JP2007226635A - Server device and client device of remote desktop system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To considerably reduce the data amount of image data transmitted from a server to a client to increase a reaction speed of a GUI without increasing a load on the client side in a remote desktop system. <P>SOLUTION: An eigenvalue calculation part 801 of a server E01 calculates a peculiar value (for example, a hash value) of image data to be displayed on a display 410 of a client E02. The calculated eigenvalue and image data are not only stored in a table but also transmitted to the client. A comparative determination part 802 refers to the eigenvalue of image data to be transmitted and eigenvalues stored in the table, and transmits only the eigenvalue to the client without transmitting the image data when the coincidence of the eigenvalue of the image data is found in the table. The client stores data received from the server into a table, and acquires image data corresponding to an eigenvalue from the table to output this image data to the display when only the eigenvalue is received from the server. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention transmits an operation instruction such as an application from a client device having an input device such as a keyboard and a display device such as a bitmap display capable of displaying video to a server device at a remote location. As a result, the present invention relates to a remote desktop system that displays an image transmitted from a server device to a client device on the client device, and more particularly to a server device and a client device of the remote desktop system.

  TSS (Time Sharing System), which has been popular since the 1970s as a remote desktop system, is a multi-user general-purpose computer, and multiple users (users) share valuable computer resources with multiple terminal devices. Can be used at the same time. Hereinafter, an example of a conventional TSS will be described with reference to FIG.

  In the TSS illustrated in FIG. 23, for example, the terminal server 102 and the terminal device 103 operating on the general-purpose computer A01 that provides the TSS are connected by the serial transmission A02, and the user A03 is transferred from the terminal device 103 to the TSS. Log in and execute the application 101. The terminal server 102 passes the character string input from the keyboard of the terminal device 103 to the input of the application 101 and sends back the character string output of the application 101 to the terminal device 103. Thereby, the terminal device 103 can display the character string received from the terminal server 102 on the display 104 and perform remote operation. The character string is converted into a bit string of a non-procedural serial transmission standard such as IEEE (Institute of Electrical and Electronic Engineers) -488 (or RS-232C), and is transmitted / received between the TSS and the terminal device 103. .

  On the other hand, the X window system that has been popular since the 1980s as a remote desktop system is a client-server type remote desktop system developed at Massachusetts Institute of Technology. In the TSS described above, only transmission and reception of character strings was possible. However, the X window system is based on the premise that the terminal device includes a bitmap display 204, and the user can use a pointing device 205 such as a mouse or a keyboard. As a result of the input, not only the character string but also video information such as a still image and a moving image is received, and this video information is displayed on the bitmap display 204, whereby the video information can be visually recognized. Hereinafter, an example of a conventional X window system will be described with reference to FIG.

  The X window system illustrated in FIG. 24 operates, for example, on an X server 202 that operates on a general-purpose computer that functions as the server B01, an X application 201 dedicated to the X server, and a terminal device that functions as the client B03. The X client 203 is configured by a communication network B02 that connects the server B01 and the client B03. When the X application 201 outputs to the X server 202 on the general-purpose computer that is the server B01, the X server 202 outputs the X data on the terminal device that is the client B03 connected via the communication network B02. A drawing data string is transmitted to the client 203. The X client 203 interprets the drawing data string and displays it on the bitmap display 204 provided in the terminal device.

  The drawing data string handled in the above X window system is a time-series set of drawing data. The drawing data is “a line of black and thickness 1 from the coordinates (X1, Y1) to (X2, Y2) of the screen”. Abstract drawing commands such as “Draw”. In addition to drawing a line, the abstract drawing command includes primitive drawing processing such as hitting a dot, drawing a square, painting the inside of the square, drawing an ellipse, and filling the inside of the ellipse.

  The drawing data string is converted into a communication protocol called the X protocol, and is transmitted and received between the X server 202 and the X client 203. On the other hand, the button pressing state of the pointing device 205 is also converted into the X protocol, and transmitted / received between the X server 202 and the X client 203.

  Furthermore, since the 1990s, VNC (Virtual Network Computing) developed at AT & T (American Telephone and Telegraph) Cambridge Laboratory has been popular. Hereinafter, an example of a conventional VNC will be described with reference to FIG.

  The VNC illustrated in FIG. 25 is a client / server type remote desktop system, similar to the X window system, and performs a drawing process based on bitmap image transmission between the VNC server 303 and the VNC client 304.

  In the VNC, a frame buffer 302 corresponding to the desktop which is the operating environment of the client C03 is provided on the general-purpose computer C01 side. The frame buffer 302 is a memory area that can store at least one bitmap image of the entire screen. It is also possible to sequentially output from the frame buffer 302 to a bitmap display (not shown) on the general-purpose computer C01 side.

  On the other hand, the VNC server 303 continuously monitors the frame buffer 302, extracts a bitmap image as a result of rendering by the application 301 from the frame buffer 302, and uses this as a rendering data string via the communication network C02. Transmit to the VNC client 304. The drawing data handled by VNC is not an abstract drawing command as in the X window system, but “draw a bitmap image of vertical and horizontal (800,600) pixels on screen coordinates (X3, Y3)”. Inefficient image containing a bit map image. Then, the VNC client 304 interprets this drawing data string and displays it on the bitmap display 305 provided in the client C03.

  Further, the drawing data string is converted into a communication protocol called a VNC protocol, and transmitted / received between the VNC server 303 and the VNC client 304. On the other hand, the button pressing state of the pointing device 306 is also converted into the VNC protocol and transmitted / received between the VNC server 303 and the VNC client 304.

  In the X window system, the X application 201 generates the drawing data string, but the VNC is characterized in that it can be applied to all applications that have the ability to draw in the frame buffer 302. Since the drawing data string is transferred once through the frame buffer 302, the application 301 does not need any special device. Therefore, in VNC, an OS (Operating System) such as Microsoft Windows (registered trademark) or Apple MacOS (registered trademark) having a drawing system completely different from the X window system operates on the general-purpose computer C01. Even in this case, it is possible to remotely control the application 301 uniformly from the same client C03.

  On the other hand, as an execution environment for current applications, PCs (Persopnal Computers) occupy a dominant market position. The PC has abundant CPU (Central Processing Unit) power, a bitmap display and frame buffer as output devices, and a mouse and keyboard as input devices. For this reason, the PC can play both roles of the server side and the client side of the remote desktop system. Currently, usage forms in which users remotely operate an application of another PC from one PC are becoming more common among users.

  In recent years, as the momentum of information protection has increased, such as the enforcement of the Personal Information Protection Law, corporate PCs containing customer lists and important documents are always kept in the company, and remote desktop systems are installed only when necessary. A centralized data management method that uses and browses from a mobile PC is drawing attention. In the centralized data management method, the important data itself is not copied to a mobile PC or the like that is carried to the outside, so that the important data is not stolen together with the mobile PC, and the safety of the important data is increased. Even if a malicious third party obtains the drawing data sequence of the remote desktop system and restores a part of the bitmap image, it is only a part of the important data displayed on the application. One million customer lists cannot be copied in an instant, increasing security.

  Next, a drawing data string of a remote desktop system in VNC or similar technology will be described in detail. The drawing data string including the uncompressed bitmap image obtained from the monitoring of the frame buffer has a huge amount of data. For example, when transmitting a 32-bit full-color bitmap image at 1024 × 768 pixels, which is a resolution of a general PC, at 10 frames / second that allows the user to feel a smooth video change, the total data amount is about 30 MB. / S (= 240 Mbps) is reached. However, the practical upper limit of the throughput (average transmission bandwidth) of ADSL (Asymmetric Digital Subscriber Line) currently used by individual users for Internet connection is about 1.5 MB / S (= 12 Mbps). is there. Therefore, it can be said that it is extremely impractical to transmit a drawing data sequence including an uncompressed bitmap image in order to smoothly display an image displayed on a PC display.

  Therefore, the following Non-Patent Document 1 monitors the frame buffer that changes in time series by taking advantage of the characteristic that “a part of the entire PC desktop screen is often updated”, and updates only the update area. A communication protocol for extracting as a differential bitmap image and transmitting the differential bitmap image as a drawing data string to a client is described. Hereinafter, a conventional VNC will be described in detail with reference to FIGS.

  The VNC server D01 and the VNC client D02 shown in FIG. 26 are obtained by extracting the minimum blocks necessary for explanation of the operation from the VNC system shown in FIG. 25. The VNC server D01 shown in FIG. The VNC client 303 shown in FIG. 26 corresponds to the VNC client 304 of the VNC system shown in FIG.

  First, each block of the VNC server D01 shown in FIG. 26 will be described. The frame buffer 401 is a memory area in which image data output from an application and corresponding to a client-side desktop image can be read and written. The frame buffer 401 stores image data at a certain moment. The frame acquisition unit 402 is a frame grabber that acquires image data from the frame buffer 401. The previous frame buffer 404 is a working memory area that stores a copy of the image data in the frame buffer 401 immediately before the update, and the comparison unit 403 includes the image data in the frame buffer 401 and the image data in the previous frame buffer 404. And a time-series change is observed to generate a drawing data string of the difference. Further, the communication unit 405 converts the drawing data string, which is the difference image data generated by the comparison unit 403, into the VNC protocol, and transmits it to the VNC client D02.

  Next, each block of the VNC client D02 shown in FIG. 26 will be described. The communication unit 406 receives the VNC protocol from the VNC server D01 and converts it into the original drawing data string. The drawing unit 407 uses the drawing data included in the drawing data string to draw the image data in the frame buffer 408 that is a memory area for holding the image data. The output unit 409 sequentially reads the frame buffer 408, performs desired signal processing such as D / A (digital / analog) conversion, and outputs the result to the display 410, thereby displaying image data on the display 410.

  Next, the operation of the VNC server D01 shown in FIG. 26 will be described with reference to the flowchart of the VNC server shown in FIG. In the VNC server D01, the frame acquisition unit 402 acquires image data (drawing data) from the frame buffer 401 (step S601), and first confirms whether or not the previous frame buffer 404 is empty. Whether or not is determined (step S602). At this time, if the previous frame buffer 404 is empty (when no image data has been written), the process proceeds to step S605. If the previous frame buffer 404 is not empty, the process proceeds to step S603.

  When the previous frame buffer 404 is not empty, the comparison unit 403 compares the difference between the image data in the previous frame buffer 404 and the image data obtained from the frame acquisition unit 402. Then, drawing data is generated, and a drawing data string that is a set of drawing data is generated (step S603). Then, the communication unit 405 converts the drawing data sequence generated by the comparison unit 403 into a VNC protocol and transmits it to the VNC client D02 (step S604). In addition, the previous frame buffer 404 is overwritten with the currently acquired image data (image data in the frame buffer 401) (step S605). Further, the VNC server D01 acquires a higher-level operation state, and ends the operation when an end condition such as, for example, a power-off button is pressed, while the end condition does not exist. Returning to step S601, the above processing is repeated. As a result, the VNC server D01 always monitors the frame buffer 401 during operation, extracts a difference from the previous frame buffer 404 as a drawing data string, further converts the drawing data string into the VNC protocol, and sends it to the VNC client D02. Keep sending.

  Note that the drawing data here is a bitmap image indicating image data of all or a part of the screen, and layout information of the bitmap image (that is, an X coordinate designating which portion on the screen is located) Y coordinate, and information such as the width and height of the bitmap image). The drawing data has, for example, the following data structure 1. The following data structure is merely an example, and the coordinate system and the order of each element may be different.

  (X coordinate on screen, Y coordinate on screen, horizontal width of bitmap image, height of bitmap image, bitmap image)... <Data structure 1>

  Next, the operation of the VNC server D01 shown in FIG. 26 will be described with reference to the flowchart of the VNC client shown in FIG. The VNC client D02 receives the VNC protocol from the VNC server D01 via the communication unit 406, and converts it into the original drawing data string (step S701). The drawing unit 407 draws image data in the frame buffer 408 using the drawing data included in the drawing data string (step S702). The output unit 409 sequentially reads the frame buffer 408, performs desired signal processing such as D / A conversion, and outputs the result to the display 410 (step S703). In addition, the VNC client D02 acquires a higher-level operation state, and ends the operation when an end condition such as, for example, the power-off button is pressed, while the end condition does not exist. Returning to step S701, the above processing is repeated. As a result, the VNC client D02 always receives the VNC protocol during operation, acquires a drawing data string, draws drawing data in the frame buffer 408, and continues to present images to the user via the display 410. .

  On the other hand, for example, Patent Document 1 below discloses an improved technique for a remote desktop system. Hereinafter, the technique disclosed in Patent Document 1 will be described with reference to FIGS. 29 to 31.

  In the technique disclosed in Patent Document 1, the data structure transmitted from the server to the client is set as follows.

(Cache information, SID, codeword) ... <RKEY>

  In FIG. 29, for example, regarding the difference image transmitted to the client in the VNC system described above, the horizontal width (W) and height (H) of the update area of the image to be updated exceed the threshold values (ThW, ThH). It is determined whether or not there is (step S2801). At this time, if both the horizontal width and height of the update area of the image to be updated do not exceed the threshold value, the process proceeds to step S2802, and otherwise, the process proceeds to step S2803.

  If both the horizontal width and height of the update area of the image to be updated do not exceed the threshold value, it is determined that the update area of the image to be updated is small and the image data is not worth caching, and the area key (RKEY) ) Is substituted for “cache not required”, “NULL” for the sequence identifier (SID), and “image data to be updated (update data)” for the code word, and transmitted to the client (step S2802). That is, when the update data update area is small, the update data is transmitted from the server to the client.

  On the other hand, if it is determined in step S2801 that at least one of the width and height of the update area of the image to be updated exceeds the threshold value, RKEY creation processing is performed (step S2803). Details of the RKEY creation process are shown in FIG.

  In FIG. 30, the server sets “cache” in the RKEY cache information of the message header (step S2901), and determines whether or not the same update area exists in the cache memory (step S2902). If it is determined in step S2902 that the same update area exists, the process advances to step S2903, and it is determined whether or not there is only one same update area in the cache memory (step S2903). In step S2902, if there is no update region having the same update region, the process proceeds to step S2910, and DCT (Discrete Cosine Transform), quantization, and entropy processing is performed to encode the update data (step S2910). ), The process proceeds to step S2909.

  If it is determined in step S2903 that only one update area exists in the cache memory, the update data is encoded by performing DCT, quantization, and entropy processing (step S2905), and a plurality of update areas are detected. The code word of the data having the same update area (code word in the cache memory) is compared with the update data encoded in step 2905 to search whether there is data having the same code word. (Step S2906). In step S2907, if data having the same code word exists, the process proceeds to step S2908. If data having the same code word does not exist, the process proceeds to step S2909. On the other hand, if there is only one update area in the cache memory in step S2903, the process proceeds to step S2904.

  In step S2904, processing is performed when there is only one data having the same update area in the cache memory. In this case, “cached” is assigned to the cache information, “SID of matched data in the cache memory” is assigned to the SID, and RKEY data created without setting anything in the code word is transmitted to the client. .

  In step S2908, processing is performed when data having the same code word exists in the cache memory. In this case, “cached” is assigned to the cache information, “SID of matched data in the cache memory” is assigned to the SID, and RKEY data created without setting anything in the code word is transmitted to the client. .

  In step S2909, processing is performed when the update areas are the same in the cache memory but the same codeword does not exist, or when the update areas are different. In this case, RKEY data in which “cache” is assigned to the cache information, “unallocated value” to the SID, and “encoded update data” is assigned to the code word is transmitted to the client.

  On the other hand, in FIG. 31, the client monitors and analyzes the RKEY cache information received from the server (step S3001). If “cache not required”, the client proceeds to step S3002. If “cache”, the client proceeds to step S3003. If “cached”, the process advances to step S3005.

  In step S3002, a process when no cache is required is performed. In this case, data to be updated directly is assigned to the code word, and this is used as update data.

  In step S3003, processing is performed when registration in the cache is necessary. In this case, since the RKEY codeword is encoded, it is decoded and the decoded data is used as update data. Further, the client registers the RKEY data in the local cache memory (step S3004).

  Further, in step S3005, a process when already cached is performed. In this case, the same RKEY data as the received RKEY SID is acquired from the local cache memory. Further, the client decodes the RKEY codeword acquired in step 3005 and sets the decoded data as update data (step S3006).

Data is displayed in the update area using the update data created in each of steps S3002, S3004, and 3006 (step S3007).
JP-T-2005-501355 (FIGS. 4-7, paragraphs 0015, 0016) Tristan Richardson, RealVNC Ltd: “The RFB Protocol” Version 3.8, 8 March 2005

  Among conventional remote desktop systems, an X window system type remote desktop system is considered to have the best transmission efficiency between the server and the client. In the X window system type remote desktop system, the drawing data has a high level of abstraction such as “draw a line”, and as a result, the amount of data is minimized. However, a special X application for generating a drawing data string for the X window system is required as a price.

  With the spread of the Internet, various PCs and general-purpose computers execute various applications to form a distributed network. For this reason, an X window system that always requires an X application does not meet the demands of the times, and it can be said that a VNC type remote desktop system with higher versatility for connection between different types is suitable.

  However, in the VNC type remote desktop system, as described above, the data amount of the drawing data string including the bitmap image tends to be enormous. In particular, in an application using a GUI (Graphic User Interface) in which beautiful buttons using bitmap images are arranged on the entire recent screen, it is not uncommon for the update area to occupy the entire screen. For example, in the case of display by a wizard-type application as shown in FIG. 32, for example, when the “Next” button is pressed, a new next screen is displayed, so the entire screen must be sent from the server to the client. There are so many opportunities to go. This causes a decrease in the response speed of the GUI, which decreases the convenience for the user and increases the user's stress.

  For example, as described above, when transmitting one 32-bit full-color bitmap image with 1024 × 768 pixels via an ADSL communication network with a throughput of 1.5 MB / S, a display time of about 2 seconds is displayed. There will be a delay. Therefore, it is desired to develop a VNC type remote desktop system capable of generating a drawing data string with a high degree of abstraction, such as an X window system type remote desktop system. However, making an application completely correspond to an X window system type abstract drawing instruction means that a new X application is newly developed, which is meaningless. This is clear considering the background of the development of VNC.

  In the technique according to Patent Document 1 described above, the update display data can be specified as “cached” or “cache unnecessary”, so that a drawing data string having a high degree of abstraction can be obtained in a VNC type remote desktop system. However, with this technology, depending on the size of the update area, there are parts that are lossy encoded and parts that are not encoded, and the display image realized on the client side is visually strange. There is also a problem that it becomes difficult to see.

  Further, in the remote desktop system, the advantage is that the load on the client side is basically small. However, in the technique according to Patent Document 1 described above, it is necessary to provide a decoder for decoding the encoded data on the client side. There is a problem that the load on the client side cannot be reduced with respect to the decoding function.

  Further, in the technique according to Patent Document 1 described above, the RKEY data to be created is created based on the update area and the size of the update area, and thus, for example, different GUIs having the same button-shaped image arrangement. Even when the same update image data exists in the update area, it is necessary to create a new RKEY because the update areas are different. Since this RKEY is stored in the cache memory in both the server and the client, the cache There is a problem that the amount increases.

  In order to solve the above-described problems, the present invention greatly reduces the amount of drawing data strings transmitted and received between the server and the client without increasing the load on the client side, and improves the response speed of the GUI. An object of the present invention is to provide a server device and a client device of a remote desktop system that can be used.

In order to achieve the above object, according to the present invention, there is provided a server device of a remote desktop system that transmits image data to be displayed on a display unit of the client device to the client device,
Table storage means for storing a table for holding data including at least a unique value for specifying the image data;
Eigenvalue calculation means for setting, as the eigenvalue for specifying the image data, a hash value obtained by performing an operation with a hash function on the image data;
The data held in the table is compared with the eigenvalue calculated by the eigenvalue calculating means, and an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculating means is found in the table. In this case, display update data that includes the eigenvalue that specifies the image data and does not include the image data is created, while an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculation unit is found in the table. If not, comparison determination means for creating display update data including both the eigenvalue specifying the image data and the image data;
Data transmission means for transmitting the display update data to the client device;
Additional registration means for registering the display update data as the data in the table;
A server device is provided.

In order to achieve the above object, according to the present invention, there is provided a server device of a remote desktop system that transmits image data to be displayed on a display unit of the client device to the client device,
Table storage means for storing a table for holding data including at least a unique value for specifying the image data;
Eigenvalue calculation means for setting, as the eigenvalue for specifying the image data, a hash value obtained by performing an operation with a hash function on the image data;
The data held in the table is compared with the eigenvalue calculated by the eigenvalue calculating means, and an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculating means is found in the table. In this case, display update data that includes the eigenvalue specifying the image data and does not include the image data is generated, while an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculation unit is found in the table. If not, comparison determination means for generating intermediate data including both the eigenvalues specifying the image data and the image data;
The data stored in the table is compared with the image data included in the intermediate data, and image data whose horizontal width and height match the image data included in the intermediate data is found in the table. If the image data included in the intermediate data is compared with the image data found in the table, the difference image data and the arrangement position of the difference image data are obtained, and the intermediate data is acquired. Regarding data, while deleting the image data and creating the display update data by inserting the difference image data and the arrangement position of the difference image data and the eigenvalue of the image data found in the table, No image data having the same width and height as the image data included in the intermediate data was found in the table. Expediently, a difference determining means for generating data for the display update from the intermediate data,
Data transmission means for transmitting the display update data to the client device;
Additional registration means for registering the display update data as the data in the table;
A server device is provided.

In order to achieve the above object, according to the present invention, there is provided a server device of a remote desktop system that transmits image data to be displayed on a display unit of the client device to the client device,
Threshold receiving means for receiving a value of the upper limit data amount of the table of the client device from the client device;
First table storage means for storing a first table for holding data including at least an eigenvalue for specifying the image data;
Second table storage means for storing a second table for holding data selected from the data held in the first table;
Eigenvalue calculation means for setting, as the eigenvalue for specifying the image data, a hash value obtained by performing an operation with a hash function on the image data;
The data held in the second table is compared with the eigenvalue calculated by the eigenvalue calculating means, and an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculating means is found in the second table. The display update data that includes the eigenvalue that specifies the image data and does not include the image data, while the eigenvalue that matches the eigenvalue calculated by the eigenvalue calculation means is If not found in the second table, the comparison determination means for creating display update data including both the eigenvalue specifying the image data and the image data;
Display update data transmission means for transmitting the display update data to the client device;
Additional registration means for registering the display update data as the data in the first table together with information indicating the storage order;
Storing the new data in the first table in the second table so that the data amount of the second table does not exceed the data amount based on the upper limit data amount; Table update control means for transmitting the data stored in the second table to the client device as table update data for updating the table of the client device simultaneously with storing the data in the second table;
A server device is provided.

  Further, according to the present invention, in addition to the above configuration, the data to be stored in the table of the client device transmitted by the data transmitting means is used to store the table on the client device side before the transmission. There is provided a server device having data conversion means for converting according to the type of memory to be used.

In order to achieve the above object, according to the present invention, a client device of a remote desktop system that displays an image based on image data received from a server device,
Display means for displaying images;
A table for storing a table for holding data including at least the eigenvalue for specifying the image data, with a hash value obtained by performing an operation using a hash function on the image data as the eigenvalue of the image data Storage means;
Data receiving means for receiving display update data for updating the display on the display means from the server device;
When the display update data received by the data receiving means includes both the eigenvalue for specifying the image data and the image data, an image to be displayed on the display means based on the image data On the other hand, when the display update data received by the data receiving means includes only the eigenvalue specifying the image data and does not include the image data, the display update data is stored in the table. A drawing for creating an image to be displayed on the display means based on image data held together with the eigenvalue in the table by comparing the existing data and the eigenvalue included in the display update data Creating means;
Output means for outputting the image created by the drawing creation means to the display means;
Additional registration means for registering the display update data received by the data receiving means as the data in the table;
A client device is provided.

In order to achieve the above object, according to the present invention, a client device of a remote desktop system that displays an image based on image data received from a server device,
Display means for displaying images;
A table for storing a table for holding data including at least the eigenvalue for specifying the image data, with a hash value obtained by performing an operation using a hash function on the image data as the eigenvalue of the image data Storage means;
Data receiving means for receiving display update data for updating the display on the display means from the server device;
The display update data received by the data receiving unit includes the differential image data, the arrangement position of the differential image data, the unique value of the image data to be compared, and the unique value of the original image data created by the difference synthesis. The difference stored in the table together with the eigenvalue from the table by comparing the data held in the table with the eigenvalue of the image data to be compared with the difference. The image data to be compared is read out, the difference image data is synthesized with the arrangement position of the read image data to create composite image data, and the difference image data and the display update data are The arrangement position of the difference image data and the eigenvalue of the image data found in the table are deleted and the combination is deleted. A difference synthesizing means for creating intermediate data by inserting the image data,
When the display update data received by the data receiving means includes both the eigenvalue and the image data for specifying the image data, an image to be displayed on the display means based on the image data is displayed. When the display update data created and received by the data receiving means includes only the eigenvalues specifying the image data and does not include the image data, the display update data is stored in the table. Compare the data and the eigenvalue included in the display update data, create an image to be displayed on the display means based on the image data held together with the eigenvalue in the table, and perform the difference synthesis With respect to the display update data created by the means, a drawing creation means for creating an image to be displayed on the display means based on the composite image data ,
Output means for outputting the image created by the drawing creation means to the display means;
Additional registration means for registering the display update data referred to when the image is created by the drawing creation means as the data in the table;
A client device is provided.

In order to achieve the above object, according to the present invention, a client device of a remote desktop system that displays an image based on image data received from a server device,
Display means for displaying images;
A table for storing a table for holding data including at least the eigenvalue for specifying the image data, with a hash value obtained by performing an operation using a hash function on the image data as the eigenvalue of the image data Storage means;
Threshold transmission means for transmitting the value of the upper limit data amount of the table stored in the table storage means to the server device;
Data receiving means for receiving display update data for drawing for updating the display on the display means and table update data for updating the table stored in the table storage means from the server device When,
When the display update data received by the data receiving means includes both the eigenvalue for specifying the image data and the image data, an image to be displayed on the display means based on the image data On the other hand, when the display update data received by the data receiving means includes only the eigenvalue specifying the image data and does not include the image data, the display update data is stored in the table. A drawing for creating an image to be displayed on the display means based on image data held together with the eigenvalue in the table by comparing the existing data and the eigenvalue included in the display update data Creating means;
Output means for outputting the image created by the drawing creation means to the display means;
An additional registration means for registering the table update data including both the eigenvalue for specifying the image data received by the data reception means and the image data as the data in the table;
A client device is provided.

  Further, according to the present invention, in addition to the above configuration, when storing the data in the table storage means, the data is converted according to the type of memory used as the table storage means, and the table storage means When the data is read out, a client device is provided that includes data conversion means for converting the data into a data structure that can be referred to when the image is created by the drawing creation means.

  The present invention has the above-described configuration, and can greatly reduce the data amount of the drawing data sequence transmitted and received between the server and the client, and improves the user's convenience by improving the response speed of the GUI. , It has the effect of reducing user stress. Further, the present invention has an effect that it is not necessary to mount a decoder on the client side, and the load on the client can be reduced. Further, according to the present invention, even when the same update image data exists in different areas, the update display data can be reproduced without newly adding to the table, and the table amount can be reduced. Has an effect. Further, according to the present invention, since all data transmitted from the server to the client is lossless compression, the image data realized on the client side is uniform, and a visually stable display can be realized on the client side. have.

  Hereinafter, first to fourth embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration example of a remote desktop system according to the first embodiment of this invention. The remote desktop system shown in FIG. 1 has a configuration in which a server E01 and a client E02 are connected via an arbitrary data transmission path.

  Hereinafter, the configuration of the server E01 illustrated in FIG. 1 will be described. The server E01 illustrated in FIG. 1 includes a frame buffer 401, a frame acquisition unit 402, a comparison unit 403, a previous frame buffer 404, an eigenvalue calculation unit 801, a comparison determination unit 802, a communication unit 803, and a table storage unit 804. ing.

  The frame buffer 401, the frame acquisition unit 402, the comparison unit 403, and the previous frame buffer 404 illustrated in FIG. 1 include the frame buffer 401 of the VNC server D01 illustrated in FIG. The frame acquisition unit 402, the comparison unit 403, and the previous frame buffer 404 can be used. That is, from the comparison unit 403 of the server E01 shown in FIG. 1, the image data in the frame buffer 401 acquired by the frame acquisition unit 402 and the image data (frame buffer in the previous frame buffer) acquired by the frame acquisition unit 402, as in the VNC system. As a result of comparison with the image data stored in the frame buffer 401 immediately before the update of the image data in 401, the drawing data of the difference between these image data is output in the format of the data structure 1 described above.

  Data in the format of the data structure 1 output from the comparison unit 403 of the server E01 illustrated in FIG. 1 is supplied to the eigenvalue calculation unit 801. The eigenvalue calculation unit 801 calculates bitmap image data of the drawing data along the data structure 1 supplied from the comparison unit 403 using a hash function, and a hash value (hereinafter, eigenvalue) unique to the bitmap image data. Is calculated). Then, the eigenvalue calculation unit 801 outputs the data of the data structure 1 including the drawing data and the calculated eigenvalue to the comparison determination unit 802.

  Although it is preferable to use a hash function to calculate the eigenvalue, other methods may be used as long as the eigenvalue is calculated for arbitrary input data. The reason why it is preferable to use the hash function is as follows. The hash function is a hash function such as MD-5 or SHA-1 used for electronic signatures, and these hash functions are 128-bit or 160-bit numerical values (values unique to arbitrary data). Is calculated. When such a hash function is used, when two pieces of data X and Y are given, if the data X and Y are the same data, the hash values H (X) and H (Y) are also equal. However, when the data X and Y are different even by 1 bit, the hash values H (X) and H (Y) take different numerical values. In principle, the hash value may be the same for different data, but the possibility is only generated with a very low probability. Therefore, the possibility that different data take the same hash value can be ignored in practice. Since the hash function is a function having the above-described characteristics, it is effective when obtaining eigenvalues from arbitrary data.

  When the comparison determination unit 802 receives the data of the data structure 1 including the drawing data supplied from the eigenvalue calculation unit 801 and the eigenvalue, the comparison determination unit 802 uses the table stored in the table storage unit 804 and uses the following data structure: Create 2 data.

  (Bitmap presence flag, X coordinate on the screen, Y coordinate on the screen, width of the bitmap image, height of the bitmap image, bitmap image, eigenvalue) ... <Data structure 2>

  As described above, the data structure 2 inserts the bitmap presence flag, the X coordinate on the screen, the Y coordinate on the screen, the width of the bitmap image, the height of the bitmap image, the bitmap image, and the eigenvalue data. It has a field to do. The bitmap presence flag field is a 1-bit field indicating whether or not a bitmap image is included in a subsequent bitmap image field. When it is determined that this bitmap image is held in the table held by the client E02, a bit indicating the absence of the bitmap image (for example, “0”) is set in the bitmap presence flag, Bitmap images should not be included in the bitmap image fields. On the other hand, if it is determined that this bitmap image is not held in the table held by the client E02, a bit indicating the presence of the bitmap image (eg, “1”) is set in the bitmap presence flag. The bitmap image is included in the bitmap image field.

  The X coordinate on the screen, the Y coordinate on the screen, the horizontal width of the bitmap image, and the height of the bitmap image are the bitmap image (the bitmap image or eigenvalue included in the bitmap image field). Is the arrangement position information indicating the arrangement position of the bitmap image specified by Here, the above four fields are used as in the VNC system, but any information and format can be adopted as long as the arrangement position of the bitmap image can be indicated.

  Also, the eigenvalue calculated from the bitmap image is inserted into the eigenvalue field. On the client E02 side, this unique value is used as information for specifying a bitmap image.

  The comparison determination unit 802 generates data including bitmap image data based on the comparison result between the eigenvalue received from the eigenvalue calculation unit 801 and the eigenvalue in the table stored in the table storage unit 804. Whether to generate data that does not include bitmap image data is determined. This data generation processing will be described in detail later.

  The table storage unit 804 stores a table prepared for additionally recording data along the data structure 2 created by the comparison determination unit 802. When the comparison determination unit 802 receives the eigenvalue and the drawing data from the eigenvalue calculation unit 801, the comparison determination unit 802 uses the table stored in the table storage unit 804 to use the data structure 2 related to the eigenvalue and the drawing data received from the eigenvalue calculation unit 801. And data of the created data structure 2 (or data of the data structure 1 and eigenvalues) are stored in a table. The comparison determination unit 802 of the server E01 determines whether or not to transmit bitmap image data to the client by comparing the eigenvalues. Therefore, even if only the eigenvalue is held in the table in the table storage unit 804, the present invention It is possible to operate.

  The table stored in the table storage unit 804 can be realized in any format as long as it can hold the data of the data structure 2 created by the comparison determination unit 802 as described above. It is possible to set the maximum number of table entries (area holding data of one data structure 2) to 1,000, and to update the table by a FIFO (First In First Out) method.

  Further, the communication unit 803 converts the data along the data structure 2 supplied from the comparison determination unit 802 into, for example, the VNC protocol and transmits the data to the client E02.

  Next, the configuration of the client E02 illustrated in FIG. 1 will be described. The client E02 illustrated in FIG. 1 includes a communication unit 805, a drawing creation unit 806, a table storage unit 807, a frame buffer 408, an output unit 409, and a display (bitmap display) 410.

  The communication unit 805 receives data conforming to the VNC protocol transmitted from the server E01, converts the data into data conforming to the data structure 2, and outputs the data to the drawing creation unit 806.

  Upon receiving the data along the data structure 2 supplied from the communication unit 805, the drawing creation unit 806 receives data included in the data along the data structure 2 supplied from the communication unit 805, or a table storage unit Image data is created using data according to the data structure 2 held in the table stored in 807, and the created image data is written into the frame buffer 408.

  When bitmap image data is already included in the data supplied from the communication unit 805, the drawing creation unit 806 writes this image data in the frame buffer 408. The image data generation processing in the drawing creation unit 806 will be described in detail later.

  The table storage unit 807 stores a table prepared for additionally recording data along the data structure 2 received by the drawing creation unit 806. When the drawing creation unit 806 receives the data of the data structure 2 from the communication unit 805, the drawing creation unit 806 creates image data to be written in the frame buffer 408 using the table stored in the table storage unit 807, and The data of data structure 2 received from 805 is stored in the table. Note that the drawing creation unit 806 of the client E02 performs a process of reading bitmap image data having a matching unique value from the table in the table storage unit 807, so that only the bitmap image data and the unique value are stored in the table in the table storage unit 807. Even if held, the present invention is operable.

  The table stored in the table storage unit 804 can be realized in an arbitrary format similarly to the table in the table storage unit 804 of the server E01. However, the server E01 needs to grasp the contents held in the table stored in the table storage unit 807 of the client E02. Therefore, for example, it is desirable that the table in the table storage unit 804 of the server E01 and the table in the table storage unit 807 of the client E02 be created and held in the same format.

  Next, an example of the operation of the server E01 illustrated in FIG. 1 will be described with reference to FIG. FIG. 2 is a flowchart illustrating an example of the operation of the server according to the first embodiment of this invention.

  In the server E01, as in the case of the VNC system, the frame acquisition unit 402 acquires image data (drawing data) from the frame buffer 401 (step S601), and for each drawing data in the drawing data string constituting the image data, a hash is obtained. The eigenvalue of the bitmap image is calculated using the function (step S901). As described above, it is not always necessary to use a hash function as long as an eigenvalue can be calculated for arbitrary input data.

  Next, by checking whether or not the previous frame buffer 404 is empty, it is determined whether or not it is the first image data acquisition operation (step S602). At this time, if the previous frame buffer 404 is empty (when no image data has been written), the comparison process and the conversion process in step S902 are skipped, and the process proceeds to step S903. If is not empty, the process proceeds to step S902.

  In step S902, the eigenvalue of each bitmap image calculated in step S901 is compared with the eigenvalue in the table stored in the table storage unit 804, and based on the comparison result, data along the data structure 1 and A process of converting the eigenvalue into data according to the data structure 2 is performed.

  Hereinafter, the details of the comparison process and the conversion process in step S902 will be described with reference to FIG. FIG. 3 is a flowchart illustrating an example of comparison processing and conversion processing performed by the comparison determination unit of the server in the first exemplary embodiment of the present invention.

  In FIG. 3, first, the comparison determination unit 802 of the server E01 compares the unique value of the drawing data supplied from the unique value calculation unit 801 with the unique value held in the table in the table storage unit 804 to calculate the unique value. It is determined whether or not the same value as the unique value of the drawing data supplied from the unit 801 is held in the table in the table storage unit 804 (step S1101).

If the same eigenvalue exists in the table in step S1101, the data along the data structure 1 is
・ Set the bitmap existence flag to “0” indicating the absence of bitmap image ・ Set the eigenvalue corresponding to the data along the data structure 1 (addition)
By deleting the bitmap image data and setting NULL, data along the data structure 2 is created (step S1102).

On the other hand, if the same eigenvalue does not exist in the table in step S1101, for the data along the data structure 1,
・ Set the bitmap existence flag to “1” indicating the existence of the bitmap image ・ Set the eigenvalue corresponding to the data along the data structure 1 (addition)
Thus, data along the data structure 2 is created (step S1103).

  Although not reflected in the drawing, if it is determined in step S602 that it is the first time, all drawing data and eigenvalues need to be transmitted from the server E01 to the client E02. Data along the data structure 2 is created according to step S1103.

  As described above, when data along the data structure 2 is created in step S1102 or S1103, or when it is determined as the first time in step S602, as shown in FIG. Data (at least eigenvalue) is additionally registered in the table of the table storage unit 804 (step S903), and is converted to data conforming to the VNC protocol, for example, and then transmitted to the client E02 (step S904). Similarly to the VNC system, the previous frame buffer 404 is overwritten with the image data acquired this time (image data in the frame buffer 401) (step S605), and some termination condition is satisfied in step S606. On the other hand, if the end condition does not exist, the process returns to step S601 and the above processing is repeated.

  Next, an example of the operation of the client E02 illustrated in FIG. 1 will be described with reference to FIG. FIG. 4 is a flowchart illustrating an example of the operation of the client according to the first embodiment of this invention.

  First, the client E02 receives data conforming to the VNC protocol transmitted from the server E01, and converts this data into data conforming to the data structure 2 (step S1001). Then, the drawing creation unit 806 stores the frame buffer 408 based on the bitmap image data included in the data along the data structure 2 or the bitmap image data in the table stored in the table storage unit 807. The drawing data to be written is created (step S1002).

  Hereinafter, the details of the drawing creation processing in step S1002 will be described with reference to FIG. FIG. 5 is a flowchart illustrating an example of a drawing creation process performed by the drawing creation unit of the client according to the first embodiment of this invention.

  5, first, the drawing creation unit 806 of the client E02 checks the value of the bitmap presence flag in the data along the data structure 2 supplied from the communication unit 805 (step S1151).

  If the value of the bitmap presence flag is “1” indicating the presence of the bitmap image in step S1151, it can be seen that the data along the data structure 2 includes the bitmap image data. In this case, the drawing creating unit 806 extracts bitmap image data from the data along the data structure 2 received from the server E01 (step S1152). Note that since the drawing creation unit 806 writes to the frame buffer 408 using the extracted bitmap image data, it is not necessary to create drawing data by referring to the table in the table storage unit 807.

  On the other hand, if the value of the bitmap presence flag is “0” indicating the absence of the bitmap image in step S1151, it can be seen that the data along the data structure 2 does not include the bitmap image data. In this case, the drawing creation unit 806 extracts a unique value from the data along the data structure 2 received from the server E01, and acquires bitmap image data corresponding to the extracted unique value from the table in the table storage unit 807. Then, bitmap image data is extracted from this data (step S1152).

  Specifically, for example, in step S1152, the drawing creation unit 806 confirms that the bitmap presence flag is “0”, and then the unique value of the input data along the data structure 2 and the table in the table storage unit 807. And the data along the data structure 2 having the same eigenvalue as the input data along the data structure 2 is obtained from the table. Then, the bitmap existence flag and the eigenvalue are deleted from the data along the acquired data structure 2 to create data along the data structure 1 and output the created data.

  Further, the drawing creating unit 806 additionally registers data (at least bitmap image data and eigenvalues) along the data structure 2 received from the server E01 in the table of the table storage unit 807 (step S1003). In this case, only the data along the data structure 2 including the bitmap image data may be additionally registered in the table.

  In FIG. 4, the drawing creating unit 806 draws image data in the frame buffer 408 using the drawing data included in the drawing data string (step S702). As described above, when it is confirmed in step S1151 of FIG. 5 that the bitmap presence flag is “1”, the drawing creation unit 806 determines that the bitmap exists from the input data along the data structure 2. The flag and eigenvalue are deleted to create data according to the data structure 1 and output the created data. Therefore, the drawing creation unit 806 sets the bitmap existence flag to “0” in step S1151 of FIG. If it is confirmed that there is, the drawing creation unit 806 performs data output based on the data acquired in step S1153 of FIG. The output unit 409 sequentially reads the frame buffer 408, performs desired signal processing such as D / A conversion, and outputs the result to the display 410 (step S703). In step S704, the operation is terminated if any termination condition is satisfied, whereas if the termination condition does not exist, the process returns to step S601 and the above processing is repeated.

  As described above, in the first embodiment of the present invention, in the remote desktop system, a unique value (for example, a hash value) is calculated from each drawing data, and each drawing data is associated with the unique value and registered in the table. This table is shared by the server and the client. As a result, when a bitmap image held in the client-side table is input as display image data, the server replaces the bitmap image with a unique value (in addition, a drawing position such as an X coordinate or a Y coordinate). By transmitting (information designating), the client can specify the bitmap image (and also the drawing position) from this eigenvalue and update the display. As a result, the amount of drawing data transferred from the server to the client is reduced.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. FIG. 6 is a block diagram showing a configuration example of the remote desktop system in the second exemplary embodiment of the present invention. The remote desktop system illustrated in FIG. 6 has a configuration in which a server F01 and a client F02 are connected via an arbitrary data transmission path.

  Hereinafter, the configuration of the server F01 illustrated in FIG. 6 will be described. A server F01 illustrated in FIG. 6 includes a frame buffer 401, a frame acquisition unit 402, a comparison unit 403, a previous frame buffer 404, an eigenvalue calculation unit 801, a comparison determination unit 1201, a difference determination unit 1202, a communication unit 1203, and a table storage. Part 1204.

  The frame buffer 401, the frame acquisition unit 402, the comparison unit 403, and the previous frame buffer 404 shown in FIG. 6 include the frame buffer 401 of the VNC server D01 shown in FIG. The frame acquisition unit 402, the comparison unit 403, and the previous frame buffer 404 can be used. That is, from the comparison unit 403 of the server F01 illustrated in FIG. 6, the image data in the frame buffer 401 acquired by the frame acquisition unit 402 and the image data (frame buffer in the previous frame buffer) acquired by the frame acquisition unit 402, as in the VNC system. As a result of comparison with the image data stored in the frame buffer 401 immediately before the update of the image data in 401, the drawing data of the difference between these image data is output in the format of the data structure 1 described above.

  In addition, the eigenvalue calculation unit 801 illustrated in FIG. 6 can use the eigenvalue calculation unit 801 illustrated in FIG. 1. That is, data in the format of data structure 1 output from the comparison unit 403 of the server F01 illustrated in FIG. 6 is supplied to the eigenvalue calculation unit 801, and the eigenvalue calculation unit 801 applies the bitmap image data of the drawing data to the eigenvalue calculation unit 801. Thus, an operation using a hash function is performed to calculate an eigenvalue (hash value).

  In the configuration of FIG. 6, the data of the data structure 1 including the drawing data output from the eigenvalue calculation unit 801 and the eigenvalue are supplied to the comparison determination unit 1201. When the comparison determination unit 1201 receives the data and the eigenvalue along the data structure 1 supplied from the eigenvalue calculation unit 801, the comparison determination unit 1201 uses the table stored in the table storage unit 1204 to convert the data of the data structure 3 below. create.

  (Bitmap presence flag, X coordinate on the screen, Y coordinate on the screen, width of the bitmap image, height of the bitmap image, image data (bitmap image or difference bitmap image + eigen value + difference area ( X coordinate, Y coordinate, horizontal width, height)), eigenvalue, difference data existence flag) ... <data structure 3>

  Among the fields of the data structure 3 described above, the bitmap presence flag, the X coordinate on the screen, the Y coordinate on the screen, the width of the bitmap image, the height of the bitmap image, and the eigenvalue fields are the above-described data. Same as structure 2.

  On the other hand, the image data field of the data structure 3 includes a case where a bitmap image is included as in the case of the data structure 2 described above, and a case where a difference bitmap image is included. When the difference bitmap image is included, the image data field further includes a unique value for specifying the difference bitmap image and arrangement position information of the difference bitmap image. The difference data presence flag field is a 1-bit field indicating whether or not a difference bitmap image is included in the image data field.

  The comparison determination unit 1201 generates data including bitmap image data based on the comparison result between the eigenvalue received from the eigenvalue calculation unit 801 and the eigenvalue in the table stored in the table storage unit 1204. Or whether to generate data that does not include bitmap image data. The basic processing of the comparison determination unit 1201 is similar to the comparison processing unit 802 shown in FIG. 1, but the processing related to the comparison determination unit 1201 will be described in detail later.

  In addition, the difference determination unit 1202 includes the data A group along the data structure 3 supplied from the comparison determination unit 1201 and the data B group along the data structure 3 held in the table in the table storage unit 1204. In order to reduce the amount of data of the data A group, the data B group is searched for data similar to the received data A group, the difference between them is obtained, and the data update of the data A group is performed. Has the function to perform. The data update process in the difference determination unit 1202 will be described in detail later.

  The table storage unit 1204 stores a table prepared for additionally recording data along the data structure 3 output to the communication unit 1203 after the update processing in the difference determination unit 1202. The comparison determination unit 1201 performs a process of searching for the eigenvalue that matches the eigenvalue received from the eigenvalue calculation unit 801 from the table stored in the table storage unit 1204, and the difference determination unit 1202 stores the data in the data structure 3. If the image contains a bitmap image, the image similar to the bitmap image is searched from the table stored in the table storage unit 1204, and the difference data of these images is acquired to the client F02. The data amount is reduced by updating the data to be transmitted.

  The table stored in the table storage unit 1204 can be realized in any format as long as it can hold the data of the data structure 3 output from the difference determination unit 1202 as described above. The maximum number of table entries (area holding data of one data structure 2) can be set to 1000, and the table can be updated by the FIFO method.

  Further, the communication unit 1203 converts the data along the data structure 3 supplied from the difference determination unit 1202 into, for example, the VNC protocol and transmits the data to the client F02.

  Next, the configuration of the client F02 illustrated in FIG. 6 will be described. The client F02 illustrated in FIG. 6 includes a communication unit 1205, a difference synthesis unit 1206, a table storage unit 1207, a drawing creation unit 1208, a frame buffer 408, an output unit 409, and a display (bitmap display) 410. .

  The frame buffer 408 and output unit 409 of the client F02 shown in FIG. 6 and the display 410 include the frame buffer 408 and output unit 409 of the VNC server D01 shown in FIG. A display 410 can be used.

  The communication unit 1205 receives data conforming to the VNC protocol transmitted from the server F01, converts the data into data conforming to the data structure 3, and outputs the data to the difference composition unit 1206.

  Also, the difference synthesis unit 1206 monitors the difference data presence flag of the data supplied from the communication unit 1205, and if the difference data presence flag indicates the presence of difference data (for example, “1”), the table Bitmap image data is synthesized using data along the data structure 3 stored in the storage unit 1207. If the difference data presence flag indicates that there is no difference data (for example, “0”), the difference synthesis unit 1206 outputs the data supplied from the communication unit 1205 to the drawing creation unit 1208 as it is. . In addition, the difference synthesis unit 1206 basically performs reverse conversion of the conversion performed by the difference determination unit 1202 of the server F01. The image data generation processing in the difference synthesis unit 1206 will be described in detail later.

  In addition, when the drawing creation unit 1208 receives the data along the data structure 3 supplied from the difference synthesis unit 1206, the drawing creation unit 1208 converts the data along the data structure 3 held in the table stored in the table storage unit 1207. The image data is created using the data, and the created image data is written into the frame buffer 408. Although there is a difference in the data structure, the drawing creation unit 1208 basically stores the data in the data structure 3 supplied from the difference synthesis unit 1206 in the same manner as the drawing creation unit 806 shown in FIG. A process of acquiring bitmap image data corresponding to the eigenvalues from the table stored in the table storage unit 1207 is performed.

  The table storage unit 1207 stores a table prepared for additionally recording data along the data structure 3 received from the server F01. Data along the data structure 3 may be written into the table from either the difference synthesis unit 1206 or the drawing creation unit 1208. Further, the difference bitmap image is held in the table, but the difference bitmap image may be held in the state received from the server F01, and the bitmap image data (the comparison target) that is the difference comparison target. Data) may be held in a state where the difference bitmap image is combined.

  Further, the table stored in the table storage unit 1207 can be realized in an arbitrary format in the same manner as the table in the table storage unit 1207 of the server F01. For example, it is desirable that the table in the table storage unit 1204 of the server F01 and the table in the table storage unit 1207 of the client F02 be created and held in the same format.

  Next, an example of the operation of the server F01 illustrated in FIG. 6 will be described with reference to FIG. FIG. 7 is a flowchart showing an example of the operation of the server according to the second embodiment of the present invention.

  In the server F01, as in the first embodiment of the present invention (see FIG. 2), the frame acquisition unit 402 acquires image data (drawing data) from the frame buffer 401 (step S601), and configures the image data. For each drawing data in the drawing data string, a unique value of the bitmap image is calculated using a hash function (step S901), and it is confirmed whether or not the first image data acquisition operation is performed by checking whether or not the previous frame buffer 404 is empty. Is determined (step S602). At this time, when the previous frame buffer 404 is empty (when the image data has never been written), the comparison process and the conversion process in step S1301 and the difference determination process in step S1302 are skipped, and the process proceeds to step S1303. On the other hand, if the previous frame buffer 404 is not empty, the process proceeds to step S1301.

  In step S1301, the eigenvalue of each bitmap image calculated in step S901 is compared with the eigenvalue in the table stored in the table storage unit 1204. Based on the comparison result, data along the data structure 1 and A process of converting the eigenvalue into data according to the data structure 3 is performed.

  Hereinafter, the details of the comparison process and the conversion process in step S1301 will be described with reference to FIG. FIG. 8 is a flowchart illustrating an example of comparison processing and conversion processing performed by the comparison determination unit of the server in the second exemplary embodiment of the present invention.

  In FIG. 8, first, the comparison determination unit 1201 of the server F01 compares the unique value of the drawing data supplied from the unique value calculation unit 801 with the unique value held in the table in the table storage unit 1204 to calculate the unique value. It is determined whether or not the same value as the unique value of the drawing data supplied from the unit 801 is held in the table in the table storage unit 1204 (step S1501).

If the same eigenvalue exists in the table in step S1501, the data along the data structure 1 is
・ Set the bitmap existence flag to “0” indicating the absence of bitmap image ・ Set the eigenvalue corresponding to the data along the data structure 1 (addition)
-Delete the bitmap image, set NULL-Set the difference data existence flag to "0" indicating the absence of the difference data, and the data along the data structure 3 is created (step S1502) .

On the other hand, if the same eigenvalue does not exist in the table in step S1501, the data along the data structure 1 is
・ Set the bitmap existence flag to “1” indicating the existence of the bitmap image ・ Set the eigenvalue corresponding to the data along the data structure 1 (addition)
By setting “0” indicating the absence of the difference data to the difference data existence flag, data along the data structure 3 is created (step S1503).

  Although not reflected in the drawing, if it is determined in step S602 that it is the first time, all drawing data and eigenvalues need to be transmitted from the server F01 to the client F02. It is desirable to create data along the data structure 3 in accordance with step S1503.

  Further, following the comparison process and the conversion process in step S1301, a difference determination process in step S1302 is performed. Hereinafter, the details of the difference determination process in step S1302 will be described with reference to FIG. FIG. 9 is a flowchart illustrating an example of the difference determination process performed by the difference determination unit of the server in the second embodiment of the present invention.

  9, the difference determination unit 1202 of the server F01 uses the value of the bitmap presence flag in the data (data created in step S1502 or S1503 in FIG. 8) along the data structure 3 supplied from the comparison determination unit 1201. Is checked (step S1601).

  If the value of the bitmap presence flag is “1” indicating the presence of the bitmap image in step S1601, it can be seen that the data along this data structure 2 includes the bitmap image data. In this case, the process proceeds to step S1602. On the other hand, if the value of the bitmap presence flag is “0” indicating the absence of the bitmap image in step S1601, the difference determination process is not necessary and the difference determination process ends.

  When the value of the bitmap presence flag is “1” indicating the presence of the bitmap image, the width and height of the bitmap image of the input data along the data structure 3 are acquired and stored in the table of the table storage unit 1204 A search is performed as to whether bitmap image data having the same width and height is held in the step S1602.

  If bitmap image data having the same width and height is not found in the table of the table storage unit 1204 in step S1602, the difference determination process ends. On the other hand, when bitmap image data having the same width and height is found in the table of the table storage unit 1204 in step S1602, the bitmap image data and eigenvalue are acquired from the table (step S1603). .

  Then, the bitmap image data acquired in step S1603 is compared with the bitmap image data of the input data along the data structure 3, and a difference between the two image data is acquired, and a difference area (difference bitmap image) is obtained. And the difference bitmap image are acquired (step S1604). For example, the X coordinate on the screen, the Y coordinate on the screen, the horizontal width of the differential bitmap image, and the height of the differential bitmap image are determined as the differential area that determines the arrangement position of the differential bitmap image.

After the difference bitmap image and the difference area are acquired in step S1604, the input data along the data structure 3 is updated based on these pieces of information. Specifically, for input data along data structure 3,
-"1" indicating the presence of image data is set in the difference data existence flag-"0" is set in the horizontal width and height of the bitmap image-Comparison target data detected from the table of the table storage unit 1204 in the image data Data along the data structure 3 is created by setting the eigenvalue (difference bitmap image data to be compared), the difference bitmap image, and the difference area (step S1605).

  As described above, when data along the data structure 3 is created in steps S1502, S1503, and S1605, or when it is determined as the first time in step S602, the data along the data structure 3 is stored in the table storage unit. It is additionally registered in the table 1204 (step S1303), and after being converted into data conforming to the VNC protocol, for example, it is transmitted to the client F02 (step S1304). Similarly to the VNC system, the previous frame buffer 404 is overwritten with the image data acquired this time (image data in the frame buffer 401) (step S605), and some termination condition is satisfied in step S606. On the other hand, if the end condition does not exist, the process returns to step S601 and the above processing is repeated.

  Next, an example of the operation of the client F02 illustrated in FIG. 6 will be described with reference to FIG. FIG. 10 is a flowchart illustrating an example of the operation of the client according to the second embodiment of this invention.

  First, the client F02 receives data conforming to the VNC protocol transmitted from the server F01, and converts this data into data conforming to the data structure 3 (step S1401). Then, in the difference synthesis unit 1206, bitmap image data included in the data along the data structure 3, bitmap image data in the table stored in the table storage unit 1207, or data along the data structure 3 Based on the difference bitmap data included in the table and the bitmap image data in the table stored in the table storage unit 1207, a difference synthesis process and a drawing creation process are performed (step S1402).

  Hereinafter, the details of the difference synthesis processing in step S1402 will be described with reference to FIG. FIG. 11 is a flowchart illustrating an example of a difference synthesis process performed by the client difference synthesis unit according to the second embodiment of this invention.

  In FIG. 11, first, the difference synthesizer 1206 of the client F02 checks the value of the difference data presence flag in the data along the data structure 3 supplied from the communication unit 1205 (step S1701).

  If the value of the difference data presence flag is “0” indicating that the difference data does not exist in step S1701, the data along the data structure 3 does not include the difference data, and the difference synthesis unit 1206 performs the difference synthesis. The processing ends, and the data along the data structure 3 is output to the drawing creation unit 1208 as it is.

  On the other hand, if the value of the difference data presence flag is “1” indicating the presence of difference data in step S1701, the unique value in the image data included in the input data along the data structure 3 received from the server F01 is acquired. Then, data along the data structure 3 having the same eigenvalue as this eigenvalue is extracted from the table (step S1702).

  Next, based on the bitmap image data in the data extracted in step 1702, the difference area (X coordinate, Y coordinate, horizontal width of the difference data included in the input data along the data structure 3 received from the server F01. , Height) is overwritten with the difference bitmap image to create a composite bitmap image (step S1703).

Then, the input data along the data structure 3 received from the server F01 is updated using the composite bitmap image created in step S1703. Specifically, for input data along data structure 3,
・ Set the difference data presence flag to “0” indicating the absence of image data. ・ Rewrite the contents of the image data with the composite bitmap image. ・ The width and height of the bitmap image are the width and height of the composite bitmap image ( That is, by rewriting with the bitmap image data of the data extracted in step S1702, data along the data structure 3 is created and output to the drawing creation unit 1208 (step S1704).

  Next, the data along the data structure 3 updated at step 1704 (input data along the data structure 3 when the difference synthesis process is not performed) is additionally registered in the table in the table storage unit 1207. (Step S1403). The drawing creation unit 1208 that has received the data along the data structure 3 from the difference synthesis unit 1206 through the above-described difference synthesis processing basically performs the same processing as in FIG. That is, in the drawing creation unit 1208, when the bitmap presence flag is “1” indicating the presence of the bitmap image, the drawing data is created from the bitmap image data included in the data received from the difference synthesis unit 1206. When the bitmap presence flag is “0” indicating the absence of the bitmap image, the bitmap image data is searched in the table based on the eigenvalue included in the data received from the difference synthesis unit 1206. Drawing data is created from the bitmap image data acquired by the search.

  As described above, the drawing creation unit 806 draws image data in the frame buffer 408 using the drawing data included in the drawing data string (step S702), and the output unit 409 sequentially reads the frame buffer 408, Desired signal processing such as D / A conversion is performed and output to the display 410 is performed (step S703). In step S704, the operation is terminated if any termination condition is satisfied, whereas if the termination condition does not exist, the process returns to step S601 and the above processing is repeated.

  FIG. 12 shows an outline of difference synthesis in the second embodiment of the present invention. For example, when the display of the start button 3101 displayed on the display is changed to the display of the end button 3102, the server F 01 acquires the difference bitmap image 3103 only for the end character portion, and the data structure 3 The difference bitmap image 3103, the arrangement position of the difference bitmap image 3103, and the unique value of the start button 3101 are inserted into the image data of the data and transmitted from the server F01 to the client F02. On the other hand, when the client F02 receives the data according to the data structure 3, the client F02 acquires the bitmap image of the start button 3101 stored in the table storage unit 1207, and synthesizes the difference bitmap image 3103. Image data for the end button 3102 is created. In the first embodiment of the present invention, compared to the case where the image data of the end button 3102 is transmitted at the time of such a display change, the data amount in the second embodiment of the present invention is larger. Thus, the difference bitmap image 3103 having a small size is transmitted, and the amount of drawing data transferred from the server F01 to the client F02 is greatly reduced.

  As described above, in the second embodiment of the present invention, in the remote desktop system, a unique value (for example, a hash value) is calculated from each drawing data, and each drawing data is associated with the unique value and registered in the table. The server transmits the difference bitmap image to the client with respect to the display change in which only a part of the shared image is updated while the table and the client are shared. As a result, with respect to a display change that updates only a part of the bitmap image held in the client-side table, the server changes the difference bitmap image (in addition, the eigenvalue or drawing value of the bitmap image to be the difference target). By transmitting (position), the client can create a composite bitmap image and update the display. As a result, the amount of drawing data transferred from the server to the client is reduced.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. FIG. 13 is a block diagram illustrating a configuration example of a remote desktop system according to the third embodiment of the present invention. The remote desktop system illustrated in FIG. 13 has a configuration in which a server G01 and a client G02 are connected via an arbitrary data transmission path.

  Hereinafter, the configuration of the server G01 illustrated in FIG. 13 will be described. The server G01 illustrated in FIG. 13 includes a frame buffer 401, a frame acquisition unit 402, a comparison unit 403, a previous frame buffer 404, an eigenvalue calculation unit 801, a comparison determination unit 802, a table storage unit 804, a data conversion unit 1801, and a communication Part 1802.

  The frame buffer 401, the frame acquisition unit 402, the comparison unit 403, the previous frame buffer 404, the eigenvalue calculation unit 801, the comparison determination unit 802, and the table storage unit 804 of the server G01 illustrated in FIG. The frame buffer 401, the frame acquisition unit 402, the comparison unit 403, the previous frame buffer 404, the eigenvalue calculation unit 801, the comparison determination unit 802, and the table storage unit 804 can be used. That is, the drawing data is output in the format of the above-described data structure 2 from the comparison determination unit 802 of the server G01 illustrated in FIG.

  Data in the format of the data structure 2 output from the comparison determination unit 802 of the server G01 illustrated in FIG. 13 is supplied to the data conversion unit 1801. The data conversion unit 1801 converts the data of the data structure 2 supplied from the comparison determination unit 802 into a bitmap image, creates data of the following data structure 4, and outputs the data to the communication unit 1802.

  (Bitmap image data in which data of data structure 2 is converted into a bitmap image)... <Data structure 4>

  Here, the data of the data structure 2 is converted into the data of the data structure 4 which is a bitmap image, but may be converted into data other than the bitmap. Further, it may be converted into a data type requested by the client G02.

  Further, the communication unit 1802 converts the data along the data structure 4 supplied from the data conversion unit 1801 into, for example, the VNC protocol and transmits the data to the client G02.

  Next, the configuration of the client G02 illustrated in FIG. 13 will be described. A client G02 illustrated in FIG. 13 includes a communication unit 1803, a data conversion unit 1804, a client buffer 1805, a drawing creation unit 1806, a frame buffer 408, an output unit 409, and a display (bitmap display) 410.

  The frame buffer 408 and output unit 409 of the client G02 shown in FIG. 13 and the display 410 include the frame buffer 408 and output unit 409 of the VNC client D02 shown in FIG. A display 410 can be used.

  The communication unit 1803 receives data according to the VNC protocol transmitted from the server G01, converts the data into data according to the data structure 4, and outputs the data to the data conversion unit 1804.

  The data conversion unit 1804 converts the data along the data structure 4 supplied from the communication unit 1803 into data along the data structure 2, and adds a table flag to the data of the data structure 2 created by the conversion. Then, data along the following data structure 5 is created, and “0” indicating that this data is received from the server G01 is set in the table flag, and is output to the drawing creating unit 1806. In the following, the data conversion process in which the data conversion unit 1804 converts the data of the data structure 4 received from the server G01 via the communication unit 1803 into the data of the data structure 5 in which the table flag is set to “0”. Is referred to as a first data conversion process.

  (Table flag, bitmap presence flag, X coordinate on the screen, Y coordinate on the screen, width of the bitmap image, height of the bitmap image, bitmap image, eigenvalue) ... <Data structure 5>

  The data structure 5 has a structure in which a table flag field is added to the data of the data structure 2. The table flag is information added to identify whether the data of the corresponding data structure 2 is data received from the server G01 via the communication unit 1803 or data read from the client buffer 1805. For example, the table flag “0” is set in the data received from the server G01, and the table flag “1” is set in the data read from the client buffer 1805.

  This table flag is an example of information added to identify which of the above data the drawing creation unit 1806 corresponds to. However, for example, drawing is performed from each of the communication unit 1803 and the client buffer 1805. If the drawing creation unit 1806 can reliably grasp the origin of data, for example, by dividing the data input port of the data that arrives at the creation unit 1806, the table flag is not necessarily added.

  Further, the data conversion unit 1804 receives the data of the data structure 4 read from the client buffer 1805 according to the instruction of the drawing creation unit 1806, converts this data into the data of the data structure 5, and converts this data into the table flag. Is set to “1” indicating that it is read from the client buffer 1805, and is output to the drawing creation unit 1806. In the following description, a second data conversion process is performed in which the data conversion unit 1804 converts the data of the data structure 4 read from the client buffer 1805 into data of the data structure 5 in which the table flag is set to “1”. This is called data conversion processing.

  In addition, the data conversion unit 1804 converts the data of the data structure 2 passed along with the write command from the drawing creation unit 1806 into data of the data structure 4 and writes the data in the client buffer 1805. In the following, a data conversion process in which the data conversion unit 1804 converts the data of the data structure 2 passed from the drawing creation unit 1806 into the data of the data structure 4 for writing to the client buffer 1805 is the third data conversion. This is called processing.

  Here, one data conversion unit 1804 has a function of performing the above-described first to third data conversion processes, but a plurality of data conversion units 1804 are provided to provide the above-described first to third data conversion processes. Data conversion processing may be performed in a shared manner.

  A client buffer 1805 is a memory owned by the client G02. For a display device equipped with a decoder such as a digital television, for example, the frame buffer of the decoder can be used. The client buffer 1805 is a bitmap image memory and can hold data of the data structure 4.

  When the drawing creation unit 1806 receives data of the data structure 5 to which the table flag “0” indicating that it has been received from the server G01 is received from the data conversion unit 1804, the drawing creation unit 1806 creates image data based on this data, The created image data is written into the frame buffer 408.

  In addition, the drawing creation unit 1806 reads desired data from the client buffer 1805 via the data conversion unit 1804, and the table flag “1” created by the data conversion unit 1804 through the second data conversion process is stored. Data of the added data structure 5 is received. Further, the drawing creating unit 1806 has a cache for temporarily holding data to which the table flag “1” is added.

  Next, an example of the operation of the server G01 illustrated in FIG. 13 will be described with reference to FIG. FIG. 14 is a flowchart illustrating an example of the operation of the server according to the third embodiment of the present invention.

  In the server G01, as in the first embodiment of the present invention (see FIG. 2), the frame acquisition unit 402 acquires image data (drawing data) from the frame buffer 401 (step S601), and configures the image data. For each drawing data in the drawing data string, a unique value of the bitmap image is calculated using a hash function (step S901), and it is confirmed whether or not the first image data acquisition operation is performed by checking whether or not the previous frame buffer 404 is empty. Is determined (step S602). At this time, when the previous frame buffer 404 is empty (when the image data has never been written), the comparison process and the conversion process in step S902 are skipped, and the additional registration process to the table in step S903 is performed. Is called. On the other hand, if the previous frame buffer 404 is not empty, an additional registration process to the table in step S903 is performed through the comparison process and the conversion process in step S902. Note that the processing up to this point is the same as the processing according to the first embodiment of the present invention.

  After the above processing, the data conversion unit 1804 converts the data along the data structure 2 into a bitmap image, and creates data along the data structure 4 (step S1901). Then, the data along the data structure 4 created in step S1901 is transmitted to the client G02 after being converted into data conforming to the VNC protocol, for example (step S1902). Similarly to the VNC system, the previous frame buffer 404 is overwritten with the image data acquired this time (image data in the frame buffer 401) (step S605), and some termination condition is satisfied in step S606. On the other hand, if the end condition does not exist, the process returns to step S601 and the above processing is repeated.

  Next, an example of the operation of the client G02 illustrated in FIG. 13 will be described with reference to FIG. FIG. 15 is a flowchart showing an example of the operation of the client according to the third embodiment of the present invention.

  In the client G02, when data conforming to the VNC protocol transmitted from the server G01 is received, the data conversion unit 1804 converts this data into data conforming to the data structure 4 (step S2001). Further, the data conversion unit 1804 converts the data of the data structure 4 that is a bitmap image into data along the data structure 5 and passes it to the drawing creation unit 1806 (step S2002). Here, the table flag “0” is set in the data of the data structure 5 passed to the drawing creation unit 1806.

  On the other hand, the drawing creation unit 1806 temporarily caches the data of the data structure 5 read from the client buffer 1805 and received from the data conversion unit 1806 (step S2003). Here, the table flag “1” is set in the data of the data structure 5 passed to the drawing creation unit 1806, and the drawing creation unit 1806 performs caching by referring to the table flag “1”.

  The drawing creation unit 1806 writes drawing data to the frame buffer 408 based on the bitmap image data included in the data along the data structure 5 or the bitmap image data in the table stored in the cache. Is created (step S2004).

  Hereinafter, the details of the drawing creation processing in step S2004 will be described with reference to FIG. FIG. 16 is a flowchart illustrating an example of a drawing creation process performed by the drawing creation unit of the client in the third embodiment of the present invention.

  In FIG. 16, the drawing creation unit 1806 of the client G02 first checks the value of the bitmap presence flag in the data along the data structure 5 in which the table flag “0” supplied from the communication unit 1805 is set ( Step S2101).

  If the value of the bitmap presence flag in the data along the data structure 5 in which the table flag “0” is set in step S2101 is “0”, the drawing creation unit 1806 displays the data along the data structure 5 Is acquired (step S2102), and is identical to the eigenvalue acquired in step 2102 from the cached data structure 5 data (data in the data structure 5 cached in step S2003). Data having a unique value is searched, and bitmap image data included in the data having the same unique value is acquired (step S2103). In the search in step S2103, data reading from the client buffer 1805 and cache processing (processing corresponding to step S2003) may be performed.

  Then, the drawing creation unit 1806 deletes the data table flag and the bitmap presence flag along the data structure 5 in which the table flag “0” supplied from the communication unit 1803 is set, and the bit acquired in step S2103. Map image data is set, and data along the data structure 1 is created (step S2104). Data along the data structure 1 is written into the frame buffer 408.

  On the other hand, if the value of the bitmap presence flag in the data along the data structure 5 in which the table flag “0” is set in step S2101 is “1”, the data structure in which the table flag “1” is set. The data table flag and the bitmap presence flag along the line 5 are deleted, and the data along the data structure 1 is created (step S2105). Further, the drawing creation unit 1806 deletes the table flag of the data along the data structure 5 supplied from the communication unit 1803, creates data along the data structure 2, and uses this data as the data of the data structure 4. Is written in the client buffer 1805 (step S2106). As described above, the data along the data structure 2 output from the drawing creation unit 1806 is converted into data of the data structure 4 through the third data conversion processing in the data conversion unit 1804 and stored in the client buffer 1805. Written.

  Further, the drawing creation unit 1806 creates data of the data structure 2 by deleting the table flag field of the data along the data structure 5 received from the data conversion unit 1804 in step S2003. Is written into the client buffer 1805 via the data converter 1804 (step S2005). At this time, the data converter 1804 performs the third data conversion process described above, and the client buffer 1805 is written as data of the data structure 4 that is a bitmap image.

  The subsequent processing is the same as in the first embodiment (see FIG. 4) of the present invention. That is, the drawing creation unit 1806 draws image data in the frame buffer 408 using the drawing data included in the drawing data string (step S702), and the output unit 409 sequentially reads the frame buffer 408, and the D / A Desired signal processing such as conversion is performed and output to the display 410 is performed (step S703). In step S704, if any end condition is satisfied, the operation is ended. If no end condition exists, the process returns to step S2001 and the above process is repeated.

  As described above, in the third embodiment of the present invention, in the remote desktop system, a unique value (for example, a hash value) is calculated from each drawing data, and each drawing data is associated with the unique value and registered in the table. This table is shared by the server and the client. At this time, by converting data on the server side into a format that can be stored in a memory that the client has in advance (for example, a decoder frame buffer in a digital television), what type of memory the client owns Even in such a case, the table can be held without adding an extra memory, and resource saving and cost reduction can be realized.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described. FIG. 17 is a block diagram illustrating a configuration example of a remote desktop system according to the fourth embodiment of the present invention. The remote desktop system illustrated in FIG. 17 has a configuration in which a server H01 and a client H02 are connected via an arbitrary data transmission path.

  Hereinafter, the configuration of the server H01 illustrated in FIG. 17 will be described. A server H01 illustrated in FIG. 17 includes a frame buffer 401, a frame acquisition unit 402, a comparison unit 403, a previous frame buffer 404, an eigenvalue calculation unit 801, a comparison determination unit 2201, a data creation unit 2202, and an update waiting table storage unit 2203. A table update control unit 2204, a table storage unit 2205, and a communication unit 2206.

  The frame buffer 401, the frame acquisition unit 402, the comparison unit 403, the previous frame buffer 404, and the eigenvalue calculation unit 801 of the server H01 illustrated in FIG. 17 include the frame buffer 401 and the frame acquisition unit 402 illustrated in FIG. The comparison unit 403, the previous frame buffer 404, and the eigenvalue calculation unit 801 can be used. That is, the data and the unique value of the data structure 1 are output from the unique value calculation unit 801 of the server H01 illustrated in FIG.

  The data of the data structure 1 and the eigenvalue output from the eigenvalue calculation unit 801 of the server H01 illustrated in FIG. 17 are supplied to the comparison determination unit 2201. The comparison determination unit 2201 has substantially the same function as the comparison determination unit 802 shown in FIG. 1, but the format of the data structure to be output is different. That is, when the comparison determination unit 2201 receives the data of the data structure 1 including the drawing data supplied from the eigenvalue calculation unit 801 and the eigenvalue, the table stored in the table storage unit 2205 (stores the data of the data structure 2). Is used to create data of data structure 6 below. Data along the data structure 6 created by the comparison / determination unit 2201 is output to the data creation unit 2202 and the communication unit 2206.

  (Table transmission flag, update time, bitmap presence flag, X coordinate on the screen, Y coordinate on the screen, width of the bitmap image, height of the bitmap image, bitmap image, eigenvalue) ... <data structure 6>

  The data structure 6 has a structure in which a table transmission flag and an update time field are added to the data of the data structure 2. In the table transmission flag field, a flag is set to indicate to the client H02 whether this data is for drawing or table updating. The comparison determination unit 2201 sets a flag “0” indicating that the data is for drawing in the table transmission flag, and outputs the flag to the data creation unit 2202 and the communication unit 2206. In the update time field, the processing time of this data (for example, the current time when processed by the comparison determining unit 2201) is set. In the update time field, information (for example, a sequence number) that can grasp the order of data to be processed may be set.

  In addition, when the data creation unit 2202 receives the data along the data structure 6 supplied from the comparison determination unit 2201, the data creation unit 2202 stores the data along the data structure 6 in the update waiting table storage unit 2203. Update processing or additional registration processing of the update waiting table (stores data of the following data structure 7) is performed.

  (Update time, table presence flag, bitmap presence flag, X coordinate on the screen, Y coordinate on the screen, width of the bitmap image, height of the bitmap image, bitmap image, eigenvalue) ... <data structure 7>

  The data structure 7 has a structure in which update time and table presence flag fields are added to the data of the data structure 2. In the update time field, the update time included in the data of the data structure 6 supplied from the comparison determination unit 2201 is set as it is, or the processing time (current time) in the data creation unit 2202 is set. The The table presence flag field is a flag indicating whether or not an entry related to this data is already stored in the table in the table storage unit 2205. For example, the data creation unit 2202 refers to the bitmap presence flag included in the data of the data structure 6 supplied from the comparison determination unit 2201, and the bitmap presence flag indicates the presence of the bitmap image data “1”. ”Is set, a table presence flag“ 0 ”indicating non-existence in the table in the table storage unit 2205 is set, and when the bitmap presence flag is“ 0 ”indicating non-existence of bitmap image data, A table presence flag “1” indicating the presence in the table in the table storage unit 2205 is set.

  The update waiting table storage unit 2203 stores a table (update waiting table) prepared for additionally recording data of the data structure 7. As described above, the update waiting table in the update waiting table storage unit 2203 is updated or additionally registered by the data creation unit 2202, and is read by the table update control unit 2204. The maximum capacity of the update waiting table that can be stored in the update waiting table storage unit 2203 is desirably larger than the maximum capacity of the table that can be stored in the table storage unit 2205. The table stored in the update waiting table storage unit 2203 can be realized in any format as long as it can hold the data of the data structure 7 as described above.

  In addition, the table update control unit 2204 is based on the update waiting table in the update waiting table storage unit 2203 at a predetermined update time or at a timing such as data storage exceeding the predetermined capacity in the update waiting table storage unit 2203, for example. Data for updating the table in the table storage unit 2205 (data of data structure 2) is created, and data to be transmitted to the client H02 via the communication unit 2206 (a table indicating that the table is for table update) Data of data structure 6 in which transmission flag “1” is set is created. The table update processing in the table update control unit 2204 will be described in detail later.

  The table storage unit 2205 stores a table prepared for additionally recording data of the data structure 2. The table in the table storage unit 2205 is updated by the table update control unit 2204 and is referred to by the comparison determination unit 2201. Note that the table stored in the table storage unit 2205 can be realized in any format as long as it can hold data having the data structure 2 as described above.

  Further, the communication unit 2206 converts the data along the data structure 6 supplied from the comparison determination unit 2201 or the table update control unit 2204 into, for example, the VNC protocol and transmits the data to the client H02.

  Next, the configuration of the client H02 illustrated in FIG. 17 will be described. A client H02 illustrated in FIG. 17 includes a communication unit 2207, a drawing creation unit 2208, a table creation unit 2209, a table storage unit 2210, a frame buffer 408, an output unit 409, and a display (bitmap display) 410. .

  The frame buffer 408 and output unit 409 of the client H02 shown in FIG. 17 and the display 410 include the frame buffer 408 and output unit 409 of the VNC server D01 shown in FIG. A display 410 can be used.

  The communication unit 2207 receives data conforming to the VNC protocol transmitted from the server H01, converts the data into data conforming to the data structure 6, and refers to the table transmission flag in the data of the data structure 6 to When the transmission flag is “0”, the data is output to the drawing creation unit 2208, and when the table transmission flag is “1”, the data is output to the table creation unit 2209.

  When the drawing creation unit 2208 receives data along the data structure 6 supplied from the communication unit 2207, as in the drawing creation unit 806 illustrated in FIG. 1, the image included in this data is displayed. Image data is created using the data or data along the data structure 6 held in the table stored in the table storage unit 2210, and the created image data is written into the frame buffer 408. Further, when the drawing creation unit 2208 receives data of the data structure 6 in which the bitmap presence flag indicating the absence of bitmap image data is set to “0”, the table storage unit corresponding to this data It is desirable to replace the update time of the data in the table in 2210 (data having the same eigenvalues) with the update time included in the data of the data structure 6 received from the communication unit 2207.

  When the table creation unit 2209 receives data along the data structure 6 supplied from the communication unit 2207, the table creation unit 2209 performs additional registration processing on the table stored in the table storage unit 2210. Further, the table creation unit 2209 monitors the capacity (total data amount) of the table in the table storage unit 2210 for each coincidence time, for example, and performs update processing so that the table becomes a predetermined capacity or less. Further, the table creation unit 2209 notifies the server H01 through the communication unit 2207 of the maximum capacity of the table that can be stored in the table storage unit 2210 (or the predetermined capacity described above).

  The table storage unit 2210 stores a table prepared for additionally recording data of the data structure 6. The table in the table storage unit 2210 is updated by the drawing creation unit 2208 or the table creation unit 2209 and is referenced by the drawing creation unit 2208. Note that the table in the table storage unit 2210 of the client H02 is synchronized with the table in the table storage unit 2205 of the server H01 by the operation in the fourth embodiment of the present invention. The table stored in the table storage unit 2205 can be realized in any format as long as it can hold data having the data structure 6 as described above.

  Next, an example of the operation of the server H01 illustrated in FIG. 17 will be described with reference to FIG. FIG. 18 is a flowchart showing an example of the operation of the server in the fourth embodiment of the present invention.

  In the server H01, as in the first embodiment of the present invention (see FIG. 2), the frame acquisition unit 402 acquires image data (drawing data) from the frame buffer 401 (step S601), and configures the image data. For each drawing data in the drawing data string, a unique value of the bitmap image is calculated using a hash function (step S901), and it is confirmed whether or not the first image data acquisition operation is performed by checking whether or not the previous frame buffer 404 is empty. Is determined (step S602). If the previous frame buffer 404 is not empty in step S602, the process proceeds to step S2301, and if the previous frame buffer 404 is empty in step S602, the process proceeds to step S2302.

  In step S2301, the eigenvalue of each bitmap image calculated in step S901 is compared with the eigenvalue in the table stored in the table storage unit 2205, and based on the comparison result, data along the data structure 1 and A process of converting the eigenvalue into data along the data structure 6 is performed. As described above, the value “0” indicating the data for drawing is set in the table transmission flag of the data of the data structure 6.

  Although not reflected in the drawing, if it is determined in step S602 that it is the first time, all drawing data and eigenvalues need to be transmitted from the server H01 to the client H02. In this case, table transmission is performed. The flag “0” is set, and data of the data structure 7 including the bitmap image data is created.

  In step S2302, the data of the created data structure 7 is additionally registered in the update waiting table in the update waiting table storage unit 2203.

  Further, the table update control unit 2204 constantly monitors an update waiting table or a predetermined timer (not shown), and determines whether or not it is the update timing of the table in the table storage unit 2205 (step). S2303). If it is determined in step S2303 that the table update timing is reached, the process proceeds to step S2304. If it is determined in step S2303 that the table is not updated, the process proceeds to step S2306.

  If it is determined in step S2303 that the table update timing is reached, the table update control unit 2204 performs processing for creating an update waiting table in the update waiting table storage unit 2203 and a table in the table storage unit 2205 (step S2303). Along with S2304, table update processing is performed (step S2305).

  Hereinafter, the details of the processing in steps S2303 to S2305 will be described with reference to FIG. FIG. 19 is a flowchart illustrating an example of the table creation process and the table update process performed by the table update control unit of the server according to the fourth embodiment of this invention.

  In FIG. 19, first, the table update control unit 2204 of the server H01 uses a timer or the like to determine whether or not a predetermined time TH1 set in advance has elapsed since the previous table update time (step S2501). . If it is determined in step S2501 that the predetermined time TH1 has not elapsed, the table update process ends.

  On the other hand, if it is determined in step S2501 that the predetermined time TH1 has elapsed, the process proceeds to step S2502, and it is determined whether or not the data amount (table amount) in the update waiting table exceeds a predetermined limit capacity TH2. The limit capacity TH2 may be set based on a value notified from the client H02, or may be set to a fixed value from the beginning. If it is determined in step S2502 that the data amount of the update waiting table exceeds the limit capacity TH2 of the client H02, the process proceeds to step S2503, and the data amount of the update wait table does not exceed the limit capacity TH2 of the client H02. If it is determined, the process of optimizing the update waiting table in steps S2503 and S2504 is skipped, and the process proceeds to step S2505.

  If it is determined in step S2502 that the amount of data in the update waiting table exceeds the limit capacity TH2 of the client H02, the table update control unit 2204 rearranges the data in the update wait table in order of update time (step S2503). ) Data is deleted in order of oldest update time until the amount of data in the rearranged update waiting table becomes equal to or less than the limit capacity TH2 (step S2504).

  Subsequently, the table update control unit 2204 creates two copy data (copy data 1 and copy data 2) by copying the data in the update waiting table (step 2505). These two pieces of copy data are used for transmission to the client H02 and for updating the table stored in the table storage unit 2205, respectively.

  For one copy data 1, the table update control unit 2204 deletes the table presence flag of the copy data 1 (data along the data structure 7), and a value “1” indicating that it is for table update. Is added to the table transmission flag, and data along the data structure 6 is created (step S2506).

  For the other copy data 2, the table update control unit 2204 deletes the table presence flag and update time of the copy data 2 (data along the data structure 7), and creates data along the data structure 2. (Step S2507).

  After the above processing is completed for all data in the update waiting table, the table presence flag of all data in the update waiting table is set to a value “1” indicating the presence in the table of the table storage unit 2205. The table in the table storage unit 2205 is updated with the copy data 2 converted into the data along the data structure 2 in step S2507 (step S2508).

  As described above, the data created in step S2301 (data along the data structure 6 of the table transmission flag “0”) and the data created in step S2506 in FIG. 19 (data of the table transmission flag “1”) The data along the structure 6) is converted into data conforming to the VNC protocol, for example, and then transmitted to the client H02 (step S2306). Similarly to the VNC system, the previous frame buffer 404 is overwritten with the image data acquired this time (image data in the frame buffer 401) (step S605), and some termination condition is satisfied in step S606. On the other hand, if the end condition does not exist, the process returns to step S601 and the above processing is repeated.

  Next, an example of the operation of the client H02 illustrated in FIG. 17 will be described with reference to FIG. FIG. 20 is a flowchart showing an example of the operation of the client according to the fourth embodiment of the present invention.

  First, the client H02 receives data conforming to the VNC protocol transmitted from the server H01, and converts this data into data conforming to the data structure 6 (step S2401). When the value of the table transmission flag included in the data of the data structure 6 is “0” indicating drawing, the data is transferred from the communication unit 2207 to the drawing creating unit 2208. In the drawing creation unit 2208, drawing to be written in the frame buffer 408 based on the bitmap image data included in the data along the data structure 6 or the bitmap image data in the table stored in the table storage unit 2210 Data creation processing is performed (step S2402).

  The processing in the drawing creation unit 2208 is basically the same as the operation shown in FIG. 5 described above except that the data format is data along the data structure 6. However, the drawing creation unit 2208 stores data in the table storage unit 2210 at the update time included in the processed data when processing the data in which the bitmap presence flag is set to “0”. It is desirable to rewrite the update time of the corresponding data in the table.

  On the other hand, when the value of the table transmission flag included in the data received from the server H01 is “1” indicating that the table is to be updated, the data is transferred from the communication unit 2207 to the table creation unit 2209. The table creation unit 2209 performs a table update process by additionally registering data of the data structure 6 supplied from the communication unit 2207 in the table (step S2403).

  Hereinafter, the details of the table update processing in step S2403 will be described with reference to FIG. FIG. 21 is a flowchart illustrating an example of a table update process performed by the client table creation unit in the fourth embodiment of the present invention.

  On the client side, monitoring is performed so that the data amount of the table in the table storage unit 2210 can be suppressed to a capacity based on a predetermined limit capacity TH2. The table creation unit 2209 determines whether or not the total data amount of the table in the table storage unit 2210 is larger than a predetermined limit capacity TH2 (step S2601). If it is determined in step S2601 that the total data amount of the table in the table storage unit 2210 is equal to or less than the predetermined limit capacity TH2, the process proceeds to step S2604.

  On the other hand, if it is determined in step S2601 that the total data amount of the table in the table storage unit 2210 is larger than the predetermined limit capacity TH2, the update time included in the data along the data structure 6 is used. The data in the table is rearranged in order of update time (step S2602). Then, data is deleted in order of oldest update time until the total data amount in the table becomes equal to or less than the limit capacity TH2 (step S2603).

  Then, the data of the data structure 6 supplied from the communication unit 2207 is additionally registered in the table in which the total data amount is reduced in step S2603 or the table in which it is determined in step S2601 that the total data amount is equal to or less than the limit capacity. (Step S2604).

  The subsequent processing is the same as in the first embodiment (see FIG. 4) of the present invention. That is, the drawing creation unit 2208 draws image data in the frame buffer 408 using the drawing data included in the drawing data string (step S702), and the output unit 409 sequentially reads the frame buffer 408, and D / A Desired signal processing such as conversion is performed and output to the display 410 is performed (step S703). In step S704, if any end condition is satisfied, the operation is terminated. If no end condition exists, the process returns to step S2401 to repeat the above processing.

  Here, only one client H02 is shown for one server H01, but as shown in FIG. 22, a plurality of clients H02 (5 in FIG. 22) are shown for one server H01. There may be one client A to E). In such a configuration, since the conventional server has transmitted data related to the same table to all clients, the data amount of the table exceeds the data amount of the memory depending on the client, and the table is retained. There was a case that I couldn't finish. However, according to the fourth embodiment of the present invention, the server H01 can transmit the data of the table corresponding to the limit capacity TH2 of each client to each client H02.

  As described above, in the fourth embodiment of the present invention, in the remote desktop system, a unique value (for example, a hash value) is calculated from each drawing data, and each drawing data is associated with the unique value and registered in the table. This table is shared by the server and the client. At this time, based on the total amount of data in the client table on the server side, such as when the memory capacity for storing the table held by the client is small or when the memory resource used to store the table is limited Table management can be performed, and the amount of drawing data transferred from the server to the client is reduced.

  In the present specification, the first to fourth embodiments of the present invention have been described independently. However, it is also possible to use any combination of these first to fourth embodiments. is there. Further, for example, a general-purpose computer can be used as a server and a client that implement the present invention. In the above description, the constituent elements of the server and the client are schematically illustrated by functional blocks. However, each of these constituent elements is realized by hardware or software (for example, a program executable by a computer). Is possible. For example, the function of each device described above may be realized by a computer by a program. Further, this program may be read from a recording medium and taken into a computer, or may be transmitted via a communication network and taken into a computer.

  The present invention can greatly reduce the data amount of a drawing data string transmitted and received between a server and a client, and improves the user's convenience by improving the response speed of the GUI, and reduces the user's stress. The effect is that it is not necessary to install a decoder on the client side and the load on the client can be reduced, and even when the same updated image data exists in different areas, it is newly added to the table Thus, the updated display data can be reproduced, and the table amount can be reduced. Further, according to the present invention, since all data transmitted from the server to the client is lossless compression, the image data realized on the client side is uniform, and a visually stable display can be realized on the client side. An operation instruction such as an application to a remote server device from a client device having an input device such as a keyboard and a display device such as a bitmap display capable of displaying video As a result, it can be applied to the technology of a remote desktop system in which a video transmitted from a server device to a client device is displayed on the client device.

It is a block diagram which shows one structural example of the remote desktop system in the 1st Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the server in the 1st Embodiment of this invention. 5 is a flowchart illustrating an example of comparison processing and conversion processing performed by a comparison determination unit of a server in the first embodiment of the present invention. It is a flowchart which shows an example of operation | movement of the client in the 1st Embodiment of this invention. 6 is a flowchart illustrating an example of a drawing creation process performed by a drawing creation unit of a client in the first embodiment of the present invention. It is a block diagram which shows the example of 1 structure of the remote desktop system in the 2nd Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the server in the 2nd Embodiment of this invention. In the 2nd Embodiment of this invention, it is a flowchart which shows an example of the comparison process and conversion process which are performed in the comparison determination part of a server. It is a flowchart which shows an example of the difference determination process performed in the difference determination part of a server in the 2nd Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the client in the 2nd Embodiment of this invention. It is a flowchart which shows an example of the difference synthetic | combination process performed in the difference synthetic | combination part of a client in the 2nd Embodiment of this invention. An outline of difference synthesis in the second embodiment of the present invention is shown. It is a block diagram which shows the example of 1 structure of the remote desktop system in the 3rd Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the server in the 3rd Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the client in the 3rd Embodiment of this invention. 14 is a flowchart illustrating an example of a drawing creation process performed by a drawing creation unit of a client in the third embodiment of the present invention. It is a block diagram which shows the example of 1 structure of the remote desktop system in the 4th Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the server in the 4th Embodiment of this invention. It is a flowchart which shows an example of the table creation process and table update process which are performed by the table update control part of a server in the 4th Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the client in the 4th Embodiment of this invention. It is a flowchart which shows an example of the table update process performed in the table preparation part of a client in the 4th Embodiment of this invention. In the 4th Embodiment of this invention, it is a figure which shows an example of a structure which a some client connects to one server. It is a system block diagram which shows an example of TSS in a prior art. It is a system block diagram which shows an example of the X window system in a prior art. It is a system block diagram which shows an example of VNC in a prior art. It is a block diagram which shows the example of 1 structure of the VNC system in a prior art. It is a flowchart which shows an example of a process of the VNC server shown in FIG. 27 is a flowchart illustrating an example of processing of the VNC client illustrated in FIG. 26. 10 is a flowchart showing an example of server processing in the remote desktop system improvement technique disclosed in Patent Document 1; It is a flowchart which shows the detailed process of the RKEY creation process of FIG. 10 is a flowchart showing an example of client processing in the remote desktop system improvement technique disclosed in Patent Document 1. It is a figure which shows the example of a display in the wizard type application in a prior art.

Explanation of symbols

101, 301 Application 102 Terminal server 103 Terminal device 104 Display 201 X application 202 X server 203 X client 204, 305, 410 Display (bitmap display)
205 Pointing device 302, 401, 408 Frame buffer 303 VNC server 304 VNC client 306 Pointing device 402 Frame acquisition unit 403 Comparison unit 404 Previous frame buffer 405, 406, 803, 805, 1203, 1205, 1802, 1803, 2206, 2207 communication Section 407 Drawing section 409 Output section 801 Eigenvalue calculation section 802, 1201, 2201 Comparison determination section 804, 807, 1204, 1207, 2205, 2210 Table storage section 806, 1208, 1806, 2208 Drawing creation section 1202 Difference determination section 1206 Difference composition Unit 1801, 1804 data conversion unit 1805 client buffer 2202 data creation unit 2203 update waiting table storage unit 2204 table Update control unit 2209 Table creation unit 3101 Start button 3102 End button 3103 Difference bitmap image A01 General-purpose computer providing TSS A02 Serial transmission A03 User B01, E01, F01, G01, H01 Server B02, C02 Communication network B03, C03, E02, F02, G02, H02 Client C01 General-purpose computer D01 VNC server D02 VNC client

Claims (8)

A server device of a remote desktop system that transmits image data to be displayed on a display unit of the client device to a client device,
Table storage means for storing a table for holding data including at least a unique value for specifying the image data;
Eigenvalue calculation means for setting, as the eigenvalue for specifying the image data, a hash value obtained by performing an operation with a hash function on the image data;
The data held in the table is compared with the eigenvalue calculated by the eigenvalue calculating means, and an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculating means is found in the table. In this case, display update data that includes the eigenvalue that specifies the image data and does not include the image data is created, while an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculation unit is found in the table. If not, comparison determination means for creating display update data including both the eigenvalue specifying the image data and the image data;
Data transmission means for transmitting the display update data to the client device;
Additional registration means for registering the display update data as the data in the table;
Server device having. A server device of a remote desktop system that transmits image data to be displayed on a display unit of the client device to a client device,
Table storage means for storing a table for holding data including at least a unique value for specifying the image data;
Eigenvalue calculation means for setting, as the eigenvalue for specifying the image data, a hash value obtained by performing an operation with a hash function on the image data;
The data held in the table is compared with the eigenvalue calculated by the eigenvalue calculating means, and an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculating means is found in the table. In this case, display update data that includes the eigenvalue specifying the image data and does not include the image data is generated, while an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculation unit is found in the table. If not, comparison determination means for generating intermediate data including both the eigenvalues specifying the image data and the image data;
The data stored in the table is compared with the image data included in the intermediate data, and image data whose horizontal width and height match the image data included in the intermediate data is found in the table. If the image data included in the intermediate data is compared with the image data found in the table, the difference image data and the arrangement position of the difference image data are obtained, and the intermediate data is acquired. Regarding data, while deleting the image data and creating the display update data by inserting the difference image data and the arrangement position of the difference image data and the eigenvalue of the image data found in the table, No image data having the same width and height as the image data included in the intermediate data was found in the table. Expediently, a difference determining means for generating data for the display update from the intermediate data,
Data transmission means for transmitting the display update data to the client device;
Additional registration means for registering the display update data as the data in the table;
Server device having. A server device of a remote desktop system that transmits image data to be displayed on a display unit of the client device to a client device,
Threshold receiving means for receiving a value of the upper limit data amount of the table of the client device from the client device;
First table storage means for storing a first table for holding data including at least an eigenvalue for specifying the image data;
Second table storage means for storing a second table for holding data selected from the data held in the first table;
Eigenvalue calculation means for setting, as the eigenvalue for specifying the image data, a hash value obtained by performing an operation with a hash function on the image data;
The data held in the second table is compared with the eigenvalue calculated by the eigenvalue calculating means, and an eigenvalue that matches the eigenvalue calculated by the eigenvalue calculating means is found in the second table. The display update data that includes the eigenvalue that specifies the image data and does not include the image data, while the eigenvalue that matches the eigenvalue calculated by the eigenvalue calculation means is If not found in the second table, the comparison determination means for creating display update data including both the eigenvalue specifying the image data and the image data;
Display update data transmission means for transmitting the display update data to the client device;
Additional registration means for registering the display update data as the data in the first table together with information indicating the storage order;
Storing the new data in the first table in the second table so that the data amount of the second table does not exceed the data amount based on the upper limit data amount; Table update control means for transmitting the data stored in the second table to the client device as table update data for updating the table of the client device simultaneously with storing the data in the second table;
Server device having.   Claims: Data conversion means for converting data to be stored in the table of the client device transmitted by the data transmission means in accordance with the type of memory used for storing the table on the client device side before the transmission. Item 4. The server device according to any one of Items 1 to 3. A client device of a remote desktop system that displays an image based on image data received from a server device,
Display means for displaying images;
A table for storing a table for holding data including at least the eigenvalue for specifying the image data, with a hash value obtained by performing an operation using a hash function on the image data as the eigenvalue of the image data Storage means;
Data receiving means for receiving display update data for updating the display on the display means from the server device;
When the display update data received by the data receiving means includes both the eigenvalue for specifying the image data and the image data, an image to be displayed on the display means based on the image data On the other hand, when the display update data received by the data receiving means includes only the eigenvalue specifying the image data and does not include the image data, the display update data is stored in the table. A drawing for creating an image to be displayed on the display means based on image data held together with the eigenvalue in the table by comparing the existing data and the eigenvalue included in the display update data Creating means;
Output means for outputting the image created by the drawing creation means to the display means;
Additional registration means for registering the display update data received by the data receiving means as the data in the table;
Client device having. A client device of a remote desktop system that displays an image based on image data received from a server device,
Display means for displaying images;
A table for storing a table for holding data including at least the eigenvalue for specifying the image data, with a hash value obtained by performing an operation using a hash function on the image data as the eigenvalue of the image data Storage means;
Data receiving means for receiving display update data for updating the display on the display means from the server device;
The display update data received by the data receiving unit includes the differential image data, the arrangement position of the differential image data, the unique value of the image data to be compared, and the unique value of the original image data created by the difference synthesis. The difference stored in the table together with the eigenvalue from the table by comparing the data held in the table with the eigenvalue of the image data to be compared with the difference. The image data to be compared is read out, the difference image data is synthesized with the arrangement position of the read image data to create composite image data, and the difference image data and the display update data are The arrangement position of the difference image data and the eigenvalue of the image data found in the table are deleted and the combination is deleted. A difference synthesizing means for creating intermediate data by inserting the image data,
When the display update data received by the data receiving means includes both the eigenvalue and the image data for specifying the image data, an image to be displayed on the display means based on the image data is displayed. When the display update data created and received by the data receiving means includes only the eigenvalues specifying the image data and does not include the image data, the display update data is stored in the table. Compare the data and the eigenvalue included in the display update data, create an image to be displayed on the display means based on the image data held together with the eigenvalue in the table, and perform the difference synthesis With respect to the display update data created by the means, a drawing creation means for creating an image to be displayed on the display means based on the composite image data ,
Output means for outputting the image created by the drawing creation means to the display means;
Additional registration means for registering the display update data referred to when the image is created by the drawing creation means as the data in the table;
Client device having. A client device of a remote desktop system that displays an image based on image data received from a server device,
Display means for displaying images;
A table for storing a table for holding data including at least the eigenvalue for specifying the image data, with a hash value obtained by performing an operation using a hash function on the image data as the eigenvalue of the image data Storage means;
Threshold transmission means for transmitting the value of the upper limit data amount of the table stored in the table storage means to the server device;
Data receiving means for receiving display update data for drawing for updating the display on the display means and table update data for updating the table stored in the table storage means from the server device When,
When the display update data received by the data receiving means includes both the eigenvalue for specifying the image data and the image data, an image to be displayed on the display means based on the image data On the other hand, when the display update data received by the data receiving means includes only the eigenvalue specifying the image data and does not include the image data, the display update data is stored in the table. A drawing for creating an image to be displayed on the display means based on image data held together with the eigenvalue in the table by comparing the existing data and the eigenvalue included in the display update data Creating means;
Output means for outputting the image created by the drawing creation means to the display means;
An additional registration means for registering the table update data including both the eigenvalue for specifying the image data received by the data reception means and the image data as the data in the table;
Client device having. When storing the data in the table storage means, the data is converted in accordance with the type of memory used as the table storage means, and when the data is read from the table storage means, the drawing creation means The client apparatus according to claim 5, further comprising a data conversion unit configured to convert the data structure into a data structure that can be referred to when the data is created.

Images