JP4418920B2 - Network file management system, device server, and file transmission method - Google Patents

Description

  The present invention relates to a device server, and more particularly to a data management method for a recording medium device.

  Conventionally, it has been proposed to connect a USB storage connected to a personal computer via a USB (Universal Serial Bus) to a network and use it as a shared storage. A USB storage control method in this case will be described with reference to FIG.

  A dedicated program is installed in advance on each client computer. The operator of the client computer 2 starts such a dedicated program and selects a connection switch on the screen. Upon receiving such selection, the device server 5 sets an exclusion flag. In this situation, when there is an access request from the client computer 3, since the exclusive flag is currently set, the device server 5 sends a message to the client stating that “access is not possible because it is in use”. Return to computer 3. When the operator of the client computer 2 finishes the work, it gives a command to the device server 5 to reset the exclusion flag by a dedicated program. Thus, by using the exclusive flag, the USB storage 14 can be used from a plurality of client computers.

  However, when such a method is used, only the client computer that has made an access request when the exclusion flag is not set can use the USB storage 14, and if the timing is missed, the USB storage 14 is used as long as it is missed. There is a problem that can not be.

  In order to solve such a problem, in Patent Document 1, when there are access requests from a plurality of clients to the USB storage 14, as a method of executing the requests in order, each client is reserved and prioritized. It is disclosed to permit access accordingly.

JP 2000-215009 A

  However, the reservation processing system disclosed in Patent Document 1 has the following problems. Although the order is preserved by making the reservation, the order of the order is maintained, but the use of the USB storage 14 by the currently used client computer is finished, but if the user of the client computer does not perform the disconnection process, the next order Client computers cannot be used, and useless blank time occurs.

  In order to solve such a problem, if there is no access for a predetermined time, it may be possible to forcibly cancel the exclusive use by the client computer as a timeout and automatically connect the reservation client computer of the next order. In other words, it is inevitable to occupy the timeout time.

  Although it is conceivable to install a file management system in the OS of the device server, this requires high processing capability for the device server.

  The present invention solves the above problem, and even when write or read processing from a plurality of client computers connected to the network is concentrated, a network file management system capable of performing write or read processing without wasted time and its It aims to provide a method.

  1) A network file management system according to the present invention comprises A) a USB storage device, B) a plurality of client computers, C) a USB device server for network connection of the USB storage device and the plurality of client computers, and D) Between each of the client computers and the USB storage device, one file is divided into blocks having a data length determined based on the cluster size of the recording unit of the USB storage device, and file transmission processing is performed as block data. E) Each client computer sends e1) header data including the data length of the block data to be transmitted via the USB device server before transmitting the block data to the USB storage device. USB E2) Upon receiving response data indicating that the header data has been received from the USB storage device via the USB device server, the block data is transmitted to and from the USB storage device. E3) Upon receipt of the NAK signal from the USB device server, the same data is sent again to the USB device server for sending to the USB storage device. F) The USB device server is sent by any one of the client computers. In the data transmission exclusive state, when data is given from the client computer to the USB storage device, it is given to the USB storage device, and when data is given from the USB storage device to the client computer, the data is sent to the USB storage device. G) a network file management system, and H) the USB device server is given h1) header data including the data length of the transmitted block data from a specific client computer. It is determined whether or not it is currently in a data transmission exclusive state by another client computer, and h2) if it is in a data transmission exclusive state by the other client computer, a NAK signal is sent to the specific client computer that transmitted the block data H3) When the data transmission is not exclusively performed by the other client computer, the data transmission is exclusively performed by the specific client computer and the header data is transmitted to the USB storage device. H4) The specific client Co After the computer is in a data transmission exclusive state, it is determined whether block data having a data length specified by the header data has been transmitted between the specific client computer and the USB storage device. In this case, the data transmission exclusive state is canceled.

  Thus, in the data transmission exclusive state, the client computer and the USB device server that sent the header data can transmit data.

  The data transmission exclusive state is canceled when block data having a data length specified by the header data is transmitted. In addition, when the data transmission is already occupied by another client computer, a NAK signal is returned for the header data from another client computer, and the client computer that has received this retransmits the header data. To do.

  Accordingly, each client computer can transfer data to the storage device in units of blocks specified by the header data.

  As a result, it is possible to provide a network file management system and method capable of performing writing or reading processing without wasted time even when writing or reading processing from a plurality of client computers connected to the network is concentrated.

  2) A USB device server according to the present invention is A) a USB device server that connects a USB storage device and a plurality of client computers over a network, and B) 1) between each of the client computers and the USB storage device. Are divided into blocks having a data length determined based on the cluster size of the recording unit of the USB storage device, and file transmission processing is performed as block data. C) Each of the client computers is c1) the USB storage Before transmitting the block data to the device, the header data including the data length of the block data to be transmitted is transmitted to the USB storage device via the USB device server, and c2) the USB device server Via the USB storage device When the response data indicating that the header data has been received is received, data transmission of the block data is started with the USB storage device. C3) When the NAK signal is received from the USB device server, the same data is again transmitted. , Sent to the USB device server for sending to the USB storage device, and D) in the data transmission exclusive state by any one of the client computers, when data is given from the client computer to the USB storage device, it is sent to the USB storage device. When the data is given to the storage device and the data from the USB storage device to the client computer is given, the data is given to the client computer. E) In the USB device server, F) From the specific client computer, the transmission When the header data including the data length of the block data to be processed is given, it is determined whether or not the data transmission is exclusively performed by another client computer, and G) the data transmission is exclusively performed by the other client computer. In this case, a NAK signal is returned to the specific client computer that has transmitted the block data. H) If the data transmission is not exclusively performed by the other client computer, the data transmission is exclusively performed by the specific client computer. In addition, the header data is transmitted to the USB storage device. I) After the specific client computer is in a data transmission exclusive state, the header data is specified between the specific client computer and the USB storage device. It is determined whether or not block data having a predetermined data length has been transmitted. If transmitted, the data transmission exclusive state is canceled.

  Thus, in the data transmission exclusive state, the client computer that has sent the header data can transmit data to and from the USB device server. The data transmission exclusive state is canceled when block data having a data length specified by the header data is transmitted. If the data transmission is already occupied by another client computer, a NAK signal is returned for the header data from another client computer. Upon receiving this, the client computer retransmits the header data. Accordingly, each client computer can transfer data to the storage device in units of blocks specified by the header data.

  As a result, it is possible to provide a network file management system and method capable of performing writing or reading processing without wasted time even when writing or reading processing from a plurality of client computers connected to the network is concentrated. .

3) A device server according to the present invention includes: A) a first connection port for inputting / outputting transmission target data encapsulated by an encapsulation rule defined by a network transmission protocol, and transmission target data not encapsulated. When the encapsulated transmission target data is given from any of the client computers connected to the first connection port via a network, the second connection port is decapsulated. Network transmission means for performing the encapsulation and transmitting the data to the designated destination when the transmission target data to which the destination is designated is given to the second connection port.
B) Control means for controlling data transmission to and from the storage device transmission means connected to the second connection port, and C) Storage equipment and data capable of writing or reading data with a single client computer Storage device transmission means for transmitting, and D) the control means comprises the following means. d1) In the data transfer mode, transfer means for performing the following transfer; d1-1) When data from the client computer that is the object of data transfer is given from the second connection port of the network data transmission means, D1-2) When the response data is given from the storage device transmission means, the second connection port of the network data transmission means is transmitted to the client computer that is the object of the data transfer. D2) When the header data indicating the data length of the block data of the specific client computer is given from the second connection port of the network data transmission means, the transfer means is in a transfer mode based on any client computer data. Judgment means for judging whether or not, d3) in the judgment result of the judgment means Accordingly, transmission control means for performing the following processing, d3-1) if the transfer means is in a data transfer mode by a client computer other than the client computer that has transmitted the header data, the client that has transmitted the header data D3-2) When the transfer means is not in a data transfer mode by any client computer, the following processing is performed. D3-2-1) The transfer means sends the header data to the computer. D3-2-2) Data transfer mode by the client computer that sent the header data is set to the data transfer mode by the sending client computer, and the header data is transmitted to the storage device transmission means by the transmission means. After sending the header data. For transmission target data exchanged between the ant computer and the storage device, it is determined whether or not block data having a data length specified by the header data has been transmitted. Is released.

  In this way, the transmission control means, when in a data transfer mode by a client computer other than the client computer that transmitted the header data, returns a failure signal to the client computer that transmitted the header data. If the data transfer mode is not set by any client computer, the following processing is performed. The transfer unit is set to a data transfer mode by the client computer that has transmitted the header data, and the header data is transmitted to the storage device transmission unit by the transmission unit. In addition, block data having a data length specified by the header data is transmitted with respect to transmission target data exchanged between the specific client computer and the storage device after the designated client computer enters the data transfer mode. If it is transmitted, the data transfer mode is canceled. Accordingly, each client computer can transfer data to the storage device in units of blocks specified by the header data. When each client computer is already in the data transfer mode by another client computer, a failure signal is given. Therefore, when such a signal is received, retransmission may be repeated until header data is accepted.

  As a result, it is possible to provide a network file management system and method capable of performing writing or reading processing without wasted time even when writing or reading processing from a plurality of client computers connected to the network is concentrated. .

4) A file transmission method according to the present invention is a method of A) file transmission from a plurality of client computers to a storage device capable of writing or reading data, and B) between each of the client computers and the storage device. In the meantime, transmission processing is performed as block data obtained by dividing one file into a plurality of blocks, and C) each of the client computers is connected to the storage device in the following processing c1) to c3). In the file transmission method for transmitting data, c1) sending header data including the data length of the block data to be transmitted to the storage device, and c2) a response indicating that the header data has been received from the storage device. When data is received, data transmission of the block data starts and c3) When the establishment signal is received, the same data is sent again to the storage device. D) A device server provided between the storage device and the plurality of client computers is caused to execute the following processing. d1) When header data including the data length of the block data to be transmitted is given from a specific client computer, it is determined whether or not it is currently dedicated to data transmission by another client computer, d2) the other If the data transmission exclusive state by the other client computer is not in the data transmission exclusive state by the other client computer, the specified signal is returned to the specific client computer that transmitted the block data D4) data between the specific client computer and the storage device in which the given transfer data is in the data transmission exclusive state. In transmission D5) block data having a data length specified by the header data between the specific client computer and the storage device after the specific client computer is in a data transmission exclusive state. Is transmitted, and if it is transmitted, the data transmission exclusive state is canceled.

  Thus, in the data transmission exclusive state, the client computer that has sent the header data can transmit data to and from the device server. The data transmission exclusive state is canceled when block data having a data length specified by the header data is transmitted. If the data transmission is already occupied by another client computer, a failure signal is returned for the header data from another client computer. Upon receiving this, the client computer retransmits the header data. Accordingly, each client computer can transfer data to the storage device in units of blocks specified by the header data.

  Accordingly, it is possible to provide a file transmission method capable of performing writing or reading processing without wasted time even when writing or reading processing from a plurality of client computers connected to the network is concentrated.

  In this specification, “transmission” is a concept including both transmission and reception. In the embodiment, “encapsulated transmission target data” refers to data transmitted with a packet header, and corresponds to block data to be read or written as well as a read command in which such data does not exist. The “storage device” corresponds to a USB hard disk in the embodiment, but may be a recording medium that can only be read, a recording medium that can be read or written, and a recording medium that can be removed. For example, various memory cards, DVDs, flexible disks, and the like are naturally included.

1. Functional block diagram description
An embodiment of the present invention will be described with reference to the drawings. The overall configuration of the present network file management system is the same as the conventional one, but the configuration of the device server 5 in FIG. 1 is different. FIG. 2 shows a functional block diagram of the device server 5 in the network file management system according to the present invention.

  The device server 5 includes network transmission means 51, control means 55, and storage device transmission means 57.

  The network transmission means 51 includes a first connection port for inputting / outputting transmission target data encapsulated by an encapsulation rule defined by a network transmission protocol, and a second connection port for inputting / outputting unencapsulated transmission target data. When the encapsulated transmission target data is given from any client computer connected to the first connection port via the network, the data is unencapsulated and output from the second connection port, When unencapsulated transmission target data with a destination specified at the two connection ports is given, the encapsulation is performed and network transmission is performed to the specified destination.

  The control means 55 is connected to the second connection port and controls data transmission with the storage device transmission means. The storage device transmission means 57 transmits data with a storage device capable of writing or reading data with a single client computer.

  The control unit 55 includes a determination unit 61, a transmission control unit 63, and a transfer unit 65.

  The transfer unit 65 performs the same processing as that of the prior art. Specifically, the following transfer is performed in the data transfer mode. When data from a client computer that is a target of data transfer is given from the second connection port of the network transmission means, the data is given to the storage device transmission means. Further, when response data is given from the storage device transmission means 57, this response data is given to the second connection port of the network transmission means 51 so as to be transmitted to the client computer to which the data is transferred.

  When the header 61 indicating the data length of the block data of the specific client computer is given from the second connection port of the network transmission unit 51, the determination unit 61 determines whether the transfer unit 65 is in any of the client computer data transfer modes. Judge whether or not.

  The transmission control unit 63 performs the following processing according to the determination result of the determination unit 61. When the transfer means 65 is in a data transfer mode by a client computer other than the client computer that has transmitted the header data, the transfer means 65 returns a failure signal to the client computer that has transmitted the header data. When the transfer means 65 is not in the data transfer mode by any client computer, the following processing is performed. The transfer unit 65 is set to a data transfer mode by the client computer that has transmitted the header data, and the header data is transmitted to the storage device transmission unit 57 by the transfer unit 65. Furthermore, the transmission target data exchanged between the client computer that transmitted the header data and the storage device after entering the data transfer mode by the client computer that transmitted the header data is specified by the header data. It is determined whether block data having a data length has been transmitted. If the block data has been transmitted, the data transfer mode is canceled.

  Thus, if the transfer mode is already set, a failure signal is returned to the client computer that sent the header data. The transfer mode is canceled with the data length specified by the header data. Accordingly, each client computer can transfer data to the storage device in units of blocks specified by the header data. When each client computer is already in the data transfer mode by another client computer, a failure signal is given. Therefore, when such a signal is received, retransmission may be repeated until header data is accepted.

  As a result, it is possible to provide a network file management system and method capable of performing writing or reading processing without wasted time even when writing or reading processing from a plurality of client computers connected to the network is concentrated. .

2. Client computer configuration
A hardware configuration of a client computer in the network file management system according to the present invention will be described with reference to FIG. The client computer 2 is a general personal computer, and includes a CPU 123, a memory 127, a hard disk 126, a monitor 130 as a display device, an optical drive 125 such as a CD / DVD drive, a LAN card 124, an input device such as a keyboard and a mouse. 132 and a bus line 129 are provided. The CPU 123 controls each unit via the bus line 129 according to each program stored in the hard disk 126. The LAN card 124 performs data communication with the device server 5 connected to the network.

  The hard disk 126 includes an operating system (OS) 139, a network driver 148, a LAN card driver 149, a virtual USB port driver 145, an application program 141, and a USB storage driver 142.

  In the present embodiment, Windows XP (registered trademark or trademark) XP of Microsoft Corporation is adopted as the OS 139, but the present invention is not limited to this.

  The application program 141 is general application software (for example, word processing software).

  The connection management program 147 is a program that acquires information from the device server 5 and manages whether connection is possible. The virtual USB port driver 145 and the network driver 148 perform communication processing with the device server 5 (see FIG. 2). Details will be described later. The LAN card driver 149 is a driver for the LAN card 124. The USB storage driver 142 is a USB storage class driver, and performs communication according to the USB communication standard.

  In the present embodiment, each of the above programs is installed in the hard disk via the optical drive 125, and the OS is expanded in the memory 127 and operates as necessary. In addition to the optical drive, the program may be installed on a hard disk from a computer-readable recording medium such as a flexible disk (FD) or an IC card. Further, it may be expanded directly into a memory from an optical drive without using a hard disk at all, may be installed in a flash memory or the like, or may be downloaded using a communication line. In addition, the program is expanded in the memory, but it may be executed directly on a non-volatile memory such as a flash memory, or may be executed on another computer through a communication line like a remote procedure call. It may be. Programs that can be executed by a computer are not limited to those programs, but those that can be directly installed and directly executed, as well as programs that need to be converted into another form (for example, data-compressed programs). In addition, those that can be executed in combination with other module parts are also included.

3. Device server configuration
The hardware configuration of the device server 5 shown in FIG. 2 will be described with reference to FIG. FIG. 4 is an example of the configuration of the device server 5 configured using a CPU.

  The device server 5 includes a CPU 23, a volatile memory 27, a nonvolatile memory 26, an interface (I / F) 28, a LAN card 24, a display / audio output unit 25, and a bus line 29. The CPU 23 controls each unit via the bus line 29 according to each program stored in the nonvolatile memory 26.

  The USB storage 14 is connected to the interface 28.

  The nonvolatile memory 26 includes an operating system (OS) 39, a USB port driver 43, a network driver 48, a LAN card driver 49, a communication driver 45, a server side connection management program 40, a storage control program 44, and a connected device information table 42. It is remembered.

  The connected device information table 42 stores information about connected peripheral devices. Specifically, a vendor ID, product ID, interface class ID, device name, and the like.

  The USB port driver 43 performs data transmission with the USB storage 14 via the interface 28. The communication driver 45 and the network driver 48 perform data transmission with the client computer via the LAN card 24. The LAN card driver 49 is a driver for the LAN card 24.

  Processing by the server side connection management program 40, the storage control program 44, the communication driver 45, and the network driver 48 will be described later.

  In this embodiment, a Linux (registered trademark or trademark) embedded real-time OS is used as the OS 39. However, the OS is not limited to this, and other OSs may be used.

4). Data structure of USB storage
The data structure of the USB storage 14 connected to the device server 5 will be briefly described with reference to FIG. The USB storage 14 stores data in the data structure of the FAT16 type disk format. In the USB storage 14, the area on the disk is managed by being distinguished into a system area and a data area. The system area is composed of three parts: an FDC descriptor, a system area, a file allocation table (FAT), and a root directory.

  The FDC descriptor and the system area are fixed-length area management information. By referring to this area, the storage format information and the size of one cluster can be known. In addition, the file allocation table and the start address and size of the root directory are known.

  The file allocation table (FAT) stores the storage use area (cluster status), and the data length is variable. Each item of FAT has a one-to-one correspondence with a cluster (data body), and the status of each cluster (free, allocated, defective cluster) is indicated. The number of the next cluster is also stored. Note that a flag indicating that the cluster is the last cluster is described for the last cluster of the file.

  In the root directory, the first cluster number of each folder and file is recorded. The contents of the target file or directory can be read out in the correct order by tracing the FAT starting from the head cluster number.

5). Data Write / Read Processing In this embodiment, data communication is performed between the device server and the USB storage 14 in accordance with the USB communication standard, and data communication is performed between the client computer and the device server in accordance with TCP / IP. .

5.1 USB Communication Standard A communication process based on the USB communication standard as a premise will be described. In the case where the client computer and the USB storage are directly connected without a device server, data write / read processing is performed as follows.

  First, the outline in the case of reading will be described. The client computer 1) designates area management information and sends a read command to the USB storage, 2) designates FAT and root directory information and sends a read command to the USB storage, and 3) designates a file to be read. Then, it is executed by three steps of transmitting a read command to the USB storage. Note that 1) and 2) can be omitted if they have already been acquired and have not been changed.

  The specification of the area management information, the specification of FAT and root directory information, and the specification of the read target file are given to the USB storage as a block header. Such a block header includes a read start position, a block length, and a flag indicating a read process of data read in the subsequent read process. When the USB storage receives such a block header, it prepares for reading and returns an ACK signal to the client computer. When the client computer receives such an ACK signal, it transmits a read command. Thereby, reading of the designated data is executed.

  That is, the client computer transmits a block header describing specific information of data to be read from now on, and upon receiving an ACK signal, transmits a read command.

  The client computer cannot read data unless it knows the data length of the data to be read. The data length of the file to be read can be extracted from the root directory and FAT information, and the root directory and FAT information can be extracted from the area management information. In the area management information, the data length is a fixed length, and the described position is also fixed. As described above, the information to be read first can be grasped by fixing the start address and the data length, so that the information necessary for the reading can be grasped.

  The data length of the data to be read is as follows: 1) The area management information is a fixed length, and the data length is short, so it can be read once, but 2) FAT information and 3) file to be read Is variable length and may be so large that it cannot be read out once. Here, the unit of one read process is determined to be a predetermined data length by the cluster size or the like (hereinafter referred to as block data). Therefore, when the unit of one reading process is exceeded, the reading process is performed by being divided into a plurality of blocks. For example, when there is data as shown in FIG. 6, the data is read by being divided by the determined block length. In this case, it is divided into four blocks, and the above-described 3) read file read processing is repeated four times. In this way, the read data is read in units of blocks.

  Next, the writing process will be described. In the case of write processing, the above steps 1) specify area management information and transmit a read command, 2) specify FAT information, and transmit a read command are the same, and then 3) write position and block A difference is that when an ACK signal is received after transmitting a block header with a specified size, a write command is transmitted together with the block to be written.

  Data conversion processing for data transmission according to the USB communication standard described in 5.1 above is performed by the OS 139 and the USB storage driver 142 of the client computer.

5.2 Data Write / Read Processing In 5.1 above, the data conversion processing for data transmission according to the USB communication standard has been described, but in reality, between the client computer and the USB storage 14, A device server is interposed, and network communication by TCP / IP is performed between the client computer and the device server. Such TCP / IP communication is divided into packets of a predetermined length, and a network header is added to each packet for transmission / reception. Since the network communication process by TCP / IP is a general communication process, description thereof is omitted. The network driver 148 performs such data processing by TCP / IP.

  The virtual USB port driver 145 and the communication driver 45 manage the tunneling header. In the present embodiment, the read command or the write command is described in an area called a tunneling header. This is because such a command is finally transferred to the USB storage 14, but it is necessary to repeatedly issue a "DATAIN" command (read command) from the device server 5. Moreover, it can also distinguish from the block data exchanged between both by describing in this tunneling header.

Below,
A read process when a read command is given from the client computer 2 will be described.

  The operator of the client computer 2 starts the connection management program 147 (see FIG. 3). The connection management program 147 searches for a device server on the network. In this case, since the device server 5 is connected, when there is such a search request, the server-side connection management program 40 of the device server 5 refers to the connected device information table 42 and lists the connected USB devices. Is transmitted to the connection management program 147. The connection management program 147 of the client computer 2 displays the list on the screen. In this case, since only the USB storage 14 is connected, the USB storage 14 is displayed in the list.

  The operator of the client computer 2 makes a connection request to the USB storage 14 from the GUI (not shown) of the connection management program 147. Such a request is sent from the connection management program 147 to the server-side connection management program 40. The server side connection management program 40 transmits the configuration information of the USB storage 14 to the virtual USB port driver 145 of the client computer 2 because the device to be connected is identified as the USB storage 14. The configuration information is information that defines the functionality of the USB device, such as device descriptor information, and is information used for USB plug and play.

The virtual USB port driver 145 establishes a logical connection with the communication driver 45 using the TCP / IP protocol, and provides configuration information to a USB plug and play mechanism (not shown) of the client computer 2. The USB plug and play process is performed.

  7 to 11, the processing by the OS 139 of the client computer 2, the USB storage driver 142, the virtual USB port driver 145 (see FIG. 3), the storage control program 44 of the device server 5, the communication driver 45, and the USB port Processing by the driver 43 (see FIG. 4) will be described.

  When the USB plug and play process is completed, the file system negotiation process is started. The USB storage driver 142 of the client computer 2 sends a block header of an area management information acquisition request to the communication driver 45 of the device server via the virtual USB port driver 145 (see FIG. 3) (step S101 in FIG. 9). ). Specifically, since the area management information has a fixed start address and size, the USB storage driver 142 sets the acquisition request in the block header information, and the virtual USB port driver 145 adds a tunneling header. To the network driver 148. As shown in FIG. 11A, the network driver 148 attaches a network header to the packet and transmits the packet.

  The network driver 48 (see FIG. 4) of the device server 5 determines whether or not to receive a packet (step S1 in FIG. 7). When such a packet is received, the tunneling header and block header information are transmitted to the communication driver 45. (See FIG. 4). The communication driver 45 reads the tunneling header and passes the block header to the storage control program 44.

  The storage control program 44 determines whether or not the given data is a block header (step S3 in FIG. 7). In this case, since it is a block header, the storage control program 44 determines whether exclusive control by another client computer is in progress (step S5). In this case, since the exclusive control is not being performed by another client computer, the storage control program 44 sets the exclusive control flag and starts the exclusive control. (Step S9).

  The storage control program 44 extracts the data length described in the block header, and stores the data length of the block transmitted from now on (step S11). Here, the size of the area management information is extracted. The storage control program 44 transmits the block header to the USB storage 14 by the USB port driver 43 (step S13). In response to this, when a signal (ACK signal) indicating that the header information has been received from the USB storage 14 is returned, the storage control program 44 uses the communication driver 45 and the network driver 48 to send this signal to the client computer 2. (Step S15).

  As a result, the device server again enters a packet reception waiting state (step S1).

  On the other hand, the virtual USB port driver 145 (see FIG. 3) of the client computer 2 determines whether to receive a NAK signal or an ACK signal (step S103 in FIG. 9). In this case, since an ACK signal is returned, the USB storage driver 142 is informed of the ACK signal, and the USB storage driver 142 transmits a read command (step S105). Specifically, the following processing is performed.

  The USB storage driver 142 passes the “DATAIN” command to the virtual USB port driver 145. The virtual USB port driver 145 sets a “DATAIN” command in the tunneling header of the packet. Then, the data size of the data to be read is determined, and this is added to the tunneling header. Such data is transmitted to the device server 5 with a network header added by the network driver 148. The data structure in this case is shown in FIG. 11B. The reason why the data size is added to the tunneling header is that it is necessary to repeat the read command as will be described later.

  The network driver 48 (see FIG. 4) of the device server 5 determines whether or not to receive a packet (step S1 in FIG. 7). When such a packet is received, the data is passed to the communication driver 45. The storage control program 44 determines whether the content of the packet received from the communication driver 45 is a block header (step S3 in FIG. 7). In this case, the given data is a tunneling header in which a read command and its data length are described. Therefore, since it is not a block header, the storage control program 44 determines whether or not such data is data from a client computer that has transmitted the already received block header (step S21 in FIG. 8). For the determination in step S21, for example, the IP address of the client computer described in the network header may be referred to.

  Here, since the received data is from the client computer that transmitted the block header, the storage control program 44 determines whether the setting of the tunneling header is “DATAIN” or “DATAOUT” (step S23). In this case, since it is “DATAIN”, the storage control program 44 instructs the USB port driver 43 to send a “DATAIN” command to the USB storage 14 (step S25).

  When the USB storage 14 receives the “DATAIN” command, the USB storage 14 transmits the data having the head address and size already specified by the block header 5 to the device server 5.

  When receiving the data, the storage control program 44 of the device server 5 determines whether or not all the specified data amount has been received (step S26). This is because, according to the USB communication standard, a size that can be acquired by one “DATAIN” command is determined. Here, it is assumed that it can be acquired by one “DATAIN” command.

  Note that the storage control program 44 gives a “DATAIN” command to the USB storage 14 via the USB port driver 43 when data corresponding to the data size specified in the tunneling header has not been received. (Step S25).

  The storage control program 44 passes the received area management information to the communication driver 45. The communication driver 45 adds a tunneling header to this and passes it to the network driver 48. The network driver 48 adds a network header to this and transmits it to the client computer 2 (step S27). The data structure in this case is shown in FIG. 11C.

  The storage control program 44 determines whether or not the data length size described in the block header has been processed (step S29 in FIG. 8). If it is determined that the data length matches the data length described in the block header, the storage control program 44 resets the exclusive control flag and ends the exclusive control (step S31). In this case, since the area management information has a size that can be completed by a single exchange, it is determined that the processing of the data length described in the block header has been completed, and the exclusive control ends.

  As a matter of course, the data described in the tunneling header (such as “DATAIN” and the amount of read data) is not included in the data length described in the block header.

  In this way, the area management information is read out.

  Next, the OS 139 of the client computer 2 determines the file management table and the root directory as read target data (step S111 in FIG. 9). Then, a reading process is performed (step S113). The process of step S113 will be described with reference to FIG.

  First, the USB storage driver 142 determines the size of one block based on the area management information stored in step S109 in FIG. 9 (step S121 in FIG. 10). In the following, a case where the file management table and the root directory can be transmitted in one block and is transmitted in three packets will be described as an example.

  The USB storage driver 142 initializes the processing target block number i (step S123), and instructs the virtual USB port driver 145 to transmit the block header of the read target data acquisition request. The virtual USB port driver 145 transmits the block header of the read target data (step S125).

  The communication driver 45 of the device server 5 determines whether or not to receive a packet (step S1 in FIG. 7). When such a packet is received, the tunneling header and block header information are passed to the communication driver 45. The communication driver 45 reads the tunneling header and passes the block header to the storage control program 44.

  The storage control program 44 determines whether or not the given data is a block header (step S3). In this case, since it is a block header, the storage control program 44 determines whether exclusive control by another client computer is in progress (step S5). In this case, since the exclusive control is not being performed by another client computer, the storage control program 44 sets the exclusive control flag and starts the exclusive control. (Step S9).

  Note that the processing in steps S9 to S15 is the same as in the case of area management information.

  On the other hand, the virtual USB port driver 145 of the client computer 2 determines whether or not to receive a NAK signal or an ACK signal (step S127 in FIG. 10). In this case, since an ACK signal is returned, the USB storage driver 142 is informed that it is an ACK signal, and the USB storage driver 142 transmits a read command. The virtual USB port driver 145 initializes the processing target packet number j (step S129), and transmits “DATAIN” as a read command for the j-th packet (step S131). Specifically, “DATAIN” is passed to the virtual USB port driver 145 for the jth packet. In response to the command, the virtual USB port driver 145 and the network driver 148 transmit a read command in the same manner as in the area management information.

  On the other hand, the network driver 48 of the device server 5 determines whether or not to receive a packet (step S1 in FIG. 7). When such a packet is received, the data is passed to the communication driver 45. The storage control program 44 determines whether the packet is header information (step S3 in FIG. 7). In this case, since the given data is a tunneling header in which a read command and its data length are described and not a block header, the storage control program 44 receives from the client computer that has transmitted the already received block header. It is determined whether it is data (step S21 in FIG. 8).

  Here, since it is data from the client computer that transmitted the block header, the storage control program 44 determines whether the setting of the tunneling header is “DATAIN” or “DATAOUT” (step S23). In this case, since it is “DATAIN”, as in the case of the area management information, the “DATAIN” command addressed to the USB storage 14 is transferred and this process is repeated until the specified data amount is reached (step S25, step S26).

  The USB storage 14 transmits the data of the head address and the size already specified by the block header in the same way as in the case of the area management information.

  The storage control program 44 (see FIG. 4) transmits the received file management table and root directory information to the client computer 2 as in the case of the area management information (step S27 in FIG. 8).

  The storage control program 44 determines whether or not the data length size described in the block header has been processed (step S29). In this case, since it does not match the data length described in the block header, the storage control program 44 returns to the process of step S1 in FIG.

  On the other hand, the virtual USB port driver 145 (see FIG. 3) of the client computer 2 determines whether to receive the read data (step S133 in FIG. 10). In this case, since the read data for the first packet is returned, the virtual USB port driver 145 determines whether or not reception of all packets for the first block has been completed (step S135). Whether all packets have been received or not can be compared with the conventional method because it is known how many packets can be received according to the amount of data to be read, as in the prior art.

  In this case, since all packets have not been received, the virtual USB port driver 145 increments the processing packet number (step S137). Then, the process of step S131 is performed for the second packet.

  Thereafter, the virtual USB port driver 145 receives the second and third packets in the same manner as the first packet.

  When the virtual USB port driver 145 of the client computer 2 receives the third packet, the virtual USB port driver 145 determines that all the packets have been received, notifies the USB storage driver 142, and proceeds from step S135 to step S139. In this case, since the data can be sent in one block, the USB storage driver 142 determines that all blocks are completed, and the reading process is completed.

  In the case of sending in a plurality of blocks, the process proceeds to step S141, the process block number is incremented, and the process from step S125 onward is repeated.

  On the other hand, after sending the third packet, the storage control program 44 (see FIG. 4) of the device server 5 determines that the received amount matches the stored data amount in step S29, and releases the exclusive control (see FIG. 4). 8 step S31).

  In this way, the file management table and root directory information are read out.

  Similarly, the corresponding file is read with reference to the file management table and the root directory information.

  Flow charts for writing are shown in FIGS. Steps S201 to S213 shown in FIG. 12 are the same as steps S101 to S113 in FIG. The difference is that the designated file is determined as a writing target in step S215, the FAT information and the root directory information are updated in step S217, and the writing process is performed in step S219.

  The update process in step S217 is substantially the same as the read process in FIG. First, Steps S221 to S229 in FIG. 13 are the same as Steps S121 to S129 in FIG. However, the difference is that the block header of the acquisition request for the write target data is transmitted in step S225.

  Further, in step S231, not only the write command but also the data to be written is transmitted. FIG. 11D shows the data structure when the data to be written is transmitted. In this way, the “DATAOUT” command (write command) is written in the tunneling header, and the write target data is given thereafter.

  Upon receiving such data, the storage control program 44 (see FIG. 4) of the device server 5 determines whether the tunneling header setting is “DATAOUT” from step S1 and step S3 in FIG. Judgment is made (step S23 in FIG. 8). In this case, since the setting of the tunneling header is “DATAOUT”, the write target data is sent to the USB storage 14 together with the “DATAOUT” command (step S35). The storage control program 44 determines whether all data has been transmitted to the USB storage 14 (step S36). When all the data has been transmitted, the storage control program 44 transmits an ACK signal to the client computer 3 (step S37).

  The virtual USB port driver 145 of the client computer 3 determines whether or not to receive an ACK signal (step S233 in FIG. 13). Since the processing from step S235 to step S241 after receiving the ACK signal is the same as that in the case of reading, description thereof will be omitted.

  In this way, the FAT information and the root directory information are updated. Thereafter, the OS 139 (see FIG. 3) of the client computer 3 performs a writing process (step S219 in FIG. 12). Since the writing process in step S219 is similar to step S217, the description thereof is omitted. In this way, the writing process is executed.

5.3 Processing in case of conflict In the above processing, when the device server 5 receives a packet of a block header from a certain client computer, it determines whether exclusive control is currently being performed by another client computer, If applicable, a NAK signal is sent back to the client computer that sent the block header packet. Such exclusive control is repeated while transmitting data having a data length specified by the block header. The client computer that has received the NAK signal retransmits the packet of the block header.

  That is, if each client computer can receive a block header packet when it is not under exclusive control by other client computers, it occupies the device server 5 while sending data of the data length specified by the block header. Can do. This enables exclusive control in units of blocks.

  Such block exclusive control between two client computers will be described with reference to FIG. FIG. 14 is a sequence chart showing processing when a read request is made from two client computers in a situation where exclusive control is not performed.

  Specifically, it is a diagram showing processing when exclusive control by the client computer 2 is started and then a block header is transmitted from the client computer 3.

  The client computer 2 transmits the block header information to the device server 5 (step C1 in FIG. 14). In response to this, the device server 5 starts exclusive control (step C2) and extracts the data length of the data block that is continuously sent from the block header information (step C3). The device server 5 transmits block header information to the USB storage 14 (step C4). The device server 5 returns the result received from the USB storage 14 to the client computer 2.

  Thereafter, when the client computer 3 transmits the block header information to the device server 5 (step C6), the device server 5 determines whether or not the exclusive control is being performed. In this case, the exclusive control by the client computer 2 is being performed. , NAK signal is returned (step C7). Since the client computer 3 receives the NAK signal, it retransmits the block header information to the device server 5 (step C8). Upon receiving such block header information, the device server 5 determines whether or not exclusive control is in progress, and returns a NAK signal since exclusive control is being performed by the client computer 2 (step C9).

  On the other hand, the client computer 2 transmits a read command to the device server 5. The device server 5 sends this to the USB storage 14. Data is sent from the USB storage 14 to the client computer 2 via the device server 5 (step C10, step C11).

  When the data transmission of the data amount specified by the block header transmitted in step C1 is completed, the device server 5 ends the exclusive control (step C12). In this state, when the client computer 3 transmits block header information to the device server 5 (step C13), the device server 5 starts exclusive control (step C14), and extracts the data length from the block header information (step C15). . Similarly, transmission of block header information and result transmission are performed (step C16, step C17).

  Although FIG. 14 illustrates the case where the read processing conflicts, exclusive control can be performed on a block-by-block basis when the read processing, the write processing, and the write processing conflict.

  By performing exclusive control in units of blocks in this way, it is possible to prevent useless blank periods from occurring even when transmission request requests from a plurality of client computers compete. Therefore, when there is no network function like a USB storage and a client computer is reading or writing, it is dedicated to that computer while writing to and reading from the file. Even a storage medium of the above type can be connected to a network and can perform writing or reading processing without wasted time.

7). Other embodiments
In the above embodiment, the case where the USB storage is adopted as the storage device has been described. However, the storage device is not limited to this as long as it is a storage device.

  Further, the present invention is not limited to the USB standard, and may be, for example, the IEEE 1394 standard. In short, when a certain computer reads and writes data, any communication standard may be used as long as it is exclusive until the processing is completed.

  In the present embodiment, the case where only one USB storage 14 is connected to the device server 5 has been described. However, other USB devices can be connected to the device server. When a request for connected device information is received from the client computer, the device server completes the processing in use when another client computer is currently using the USB device other than the USB storage device. Unless it is, it cannot be used simultaneously from two client computers. Therefore, as in the conventional case, a notification display or the like indicating that “cannot be used because it is currently in use” may be performed.

  In the present embodiment, the FAT16 type disk format has been described as an example, but the present invention can be similarly applied to other disk formats.

  In the description of the above embodiment, the CPU is used to realize the functions shown in FIG. 2, and this is realized by software. However, some or all of them may be realized by hardware such as a logic circuit.

  In this embodiment, it is not necessary to change the control program of the conventional device server for the client computer only by installing a new control program in the device server. Moreover, although the case where it processed using a some driver etc. in order to perform the said process was demonstrated, these may be put together.

  In addition, you may make it make an operating system (OS) process a part of said program.

It is a figure which shows the outline | summary of the conventional network file management system. It is a functional block diagram of the device server 5 concerning this invention. It is a figure which shows an example of the hardware constitution which implement | achieved the client computer in the network file management system concerning this invention using CPU. It is a figure which shows an example of the hardware constitution which implement | achieved the device server in the network file management system concerning this invention using CPU. 3 is a data structure of a storage area of the USB storage 14. It is a figure explaining the data transmission in USB communication specification. 4 is a process flowchart in the device server 5; 4 is a process flowchart in the device server 5; It is a read-out process flowchart in a client computer. 9 is a detailed flowchart of step S117 in FIG. This is a data structure of data exchanged between the client computer and the device server. It is a write-in process flowchart in a client computer. 12 is a detailed flowchart of step S217 in FIG. It is a figure explaining a process when block header information competes from a plurality of client computers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Network file management system 2 ... Client computer 3 ... Client computer 4 ... Client computer 5 ... Device server 14 ... USB storage

Claims (4)

A) USB storage device,
B) Multiple client computers,
C) a USB device server for connecting the USB storage device and the plurality of client computers via a network;
With
D) Between each of the client computers and the USB storage device, one file is divided into blocks having a data length determined based on the cluster size of the recording unit of the USB storage device, and file transmission processing is performed as block data. Is done,
E) Each of the client computers
e1) Before transmitting the block data to and from the USB storage device, send header data including the data length of the block data to be transmitted to the USB storage device via the USB device server,
e2) Upon receiving response data indicating that the header data has been received from the USB storage device via the USB device server, the block data transmission to the USB storage device is started.
e3) Upon receipt of the NAK signal from the USB device server, the same data is sent again to the USB device server for sending to the USB storage device,
F) In the data transmission exclusive state by any one of the client computers, the USB device server gives data to the USB storage device when data is given from the client computer to the USB storage device. Given data to the client computer, give it to the client computer,
G) A network file management system,
H) The USB device server
h1) Given header data including the data length of the block data to be transmitted from a specific client computer, it is determined whether or not it is currently in a data transmission exclusive state by another client computer,
h2) If the data transmission is exclusive by the other client computer, a NAK signal is returned to the specific client computer that transmitted the block data,
h3) If the data transmission is not exclusively performed by the other client computer, the data transmission is exclusively performed by the specific client computer and the header data is transmitted to the USB storage device.
h4) After the data transmission exclusive state for the specific client computer, it is determined whether block data having a data length specified by the header data is transmitted between the specific client computer and the USB storage device. And, if transmitted, cancel the data transmission exclusive state,
A network file management system. A) A USB device server for connecting a USB storage device and a plurality of client computers over a network,
B) Between each of the client computers and the USB storage device, one file is divided into blocks having a data length determined based on the cluster size of the recording unit of the USB storage device, and file transmission processing is performed as block data. Is done,
C) Each client computer
c1) Before transmitting the block data to and from the USB storage device, send header data including the data length of the block data to be transmitted to the USB storage device via the USB device server,
c2) Upon receiving response data indicating that the header data has been received from the USB storage device via the USB device server, the block data data transmission to the USB storage device is started.
c3) Upon receiving a NAK signal from the USB device server, the same data is sent again to the USB device server to send it to the USB storage device,
D) In a data transmission exclusive state by any one of the client computers, when data is given from the client computer to the USB storage device, it is given to the USB storage device, and data from the USB storage device to the client computer is given. Is given to the client computer,
E) In the USB device server,
F) When header data including the data length of the block data to be transmitted is given from a specific client computer, it is determined whether or not the data transmission is currently occupied by another client computer.
G) If it is in a state exclusively used for data transmission by the other client computer, a NAK signal is returned to the specific client computer that transmitted the block data,
H) If the data transmission is not exclusively performed by the other client computer, the data transmission is exclusively performed by the specific client computer, and the header data is transmitted to the USB storage device.
I) Whether or not block data having a data length specified by the header data has been transmitted between the specific client computer and the USB storage device after the specific client computer is in a data transmission exclusive state. And, if transmitted, cancel the data transmission exclusive state,
USB device server characterized by A) having a first connection port for inputting / outputting transmission target data encapsulated by the encapsulation rule defined by the network transmission protocol, and a second connection port for inputting / outputting unencapsulated transmission target data; When the encapsulated data to be transmitted is given from any client computer connected to the first connection port via a network, the data is unencapsulated and output from the second connection port. A network transmission means for performing the encapsulation and transmitting the data to the designated destination when given non-encapsulated transmission target data with the designated destination;
B) Control means connected to the second connection port for controlling data transmission with the storage device transmission means,
C) A storage device capable of writing or reading data with a single client computer and a storage device transmission means for transmitting data.
D) The control means includes the following means:
d1) In the data transfer mode, transfer means that performs the following transfer:
d1-1) When the data from the client computer that is the object of data transfer is given from the second connection port of the network data transmission means, the data is given to the storage device transmission means.
d1-2) When response data is given from the storage device transmission means, it is given to the second connection port of the network data transmission means so as to be transmitted to the client computer to which the data is transferred.
d2) When header data indicating the data length of the block data of the specific client computer is given from the second connection port of the network data transmission means, whether or not the transfer means is in a transfer mode by any client computer data Judgment means to judge,
d3) Transmission control means for performing the following processing according to the determination result of the determination means,
d3-1) When the transfer means is in a data transfer mode by a client computer other than the client computer that transmitted the header data, the client computer that transmitted the header data returns a failure signal.
d3-2) If the transfer means is not in a data transfer mode by any client computer, perform the following processing:
d3-2-1) The transfer unit is set to a data transfer mode by the client computer that has transmitted the header data, and the header data is transmitted to the storage device transmission unit by the transmission unit.
d3-2-2) For the transmission target data exchanged between the client computer that transmitted the header data and the storage device after entering the data transfer mode by the client computer that transmitted the header data, the header data Determining whether or not block data having a data length specified in (1) is transmitted, and canceling the data transfer mode if transmitted.
A device server characterized by A) A method of transmitting files from a plurality of client computers to a storage device capable of writing or reading data,
B) Transmission processing is performed between each client computer and the storage device as block data obtained by dividing one file into a plurality of blocks,
C) In the file transmission method in which each of the client computers transmits the block data to and from the storage device by the following processes c1) to c3):
c1) Sending the header data including the data length of the block data to be transmitted to the storage device,
c2) After receiving response data indicating that the header data has been received from the storage device, data transmission of the block data is started,
c3) When the failure signal is received, the same data is sent again to the storage device.
D) causing a device server provided between the storage device and the plurality of client computers to execute the following processing;
d1) When header data including the data length of the block data to be transmitted is given from a specific client computer, it is determined whether or not it is currently dedicated to data transmission by another client computer.
d2) If the data transmission is exclusively performed by the other client computer, a failure signal is returned to the specific client computer that has transmitted the block data.
d3) If the data transmission is not exclusively performed by the other client computer, the data transmission is exclusively performed by the specific client computer and the header data is transmitted to the storage device.
d4) If the given transfer data is data transmission between the specific client computer and the storage device in the data transmission exclusive state, the data is transferred.
d5) After the data transmission exclusive state for the specific client computer, it is determined whether block data having a data length specified by the header data has been transmitted between the specific client computer and the storage device. , If transmitted, release the data transmission exclusive state,
A file transmission method characterized by the above.

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