Application-Layer Traffic Optimization (ALTO) guides an application, especially a Peer to Peer (P2P) application, to select hosts from its candidate set. ALTO is a promising technique for future network, as it is able to jointly optimize network resource utilization and application performance. The ALTO protocol is Client-Server based. Applications work as ALTO clients to fetch PID information from the ALTO server, but the ALTO server can't send the notification to ALTO clients, even if there is a major change to the networks. This draft discusses the requirements for server initialized notification, and proposes one mechanism to enable the ALTO server notification.