Abstract:
In a computer system including a job scheduler which divides an input job and determines a client apparatus to assign the divided job, and a task manager which transmits the divided job to the client apparatus determined by the job scheduler, the job scheduler assigns the same job to a plurality of client apparatuses when the number of client apparatuses is larger than the number of divided jobs, and when the job is finished in one of the plurality of client apparatuses assigned the same job, execution of the job in the remaining client apparatuses is canceled so that the time until all jobs are finished is shortened.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a computer system and a job assignment method in the system and, more particularly, to a job assignment method when grid computing is applied to a computer system in which a host computer and a plurality of client apparatuses are connected to each other through a network.  
       BACKGROUND OF THE INVENTION  
       [0002]     In recent years, grid computing (to be also simply referred to as “grid” hereinafter) has received a great deal of attention, which makes a plurality of computers connected through a network available as if they were a single system. Attempts to apply it to various fields have been made.  
         [0003]      FIG. 1  is a block diagram for explaining the architecture of grid computing. There exist several kinds of grids. One called a desktop grid will be explained here, which executes a job by using the vacant time of the CPU of, e.g., a desktop PC.  
         [0004]     Referring to  FIG. 1 , a client  10  is a device to which a user inputs a job as a request. The input job is transferred to a task manager (to be abbreviated as TM hereinafter)  20 . The TM  20  transmits the contents of the job to a dynamic job scheduler (to be abbreviated as DJS hereinafter)  30 .  
         [0005]     The DJS  30  manages the resources of all of a plurality of host devices  41  to  43  each of which includes a broker  411  and resource manager (to be abbreviated as RM hereinafter)  412  and is recognized as a resource. The DJS  30  analyzes the job, selects the broker  411  of an optimum resource, and notifies the TM  20  of it. “Resource” means the vacant state of an available CPU.  
         [0006]     The broker  411  registers, in the DJS  30 , resource information acquired by the RM  412  and inputs the job to an optimum resource in accordance with the request from the TM  20 . When the job is finished, the broker  411  notifies the TM  20  of the completion of the job.  
         [0007]     The TM  20  inputs the job to the optimum broker  411  selected by the DJS  30  and monitors the state of progress of the job. Upon receiving the completion notification from the broker  411 , the TM  20  notifies the client  10  of the result. When a change or error (e.g., a failure or reception of another job) has occurred in the resource, the RM  412  notifies the broker  411  of it.  
         [0008]     With this mechanism, a job is distributed to a resource such as a CPU which is normally unused so that distributed processing can be executed by a plurality of devices without making the user conscious. Hence, desktop grid computing is implemented.  
         [0009]     Scientific research has extensively been done for implementing high-speed processing by collecting the CPU powers of computers using the above-described grid computing technologies. However, application of grid computing to an incorporated device such as MFP (Multi Function Peripheral) called a multifunction apparatus or SFP (Single Function Peripheral) has not been implemented yet.  
         [0010]     For example, when this technology is applied to an image forming system including MFP connected to an office LAN, PCs, server, and MFP on the LAN are used as resources to be subjected to distributed processing.  
         [0011]     When a job is divided and distributed in this arrangement, the job cannot finish until the distributed processes in all devices are finished. If the user of the terminal of a client requests another job processing (local job processing), this processing is preferentially done. Since the above-described distributed job can be stopped any time at the discretion of each client, processing takes a longer time after all.  
       SUMMARY OF THE INVENTION  
       [0012]     It is an object of the present invention to shorten the total processing time when divided jobs are distributed to a plurality of clients.  
         [0013]     In order to achieve the above object, according to an aspect of the present invention, there is provided a job assignment method in a computer system including a job scheduler which divides an input job and determines a client apparatus to assign the divided job, and a task manager which transmits the divided job to the client apparatus determined by the job scheduler, comprising causing the job scheduler to assign the same job to a plurality of client apparatuses when the number of client apparatuses is larger than the number of divided jobs, and when the job is finished in one of the plurality of client apparatuses assigned the same job, canceling execution of the job in the remaining client apparatuses.  
         [0014]     That is, according to the present invention, in a computer system including a job scheduler which divides an input job and determines a client apparatus to assign the divided job, and a task manager which transmits the divided job to the client apparatus determined by the job scheduler, the job scheduler assigns the same job to a plurality of client apparatuses when the number of client apparatuses is larger than the number of divided jobs, and when the job is finished in one of the plurality of client apparatuses assigned the same job, execution of the job in the remaining client apparatuses is canceled.  
         [0015]     When the number of client apparatuses is larger than the number of divided jobs, the processing time of each divided job is that in the client apparatus which has finished the processing at the earliest timing.  
         [0016]     Hence, the time until all jobs are finished can be shortened.  
         [0017]     The job scheduler may divide the plurality of client apparatuses into a plurality of groups and determine the client apparatus to assign the divided job for each group.  
         [0018]     The canceling step may comprise a detection step of detecting whether all the divided jobs are finished in each group, and when it is detected in the detection step that all the divided jobs are finished in a group, execution of the job in the remaining groups is forcibly canceled.  
         [0019]     The job scheduler may assign in turn the divided jobs to, of the plurality of client apparatuses, all client apparatuses capable of receiving the job.  
         [0020]     The job scheduler may comprise storage means for storing information about each client apparatus and determine an assignment order of the divided jobs on the basis of the information stored in the storage means.  
         [0021]     In this case, the information may contain one of information about performance of a resource of the client apparatus and information about an execution result of a job in the client apparatus.  
         [0022]     The present invention can be applied to an image forming system in which an apparatus including the job scheduler and the task manager or at least one of the client apparatuses is an image forming apparatus.  
         [0023]     The above object can also be achieved by an information processing apparatus capable of operating as the host computer of the computer system, a computer system including a host computer and client apparatuses, a computer program which causes a computer apparatus to execute the job assignment method, and a storage medium which stores the program.  
         [0024]     Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
         [0026]      FIG. 1  is a block diagram showing the basic arrangement of grid computing;  
         [0027]      FIG. 2  is a block diagram showing the basic arrangement of an image forming system according to the present invention;  
         [0028]      FIG. 3  is a view showing the outer appearance of an image forming apparatus;  
         [0029]      FIG. 4  is a block diagram showing the control configuration of the image forming apparatus;  
         [0030]      FIG. 5  is a flowchart of job assignment processing in a DJS according to the first embodiment;  
         [0031]      FIG. 6  is a flowchart showing processing of the DJS according to the first embodiment;  
         [0032]      FIG. 7  is a flowchart showing processing of a TM according to the first embodiment;  
         [0033]      FIG. 8  is a flowchart showing processing of a broker according to the first embodiment;  
         [0034]      FIG. 9  is a flowchart showing processing of a DJS according to the second embodiment; and  
         [0035]      FIG. 10  is a view for explaining a detailed example of the second embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]     Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings. Note that each element in the following embodiments is not intended to limit the scope of the invention, but is described only as an example.  
         [0000]     (Basic Arrangement)  
         [0037]     The basic arrangement of an image forming system according to the present invention, which is common to the following embodiments, will be described first.  
         [0038]      FIG. 2  is a block diagram showing the basic arrangement of the image forming system according to the present invention, in which grid computing is applied to PDL processing (rendering processing of a page description language to a raster image) of a printer. In the arrangement shown in  FIG. 1 , the modules included in the grid are handled as separate devices. However, when the system is applied to an image forming apparatus such as MFP or printer, generally, a plurality of modules are present in one device.  
         [0039]     In the arrangement shown in  FIG. 2 , the user inputs a job such as a print instruction from a client PC  110 . The input job is analyzed by an image forming apparatus  120  such as a printer having TM and DJS -functions. Distributed processing by grid computing is executed by using the resources of three PCs, i.e., PC  1  ( 141 ), PC  2  ( 142 ), and PC  3  ( 143 ) each having a broker and RM.  
         [0040]     In the arrangement shown in  FIG. 2 , the image forming apparatus  120  also has the function of the host in grid computing. A PC except the image forming apparatus  120  may have the function of the host, as a matter of course.  
         [0041]     When the print job of PDL is input from the client PC  110 , the job is appropriately distributed to the resources of the PCs  141  to  143  through the TM and DJS of the image forming apparatus  120 . At this time, the application program for image rendering processing of PDL is also simultaneously transmitted from the image forming apparatus  120  to each PC.  
         [0042]     Images which are formed by causing the respective PCs to render PDL are collected by the image forming apparatus  120  and finally output in the collected state.  
         [0043]     The number of clients (resources) to be subjected to distributed processing is not particularly limited. Three or more clients may be used. The resource of the client PC  110  to which the job is input or the resource of the image forming apparatus  120  may be subjected to distributed processing.  
       First Embodiment  
       [0000]     (Hardware Configuration of Image Forming Apparatus)  
         [0044]      FIG. 3  is a view showing the outer appearance of an image forming apparatus having a copy function according to the first embodiment. A scanner  201  serving as an image input device illuminates an image on a paper sheet as a document and scans a CCD line sensor (not shown) to generate raster image data.  
         [0045]     The user sets document paper sheets on a tray  203  of a document feeder  204  and inputs a reading operation start instruction from an operation unit  202 . The controller CPU of the image forming apparatus gives an instruction to the scanner  201 . The feeder  204  feeds the document paper sheets one by one. The scanner  201  reads the document images.  
         [0046]     The operation unit  202  serves as a user interface to do setting instruction or status display in the copy operation or designate various kinds of operation settings.  
         [0047]     A printer engine  103  serving as an image output device prints the raster image data on paper sheets. The printer engine  103  can employ any scheme such as the electrophotography scheme using a photosensitive drum or photosensitive belt or the inkjet scheme to print an image on a paper sheet directly by discharging ink from a micro nozzle array. The print operation is activated by an instruction from the controller CPU.  
         [0048]     The printer engine  103  has a plurality of paper feed stages to select different paper sizes or different paper orientations and comprises corresponding paper sheet cassettes  206 ,  207 , and  208 . A discharge tray  205  receives printed paper sheets.  
         [0049]      FIG. 4  is a block diagram showing the control configuration of the image forming apparatus of this embodiment. A printer controller  102  is connected to the scanner  201  serving as an image input device and the printer engine  103  serving as an image output device. The printer controller  102  also transmits/receives print data, image information, and device information to/from each client through a client I/F  308 .  
         [0050]     A CPU  301  is a controller to control the entire system. A RAM  302  is a system work memory used by the CPU  301  to operate. The RAM  302  also serves as an image memory to temporarily store image data. A ROM  303  is a boot ROM which stores the boot program of the system. An HDD  304  is a hard disk drive to store system software and image data.  
         [0051]     An operation unit I/F  306  is an interface to the operation unit (UI)  202  and outputs, to the operation unit  202 , image data to be displayed on it. The operation unit I/F  306  also transmits information input by the user through the operation unit  202  to the CPU  301 . Environment setting information such as an operation mode input from the operation unit  202  is stored in an NVRAM  316  serving as a nonvolatile memory.  
         [0052]     The client I/F  308  transmits/receives information to/from each client. The above-described devices are arranged on a system bus  307 .  
         [0053]     An image bus I/F  305  serving as a bus bridge connects the system bus  307  to an image bus  309  which transfers image data at a high speed, and the image bus I/F  305  converts the data structure.  
         [0054]     The following devices are arranged on the image bus  309 . A raster image processor (RIP)  310  renders a PDL code transmitted from the network to a bitmap image. A device I/F unit  311  connects the scanner  201  and printer engine  103  serving as image input and output devices to the printer controller  102  to convert the synchronous and asynchronous systems of image data.  
         [0055]     A scanner image processing unit  312  corrects, manipulates, or edits input image data. A printer image processing unit  313  executes printer correction or resolution conversion for print output image data. An image rotating unit  314  rotates image data. An image compression unit  315  executes JPEG compression/expansion processing for multilevel image data and JBIG, MMR, or MH compression/expansion processing for binary image data.  
         [0056]     The image forming apparatus of this embodiment having the above arrangement is connected to each client (PC) through the client interface (e.g., intercommunicable network interface such as Ethernet)  308  and also operates as a host to execute load distributed processing by grid computing.  
         [0000]     (Job Distributed Processing)  
         [0057]     Job distributed processing of this embodiment will be described below with reference to flowcharts shown in FIGS.  5  to  8 .  
         [0058]      FIG. 5  is a flowchart of job assignment processing in which a DJS groups the clients and instructs a broker to execute a job divided for each group.  FIG. 6  is a flowchart of processing of causing the DJS to instruct forcible termination.  FIG. 7  is a flowchart of processing of causing a TM to notify a broker of an instruction from the DJS and send a notification from the broker to the DJS.  FIG. 8  is a flowchart showing processing of causing the broker to execute an instruction from the TM.  
         [0059]     The flow of job assignment processing by the DJS will be described first with reference to  FIG. 5 . In this example, the number of clients to be subjected to distributed processing in grid computing is 20, and the number of divided jobs is 8.  
         [0060]     When job assignment processing starts, in step S 502 , using the number of clients of the grid and the number of divided jobs, which are acquired in advance, the number of clients (20) is divided by the number of divided jobs (8). In step S 503 , groups in number corresponding to the quotient are created. In this example, the number of groups is 2. Each group only needs to include 8 or more clients. In step S 504 , the divided jobs are assigned to the two groups.  
         [0061]     More specifically, in this example, the same job is assigned to one client in each group, i.e., two clients in total. Finally, in step S 505 , the correspondence between the broker of each client and the assigned divided job is transmitted to the TM, and the processing is finished.  
         [0062]     The information representing the correspondence between the broker of each client and the assigned divided job is used in processing to be described later and is therefore held in the DJS itself in, e.g., a table format.  
         [0063]     The operations of the DJS, TM, and broker during execution of the divided jobs will be described next with reference to  FIGS. 6, 7 , and  8 .  
         [0064]     In the DJS, the flow advances from step S 505  to step S 602  to wait for reception from the TM. When a notification is received from the TM, it is determined in step S 603  whether a job finish notification is received. If NO in step S 603 , the flow returns to step S 602  to set the reception wait state again. If a job finish notification (transmitted in step S 707  to be described later) is received from the TM, the flow advances to step S 604  to search for another broker (present in the other group) which is executing the same divided job on the basis of the information held by the DJS itself. In step S 605 , the DJS transmits a notification to the TM to output a divided job forcible termination instruction to the broker assigned the same job. Then, the reception wait state is set again.  
         [0065]     In step S 702 , the TM waits for reception from the DJS or broker. Examples of notifications received by the TM are a notification transmitted from the DJS in step S 605 , a notification transmitted from the broker in step S 806  to be described later, and a normal job request notification from the DJS.  
         [0066]     In step S 703 , it is determined whether the received notification is a job request from the DJS. If YES in step S 703 , the flow advances to step S 704  to receive the job and broker information. In step S 705 , a designated job is transmitted to a designated broker as a job request. The flow returns to step S 702  to set the reception wait state again.  
         [0067]     If NO in step S 703 , the flow advances to step S 706  to determine whether the received notification is a job finish notification from a broker. If YES in step S 706 , the flow advances to step S 707  to transmit the job finish notification to the DJS. The flow returns to step S 702  to set the reception wait state again.  
         [0068]     If NO in step S 706 , the flow advances to step S 708  to determine whether the received notification is a divided job forcible termination notification from the DJS. If YES in step S 708 , the flow advances to step S 709  to transmit the job forcible termination notification to the corresponding broker. The flow returns to step S 702  to set the reception wait state again.  
         [0069]     If NO in step S 708 , the flow returns to step S 702  without executing any processing to set the reception wait state again.  
         [0070]     In step S 802 , each broker waits for reception of the job request notification transmitted from the TM in step S 705  or the job forcible termination notification transmitted in step S 709 . When a notification is received from the TM, the flow advances to step S 803  to determine whether the notification is a job request.  
         [0071]     If YES in step S 803 , the flow advances to step S 804  to receive the contents (data and program) of the job to be executed. In step S 805 , the job is executed. After the job is finished, a job finish notification is transmitted to the TM in step S 806 . The flow returns to step S 802  to set the reception wait state again.  
         [0072]     If NO in step S 803 , the flow advances to step S 807  to determine whether the notification received from the TM is a divided job forcible termination notification. If YES in step S 807 , the flow advances to step S 808  to forcibly terminate the job currently being executed. The flow returns to step S 802  to set the reception wait state again.  
         [0073]     If NO in step S 807 , the flow returns to step S 802  without executing any processing to set the reception wait state again.  
         [0074]     The DJS, TM, and each broker operate in the above-described way. When a divided job is finished in one group, the same divided job which is being executed in the other group is forcibly terminated. The processing time of each divided job is that in the group which has finished the processing at the earliest timing. Hence, the time until all jobs are finished can be shortened.  
       Modification to First Embodiment  
       [0075]     In the above-described first embodiment, no particular standard is used in grouping in step S 503  of the flow shown in  FIG. 5 . Grouping may be done in accordance with the capability of each resource transmitted from the broker, such as the processing speed of the resource (CPU) of the client or the capacity of the memory. In this case, the time until the job is finished can be made shorter at a high probability by grouping clients with a high processing speed.  
         [0076]     In the above embodiment, each divided job is used as the unit of forcible termination. In a large-scale system including an enormous number of clients, forcible termination may be executed not for each divided job but for each group which executes the whole job. In, this case, the number of free clients increases. It is effective when the number of requested jobs is large, or the job is often interrupted in each client by user operation.  
       Second Embodiment  
       [0077]     An image forming system according to the second embodiment of the present invention will be described below. The image forming system of the second embodiment is similar to the first embodiment. A description of the same parts as in the first embodiment will be omitted, and characteristic parts of the second embodiment will mainly be described.  
         [0078]     In the first embodiment, clients are grouped, and each group is instructed to execute divided jobs. In the second embodiment, so-called round robin assignment processing is executed in which divided jobs are assigned in turn to executable clients (brokers) so that the time until all jobs are finished can be shortened even when, e.g., the number of clients to be subjected to distributed processing is small.  
         [0079]      FIG. 9  is a flowchart showing processing of a DJS according to this embodiment. The processing shown in  FIG. 5  to assign divided jobs to brokers and the operation shown in  FIG. 6  after divided job assignment in the first embodiment are shown as one flowchart. The operations of the TM and broker after divided job assignment are the same as those shown in the flowcharts of  FIGS. 7 and 8  described in the first embodiment.  
         [0080]     In step S 902 , the DJS waits for reception from the TM. Upon receiving a notification from the TM, the flow advances to step S 903  to determine whether the received notification is a job request. If YES in step S 903 , the flow advances to step S 904 . Otherwise, the flow advances to step S 908 .  
         [0081]     In step S 904 , it is determined whether a divided job of the received job is present. If YES in step S 904 , the flow advances to step S 906 . If NO in step S 904 , the flow advances to step S 905  to return the processing to the first divided job. Then, the flow advances to step S 906 .  
         [0082]     In step S 906 , it is determined whether a broker capable of receiving the job is present. If YES in step S 906 , the flow advances to step S 907  to notify the TM that it should request the broker to execute the job. The flow returns to step S 904 . As long as a broker capable of receiving the job is present, the processing in steps S 904  to S 907  is repeated. If NO in step S 906 , the flow returns to step S 902 .  
         [0083]     If NO in step S 903 , the flow advances to step S 908  to determine whether the received notification is a job forcible termination notification. If YES in step S 908 , the flow advances to step S 909  to search for another broker which is executing the same job. In step S 910 , the DJS transmits a notification to the TM to output a divided job forcible termination instruction to the broker assigned the same job. Then, the flow returns to step S 902  to set the reception wait state again. If NO in step S 908 , the flow returns to step S 902  without executing any processing to set the reception wait state again.  
         [0084]     An example of divided job assignment processing according to this embodiment will be described with reference to  FIG. 10 . In the illustrated example, the number of clients (brokers) to be subjected to distributed processing included in the image forming system is 14, and the number of divided jobs is 8.  
         [0085]     Referring to  FIG. 10 , a to n along the ordinate indicate the 14 different brokers. The frame next to each broker indicates processing contents in that broker. Each number in the frames indicates a divided job number. Hatching indicates a distributed processing disable state by a user interrupt.  
         [0086]     At divided job assignment start time t 0 , the brokers g and k are not subjected to distributed processing by grid computing. For this reason, eight divided jobs  1  to  8  are assigned to 12 brokers, as shown in  FIG. 10 .  
         [0087]     At time t 1 , of the eight divided jobs, job  1  and job  5  are finished. The three brokers a, e, and j which were executing jobs  1  and  5  are assigned unfinished jobs  6  to  8  next to job  5 , respectively. At time t 2 , job  2  is finished. The brokers b and l which were executing job  2  are assigned unfinished jobs  3  and  4 , respectively. At time t 3 , job  3  is finished. The brokers b and m which were executing job  3  are assigned jobs  6  and. 7 , respectively. At time t 4 , jobs  4  and  7  are finished. The brokers b, e, h, l, and n which were executing jobs  4  and  7  are assigned unfinished jobs  6  and  8 . When jobs  6  and  8  are finished at time t 5 , all divided jobs are finished.  
         [0088]     As described above, according to this embodiment, when the number of clients is not so large relative to the number of divided jobs, executable clients can effectively be used. Hence, the time until all jobs are finished can be shortened.  
       Third Embodiment  
       [0089]     An image forming system according to the third embodiment of the present invention will be described below. The image forming system of the third embodiment is similar to the first and second embodiments. A description of the same parts as in the first and second embodiments will be omitted, and characteristic parts of the third embodiment will mainly be described.  
         [0090]     In the first and second embodiments, no priority orders are given to the brokers in assigning the divided jobs. In the third embodiment, evaluation information based on a predetermined criterion is prepared for each broker. The pieces of evaluation information are held in a predetermined area of the DJS in, e.g., a table format. Divided jobs are assigned in an order according to the evaluation information of the brokers.  
         [0091]     As the evaluation information, for example, a score is prepared for each broker. In step S 604 , the DJS increments the score of a broker from which a job finish notification is received. The DJS decrements the score of each broker which is executing the same job and should receive a forcible termination instruction in step S 605  or S 910 . Divided jobs are preferably assigned to the brokers in descending order of scores.  
         [0092]     In this case, a job is preferentially assigned to a broker which has normally finished jobs a number of times. Hence, divided job assignment to each broker is rationalized. As a result, the time until all lobs are finished can be shortened.  
       Modification to Third Embodiment  
       [0093]     In the third embodiment, evaluation information (score) is incremented or decremented depending on whether a job is normally finished or forcibly terminated. Instead, the evaluation point may be changed on the basis of the capability of the resource (CPU, OS, or hardware resource) of each broker, time, location, department, user setting, processing time required for normal finish, or past record.  
         [0094]     In place of evaluation information, log information of job execution by each broker (client) may be stored, and a broker to be assigned a job may be determined on the basis of the log information.  
         [0095]     In the third embodiment, jobs are assigned in descending order of scores. Conversely, control may be done not to assign a job to a broker with a low score.  
       Other Embodiment  
       [0096]     The present invention may be applied to a grid computing system (grid network) including a plurality of devices or a single device (host computer) included in a grid network.  
         [0097]     The above-described embodiments may appropriately be combined as needed.  
         [0098]     Furthermore, the invention can be implemented by supplying a software program, which implements the functions of the foregoing embodiments (program corresponds to flowcharts shown in FIGS.  5  to  9 ), directly or indirectly to a system or apparatus, reading the supplied program code with a computer of the system or apparatus, and then executing the program code. In this case, so long as the system or apparatus has the functions of the program, the mode of implementation need not rely upon a program.  
         [0099]     Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. In other words, the claims of the present invention also cover a computer program for the purpose of implementing the functions of the present invention.  
         [0100]     In this case, so long as the system or apparatus has the functions of the program, the program may be executed in any form, such as an object code, a program executed by an interpreter, or scrip data supplied to an operating system.  
         [0101]     Example of storage media that can be used for supplying the program are a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a non-volatile type memory card, a ROM, and a DVD (DVD-ROM and a DVD-R).  
         [0102]     As for the method of supplying the program, a client computer can be connected to a website on the Internet using a browser of the client computer, and the computer program of the present invention or an automatically-installable compressed file of the program can be downloaded to a recording medium such as a hard disk. Further, the program of the present invention can be supplied by dividing the program code constituting the program into a plurality of files and downloading the files from different websites. In other words, a WWW (World Wide Web) server that downloads, to multiple users, the program files that implement the functions of the present invention by computer is also covered by the claims of the present invention.  
         [0103]     It is also possible to encrypt and store the program of the present invention on a storage medium such as a CD-ROM, distribute the storage medium to users, allow users who meet certain requirements to download decryption key information from a website via the Internet, and allow these users to decrypt the encrypted program by using the key information, whereby the program is installed in the user computer.  
         [0104]     Besides the cases where the aforementioned functions according to the embodiments are implemented by executing the read program by computer, an operating system or the like running on the computer may perform all or a part of the actual processing so that the functions of the foregoing embodiments can be implemented by this processing.  
         [0105]     Furthermore, after the program read from the storage medium is written to a function expansion board inserted into the computer or to a memory provided in a function expansion unit connected to the computer, a CPU or the like mounted on the function expansion board or function expansion unit performs all or a part of the actual processing so that the functions of the foregoing embodiments can be implemented by this processing.  
         [0106]     As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.  
       CLAIM OF PRIORITY  
       [0107]     This application claims priority from Japanese Patent Application No. 2004-171768, filed Jun. 9, 2004, which is hereby incorporated by reference.