global protocol Proto(role A, role C, role S)
{
    start(Int) from C to S;
    redirect(Int) from S to C;
    login(Int) from C to A;
    auth(Int) from A to C;
    password(Int) from C to A;
    choice at A
    {
        success(Int) from A to C;
        success(Int) from C to S;
        get(Token) from S to A;
        put(Token) from A to S;
        put(Token) from S to C;
    }
    or
    {
        fail(Int) from A to C;
        fail(Int) from C to S;
        received(Int) from S to C;
    }
}