JP7716107B2 - Device server, network system, device server control method, and program - Google Patents

Description

The present invention relates to a device server, a network system, a device server control method, and a program.

For example, Patent Document 1 discloses a technology in which a peripheral device (device) that supports multiple device classes displays on a display a list of device classes that are determined to be connectable to a computer (host device) that has host functionality for multiple device classes, and performs data communication using a device class selected by the user.

JP 2012-003470 A

However, the technology described in Patent Document 1 can use a large amount of network bandwidth, for example, when using a device that is locally connected to a device server via a network from a host device.

The present invention was made to solve the above problem, and aims to provide a device server or the like that can achieve stable communication when a host device uses a USB device via the device server.

In order to solve the above problem, a device server according to one aspect of the present invention is a device server that supports USB (Universal Serial a first communication interface connected to a USB (Universal Serial Bus) device and performing at least one of audio and video data communication with the USB device; a second communication interface connected to a host device; an acquisition unit that acquires mode information indicating multiple operating modes of the USB device; a calculation unit that calculates, for each of the multiple operating modes based on the mode information acquired by the acquisition unit, a first communication bandwidth used for communication between the USB device and the first communication interface when the USB device operates in that operating mode, and calculates a second communication bandwidth that can be used for communication between the host device and the second communication interface; a determination unit that determines whether each of the multiple first communication bandwidths calculated by the calculation unit exceeds the second communication bandwidth; an update unit that updates the mode information by deleting an operating mode from the multiple operating modes for which the determination unit determines that the calculated first communication bandwidth for that operating mode exceeds the second communication bandwidth; and an output unit that outputs the mode information updated by the update unit to the host device via the second communication interface.

With this, the device server can acquire mode information for the USB device and output updated mode information to the host device in which, from among multiple first communication bands used for communication with the USB device when the USB device is operated in each of multiple operating modes, any operating mode that exceeds the second communication band usable for communication with the host device is deleted. The host device can select an operating mode to be executed by the USB device from the multiple operating modes indicated by the updated mode information, thereby securing a communication band in the second communication band to be used for controlling the operation of the USB device. This allows the device server to operate the USB device in an appropriate operating mode. In this way, the device server can achieve stable communication when the host device uses the USB device via the device server.

Furthermore, when the USB device is operating in an operating mode selected by the host device based on the updated mode information, the determination unit may determine whether the first communication bandwidth calculated for that operating mode exceeds the second communication bandwidth. If the determination unit determines that the first communication bandwidth exceeds the second communication bandwidth, the update unit re-updates the updated mode information by deleting, from among the multiple operating modes indicated by the updated mode information, an operating mode for which the determination unit determines that the first communication bandwidth calculated for that operating mode exceeds the second communication bandwidth. When the updated mode information is re-updated, the first communication interface may disconnect from the USB device. When the first communication interface reconnects to the USB device, the output unit may output the mode information re-updated by the update unit to the host device via the second communication interface.

According to this, if the first communication bandwidth used for communication with the USB device exceeds the second communication bandwidth while the USB device is operating, the device server re-updates the updated mode information, allowing the mode information to be updated appropriately in response to fluctuations in communication conditions. Furthermore, after re-updating the updated mode information, the device server temporarily disconnects the communication connection with the USB device, reconnects to the USB device, and then outputs the re-updated mode information to the host device. This allows the host device to select an operating mode after resetting the communication state. More specifically, after resetting the communication state, the host device can select an operating mode to be executed by the USB device from among the multiple operating modes indicated by the re-updated mode information, thereby securing a communication bandwidth in the second communication bandwidth used to control the operation of the USB device. This allows the network system to maintain normal operation of the USB device. In this way, the device server can achieve stable communication when the host device is using the USB device via the device server.

Furthermore, when the host device receives an instruction to secure a predetermined communication bandwidth from the second communication bandwidth, the calculation unit may calculate a difference in communication bandwidth by subtracting the predetermined communication bandwidth from the second communication bandwidth, the determination unit may determine whether each of the multiple first communication bandwidths calculated by the calculation unit exceeds the difference in communication bandwidth, and the update unit may update the mode information by deleting an operating mode from the multiple operating modes for which the determination unit determines that the calculated first communication bandwidth for that operating mode exceeds the difference in communication bandwidth.

When the device server receives an instruction to reserve a specified communication bandwidth for another communication in the second communication bandwidth, it can output updated mode information to the host device that deletes, from the multiple first communication bandwidths used for communication with the USB device when the USB device is operated in each of the multiple operation modes indicated in the mode information, any operation mode that exceeds the differential communication bandwidth obtained by subtracting the specified communication bandwidth from the second communication bandwidth. The host device can select an operation mode to be executed by the USB device from the multiple operation modes indicated by the updated mode information, thereby securing the specified communication bandwidth in the second communication bandwidth while also securing the communication bandwidth used to control the operation of the USB device. This allows the device server to operate the USB device in an appropriate operation mode. In this way, the device server can achieve stable communication while securing the specified communication bandwidth when the host device uses the USB device via the device server.

Furthermore, when the USB device is operating in an operating mode selected by the host device based on the updated mode information, the determination unit determines whether the first communication bandwidth calculated for that operating mode exceeds the differential communication bandwidth. When the determination unit determines that the first communication bandwidth exceeds the differential communication bandwidth, the update unit re-updates the updated mode information by deleting, from among the multiple operating modes indicated by the updated mode information, an operating mode for which the determination unit determines that the first communication bandwidth calculated for that operating mode exceeds the differential communication bandwidth. When the updated mode information is re-updated, the first communication interface may disconnect from the USB device. When the first communication interface reconnects to the USB device, the output unit may output the mode information re-updated by the update unit to the host device via the second communication interface.

According to this, if the first communication bandwidth used for communication with the USB device exceeds the differential communication bandwidth while the USB device is operating, the device server re-updates the updated mode information, allowing the mode information to be updated appropriately in response to fluctuations in the communication state. Furthermore, after re-updating the updated mode information, the device server temporarily disconnects the communication connection with the USB device, reconnects to the USB device, and then outputs the re-updated mode information to the host device. This allows the host device to select an operating mode after resetting the communication state. More specifically, after resetting the communication state, the host device can select an operating mode to be executed by the USB device from among the multiple operating modes indicated by the re-updated mode information. This allows the second communication bandwidth to be secured while also securing the communication bandwidth used to control the operation of the USB device. This allows the network system to maintain normal operation of the USB device. In this way, the device server can achieve stable communication while securing the specified communication bandwidth when the host device is using the USB device via the device server.

The USB device may also transmit at least one of video and audio data to the first communication interface.

This allows the device server to transmit at least one of the video and audio data sent from the USB device to the host device via the second communication interface. This allows the device server to relay at least one of the video and audio data communications between the host device and the USB device.

A network system according to one aspect of the present invention includes a device server according to another aspect of the present invention, wherein the host device transmits a signal to the USB device requesting data transmission; in the device server, the determination unit determines that the first communication bandwidth exceeds the second communication bandwidth when the number of times the signal is transmitted from the host device within a predetermined time period is equal to or greater than a threshold; the update unit re-updates the updated mode information by deleting an operating mode, from among multiple operating modes indicated by the updated mode information, for which the determination unit determines that the calculated first communication bandwidth for that operating mode exceeds the second communication bandwidth; the first communication interface disconnects from the USB device when the updated mode information is re-updated; and the output unit outputs the mode information re-updated by the update unit to the host device via the second communication interface when the first communication interface reconnects to the USB device.

According to this, the network system determines that the first communication bandwidth has exceeded the second communication bandwidth when the number of times the host device transmits a signal requesting data transmission to the USB device within a predetermined time period is equal to or exceeds a threshold, thereby enabling monitoring of fluctuations in communication conditions. Furthermore, in the network system, the device server can output updated mode information to the host device, deleting, from among the multiple first communication bandwidths used for communication between the device server and the USB device when the USB device is operated in each of the multiple operating modes indicated in the updated mode information, any operating modes that exceed the second communication bandwidth available for communication between the device server and the host device. Since the host device can select an operating mode to be executed by the USB device from the multiple operating modes indicated by the updated mode information, when the host device is using the USB device via the device server, it can secure a communication bandwidth in the second communication bandwidth used to control the operation of the USB device. This contributes to maintaining the normal operation of the USB device. In this way, the network system can achieve stable communication when the host device is using the USB device via the device server. Note that the updated mode information may be mode information acquired when the device server initiates connection to the USB device. In this case, the above-mentioned re-updated mode information is the updated mode information.

In accordance with another aspect of the present invention, a device server control method includes: a first communication step of connecting to a USB device and performing at least one of audio and video data communication with the USB device; a second communication step of connecting to a host device; an acquisition step of acquiring mode information indicating multiple operating modes of the USB device; a calculation step of calculating, for each of the multiple operating modes based on the mode information acquired in the acquisition step, a first communication bandwidth to be used for communication with the USB device when the USB device operates in that operating mode, and calculating a second communication bandwidth usable for communication with the host device; a determination step of determining whether the multiple first communication bandwidths calculated in the calculation step exceed the second communication bandwidth; an update step of updating the mode information by deleting an operating mode from the multiple operating modes for which it is determined in the determination step that the calculated first communication bandwidth for that operating mode exceeds the second communication bandwidth; and an output step of outputting the mode information updated in the update step to the host device.

This achieves the same effect as the device server described above.

Furthermore, one aspect of the present invention is a program that causes a computer to execute the above-mentioned provision method.

It has the same effect as the device server above.

The present invention can be realized not only as an apparatus, but also as a method in which the processing means constituting the apparatus are steps, as a program that causes a computer to execute those steps, as a computer-readable recording medium such as a CD-ROM on which the program is recorded, or as information, data, or signals that represent the program. These programs, information, data, and signals may also be distributed via a communications network such as the Internet.

This invention enables a device server to achieve stable communication when a USB device is used from a host device via the device server.

FIG. 1 is a schematic diagram showing the configuration of a network system and a device server according to an embodiment. FIG. 2 is a flowchart illustrating an example of processing executed by the device server according to the embodiment. FIG. 3 is a flowchart showing the detailed flow of steps S06 and S07 in FIG. FIG. 4 is a diagram showing an example of mode information that is stored in advance in a USB device and indicates a plurality of operation modes in which the device can operate. FIG. 5 is a flowchart illustrating another example of the process executed by the device server according to the embodiment. FIG. 6 is a flowchart showing the detailed flow of steps S23 and S24 in FIG. FIG. 7 is a sequence diagram illustrating an example of processing executed by the network system according to the embodiment. FIG. 8 is a sequence diagram illustrating another example of the process executed by the network system according to the embodiment.

The following describes the embodiments in detail, with reference to the drawings.

The embodiments described below each represent a preferred specific example of the present invention. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components that are not recited in the independent claims that represent the highest concept of the present invention will be described as optional components that constitute a more preferred embodiment. Note that identical components will be assigned the same reference numerals, and descriptions may be omitted.

(Embodiment)
In this embodiment, a network system and a device server that can realize stable communication when a USB device is used from a host device via the device server will be described.

First, the network system according to this embodiment will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the configuration of the network system and device server according to this embodiment.

As shown in FIG. 1, the network system 1 includes, for example, a device server 10 and a host device 20. The device server 10 is a device that connects to the host device 20 and a USB device 30 and is a USB device server that makes the USB device 30 available to the host device 20 via the network. The USB device 30 is a device that communicates at least one of video and audio data with the host device 20 via the device server 10, such as a USB Video Class (UVC) web camera or a USB Audio Class (UAC) web audio device (e.g., a microphone or speaker). The host device 20 is a device operated by a user to configure various settings for connecting to the USB device 30 via the device server 10. The host device 20 is implemented, for example, as an information terminal such as a personal computer, smartphone, or tablet terminal. The host device 20 is realized, for example, by installing a specific application program on a general-purpose information terminal. Here, the specific application program is an application that connects to the device server 10 via a network and makes the USB device 30 available, and more specifically, is a management tool that manages the connection and disconnection between the host device 20 and the USB device.

In the example of FIG. 1, the device server 10 and the host device 20 are directly connected for communication without going through a repeater such as a router, but they may also be connected through a repeater such as a router (not shown). For example, when the device server 10 and the host device 20 are connected through a repeater, they may be connected via a wireless access point device using wireless communication such as Wi-Fi (registered trademark), or via an L2 switch or L3 switch using wired communication such as Ethernet (registered trademark). Also, for example, when the device server 10 and the host device 20 are connected through a repeater, the communication between the host device 20 and the repeater and the communication between the repeater and the device server 10 may use the same communication method, or they may use different communication methods.

In the example of FIG. 1, each of the host devices 20 and USB devices 30 is connected to the device server 10, but this is not limiting and multiple connections may be possible. In other words, multiple host devices 20 and multiple USB devices 30 may each be connected to the device server 10. The communication method between the device server 10 and the USB devices 30 is USB communication.

Next, referring back to Figure 1, the components of the device server 10 will be described. The device server 10 includes, for example, a first communication interface 11 (first communication IF in the figure), a second communication interface 12 (second communication IF in the figure), a control unit 13, and a memory unit 14.

The first communication interface 11 is a communication circuit (or communication module) that connects to the USB device 30 and performs audio and/or video data communication with the USB device 30. The first communication interface 11 communicates with the USB device 30 via USB communication or a local communication network, for example. The communication performed by the first communication interface 11 may be wireless or wired.

The second communication interface 12 is a communication circuit (or communication module) that connects to the host device 20. The second communication interface 12 may communicate with the host device 20 via, for example, a wide area communication network or a local area communication network, or may communicate with the host device 20 via both a wide area communication network and a local area communication network. In the latter case, the second communication interface 12 is connected to the host device 20 via a repeater (not shown). Note that there are no particular limitations on the communication method used by the second communication interface 12.

The control unit 13 performs various information processing related to the device server 10. The control unit 13 is realized, for example, by a microcomputer, but may also be realized by a processor or dedicated circuit. The functions of the control unit 13 are realized when hardware such as a microcomputer or processor that constitutes the control unit 13 executes a computer program (software) stored in the memory unit 14.

The control unit 13 includes, as functional components, an acquisition unit 13a, a calculation unit 13b, a determination unit 13c, an update unit 13d, and an output unit 13e. Specific processing performed by the acquisition unit 13a, calculation unit 13b, determination unit 13c, update unit 13d, and output unit 13e will be described later.

The memory unit 14 is a storage device that stores computer programs executed by the control unit 13. The memory unit 14 can also temporarily store information that needs to be stored due to information processing performed by the first communication interface 11, the second communication interface 12, and the control unit 13. The memory unit 14 is realized, for example, by an HDD (Hard Disk Drive), but may also be realized by semiconductor memory.

Next, an example of processing executed by the device server 10 according to this embodiment will be described with reference to Figures 2, 3, and 4. Figure 2 is a flow diagram showing an example of processing executed by the device server 10 according to this embodiment. Figure 3 is a flow diagram showing the detailed flow of steps S06 and S07 in Figure 2. Figure 4 is a diagram showing an example of mode information stored in advance in the USB device 30, indicating multiple operating modes in which the device can operate.

As shown in FIG. 2, in step S01, the second communication interface 12 connects to the host device 20. Although not shown, for example, when the device server 10 receives a command to connect to the host device 20 from a specific application on the host device 20 operated by a user, it transmits a response signal to the host device 20 and connects to the host device 20 via the second communication interface 12.

In step S02, the first communication interface 11 connects to the USB device 30. Although not shown, when the device server 10 receives a command to connect to the USB device from a specific application in the host device 20, it sends a signal requesting connection (hereinafter also referred to as a connection request) to the USB device 30. Then, when the device server 10 receives a response signal to the connection request from the USB device 30, it connects to the USB device 30 via the first communication interface 11.

In step S03, the acquisition unit 13a acquires mode information indicating multiple operating modes of the USB device 30 from the USB device 30. In other words, the mode information is, more specifically, information pre-stored by the USB device 30 that indicates multiple operating modes in which the device itself can operate. For example, if the USB device 30 is a web camera, the mode information includes multiple combinations of resolution, frame rate, and bit rate. The mode information may also include format information, color information, and the like. Also, for example, if the web camera is equipped with a microphone or speaker, the mode information includes information indicating multiple operating modes of the microphone or speaker. The acquisition unit 13a may acquire the mode information from the USB device 30 at any timing. For example, the acquisition of the mode information may be performed by initial setting or by user instruction. Furthermore, for example, the acquisition unit 13a may acquire mode information from the USB device 30 when the device server 10 starts connecting to the USB device 30 after the USB device 30 is powered on, or may acquire mode information every time a certain period (a certain amount of time) has elapsed after the connection.

Now, with reference to Figure 4, we will explain in detail the mode information that indicates the multiple operating modes of the USB device 30.

As shown in FIG. 4, each of the multiple operating modes A through E includes information such as different resolutions and bit rates. For example, operating mode A includes a resolution of 640 x 480 pixels and a bit rate ranging from a minimum of 3.72 MB/s to a maximum of 18.432 MB/s, while operating mode B includes a resolution of 160 x 120 pixels and a bit rate ranging from a minimum of 192 KB/s to a maximum of 1.152 MB/s. Based on the mode information (e.g., operating modes A through E) obtained via the device server 10, the host device 20 selects one operating mode (e.g., operating mode B) to be executed by the USB device 30 and transmits an instruction to execute the selected operating mode (e.g., operating mode B) to the USB device 30 via the device server 10. This allows the host device 20 to control the operation of the USB device 30 (i.e., use the USB device 30) via the device server 10 while securing a communication bandwidth appropriate for the selected operating mode (e.g., a communication bandwidth available for communication in operating mode B).

Referring again to FIG. 2. In step S04 of FIG. 2, the calculation unit 13b calculates, for each of a plurality of operation modes, the first communication bandwidth used for communication between the USB device 30 and the first communication interface 11 when the USB device 30 operates in that operation mode, based on the mode information acquired by the acquisition unit 13a. For example, based on the mode information indicating the plurality of operation modes of the USB device 30 acquired by the acquisition unit 13a, the calculation unit 13b calculates, for each operation mode, the first communication bandwidth used when communication is performed between the USB device 30 and the first communication interface 11 in that operation mode (e.g., a resolution of 640 x 480 pixels and a frame rate of 30 fps).

In step S05, the calculation unit 13b calculates the second communication bandwidth available for communication between the host device 20 and the second communication interface 12. Unlike the calculation of the first communication bandwidth, the calculation of the second communication bandwidth is performed by actual measurement. For example, the calculation unit 13b calculates the available second communication bandwidth by sending communication packets to the second communication interface 12 at a predetermined communication rate and actually measuring the communication packets that the host device 20 can receive.

In step S06, the determination unit 13c determines whether each of the multiple first communication bands calculated by the calculation unit 13b exceeds the second communication band. According to this determination, for example, if it is determined that the first communication band calculated by the calculation unit 13b exceeds the second communication band, this means that the first communication band required to use the corresponding operating mode cannot be secured for communication via the second communication interface.

In step S07, the update unit 13d deletes any of the multiple operation modes for which the determination unit 13c has determined that the first communication band calculated for that operation mode exceeds the second communication band, thereby updating the mode information to one that can appropriately control the USB device 30 over the second communication band.

Now, steps S06 and S07 will be explained in more detail with reference to Figure 3.

As shown in FIG. 3, in step S11, the determination unit 13c starts loop processing for each of the multiple operation modes.

In step S12, the determination unit 13c determines whether the first communication band when the USB device 30 operates in that operating mode is longer than the second communication band. If the determination unit 13c determines that the first communication band is longer than the second communication band (Yes in step S12), the update unit 13d deletes that operating mode from the mode information acquired by the acquisition unit 13a in step S03 (step S13). On the other hand, if the determination unit 13c determines that the first communication band is not longer than the second communication band (No in step S12), the update unit 13d does not delete that operating mode from the mode information acquired by the acquisition unit 13a in step S03 (step S14).

Although not shown in FIG. 3, after step S13 or S14, the determination unit 13c determines whether the loop processing has ended for all of the multiple operating modes, and if it determines that the loop processing has ended, ends the loop processing for each operating mode (step S15).

Referring again to FIG. 2, in step S08 of FIG. 2, the output unit 13e outputs the mode information updated by the update unit 13d to the host device 20 via the second communication interface 12. This enables the host device 20 to stably communicate with the USB device 30 via the device server 10.

Note that in FIG. 2, the processes of steps S03 to S05 do not necessarily have to be performed in this order. For example, after step S02, steps S05, S03, and S04 may be performed in this order, or steps S03, S05, and S04 may be performed in this order. Furthermore, the processes of steps S03 to S05 may be performed simultaneously in parallel.

Although not shown, the host device 20 selects the operation mode to be executed by the USB device 30 based on the mode information output from the device server 10, and sends an instruction to execute the selected operation mode to the USB device 30 via the device server 10. This allows the host device 20 to control the operation of the USB device 30 via the device server 10.

Note that when the USB device 30 is operating in accordance with instructions from the host device 20, the device server 10 re-updates the mode information in accordance with the communication state, and the process flow for controlling the operation of the USB device 30 based on the re-updated mode information will be described later in another example of processing executed by the network system 1.

Next, another example of processing executed by the device server 10 according to this embodiment will be described with reference to Figures 5 and 6. Figure 5 is a flow diagram showing another example of processing executed by the device server 10 according to this embodiment. Figure 6 is a flow diagram showing the detailed flow of steps S23 and S24 in Figure 5.

Note that steps S01 to S05 shown in Figure 5 are the same processes as steps S01 to S05 in Figure 2, and therefore will not be described here.

In the above example of processing, the flow from the host device 20 connecting to the USB device via the device server 10 to obtaining mode information updated by the device server 10 was described. In another example of processing, a processing example will be described in which the device server 10 receives from the host device 20 an instruction to reserve a specified communication band for other communication within the second communication band that can be used for communication between the host device 20 and the device server 10 (more specifically, the second communication interface 12). Note that the instruction to reserve a specified communication band within the second communication band is applied in cases where there is another communication within the second communication band that is desired to be used preferentially in addition to communication with the USB device 30 (for example, reserving the second communication band for another host device 20).

Although not shown in Figure 5, when the host device 20 receives an instruction to reserve a specified communication band within the second communication band, it sends the instruction to the device server 10.

In step S21, the second communication interface 12 receives an instruction to reserve a specified communication bandwidth from the host device 20. At this time, the second communication interface 12 notifies the calculation unit 13b of the instruction (not shown).

In step S22, the calculation unit 13b calculates the differential communication bandwidth, which is the remainder after subtracting the specified communication bandwidth from the second communication bandwidth.

In step S23, the determination unit 13c determines whether each of the multiple first communication bands calculated by the calculation unit 13b in step S04 exceeds the differential communication band.

In step S24, the update unit 13d updates the mode information by deleting, from among the multiple operation modes, an operation mode for which the determination unit 13c has determined that the calculated first communication bandwidth for that operation mode exceeds the differential communication bandwidth.

Now, steps S23 and S24 will be explained in more detail with reference to Figure 6.

As shown in FIG. 6, in step S31, the determination unit 13c starts loop processing for each of the multiple operation modes.

In step S32, the determination unit 13c determines whether the first communication bandwidth when the USB device 30 operates in that operation mode is greater than the differential communication bandwidth. If the determination unit 13c determines that the first communication bandwidth is greater than the differential communication bandwidth (Yes in step S32), the update unit 13d deletes that operation mode from the mode information acquired by the acquisition unit 13a in step S03 (step S33). On the other hand, if the determination unit 13c determines that the first communication bandwidth is not greater than the differential communication bandwidth (No in step S32), the update unit 13d does not delete that operation mode from the mode information acquired by the acquisition unit 13a in step S03 (step S34).

Although not shown in FIG. 6, after step S33 or S34, the determination unit 13c determines whether the loop processing has ended for all of the multiple operating modes, and if it determines that the loop processing has ended, ends the loop processing for each operating mode (step S35).

Referring again to FIG. 5, in step S25 of FIG. 5, the output unit 13e outputs the mode information updated by the update unit 13d to the host device 20 via the second communication interface 12. This allows the host device 20 to stably communicate with the USB device 30 via the device server 10 while securing a specific communication band within the second communication band designated by the user.

Although not shown, the host device 20 selects the operation mode to be executed by the USB device 30 based on the mode information output from the device server 10, and sends an instruction to execute the selected operation mode to the USB device 30 via the device server 10. This allows the host device 20 to control the operation of the USB device 30 (i.e., use the USB device 30) via the device server 10 while securing a predetermined communication bandwidth.

Note that, when the USB device 30 is operating in accordance with instructions from the host device 20, the device server 10 re-updates the mode information according to the communication state and controls the operation of the USB device 30 based on the re-updated mode information. In this process, the "second communication bandwidth" described in other examples of processing executed by the network system 1 should be read as "differential communication bandwidth."

Next, an example of processing executed by the network system 1 according to this embodiment will be described with reference to FIG. 7. FIG. 7 is a sequence diagram showing an example of processing executed by the network system 1 according to this embodiment. Here, an example of processing will be described in which the host device 20 initiates a connection with the USB device 30 via the device server 10 and controls the operation of the USB device 30.

As shown in FIG. 7, when the host device 20 receives a connection command to the device server 10 input by the user, it initiates a connection with the device server 10. More specifically, the host device 20 sends a connection command to the device server 10, and when it receives a response signal from the device server 10, it initiates a connection with the device server 10.

When the host device 20 receives a connection command to the USB device 30 input by the user (step S41), it sends the connection command to the device server 10 (step S42).

When the device server 10 receives a connection command to the USB device 30 from the host device 20, it sends a connection request to the USB device 30 (step S43).

When the USB device 30 receives the connection request from the device server 10, it transmits a response signal (step S44). At this time, the USB device 30 transmits mode information along with the response signal.

The acquisition unit 13a of the device server 10 acquires the mode information along with the response signal from the USB device 30 (step S45) and stores the acquired mode information in the memory unit 14 (not shown in Figure 7). At this time, the device server 10 transmits the response signal to the host device 20 via the second communication interface 12 (step S46).

When the host device 20 receives the response signal from the device server 10, it initiates a virtual USB connection (step S47). More specifically, the host device 20 performs processing to recognize the USB device 30 as being able to be driven via the device server 10 using a USB device driver provided by the device server 10. This processing allows the host device 20 to use the USB device 30 connected to the device server 10 as if it were directly connected to the host device 20.

The calculation unit 13b of the device server 10 calculates the second communication bandwidth for communication between the host device 20 and the device server 10 (more specifically, the second communication interface 12) through actual measurement (step S48).

The calculation unit 13b of the device server 10 reads the mode information stored in the memory unit 14 (not shown in Figure 7). Then, based on the mode information, the calculation unit 13b calculates, for each of a plurality of operating modes, the first communication bandwidth to be used for communication between the USB device 30 and the device server 10 (more specifically, the first communication interface 11) when the USB device 30 operates in that operating mode (step S49).

The determination unit 13c of the device server 10 determines whether each of the multiple first communication bands calculated by the calculation unit 13b exceeds the second communication band (step S50).

The update unit 13d of the device server 10 updates the mode information acquired by the acquisition unit 13a in step S45 by deleting any operation mode for which the determination unit 13c has determined that the calculated first communication band for that operation mode exceeds the second communication band (step S51). The update unit 13d then stores the updated mode information in the memory unit 14 (not shown in FIG. 7).

When the virtual USB connection is initiated (step S47), the host device 20 sends a signal requesting mode information (hereinafter referred to as a mode information request) to the device server 10 (step S52).

When the output unit 13e of the device server 10 receives the request for mode information, it reads the updated mode information from the memory unit 14 (not shown in Figure 7) and outputs the updated mode information to the host device 20 via the second communication interface 12 (step S53).

When the host device 20 acquires the updated mode information (step S54), it determines the operating mode to be executed by the USB device 30 from the multiple operating modes indicated by the updated mode information (step S55).

The host device 20 sends a command (hereinafter referred to as an execution command) to the device server 10 to cause the USB device 30 to execute the determined operating mode (step S56).

When the device server 10 receives an execution command from the host device 20 (not shown in Figure 7), it sends the execution command to the USB device 30 (step S57).

When the USB device 30 receives the execution command (not shown in Figure 7), it begins operation in the operating mode determined by the host device 20 in step S55 (step S58).

By performing the series of processes shown in FIG. 7, the network system 1 can update the mode information so that a communication band usable for controlling the USB device 30 is secured in the second communication band usable for communication between the host device 20 and the device server 10 before using the USB device 30 from the host device 20 via the device server 10. This allows the network system 1 to operate the USB device in an appropriate operating mode when using the USB device 30 from the host device 20 via the device server 10, thereby achieving stable communication.

As explained in FIG. 5, when the host device 20 receives an instruction to reserve a predetermined communication bandwidth for another communication, the second communication bandwidth is set to the differential communication bandwidth obtained by subtracting the predetermined communication bandwidth from the second communication bandwidth, and the series of processes shown in FIG. 7 are performed. This allows the network system 1 to achieve stable communication while reserving the predetermined communication bandwidth.

Next, another example of processing executed by the network system 1 according to this embodiment will be described with reference to FIG. 8. FIG. 8 is a sequence diagram showing another example of processing executed by the network system 1 according to this embodiment. Here, an example of processing will be described in which, after the host device 20 starts a connection with the USB device 30 via the device server 10 according to the sequence shown in FIG. 7, the second communication bandwidth is calculated and it is determined that the first communication bandwidth exceeds the second communication bandwidth.

In step S58 of FIG. 7, when the USB device 30 begins operating in the operating mode determined by the host device 20, the USB device 30 transmits at least one of video and audio data, and the host device 20 acquires this data transmitted from the USB device 30 via the device server 10 (not shown in FIGS. 7 and 8).

The host device 20 is expected to store a predetermined amount of data (e.g., the amount of data required for playback of several hundred milliseconds to several seconds) in a storage device (also called a buffer) in order to properly play back at least one of the video and audio using the acquired data. When the amount of data stored by the host device 20 is insufficient (not shown in Figure 8), the host device 20 sends a signal (hereinafter referred to as a data request) to the USB device 30 requesting the transmission of the missing data (step S60 in Figure 8).

When the device server 10 receives a data request sent from the host device 20 (not shown in Figure 8), it sends the data request to the USB device 30 (step S61).

When the USB device 30 receives a data request sent from the device server 10 (not shown in Figure 8), it sends the data to the device server 10 (step S62), and the device server 10 sends the data obtained from the USB device 30 to the host device 20 (step S63). Note that steps S60 to S63 are executed repeatedly.

The determination unit 13c of the device server 10 determines whether the first communication bandwidth used for communication between the USB device 30 and the device server 10 (here, data transmission from the USB device 30 to the device server 10) exceeds the second communication bandwidth available for communication between the device server 10 and the host device 20. This determination may be performed for a predetermined number of communications, with steps S60 to S63 counted as one communication. For example, the determination unit 13c determines that the first communication bandwidth exceeds the second communication bandwidth if the number of times a signal requesting data transmission from the host device 20 to the USB device 30 is transmitted from the host device 20 within a predetermined period of time is equal to or exceeds a threshold. In other words, the determination unit 13c recognizes that a change in the communication bandwidth between the device server 10 and the host device 20 (the so-called second communication bandwidth) has occurred, resulting in an increase in the number of times the signal is transmitted within a predetermined period of time, due to the number of times the signal is transmitted from the host device 20 requesting data transmission being equal to or exceeds the threshold. As a result, the determination unit 13c determines that the first communication bandwidth exceeds the second communication bandwidth and notifies the update unit 13d of this fact. The threshold value may be set, for example, to 1.1 to 1.5 times the number of times that the host device 20 sends a signal requesting data transmission to the USB device 30 within a specified period of time when the communication bandwidth between the host device 20 and the device server 10 is sufficient.

If the determination unit 13c determines that the first communication band exceeds the second communication band (step S64), the update unit 13d of the device server 10 re-updates the mode information updated in step S51 of FIG. 7 (step S65). Note that if the determination unit 13c of the device server 10 determines that the first communication band does not exceed the second communication band, the processing from step S64 onwards is not performed.

The determination unit 13c of the device server 10 determines that the first communication band exceeds the second communication band in the following cases, for example:

For example, the determination unit 13c determines that the first communication bandwidth exceeds the second communication bandwidth by determining whether data can be transmitted in response to a data request received from the host device 20.

A data request sent by the host device 20 includes, for example, a specified time and a specified data amount. The specified time and specified data amount included in the data request mean that the data request requests the transmission of the specified amount of data within the specified time. In this case, when the device server 10 receives a data request, it attempts to transmit the specified amount of data within the specified time, but if the communication bandwidth between the host device 20 and the device server 10 is insufficient, it will not be able to transmit the specified amount of data within the specified time. Therefore, if the determination unit 13c determines that the specified amount of data cannot be transmitted to the host device 20 within the specified time included in the data request, it determines that the first communication bandwidth has exceeded the second communication bandwidth.

Furthermore, for example, the determination unit 13c determines whether the first communication bandwidth has exceeded the second communication bandwidth using changes in the reception interval of data requests received from the host device 20.

In this case, if the communication bandwidth between the host device 20 and the device server 10 is sufficient, it is expected that the data request transmission intervals will be equal (also called normal intervals). However, if the communication bandwidth is insufficient, the data request transmission intervals will be shorter than the normal intervals. Therefore, if the determination unit 13c determines that the reception intervals of data requests received from the host device 20 are shorter than the normal intervals, it determines that the first communication bandwidth has exceeded the second communication bandwidth.

In this case, the update unit 13d of the device server 10 re-updates the updated mode information by deleting, from among the multiple operation modes indicated in the mode information updated by the update unit 13d in step S51 of FIG. 7, an operation mode for which the determination unit 13c has determined that the calculated first communication bandwidth for that operation mode exceeds the current second communication bandwidth (step S65). At this time, the update unit 13d stores the re-updated mode information in the memory unit 14 (not shown in FIG. 8).

The device server 10 then sends a disconnection command to the USB device 30 (step S66).

When the USB device 30 receives the disconnection command sent from the device server 10 (not shown in Figure 8), it sends a response signal to the device server 10 (step S67).

When the first communication interface 11 of the device server 10 receives a response signal from the USB device 30 (not shown in Figure 8), it disconnects from the USB device 30 (step S68).

The second communication interface 12 of the device server 10 sends a disconnection notification to the host device 20 notifying that the connection with the USB device 30 has been disconnected (step S69).

When the host device 20 receives the disconnection notification sent from the device server 10, it recognizes that the connection with the USB device 30 has been disconnected and disconnects the connection with the USB device 30 (step S70).

The first communication interface 11 of the device server 10 transmits a signal (connection request) requesting connection with the USB device 30 (step S71).

When the USB device 30 receives the connection request sent from the device server 10, it sends a response signal (step S72).

When the device server 10 receives the response signal sent from the USB device 30, it resumes the connection with the USB device 30 (step S73) and sends a connection notification to the host device 20 notifying it that the connection with the USB device 30 has resumed (step S74).

When the host device 20 receives the connection notification sent from the device server 10, it sends a response signal to the device server 10 (step S75) and initiates a virtual USB connection (step S76).

The host device 20 transmits a signal requesting mode information (so-called a mode information request) (step S77).

When the output unit 13e of the device server 10 receives a request for mode information from the host device 20, it reads the mode information re-updated in step S65 from the memory unit 14 (not shown in Figure 8), and outputs the mode information re-updated in step S65 to the host device 20 via the second communication interface 12 (step S78).

When the host device 20 receives the updated mode information output from the device server 10 (step S79), it determines the operating mode to be executed by the USB device 30 from the multiple operating modes indicated by the updated mode information (step S80).

The host device 20 sends a command (so-called execution command) to the device server 10 to cause the USB device 30 to execute the determined operating mode (step S81).

When the device server 10 receives an execution command from the host device 20 (not shown in Figure 8), it sends the execution command to the USB device 30 (step S82).

When the USB device 30 receives the execution command (not shown in Figure 8), it begins operation in the operating mode determined by the host device 20 in step S80 (step S83).

By performing the series of processes shown in FIG. 8, when the network system 1 is using the USB device 30 from the host device 20 via the device server 10 (in other words, when it is controlling the operation of the USB device 30), it can cause the USB device 30 to transmit data in an operating mode that matches the available bandwidth in the second communication band that can be used for communication between the host device 20 and the device server 10. As a result, when the USB device 30 is being used from the host device 20 via the device server 10, the network system 1 can maintain the normal operating mode of the USB device 30, thereby achieving stable communication.

If the host device 20 receives an instruction to reserve a predetermined communication bandwidth in advance, the second communication bandwidth is treated as the difference communication bandwidth, which is the remainder obtained by subtracting the predetermined communication bandwidth from the second communication bandwidth, and the series of processes shown in Figure 8 are performed. This allows the network system 1 to achieve stable communication while reserving the predetermined communication bandwidth.

As described above, the device server of this embodiment can acquire mode information for a USB device and output updated mode information to the host device in which, from among multiple first communication bands used for communication with the USB device when the USB device is operated in each of multiple operating modes, any operating mode that exceeds the second communication band usable for communication with the host device is deleted. The host device can select an operating mode to be executed by the USB device from the multiple operating modes indicated by the updated mode information, thereby securing a communication band in the second communication band to be used for controlling the operation of the USB device. This allows the device server to operate the USB device in an appropriate operating mode. In this way, the device server can achieve stable communication when the host device uses the USB device via the device server.

Furthermore, if the first communication band used for communication with the USB device exceeds the second communication band while the USB device is operating, the device server re-updates the updated mode information, allowing the mode information to be updated appropriately in response to fluctuations in communication conditions. Furthermore, after re-updating the updated mode information, the device server temporarily disconnects the communication connection with the USB device, reconnects to the USB device, and then outputs the re-updated mode information to the host device. This allows the host device to select an operating mode after resetting the communication state. More specifically, after resetting the communication state, the host device can select an operating mode to be executed by the USB device from among the multiple operating modes indicated by the re-updated mode information, thereby securing a communication band in the second communication band used to control the operation of the USB device. This allows the network system to maintain normal operation of the USB device. In this way, the device server can achieve stable communication when the host device is using the USB device via the device server.

Furthermore, when an instruction to secure a specified communication bandwidth in the second communication bandwidth is received, the device server can output updated mode information to the host device that deletes, from the multiple first communication bandwidths used for communication with the USB device when the USB device is operated in each of the multiple operation modes indicated by the mode information, any operation mode that exceeds the differential communication bandwidth obtained by subtracting the specified communication bandwidth from the second communication bandwidth. The host device can select an operation mode to be executed by the USB device from the multiple operation modes indicated by the updated mode information, and can therefore secure the communication bandwidth used to control the operation of the USB device while securing the specified communication bandwidth in the second communication bandwidth. This allows the device server to operate the USB device in an appropriate operation mode. In this way, when the host device uses the USB device via the device server, the device server can achieve stable communication while securing the specified communication bandwidth.

Furthermore, if the first communication bandwidth used for communication with the USB device exceeds the differential communication bandwidth while the USB device is operating, the device server re-updates the updated mode information, thereby enabling the mode information to be updated appropriately in response to fluctuations in the communication state. Furthermore, after re-updating the updated mode information, the device server temporarily disconnects the communication connection with the USB device, reconnects to the USB device, and then outputs the re-updated mode information to the host device. This allows the host device to select an operating mode after resetting the communication state. More specifically, after resetting the communication state, the host device can select an operating mode to be executed by the USB device from among the multiple operating modes indicated by the re-updated mode information. This allows the second communication bandwidth to be secured while also securing the communication bandwidth used to control the operation of the USB device. This allows the network system to maintain normal operation of the USB device. In this way, the device server can achieve stable communication while securing the specified communication bandwidth when the host device is using the USB device via the device server.

The device server can also transmit at least one of the video and audio data sent from the USB device to the host device via the second communication interface. This allows the device server to relay at least one of the video and audio data communications between the host device and the USB device.

The network system can monitor fluctuations in communication conditions by determining that the first communication bandwidth has exceeded the second communication bandwidth when the number of times a signal requesting data transmission from the host device to the USB device within a specified time period is equal to or exceeds a threshold. In the network system, the device server can output updated mode information to the host device, deleting any of the first communication bandwidths used for communication between the device server and the USB device when the USB device is operated in each of the multiple operating modes indicated in the updated mode information that exceed the second communication bandwidth available for communication between the device server and the host device. The host device can select an operating mode to be executed by the USB device from the multiple operating modes indicated in the updated mode information, thereby ensuring a communication bandwidth in the second communication bandwidth used to control the operation of the USB device when the host device is using the USB device via the device server. This contributes to maintaining normal operation of the USB device. In this way, the network system can achieve stable communication when the host device is using the USB device via the device server. The updated mode information may be mode information acquired when the device server initiates connection to the USB device. In this case, the above-mentioned re-updated mode information is the updated mode information.

The present invention can be realized not only as an apparatus, but also as a method in which the processing means constituting the apparatus are steps, as a program that causes a computer to execute those steps, as a computer-readable recording medium such as a CD-ROM on which the program is recorded, or as information, data, or signals that represent the program. These programs, information, data, and signals may also be distributed via a communications network such as the Internet.

The device server, network system, device server control method, and program of the present invention have been described above based on an embodiment, but the present invention is not limited to this embodiment. Various modifications conceivable by those skilled in the art to this embodiment, as well as configurations constructed by combining components from different embodiments, are also included within the scope of the present invention, as long as they do not deviate from the spirit of the present invention.

This invention can be used in device servers and other devices that enable stable communication when using USB devices from a host device via a device server.

REFERENCE SIGNS LIST 1 Network system 10 Device server 11 First communication interface 12 Second communication interface 13 Control unit 13a Acquisition unit 13b Calculation unit 13c Determination unit 13d Update unit 13e Output unit 14 Storage unit 20 Host device 30 USB device

Claims (8)

a first communication interface that is connected to a USB (Universal Serial Bus) device and that performs at least one of audio and video data communication with the USB device;
a second communication interface for connecting to a host device;
an acquisition unit that acquires mode information indicating a plurality of operation modes of the USB device;
a calculation unit that calculates, for each of the plurality of operation modes based on the mode information acquired by the acquisition unit, a first communication bandwidth that is used for communication between the USB device and the first communication interface when the USB device operates in that operation mode, and calculates a second communication bandwidth that is usable for communication between the host device and the second communication interface;
a determination unit that determines whether each of the plurality of first communication bands calculated by the calculation unit exceeds the second communication band;
an update unit that updates the mode information by deleting an operation mode, among the plurality of operation modes, for which it has been determined by the determination unit that the first communication band calculated for that operation mode exceeds the second communication band;
an output unit that outputs the mode information updated by the update unit to the host device via the second communication interface;
Equipped with
Device server. the determination unit determines, when the USB device is operating in an operation mode selected by the host device based on the updated mode information, whether the first communication bandwidth calculated for the operation mode exceeds the second communication bandwidth;
when the determination unit determines that the first communication band exceeds the second communication band, the update unit re-updates the updated mode information by deleting an operation mode, from among the plurality of operation modes indicated by the updated mode information, for which the determination unit determines that the first communication band calculated for that operation mode exceeds the second communication band;
When the updated mode information is updated again, the first communication interface disconnects the connection with the USB device;
When the first communication interface is connected to the USB device again, the output unit outputs the mode information re-updated by the update unit to the host device via the second communication interface.
The device server of claim 1 . the calculation unit, when the host device receives an instruction to reserve a predetermined communication bandwidth from the second communication bandwidth, calculates a difference communication bandwidth by subtracting the predetermined communication bandwidth from the second communication bandwidth;
the determination unit determines whether each of the plurality of first communication bands calculated by the calculation unit exceeds the differential communication band;
the update unit updates the mode information by deleting an operation mode, among the plurality of operation modes, for which the determination unit has determined that the first communication bandwidth calculated for that operation mode exceeds the differential communication bandwidth.
The device server of claim 1 . the determination unit determines, when the USB device is operating in an operation mode selected by the host device based on the updated mode information, whether or not the first communication bandwidth calculated for the operation mode exceeds the differential communication bandwidth;
When the determination unit determines that the first communication band exceeds the differential communication band, the update unit re-updates the updated mode information by deleting an operation mode, from among the plurality of operation modes indicated by the updated mode information, for which the determination unit determines that the first communication band calculated for that operation mode exceeds the differential communication band;
When the updated mode information is updated again, the first communication interface disconnects the connection with the USB device;
When the first communication interface is connected to the USB device again, the output unit outputs the mode information re-updated by the update unit to the host device via the second communication interface.
The device server of claim 3 . the USB device transmits at least one of video and audio data to the first communication interface;
The device server according to any one of claims 1 to 4. The device server according to claim 1,
The host device transmits a signal to the USB device requesting the transmission of data;
In the device server,
the determination unit determines that the first communication band exceeds the second communication band when the number of times the signal is transmitted from the host device within a predetermined time is equal to or greater than a threshold value;
the update unit re-updates the updated mode information by deleting an operation mode, from among the plurality of operation modes indicated by the updated mode information, for which it has been determined by the determination unit that the first communication band calculated for that operation mode exceeds the second communication band;
When the updated mode information is updated again, the first communication interface disconnects the connection with the USB device;
When the first communication interface is connected to the USB device again, the output unit outputs the mode information re-updated by the update unit to the host device via the second communication interface.
Network system. a first communication step of connecting to a USB device and performing at least one of audio and video data communication with the USB device;
a second communication step of connecting to a host device;
an acquisition step of acquiring mode information indicating a plurality of operation modes of the USB device;
a calculation step of calculating, for each of the plurality of operation modes based on the mode information acquired in the acquisition step, a first communication bandwidth to be used for communication with the USB device when the USB device operates in that operation mode, and calculating a second communication bandwidth that can be used for communication with the host device;
a determination step of determining whether the plurality of first communication bands calculated in the calculation step exceed the second communication band;
an updating step of updating the mode information by deleting an operation mode, among the plurality of operation modes, for which it has been determined in the determining step that the first communication band calculated for that operation mode exceeds the second communication band;
an output step of outputting the mode information updated in the update step to the host device;
Including,
A method for controlling a device server. A program that causes a computer to execute the device server control method according to claim 7.