C: Client;
S: Server;
B: Backend;
->C: Hit;
{
    box C==C: Generate\nrequest;
    {
        C=>S: Request;
        note: This must\nbe very fast;
        box S..B: Server gets info
        {
            S>>B: Query;
            S<<B: Response;
        };
        vertical brace at S-: Query;
        C<=S: Reply;
    };
    vertical bracket: Request/Response
        [line.corner=bevel];
};
vertical range: Whole process;
