Patent ID: 7826392

Claim:
An advertisement search agent system comprising: a message acquisition unit configured to acquire advertisement search messages including a search message, a service availability advertisement message, and a service unavailability advertisement message broadcast or multicast by a node connected to one of a plurality of domains; a message database configured to store the advertisement search messages acquired by said message acquisition unit; a node connection monitoring unit configured to detect a connection of a node to any one of the plurality of said domains; a delivery message extractor configured to execute at least one of a first extracting function configured to extract only said search message and said service availability advertisement message delivered from a connected node recently connected to a first domain, of said advertisement search messages stored in said message database, and configured to execute a second extracting function configured to recognize a second node connected to the first domain, and to extract only said search message and said service availability advertisement message delivered from the second node connected to said first domain, when the connection of said connected node to the first domain is detected by said node connection monitoring unit; and a message delivery unit configured to execute at least one of a first delivery function configured to deliver said search message and said service availability advertisement message extracted by said first extracting function of said delivery message extractor to the first domain, and configured to execute a second delivery function configured to deliver said search message and said service availability advertisement message extracted by said second extracting function of said delivery message extractor to the connected node, when the connection of said connected node to the first domain is detected by said node connection monitoring unit.