Patent ID: 8516081

Claim:
A delivery server comprising: a processor including a content output unit to output a content; a delivery request receiving unit to receive delivery requests transmitted from client terminals connected to a network via a proxy server also connected to the network; a determination unit to determine whether the delivery server can deliver content to all client terminals based on a number of delivery requests received; and a transmitting unit to stream the content via the content output unit to all of the client terminals when delivery to all of the client terminals can be performed by the delivery server, and to stream the content to a subset of the client terminals and a multicast server connected to the network when delivery to all client terminals cannot be performed by the delivery server, wherein the transmitting unit transmits an acknowledgement via the proxy server to all of the client terminals when delivery to all client terminals can be performed by the delivery server, and the transmitting unit transmits a transfer command via the proxy server to a second subset of the client terminals when delivery to all client terminals cannot be performed by the delivery server, the transfer command including information to establish sessions between the second subset of client terminals and the multicast server.