Can VS Code extensions get URI requests from other programs?

I found information on the official docs that onUri can be used as an activation event. So, my extension can be activated from, say, a WPF program written in C# by calling the URI such as vscode://myextension/arg1=foo&arg2=bar. But nowhere does it say how I can get the arguments that were passed with the URI request. Or even just get a raw string of it.

My question is, can it be done and if not, is there any other way to make a VS Code extension interact with another program?

Solution

Yes, you can use vscode.window.registerUriHandler() for this:

Registers a uri handler capable of handling system-wide uris. In case there are multiple windows open, the topmost window will handle the uri. A uri handler is scoped to the extension it is contributed from; it will only be able to handle uris which are directed to the extension itself. A uri must respect the following rules:

The uri-scheme must be the vscode.env.uriScheme;

The uri-authority must be the extension id (eg. my.extension);

The uri-path, -query and -fragment parts are arbitrary.

For example, if the my.extension extension registers a uri handler, it will only be allowed to handle uris with the prefix product-name://my.extension.

An extension can only register a single uri handler in its entire activation lifetime.

Note: There is an activation event onUri that fires when a uri directed for the current extension is about to be handled.

Usage is quite simple:

vscode.window.registerUriHandler({
    handleUri(uri:vscode.Uri) {
        // do something with the URI
    }
});