JP6175681B2 - USB device server - Google Patents

Description

  The present invention relates to a communication control technique, and more particularly to a USB device server that connects a network and a USB device.

  Conventionally, a host device such as a personal computer having a USB port conforming to the USB (Universal Serial Bus) standard can exchange data with a USB device (peripheral device) via the USB port. The USB device is a peripheral device that performs communication in conformity with the USB standard, such as a speaker, a monitor, a USB memory, a hard disk device, a printer, a keyboard, a mouse, and an audio player.

  There is also known a USB device server that links a network and a USB device so that one or more host devices connected to a network such as a LAN (Local Area Network) can use the USB device via the network. (See Patent Document 1).

  Further, a technique for determining whether or not to compress data during communication between a host device and a peripheral device is known (see Patent Document 2).

JP 2008-287453 A JP 2001-102935 A

  In the technique of Patent Document 2, a threshold value that is a criterion for determining whether or not to perform compression is changed in accordance with the amount of data to be transmitted, and the threshold value and data are converted into a specific compression method (run-length compression, Huffman coding). Etc.), depending on the content of the data to be transmitted, the specific compression method is not always suitable for efficient transmission. It does not always become.

  Therefore, the present invention can realize efficient data transmission on the network when the host device communicates with the USB device by a method different from the technique of Patent Document 2 that determines whether or not to compress data. A USB device server is provided.

  A USB device server according to an aspect of the present invention includes a first connection unit that is an interface for connecting to a USB (Universal Serial Bus) device and a second interface that is connected to a network to which a host device is connected. A connection unit, a storage unit that stores relationship information in which each of a plurality of compression methods is associated with an attribute of a USB device, a specifying unit that specifies an attribute of a USB device connected to the first connection unit, and Data transmitted and received between the selection unit that selects a compression method according to the attribute specified by the specifying unit based on the relationship information, and the USB device connected to the host device and the first connection unit A USB device comprising: a control unit that controls to be transmitted on the network in a state compressed by the compression method selected by the selection unit. Is Susaba.

  The USB device server according to an aspect of the present invention can realize efficient data transmission over a network when the host device communicates with the USB device.

It is a network block diagram of the communication system which concerns on embodiment. It is a hardware block diagram of the USB device server in a communication system. It is a functional block diagram of a USB device server. It is a figure which shows the data structure and content example of the relationship information which a USB device server hold | maintains. It is a functional block diagram of the control part of a USB device server. It is a functional block diagram of the host device in a communication system. It is a flowchart which shows the communication control process in a USB device server. It is a flowchart which shows the USB device control process in a host device. It is a figure which shows the communication sequence between the devices via a USB device server. It is a flowchart which shows the USB device control process which concerns on a modification.

In order to realize efficient data transmission over a network when a host device communicates with a USB device, a USB device server according to one aspect of the present invention is an interface for connecting to a USB (Universal Serial Bus) device. A first connection unit, a second connection unit that is an interface for connecting to a network to which a host device is connected, and a memory that stores relation information in which each of a plurality of compression methods is associated with an attribute of a USB device A specifying unit that specifies an attribute of a USB device connected to the first connection unit, a selection unit that selects a compression method according to the attribute specified by the specifying unit based on the relationship information, Data to be transmitted / received between the host device and the USB device connected to the first connection unit is selected by the selection unit. And a control unit that controls to be transmitted on the network in a compressed state by condensation method, the attributes of the USB device is represented by the class identification information, the identification unit connected to the first connecting portion The attribute is specified by the class identification information acquired from the USB device, and the relation information corresponds to two different compression methods, respectively, class identification information indicating the first class and class identification information indicating the second class. In addition, when the class identification information acquired from the USB device connected to the first connection unit indicates the first class, the selection unit selects a compression method associated with the first class in the relationship information. USB device server to be selected .

  Here, the attribute of the USB device refers to what property the data that the USB device communicates with the host device has. Examples of attributes include an attribute indicating a USB device that communicates audio data, an attribute indicating a USB device that communicates image data, and the like. It is assumed that the operation is performed by setting the related information so as to determine a suitable compression method for each attribute of the USB device based on conventional knowledge, theory, or simulation. In addition, compression by the selected compression method is performed by software or hardware that realizes data conversion by a compression algorithm determined by the selected compression method, and this data conversion target is data to be transmitted on the network. Is at least part of. The control by the control unit may be control of an external device (host device or the like) or control of the own device (USB device server) itself.

  With the above configuration, by determining a suitable compression method for each USB device attribute as related information, one of a plurality of compression methods is selected according to the USB device attribute and the data is compressed. Therefore, the user can realize efficient data transmission on the network without performing a special operation.

  For example, the control unit receives data transmitted from the USB device in conformity with the USB standard via the first connection unit, and compresses the data using the compression method selected by the selection unit. Then, it may be converted into a format that can be transmitted by the network and then sent to the network via the second connection unit.

  As a result, when the same data as when the USB device is directly connected to the USB port of the host device is sent, the data sent from the USB device is compressed by the USB device server and transmitted to the host device. It will be. For this reason, since transmission delay on the network can be reduced, even a USB device that does not have a data compression function can smoothly communicate with a host device on the network.

In addition, for example, the control unit responds to the USB request block (URB) from the host device among the data from the USB device, with respect to the compression by the selected compression method for the data from the USB device. for the response data may be performed by performing data conversion determined by the compression method.

  As a result, the data that the USB device transmits to the host device according to the URB (USB Request Block) of the host device, that is, the data that is assumed to show the attribute of the USB device, is a suitable compression method corresponding to the attribute. Since it is compressed, efficient transmission can be realized.

  The control unit may add a header to the data compressed by the selected compression method and send the data to the network, and may include information indicating the compression method in the header.

  As a result, the host device that has received the compressed data via the network can specify the compression method by referring to the header and perform decompression according to the compression method. It can be extracted.

  Further, when a request for information about the USB device is received from the host device via the second connection unit, the control unit acquires the USB device acquired from the USB device connected to the first connection unit. Information and information indicating the compression method selected by the selection unit may be transmitted to the host device via the second connection unit.

  As a result, the host device requests the information about the USB device when trying to use the USB device, so that the host device can know the compression method for compressing the data such as URB transmitted to the USB device. become.

  In addition, the control unit performs compression by the selected compression method on the data from the USB device only for specific data among the data from the USB device, and other than the specific data. It is good also as not giving to data.

  As a result, it is also possible not to compress data that has little merit in performing compression (for example, a small amount of data such as commands and statuses).

  The control unit transmits information indicating the compression method selected by the selection unit to the host device via the network, and the control unit further transmits the data transmitted from the host device through the network. The data is received via the first connection unit, and the data is expanded by an expansion method corresponding to the compression method selected by the selection unit, and then converted into a format for transmission in accordance with the USB standard. To the USB device via the first connection unit.

  Thereby, the USB device server transmits the compression method to the host device, and the host device receives the data compressed by the compression method via the network, so that efficient data transmission over the network can be realized. .

  Further, the attribute of the USB device is represented by class identification information, and the specifying unit specifies the attribute by class identification information acquired from the USB device connected to the first connection unit, and the relation information is: Two different compression methods are associated with class identification information indicating a first class and class identification information indicating a second class, respectively, and the selection unit is acquired from a USB device connected to the first connection unit When the class identification information indicates the first class, a different compression method may be selected from when the class identification information indicates the second class. Here, the class identification information is information indicating the type of function of the USB device.

  This makes it possible to determine an appropriate compression method for each function as the related information.

  The specifying unit may specify the attribute based on a device descriptor or an interface descriptor acquired from a USB device connected to the first connection unit.

  Accordingly, the USB device server can select an appropriate compression method for compressing data of the USB device on the network by acquiring the device descriptor or the interface descriptor from the USB device.

  The first class may be an audio class, the second class may be a storage class, and the relationship information may associate class identification information indicating the first class with a Huffman compression method.

  As a result, the audio data transmitted and received between the audio class USB device and the host device can be compressed by the Huffman compression method, so that the data can be compressed with high efficiency to some extent and efficient data transmission on the network can be realized. Note that compressing audio data by the Huffman compression method means that, for example, in stereo audio of two channels on the left and right, differential data of audio between both channels is extracted and Huffman compression is performed on the difference data. . Huffman compression is the one that minimizes the average code length by obtaining the appearance probability of each data value in advance and expressing characters with a high appearance probability with short codes and characters with a low appearance probability with long codes. is there.

  The USB device server may further include an update unit that updates the relationship information.

  As a result, when a more effective compression method is found for a USB device having a specific attribute during operation, the correspondence relationship between the attribute of the USB device and the compression method can be changed according to the instruction of the host device or the user. become.

A control program according to an aspect of the present invention is a program for transmitting data to be transmitted to a USB device in conformity with the USB standard to a USB device server connected to the USB device via a network. A control program for causing a host device including a processor to execute processing, wherein the processing includes receiving a step of receiving information indicating an attribute of the USB device from the USB device server, and each of a plurality of compression methods. A selection step for selecting one of a plurality of compression methods according to the attribute indicated by the information received in the reception step based on the relationship information in which the attribute of the USB device is associated, and conforming to the USB standard The data to be transmitted to the USB device is stored in the pressure selected in the selection step. Look including a transmission step of compressing in a manner to transmit over the network to the USB device server, information indicating the attributes of the USB device that is received by the receiving step, the USB device server said USB Information indicating class identification information acquired from a device, wherein the relation information associates two different compression methods with class identification information indicating a first class and class identification information indicating a second class, respectively, and the selection In the step, when the information indicating the class identification information received in the reception step indicates a first class, the control program selects a compression method associated with the first class in the relationship information .

  With this control program, the host device can select a compression method according to the attributes of the USB device and efficiently compress the data to be transmitted over the network.

  These comprehensive or specific various aspects include one or a plurality of combinations of an apparatus, a system, a method, an integrated circuit, a computer program, a computer-readable recording medium, and the like.

  Hereinafter, embodiments will be described with reference to the drawings.

  Each of the embodiments shown here shows a preferred specific example of the present invention. Accordingly, the numerical values, shapes, materials, components, component arrangement and connection forms, steps (steps) and order of steps, and the like shown in the following embodiments are examples and limit the present invention. is not. Among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are constituent elements that can be arbitrarily added. Each figure is a mimetic diagram and is not necessarily illustrated strictly.

  In each embodiment, when relaying communication between a USB device and a host device connected to the network, the data is compressed on the compression method selected according to the attribute of the USB device and transmitted over the network. A USB device server that performs control will be described.

(Embodiment 1)
Embodiments as one embodiment of the present invention will be described below.

(Constitution)
FIG. 1 is a network configuration diagram of a communication system 10 according to an embodiment.

  The communication system 10 is a system for performing communication between a plurality of devices via a network 20 such as a wired LAN connected by an Ethernet (registered trademark) cable. The devices connected to the network 20 include a host device 200a, a host device 200b, and a USB device server 100.

  Here, the USB device server 100 is connected to the USB device 300a and the USB device 300b via the USB cables 30a and 30b, respectively, and has a function of making the USB device usable from a device connected to the network. By the operation of the USB device server 100, the host device 200a and the host device 200b can use the USB device 300a or the USB device 300b. The USB device server 100 functions so that each USB device communicates exclusively with one host device. The network 20 such as a wired LAN is compliant with, for example, the IEEE 802.3 standard.

  The host devices 200a and 200b are personal computers, communication devices, and the like that include a processor, a memory, an Ethernet controller, a display device, and the like. The USB devices 300a and 300b are peripheral devices that perform communication in conformity with the USB standard, such as a speaker, a monitor, a USB memory, a hard disk device, a printer, a keyboard, a mouse, and an audio player. Note that the USB standard is USBImplementers Forum, Inc. It is managed by. Further, the USB devices 300a and 300b may be capable of inserting and removing the USB cables 30a and 30b, respectively, or may be integrated with the USB cables 30a and 30b. That is, the USB devices 300a and 300b themselves may be directly detachable with respect to the USB standard interface (I / F) connector provided in the USB device server 100 (for example, the above-described USB memory or the like).

  Hereinafter, the configuration of the USB device server 100 will be described.

  FIG. 2 is a hardware configuration diagram of the USB device server 100 in the communication system 10.

  The USB device server 100 is a communication device that includes a processor 101, a storage device 102, a network communication interface (I / F) 103, a USB communication interface (I / F) 104, and a bus 105. Here, the storage device 102 is a memory such as a ROM and a RAM, and the network communication I / F 103 is an Ethernet controller, a LAN port (Ethernet terminal), or the like. The USB communication I / F 104 is a USB controller, a USB port through which a USB cable connector can be inserted and removed, and the like. Although the USB communication I / F 104 is described as having a plurality of USB ports here, a plurality of USB communication I / Fs 104 are not necessarily required.

  FIG. 3 is a functional block diagram of the USB device server 100.

  The USB device server 100 has a first connection unit 110, a second connection unit 120, a storage unit 130, a specifying unit 140, a selection unit 150, a control unit 160, and an update unit 170 in terms of functions, and communication control processing ( (To be described later).

  Here, the first connection unit 110 is realized by the USB communication I / F 104 or the like, and functions as an interface for transmitting / receiving data to / from the USB device according to the USB standard.

  The second connection unit 120 is realized by the network communication I / F 103 or the like, and functions as an interface for transmitting / receiving data to / from a host device connected to the network 20. Data transmission / reception by the second connection unit 120 is performed based on the TCP / IP protocol by using Ethernet as the network interface layer and encapsulating data (USB data) transmitted / received in the USB standard.

  The storage unit 130 is realized by the storage device 102 and stores relationship information 400 in which the compression method and the attribute of the USB device are associated with each other, and also stores a control program for causing the processor to execute each function. Here, the relationship information 400 will be described.

  FIG. 4 is a diagram illustrating a data configuration and content example of the relationship information 400. The relationship information 400 is information in which class identification information 401 and a compression method 402 are associated with each other as shown in FIG. The class identification information 401 is information (information indicating a device class) for distinguishing a function type that is an attribute of the USB device. The compression method 402 is information for identifying the compression method.

  This relationship information is set by a manufacturer, an operation manager, or the like, and a suitable compression method is determined for each attribute of the USB device based on empirical or theoretical considerations or simulations. In the content example of FIG. 4, in the audio class indicating the function of handling audio data, a character string is delimited for each constant bit, and the delimited character string is statistically processed to form a pattern having a higher appearance probability. On the other hand, a compression method called Huffman compression, which compresses data by giving a shorter code, is associated. On the other hand, a storage class (mass storage class) indicating a large-capacity storage function has a symbol that starts from a position in which certain data is focused It is illustrated that a compression method called LZ77 compression in which data is compressed by searching whether a column has appeared before that and replacing the symbol string with a pointer of its appearance position and length is exemplified. Note that USB devices having a function of handling audio data include, for example, a microphone and a speaker. USB devices having a large capacity storage function include a USB memory and a hard disk device.

  Returning to the description of the functional components of the USB device server 100 again.

  The specifying unit 140 has a function of specifying the attribute of the USB device from device information received from the USB device via the first connection unit 110 under the control of the control unit 160. Specifically, this is a function of extracting class identification information indicating a device class from a device descriptor or interface descriptor received from a USB device and specifying it as an attribute of the USB device connected to the first connection unit 110.

  The selection unit 150 refers to the relationship information 400 stored in the storage unit 130, selects one compression method according to the attribute of the USB device specified by the specification unit 140, and transmits it to the control unit 160 Have For example, if the attribute of the USB device specified by the specifying unit 140 indicates an audio class, the class identification information 401 in the relationship information 400 (see FIG. 4) indicates the compression method (indicated by the compression method 402 corresponding to the audio class). In the content example of FIG. 4, Huffman compression) is selected.

  The control unit 160 has a function of controlling communication with a device (such as a host device) connected to the network 20 via the second connection unit 120 and a USB device connected via the first connection unit 110. . In particular, control is performed so that data transmitted and received between the host device and the USB device connected to the first connection unit 110 is transmitted on the network 20 in a state compressed by the compression method transmitted from the selection unit 150. Has the function of

  FIG. 5 shows functional blocks that are components of the control unit 160. As shown in the figure, the control unit 160 includes a network communication unit 161, a compression / decompression control unit 162, and a USB communication unit 163. Here, the network communication unit 161 has a function of controlling communication on the network 20 according to various TCP / IP protocols. The compression / decompression control unit 162 includes a compression algorithm corresponding to each of a plurality of compression methods indicated by the relationship information 400 and a mechanism realized by hardware or software for performing data conversion based on the decompression algorithm, and compresses data. And the function of performing expansion. In addition, the USB communication unit 163 has a function of controlling to perform communication according to the USB standard.

  With these components, the control unit 160 receives data transmitted from the USB device in conformity with the USB standard via the first connection unit 110, and uses the compression method selected by the selection unit 150. After being compressed and encapsulated, it is sent to the network 20 via the second connection unit 120. This encapsulation is to add a header including various control information to data to be transmitted to the network 20 so as to conform to a format defined by each protocol of each layer of TCP / IP. Further, the compression by the compression method transmitted from the selection unit 150 is executed by performing data conversion determined by the compression method on the data to be transmitted (may be a part of the data as will be described later). Conversely, when data transmitted from the host device on the network 20 is received via the second connection unit 120, the control unit 160 decapsulates the data and then decompresses the data in accordance with the compression method. Are transferred to the USB device via the first connection unit 110. Note that decapsulation is the reverse process of encapsulation, and is to remove a header or the like including various control information. Note that the control unit 160 has a function of transmitting the device information received from the USB device to the specifying unit 140, or the update unit 170 receives the update information of the related information 400 via the network 20 when the related information 400 is received. It also has a function for updating. This update request is made with information indicating a set of class identification information and a compression method (a form in which each is associated).

  The update unit 170 has a function of receiving the instruction to update the relationship information 400 from the control unit 160 and updating the relationship information 400 stored in the storage unit 130.

  Note that all or some of the functions of the specifying unit 140, the selection unit 150, the control unit 160, and the update unit 170 are performed by the processor 101 executing a control program stored in the storage device 102 configuring the USB device server 100. Realized.

  Hereinafter, functions related to communication in the host devices 200a and 200b will be described.

  FIG. 6 is a functional block diagram of the host device 200a.

  As shown in the figure, the host device 200a includes an application program unit 201, a USB device driver unit 202, a compression / decompression control unit 203, and a network communication control unit 204.

  Here, the application program unit 201 has a function of executing, by a processor, an application program that performs processing using a USB device. This application program includes a process of requesting information (for example, list information) of available USB devices from the USB device server 100 and exchanging data with a USB device selected in accordance with user input. This application program uses the address (for example, MAC (Media Access Control) address) of the USB device server 100 for communication via the network 20 obtained by user input or the like.

  The USB device driver unit 202 has a function of causing a processor to execute a device driver for communicating with a USB device in accordance with the USB standard.

  The compression / decompression control unit 203 includes a compression algorithm corresponding to each of one or more compression methods and a mechanism realized by hardware or software for performing data conversion based on the decompression algorithm, and a function for compressing and decompressing data Have That is, the compression / decompression control unit 203 compresses the data output from the USB device driver unit 202 and inputs it to the network communication control unit 204, and decompresses the data output from the network communication control unit 204 and inputs it to the USB device driver unit 202. To do.

  The network communication control unit 204 has a function of performing control (encapsulation, decapsulation, etc.) so as to perform communication on the network 20 in accordance with various TCP / IP protocols. With these components, the host device 200a compresses and encapsulates at least a part of data to be transmitted to the USB device based on the application program, and transmits the compressed data to the network 20. Further, the data transmitted by the USB device is received from the network 20 and decapsulated and decompressed so that it can be used in the application program. As a result, the compressed data is transmitted on the network 20, the communication band load is reduced, and the transmission delay is reduced as compared with the case of non-compression.

(Operation)
Hereinafter, the operation of each device in the communication system 10 having the above-described configuration will be described.

  FIG. 7 is a flowchart showing communication control processing in the USB device server. This communication control process is a process executed in the USB device server 100 in order for the host device to use the USB device after the USB device is connected. Here, assuming that the USB devices 300a and 300b are connected to the USB device server 100 (see FIG. 1), the communication control processing will be described by taking as an example the case where the host device 200a uses the USB device 300a.

  The control unit 160 of the USB device server 100 acquires USB device information (device descriptor and the like) from the USB devices 300a and 300b connected to the USB ports of the first connection unit 110 (step S11). That is, the control unit 160 controls the USB devices 300a and 300b to perform configuration by control transfer according to the USB standard, and as a result, device descriptors are acquired from the USB devices 300a and 300b.

  The device descriptor includes information such as the manufacturer ID and product ID of the USB device, and may also include device class information. According to the configuration, the USB device server 100 can acquire information necessary for communication with each USB device and select an appropriate driver for communication. If the device descriptor does not include device class information, the control unit 160 may acquire the interface descriptor from the USB device and transmit the device information (device descriptor, interface descriptor) to the specifying unit 140. The identifying unit 140 extracts class identification information indicating a device class from the device information and identifies it as an attribute of the USB device.

  Subsequently, the selection unit 150 of the USB device server 100 refers to the relationship information stored in the storage unit 130, and compresses each of the USB devices 300a and 300b according to the attribute of the USB device specified by the specifying unit 140. Is selected (step S12). The compression method selected for each connected USB device is transmitted to the control unit 160.

After that, the control unit 160 that has acquired the request for USB device information from the host device 200a via the second connection unit 120 (step S13), information on the USB devices 300a and 300b, information on the selected compression method, Is returned (step S14). The information about the USB devices 300a and 300b to be returned is based on the device information acquired from the USB devices 300a and 300b. The host device 200a displays the acquired information on each USB device on the display device, determines a USB device to be a communication partner in response to an operation such as selection by the user as required, and starts communication with the USB device. It will be.
Here, the description will be continued assuming that communication with the USB device 300a is started. This communication is performed by compressing data (URB (USB Request Block) or the like) for the USB device by a compression method acquired from the USB device server 100.

  When the host device 200a and the USB device 300a communicate with each other, the control unit 160 performs control so that communication on the network 20 is performed by decompressing the USB device 300a using the compression method selected or decompressing in response to the decompression method. (Step S15). That is, the control unit 160 decompresses the data received from the host device 200a by the decompression method corresponding to the selected compression method and transfers the data to the USB device 300a, and the data from the USB device 300a by the selected compression method. It compresses and transfers to the host device 200a.

  FIG. 8 is a flowchart showing USB device control processing performed by the host device 200a. This USB device control processing is performed in order to use the USB device 300a in accordance with the operation of the user of the host device 200a (for example, key input on the host device, pressing of the Push-SW provided on the host device itself). This is a process to be performed. For example, it is executed when a user wants to print a document file on the host device with a printer that is one of the USB devices, or when a user wants to record a file on the host device in a specific USB memory.

  The host device 200a transmits a request for USB device information to the USB device server 100 under the control of the application program unit 201 according to the user's operation (step S21). Alternatively, instead of step S21, the USB device server 100 itself may send the USB device information to the host device 200a. This is realized, for example, by establishing a TCP (Transmission Control Protocol) session in the network 20 by the network communication control unit 204 and transmitting a predetermined command to the USB device server 100.

  Correspondingly, the device information and the compression method are transmitted from the USB device server 100, so the host device 200a receives these via the network 20 (step S22). Since the information of the USB devices 300a and 300b is acquired in step S14 described above, the host device 200a displays the acquired information on the display device, and determines the USB device of the communication partner according to the operation such as selection by the user. Communication with the USB device is started. When the USB device of the communication partner is determined, the corresponding device driver is selected based on the device information, and preparation for communication is made.

  Here, the description will be continued assuming that the host device 200a communicates with the USB device 300a. The host device 200a compresses data (URB or the like) for the USB device 300a by the compression method acquired in step S22, transmits the data to the USB device server 100, and transfers data from the USB device 300a (transferred from the USB device server 100). The response data to the URB, etc.) is decompressed and used by the decompression method corresponding to the acquired compression method (step S23). The compression in the host device 200a is executed by the compression / decompression control unit 203 on the data for the USB device output from the USB device driver unit 202. The compressed data is encapsulated by the network communication control unit 204 and transmitted to the network 20. Decompression is executed by the compression / decompression control unit 203 on the decapsulated data output from the network communication control unit 204. Then, the decompressed data is transmitted to the USB device driver unit 202.

  Hereinafter, operations related to data transmission / reception between the host device and the USB device in the communication system 10 will be described.

  FIG. 9 is a diagram illustrating a communication sequence among the host device 200a, the USB device server 100, and the USB device 300a.

  Here, description will be given using an example in which the USB device 300a is a speaker.

  In the host device 200a, the application program unit 201 and the USB device driver unit 202 generate a URB for controlling the USB device 300a (step S51). Here, in order for audio data included in an audio file in the host device 200a to be reproduced by a speaker, a certain amount of the audio data and the like is stored in the URB. As a premise, the USB device server 100 has already acquired a device descriptor including information indicating an audio class from the USB device 300a that is a speaker, and selects a Huffman compression method based on the relationship information 400 illustrated in FIG. It shall be. Then, it is assumed that the host device 200a has already acquired the compression method information from the USB device server 100 (FIG. 8, step S22).

  The compression / decompression control unit 203 of the host device 200a compresses the generated URB by performing data conversion on the USB device 300a using a compression algorithm corresponding to the compression method selected by the USB device server 100 (step S52). ). That is, URB is compressed by Huffman compression.

  Subsequently, the network communication control unit 204 of the host device 200a performs control so that the compressed URB is encapsulated and transmitted to the network 20 (step S53).

  The USB device server 100 receives the URB via the second connection unit 120 (step S54), decapsulates the URB by the network communication unit 161 of the control unit 160 (step S55), and decompresses the URB by the compression / decompression control unit 162. (Step S56). This expansion is an inverse transformation of Huffman compression. Then, the USB communication unit 163 of the control unit 160 transmits the decompressed URB to the USB device 300a via the first connection unit 110 (step S57).

  The USB device 300a receives the URB (step S58), performs processing according to the URB (step S59), and transmits response data representing the processing result (step S60). Specifically, the USB device 300a receives the audio data, reproduces the audio with a speaker based on the audio data, and transmits, as a processing result, for example, response data indicating normal reproduction to the USB device server 100.

  Correspondingly, in the USB device server 100, the USB communication unit 163 receives the response data via the first connection unit 110 (step S61), and the compression / decompression control unit 162 performs Huffman compression on the response data (step S61). S62). Then, the response data compressed by the network communication unit 161 is encapsulated and transmitted via the network 20 to the host device 200a that is the transmission source of the URB (step S63).

  When the host device 200a receives the response data (step S64), the network communication control unit 204 decapsulates the response data (step S65), and the compression / decompression control unit 203 decompresses the response data (step S66). This expansion is also an inverse transformation of Huffman compression. Then, the host device 200a performs processing according to the expanded response data (step S67). The process according to the response data is, for example, a process of displaying an error message on the display device when the response data indicates an abnormality. If the response data indicates normality, a process of controlling to repeat steps S51 to S67 in order to reproduce a certain amount of audio data following the audio data already stored in the URB in step S51 by the speaker. It is.

  As described above, by sequentially switching the data stored in the URB and repeatedly executing steps S51 to S67, the contents of the audio file in the host device 200a are reproduced on the USB device 300a (speaker).

(Embodiment 2)
The second embodiment (modification) in which a part of the USB device control processing (see FIG. 8) performed by the host devices 200a and 200b in the above-described embodiment is changed will be described below.

  FIG. 10 is a flowchart showing a modification of the USB device control process. It is assumed that the USB device control process shown in the figure is performed by the host device 200a and uses the USB device 300a. Note that the description of the same points as in the first embodiment will be omitted.

  The host device 200a transmits a request for USB device information to the USB device server 100 under the control of the application program unit 201 according to the user's operation (step S21).

  Correspondingly, device information is transmitted from the USB device server 100, so the host device 200a receives it via the network 20 (step S22a). Unlike the first embodiment, the USB device server 100 does not transmit compression method information.

  Then, the host device 200a itself selects a compression method by the same method (FIG. 7, step S12) as the USB device server 100 in the first embodiment (step S22b).

  Thereafter, as in the first embodiment, the host device 200a compresses the data (URB or the like) for the USB device 300a by the selected compression method and transmits the data to the USB device server 100. Then, the data from the USB device 300a transferred from the USB device server 100 (response data to URB, etc.) is decompressed and used by the decompression method corresponding to the selected compression method (step S23).

  The host device 200b can perform the same processing as the host device 200a. In addition, in order to select the compression method in step S22b, the host devices 200a and 200b hold the relationship information 400 described above in the memory and perform selection based on the relationship information 400. Become.

(Other embodiments, etc.)
The embodiments of the communication system including the USB device server have been described above. However, the embodiments described above are merely examples, and it is needless to say that various modifications can be made.

  The network 20 shown in the above-described embodiment is a wired LAN based on Ethernet. However, the network 20 is not necessarily a wired LAN based on Ethernet, and includes, for example, a wireless LAN portion according to the IEEE 802.11 series standard. May be.

  In the above-described embodiment, the compression method is determined in advance by the relationship information depending on the attribute of the USB device, and does not change. However, the USB device server may acquire information indicating the performance of the host device and information indicating the communication state of the network and change the compression method according to these. For example, a default compression method may be determined based on relationship information, and the default compression method may be changed to another predetermined compression method with a lower processing load only when the performance of the host device is lower than a predetermined threshold. Good. In addition, the default compression method may be changed only when the network communication state (communication band usage rate or the like) is in a predetermined state. Note that the compression method may be dynamically changed according to the communication state of the network.

  In addition, communication between the USB device server and the host device conforms to TCP / IP, and various information (information for switching the logical connection state of the USB device, etc.) according to a proprietary protocol decided between the two. It may be a thing which gives and receives.

  In the above-described embodiment, since the USB device server and the host device share the compression method information, the compression method information is transmitted from the USB device server in response to the USB device information request from the host device. It was decided to be done. However, the compression method information may be included in a header of data that is compressed and transmitted over the network (a header added by encapsulation for network transmission). This header may be in accordance with a unique protocol negotiated between the USB device server and the host device. In particular, when the compression method is dynamically changed, it is effective to include the compression method information in the header.

  In the above-described embodiment, the relationship information is expressed in the table format in FIG. 4, but the information may not be necessarily in the table format but may be information indicating the correspondence between the attribute of the USB device and the compression method. May be expressed as a processing structure in a program, for example.

  In the above-described embodiment, the attribute of the USB device is determined by the class identification information indicating the device class. However, what properties are included in the information (device descriptor etc.) acquired from the USB device and the data (all or part of the data) that the USB device communicates with the host device? It may be determined by information representing For example, the attribute of the USB device may be determined by the manufacturer ID and the product ID. For example, in the case of a specific product (for example, a scanner) of a specific manufacturer specified by the manufacturer ID and the product ID, the related information is defined so that the compression method is LZ77 compression in order to compress the image data with high efficiency. You may keep it. Further, for example, the relationship information may be determined so as to associate a compression method that compresses data in a compression unit that matches the size of the data reception buffer of a specific product of a specific manufacturer. The USB device server may change the default compression method using the transfer method and transfer direction information acquired from the USB device. For example, in the case of isochronous transfer and transfer in the OUT direction (output direction), it is estimated that the transfer is audio data, and the compression method is Huffman compression.

  In addition, data conversion by a compression algorithm corresponding to a compression method selected according to the attribute of the USB device may be performed on only a part of the data transmitted on the network. Further, when the amount of data transmitted at a time is smaller than a certain standard, compression may not be performed. Thereby, for example, commands, statuses, and the like are not compressed. Further, when the USB device is a hard disk device, the data transmitted from the USB device server or the host device is not compressed when the content data of the file having a specific extension indicating that the data is already compressed. Also good. The specific extension in this case is, for example, JPG attached to a JPEG (Joint Photographic Experts Group) compressed file, ZIP attached to a ZIP compressed file, or the like.

  In addition, when the USB device has a compression / decompression function, the USB device server causes the USB device to transmit the compressed data instead of compressing itself, and transmits the compressed data instead of decompressing itself. The device may be stretched.

  It should be noted that all or part of the various processes (such as the processes shown in FIGS. 7 to 10) performed by each device described above may be executed by hardware of each device or software. The execution of processing by software is realized by a processor included in each device executing a control program stored in a memory. Further, the control program may be recorded on a recording medium and distributed or distributed. For example, by installing the distributed control program in the devices and causing the processors of the devices to execute, it is possible to cause the devices to perform various processes (such as the processes illustrated in FIGS. 7 to 10).

  In addition, a form obtained by subjecting each of the above-described embodiments to various modifications that a person skilled in the art can naturally conceive, or a form realized by arbitrarily combining the components and functions shown in each of the embodiments. It is included in the scope of the present invention.

  The present invention can be used when a device (host device) connected to a network uses a USB device.

DESCRIPTION OF SYMBOLS 10 Communication system 20 Network 30a, 30b USB cable 100 USB device server 101 Processor 102 Storage device 103 Network communication I / F
104 USB communication I / F
105 Bus 110 First connection unit 120 Second connection unit 130 Storage unit 140 Identification unit 150 Selection unit 160 Control unit 161 Network communication unit 162 Compression / decompression control unit 163 USB communication unit 170 Update unit 200a, 200b Host device 201 Application program unit 202 USB device driver unit 203 Compression / decompression control unit 204 Network communication control unit 300a, 300b USB device

Claims (12)

A first connection unit that is an interface for connecting to a USB (Universal Serial Bus) device;
A second connection unit that is an interface for connecting to a network to which a host device is connected;
A storage unit that stores relationship information in which each of a plurality of compression methods is associated with an attribute of a USB device;
A specifying unit for specifying an attribute of the USB device connected to the first connecting unit;
A selection unit that selects a compression method according to the attribute specified by the specifying unit based on the relationship information;
Control that data transmitted and received between the host device and the USB device connected to the first connection unit is transmitted over the network in a state compressed by the compression method selected by the selection unit and a control unit which,
The attribute of the USB device is represented by class identification information,
The specifying unit specifies the attribute by class identification information acquired from a USB device connected to the first connection unit,
The relationship information associates two different compression methods with class identification information indicating the first class and class identification information indicating the second class, respectively.
When the class identification information acquired from the USB device connected to the first connection unit indicates the first class, the selection unit selects a compression method associated with the first class using the relationship information. USB device server. The control unit receives data transmitted from the USB device in conformity with the USB standard via the first connection unit, and after compressing the data by the compression method selected by the selection unit, The USB device server according to claim 1, wherein the USB device server is converted to a format that can be transmitted through the network, and then transmitted to the network via the second connection unit. Wherein the control unit, the compression in the selected compression scheme for data from the USB device, of the data from the USB device, the response data that responds to the USB request block (URB) from the host device The USB device server according to claim 2, wherein the data conversion is performed by performing data conversion determined by the compression method. The USB device server according to claim 3, wherein the control unit adds a header to the data compressed by the selected compression method and transmits the data to the network, and includes information indicating the compression method in the header. When a request for information about a USB device is received from a host device via the second connection unit, the control unit receives information about the USB device acquired from the USB device connected to the first connection unit, and The USB device server according to claim 2, wherein information indicating the compression method selected by the selection unit is transmitted to a host device via the second connection unit. The control unit compresses the data from the USB device in the selected compression method only for specific data among the data from the USB device, and converts the data to data other than the specific data. The USB device server according to claim 2, which is not applied to the USB device server. The control unit transmits information indicating the compression method selected by the selection unit to the host device via the network,
The control unit further receives data transmitted from the host device through the network via the first connection unit, and decompresses the data in a decompression method corresponding to the compression method selected by the selection unit. The USB device server according to claim 1, wherein the data is converted into a format for transmission in conformity with the USB standard and then transmitted to the USB device via the first connection unit. The specifying unit, USB device server of claim 1, wherein identifying the attribute based on the device descriptor or the interface descriptor obtained from the USB device connected to the first connecting portion. The first class is an audio class, the second class is a storage class,
The relationship information, USB device server of claim 1, wherein the association with the class identification information and Huffman compression scheme illustrating a first class. The USB device server further includes
USB device server of claim 1, further comprising an update unit that updates the relationship information. For causing a host device including a processor to execute processing for transmitting data to be transmitted to a USB device in conformity with the USB standard to a USB device server connected to the USB device via a network. A control program,
The process is
A receiving step of receiving information indicating an attribute of the USB device from the USB device server;
A selection step of selecting one of the plurality of compression methods according to the attribute indicated by the information received in the reception step based on the relationship information in which each of the plurality of compression methods is associated with the attribute of the USB device. When,
Including a transmission step of compressing data to be transmitted to the USB device in compliance with the USB standard using the compression method selected in the selection step and transmitting the data to the USB device server via the network. See
The information indicating the attribute of the USB device received in the receiving step is information indicating the class identification information acquired from the USB device by the USB device server,
The relationship information associates two different compression methods with class identification information indicating the first class and class identification information indicating the second class, respectively.
In the selection step, when the information indicating the class identification information received in the reception step indicates a first class, a control program for selecting a compression method associated with the first class in the relationship information . The process further includes a requesting step of requesting information indicating the attribute of the USB device from the USB device server.
  The control program according to claim 11.

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