1. An image forming apparatus for forming an image, comprising: a receiving part configured to receive, from a requesting device, a ticket showing a use permission of an object data set, the ticket being obtained by the requesting device from a repository apparatus; a sending part configured to send the received ticket to the repository apparatus and to receive, in response, a document identification corresponding to the object data set; a process indication receiving part configured to receive, from the requesting device, a process instruction that requests execution of a process corresponding to the object data set; and a process executing part configured to execute the process in accordance with a process instruction description specified by an instruction description identification indicated by the process instruction.