1. An image processing apparatus in a native environment constructed based on a first command group processed by a processor configuring hardware and having an interpreter environment, for dynamically implementing a program constructed based on a second command group defined independently of the first command group, the apparatus comprising: data stream receiving means for receiving an input data stream including a process request from a client in the native environment; data processing means for generating an intermediate data stream in each of a plurality of stages into which the input data stream is divided in interpretation in the native environment; filter means for filtering the intermediate data stream and generating a filtered data stream in the interpreter environment; interface means for retrieving and writing back the intermediate data stream between itself and the filter means in the native environment; and filter management means for transferring the intermediate data stream retrieved via the interface means in the native environment to corresponding filter means in the interpreter environment and writing back the filtered data stream via the interface means.