Patent ID: 7953875

Claim:
A distributed computer system comprising: a plurality of computers, each computer storing data items, each data item being assigned to one of a plurality of virtual directories; each computer that has a said data item stored thereon having at least one node of a virtual network for directory look-up, said node for directory look-up comprising (i) data identifying that one of the plurality of virtual directories with which the node for directory look-up is associated, (ii) linking data comprising addresses of other such nodes for directory look-up, and (iii) software operable (a) in response to an enquiry message that identifies another of the virtual directories forwarding the message to another node for directory look-up of the network, and (b) in response to an enquiry message that identifies the virtual directory with which the node for directory look-up is associated, generating a reply message identifying a computer that the node for directory look-up is located on; each computer that has a said data item stored thereon having, for each item stored thereon, a node of a virtual network for item look-up, said node for item look-up comprising (i) data identifying the item with which the node for item look-up is associated, (ii) linking data comprising addresses of other such nodes for item look-up each associated with an item assigned to the same virtual directory, whereby said linking data together define a plurality of virtual networks for item look-up, each of which networks corresponds to a respective different virtual directory, and (iii) software operable (a) in response to an enquiry message that identifies another of the items, forwarding the message to another node for item look-up of the network, and (b) in response to an enquiry message that identifies the item with which the node for item look-up is associated, generating a reply message including the identified item; and wherein at least one computer has retrieval means, responsive to receipt of a query identifying a directory and an item within that directory, to (i) send to a node of the virtual network for directory look-up an enquiry message identifying the directory, (ii) upon receipt of a reply message thereto, to send to the computer identified in the reply message an enquiry message identifying the item, and (iii) to receive the reply message containing the item, in which each computer having retrieval means includes also secondary retrieval means operable (a) upon receipt of a reply message identifying a computer having one or more items in a particular directory to identify further computers having one or more items in that directory; and (b) to create a list of items in that directory.