If you register a particular URI scheme in a #WebKitWebContext, using webkit_web_context_register_uri_scheme(), you have to provide a #WebKitURISchemeRequestCallback. After that, when a URI request is made with that particular scheme, your callback will be called. There you will be able to access properties such as the scheme, the URI and path, and the #WebKitWebView that initiated the request, and also finish the request with webkit_uri_scheme_request_finish().