It should run the command:

I've found it will also work in the keys HKCU\Software\Classes and HKLM\Software\Classes too. It isn't listed in the Control Panel\Programs\Default Programs\Set Associations list however. Other keys might need to be updated or it would have to be registered with Windows somehow.

This seems to continue to work all the way up to Windows 10 and possibly 11.

Answer 2

The Registering an Application to a URL Protocol article details the process. There is a utility on GitHub that can be used to register custom URL protocols. The source code is provided.