Stream data processing apparatus

A stream data processing apparatus for performing multiple processing steps during a processing of stream data, said stream data processing apparatus comprising:

• a transmitting-end processing section for performing a processing step, of one of said multiple processing steps, of processing data contained in the stream data, and transmitting the processed data;
• a receiving-end processing section for receiving the processed data transmitted from said transmitting-end processing section, for receiving empty data, and for performing another processing step, of a next one of said multiple processing steps, of processing the received data;
• a control section for transmitting a change signal to instruct a change of a subject of processing, the change signal being transmitted to said transmitting-end processing section and to said receiving-end processing section;
• a data temporary storage section including a physical memory for temporarily storing the processed data transmitted from said transmitting-end processing section;
• an empty data storage section for erasing any data written thereto in response to a data write, and for returning empty data in response to a data read, such that the empty data is a packet having a payload of 0 bytes and indicates an end of file;
• and
• a connection management section for (i) allowing the processed data transmitted from said transmitting-end processing section to be received by said receiving-end processing section, via said data temporary storage section, by performing a data write to and a data read from said data temporary storage section, and (ii) allowing empty data to be received by said receiving-end processing section, via said empty data storage section, by performing the data write to and the data read from said empty data storage section, wherein:
• said control section, said transmitting-end processing section, said receiving-end processing section, and said connection management section are interconnected and configured such that, if a change signal is transmitted from said control section (i) to said transmitting-end processing section, said transmitting-end processing section is operable to output a transmitting-end clear request to said connection management section, and (ii) to said receiving-end processing section, said receiving-end processing section is operable to output a receiving-end clear request to said connection management section;
• said connection management section is operable to (i) switch a write destination of the processed data transmitted from said transmitting-end processing section, the write destination being switched between said data temporary storage section and said empty data storage section, and (ii) switch a read source of any data, including the processed data and empty data, received by said receiving-end processing section, the read source being switched between said data temporary storage section and said empty data storage section;
• the switching of the write destination and the switching of the read source being executed by said connection management section based on whether said connection management section is in (i) a normal operation state, (ii) a receiving-end clear wait state which exists after the transmitting-end clear request is received by said connection management section and until the receiving-end clear request is received by said connection management section, or (iii) a transmitting-end clear wait state which exists after the receiving-end clear request is received by said connection management section and until the transmitting-end clear request is received by said connection management section.