Patent ID: 8086570

Claim:
A document management server connected to a network that receives documents from a client, comprising: an identification information providing unit that receives a request for duplicated copy identification information required for accessing a document from a client, generates unique duplicated copy identification information for the received request, wherein the generated duplicated copy identification information is not identical to any already-generated original copy identification information and other duplicated copy identification information, and sends the generated duplicated copy identification information to the client; a relation information management unit that manages relation information between the original copy identification information designated by the request and the duplicated copy identification information generated for the request, the original copy identification information uniquely identifying the document; a history information management unit that manages information by associating the client who has sent the request, with the duplicated copy identification information generated for the request; an identification information obtaining unit that send the request to obtain identification information and receives the generated duplicated copy identification information as a response; a document-obtaining unit that sends a document access request, which designates the obtained duplicated copy identification information, to obtain a document associated with the duplicated copy identification information; a document-providing unit that receives an access request for the document, identifies the original copy identification information corresponding to the access request by referencing the duplicated copy identification information designated by the access request and the relation information, and sends the document identified by the identified original copy identification information as a response to the access request; and an identification information changing unit that changes the identification information designated by the access request according to the updating information received as the response to the access request.