Patent ID: 7693814

Claim:
A method for communicating information between clients of a data repository that have each deposited an identical data item into the data repository, the method comprising: depositing a plurality of data items into the data repository in response to requests by a plurality of client programs sent to one or more server computers of the data repository, with deposits of data items that have identical content identified by the data repository and this identification used to conserve storage space; depositing a first data item into the data repository in response to a request sent by a first client program running on a first client computer, the depositing of the first data item comprising: ensuring, by the one or more server computers, that a stored data item identical to the first data item exists in the data repository, and creating a first credential that can be used as part of a retrieval request sent to the one or more server computers to verify that the first client program has permission to retrieve the stored data item; independently depositing a second data item that is identical in content to the first data item, in response to a request sent by a second client program running on a second client computer, the depositing of the second data item comprising: discovering, by the one or more server computers, that the second data item is identical to the stored data item, and creating a second credential that can be used as part of a retrieval request sent to the one or more server computers to verify that the second client program has permission to retrieve the stored data item; creating an informational tag associated with the stored data item, in response to a request sent by the first client program to the one or more server computers, wherein contents of the created informational tag is specified by the first client program; and retrieving the contents of the informational tag created by the first client program, in response to a request by the second client program to retrieve informational tags associated with the stored data item; wherein client programs that have not deposited data items that are identical in content to the stored data item cannot retrieve the contents of the created informational tag; and wherein the created informational tag is used to communicate information between clients of the data repository but its contents is not interpreted by the data repository itself.