String host = u.getHost();
AssembledDirectory directory = AssembledContextFactory.getInstance().find(host);
if (directory == null) throw new IOException("vfs does not exist: " + u.toString());
VirtualFile vf = directory.findChild(u.getPath());
if (vf == null) throw new IOException("vfs does not exist: " + u.toString());
return new VirtualFileURLConnection(u, vf);
}