US Patent 7511842 Image forming apparatus

An image forming apparatus includes a document control service that generates authentication information corresponding to the request to output a stored document and transmits the authentication information to the network service, and a document output service that receives the authentication information from the network service, obtains the stored document corresponding to the authentication information, and outputs the obtained stored document. After authenticating the stored document, the document control service generates authentication information corresponding to a request to output the stored document from an external network apparatus. The document control service, the external network apparatus, and the document output service can exchange the authentication information instead of the stored document.