Abstract:
A computer network system is disclosed, in which the process of distributing software resources from a server to clients is dispersed so that the downloading time and the data amount for each session of the distribution process is adjusted, thereby making it possible to reduce the load of the whole network at the time of distribution of the software resources.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a computer system connected with two computers, and a computer network system connected with three or more computers, or more in particular to a function of distributing software resources to each client from a server in a client/server system. Also, the invention relates to a computer connected with the computer network system for receiving the software resources distributed thereto, and a recording medium for recording a computer program for that purpose. 
     In a self-maintenance system for computers, a copy of data (application files, data files, etc.) are stored in a backup area as backup data, and in the case where a fault is found in a given data at the time of self-diagnosis, or in the case where the computer is infected by a computer virus, the data involved are rewritten and replaced by the data stored in the backup area thereby to recovery the data immediately. 
     In recent years, on the other hand, with the improvement in the computer performance, the use of a computer network system such as a client/server system connecting a plurality of computers by a network has extended. In the client/server system, a trouble affecting the whole network system is liable to occur due to an operating error of the user or a simple error in configuration. In such a case, the maintenance operation itself becomes impossible, often resulting in a system down before the trouble is eliminated. This likelihood increases with the number of computers connected to the network. With the increase in the size of the network system, therefore, the resulting economic loss cannot be ignored. The self-maintenance, therefore, is more crucial for a network system such as the client/server system than for a stand-alone computer used in isolation. 
     Further, a system such as a client/server system using a plurality of computers as clients and servers, the infection by computer viruses has recently posed a serious problem. Specifically, once a computer virus intrudes one of a plurality of the computers making up a client/server system, all the clients and servers are infected through the network, thereby leading to a serious loss. For operating the client/server system smoothly, therefore, an efficient system maintenance is very important. 
     With the computer network system such as the client/server system described above, in the case where software resources or new application software is installed in a client, for example, the particular data are registered in a server. Also, in the case of version up or bug correction of the application software used currently by a client, the difference data are registered in the server. In any of these cases, the operating environment of individual clients is renewed by distributing the registered data to the clients from the server. 
     The process of distributing the software resources in the client/server system making up a computer network system is conventionally carried out as a collective process in downloading from the server to each client and setting the downloaded software resources as the ones available for use by each client. In the meantime, no client can be operable before the completion of the process (downloading and the application processing of the update data) for distributing the software resources to all the clients connected to the network. 
     Also, the operating system (OS) and the application software of the individual computers have recently increased in size and have become complicated. With the increase in the size of the operating system and the application software and the increase in the number of clients connected to the network as described above, the distribution of the software resources has come to consume a considerable length of time. Thus, the distribution of software resources from the server to the clients requires an ever-increasing length of time, which tends to increase the time during which the clients cannot be used. 
     SUMMARY OF THE INVENTION 
     The present invention has been developed in view of the situation described above and the object thereof is to provide a computer system network in which the process for distributing software resources from a server to clients is dispersed to adjust the download time and the data amount for each distribution process thereby reducing the load of the whole network at the time of distributing software resources. Another object of the invention is to provide a computer connected to the computer network system for receiving the software resources distributed thereto, and a recording medium with a computer program being recorded for realizing such a process with a general-purpose computer. 
     According to the present invention, there is provided a computer network system such as a client/server system, in which in short, update data are divided and downloaded from a first computer (server unit, for example) to a second computer (client unit). 
     A computer system according to the invention comprises a first computer including a data storage unit for storing data to be used by other computers, is connected with a second computer including an operating data storage unit for storing data used for the operation of the second computer, the second computer receiving the transferred data stored in the data storage unit of the first computer and storing it in the operating data storage unit of the second computer thereby to use the particular data, wherein the first computer includes a transfer condition storage unit for storing the conditions for transferring the data stored in the data storage unit to the operating data storage unit of the second computer, and the second computer includes a determination unit for determining the possibility of dividing and transferring the data stored in the data storage unit of the first computer in accordance with the contents stored in the transfer condition storage unit of the first computer, a transfer processing unit for dividing and transferring the data stored in the data storage unit of the first computer in the case where the determination unit determines that the divide transfer is possible, and a data storage unit for sequentially accumulating and storing the data which the transfer processing unit causes the first computer to divide and transfer from the data storage unit of the first computer, the data stored in the data storage unit being adapted to be stored in the operating data storage unit. 
     More specifically, the computer system according to the invention wherein a first computer including a storage unit for storing data to be used by other computers, is connected with a second computer including a storage unit for storing data used for the operation of the second computer, the second computer receiving the transferred data stored in the storage unit of the first computer and storing it in the storage unit of the second computer thereby to use the same data, wherein the first computer stores the conditions for data transfer to the storage unit, of the second computer in the own storage unit, and the second computer includes a control unit connected to the storage unit of the second computer and capable of performing the operation of determining whether the divide transfer of the data stored in the storage unit of the first computer is possible or not according to the transfer conditions stored in the storage unit of the first computer, the operation of causing the first computer to divide and transfer the data stored in the storage unit of the first computer in the case where it is determined that the divide transfer is possible, and the operation of sequentially accumulating and storing the data divided and transferred from the storage unit of the first computer in the storage unit of the second computer. 
     As described above, in a computer system according to the present invention, the data stored in the data storage unit of the first computer is divided and transferred to, at appropriate timing, and accumulated in the data storage unit of the second computer, and at the time point when all the data are transferred and stored as one data, the data are stored in the operating data storage unit and becomes available for use. 
     As a result, as compared with the conventional system in which the update data are collectively distributed and the second computer is not operable before the update data are completely distributed, the update data are divided and transferred in the intervals during the operation in the computer network system according to the invention. 
     Also, in the computer system according to the invention having the configuration described above, the conditions for transfer include at least one of the possibility of divide transfer, the presence or absence of the designation of preferential transfer, the presence or absence of the designation of the date of transfer completion, the presence or absence of the limitation of the number of times to divide the data, the presence or absence of the limitation of the amount of the data transferred at a time, related to the data stored in the data storage unit of the first computer and the presence or absence of the limitation due to the load of the second computer. 
     In the computer system according to the invention described above, the possibility of the divide transfer of the data to the second computer is determined according to the transfer conditions, and therefore it is possible to determine whether the data are divided and transferred in accordance with the operating conditions of the computer and, if divided and transferred, to set various conditions. 
     A computer network system according to the invention wherein at least one first computer including a data storage unit for storing data to be used by other computers, and a plurality of second computers each including an operating data storage unit for storing data used for the operation of the second computer, the second computer receiving the transferred data stored in the data storage unit of the first computer and storing it in the operating data storage unit of the second computer thereby to use the particular data, are connected by a network, wherein the first computer includes a transfer condition storage unit for storing the conditions for transferring the data stored in the data storage unit to the operating data storage unit of the second computers, and the second computers each include a determination unit for determining the possibility of dividing and transferring the data stored in the data storage unit of the first computer in accordance with the contents stored in the transfer condition storage unit of the first computer, a transfer processing unit for dividing and transferring the data stored in the data storage unit of the first computer in the case where the determination unit determines that the divide transfer is possible, and a data storage unit for sequentially accumulating and storing the data which the transfer processing unit causes the first computer to divide and transfer from the data storage unit of the first computer, the data stored in the data storage unit being adapted to be stored in the operating data storage unit. 
     More specifically, the computer network system according to the invention wherein at least one first computer including a storage unit for storing the data to be used by other computers, and a plurality of second computers each including a storage unit for storing the data used for the operation of the second computer, the second computer receiving the transferred data stored in the storage unit of the first computer and storing it in the own storage unit thereby to use the particular data, are connected by a network, wherein the first computer stores the conditions for data transfer to the storage unit of the second computer in the own storage unit, and the second computers each include a control unit connected to the storage unit of the second computer and capable of performing the operation of determining whether the divide transfer of the data stored in the storage unit of the first computer is possible or not according to the transfer conditions stored in the storage unit of the first computer, the operation of dividing and transferring the data stored in the storage unit of the first computer in the case where it is determined that the divide transfer is possible, and the operation of sequentially accumulating and storing the data divided and transferred from the storage unit of the first computer in the storage unit of the second computer. 
     As described above, in a computer network system according to the present invention, the data stored in the data storage unit of the first computer is divided and transferred to, at appropriate timing and accumulated in the data storage unit of each of the second computers, and at the time point when all the data are transferred to and stored in each of the second computers as one complete data, the data are stored in the operating data storage unit and becomes available for use. 
     Also, in the computer network system according to the invention having the configuration described above, the conditions for transfer include at least one of the possibility of divide transfer, the presence or absence of the designation of preferential transfer, the presence or absence of the designation of the date of transfer completion, the presence or absence of the limitation of the number of times to divide the data, the presence or absence of the limitation of the amount of the data transferred at a time, related to the data stored in the data storage unit of the first computer, and the presence or absence of the limitation due to the load of the second computer. 
     In the computer network system according to the invention described above, the possibility of the divide transfer of the data to the second computers is determined according to the transfer conditions, and therefore it is possible to determine whether the data are divided and transferred in accordance with the operating conditions of each of the second computers and, if divided and transferred, to set various conditions for each of the second computers. 
     A computer according to the invention comprises an operating data storage unit for storing data to be used for the own operation, the computer receiving the transferred data to be used by the computer from other computers and storing it in the operating data storage unit thereof thereby to use the particular data, the computer further comprising a determination unit for determining the possibility of dividing and transferring the data from other computers in accordance with predetermined conditions, a transfer processing unit for dividing and transferring the data from other computers in the case where the determination unit determines that the divide transfer is possible, and a data storage unit for sequentially accumulating the data which the transfer processing unit causes other computers to divide and transfer, the data stored in the data storage unit being adapted to be stored in the operating data storage unit. 
     More specifically, the computer according to the invention comprises a storage unit for storing the data to be used for the own operation, receives the transferred data to be used by itself from other computers and uses the particular data, the computer further comprising a control unit connected to the storage unit and capable of performing the operation of determining whether the divide transfer of the data from other computers is possible or not according to predetermined conditions, the operation of dividing and transferring the data from other computers in the case where it is determined that the divide transfer is possible, the operation of sequentially accumulating and storing the data divided and transferred from other computers in the storage unit, and the operation of rendering the stored data available for use for the own operation. 
     As described above, in a computer according to the present invention, the data from other computers is divided and transferred to, at appropriate timing, and accumulated in the data storage unit, and at the time point when all the data are transferred and stored as one complete data, the data are stored in the operating data storage unit and becomes available for use. 
     Also, in the computer according to the invention having the configuration described above, the predetermined conditions include at least one of the possibility of divide transfer, the presence or absence of the designation of preferential transfer, the presence or absence of the designation of the date of transfer completion, the presence or absence of the limitation of the number of times to divide the data the presence or absence of the limitation of the amount of the data transferred at a time, related to the data to be transferred from other computers, and the presence or absence of the limitation due to the own load. 
     In the computer according to the invention described above, the possibility of the divide transfer of the data is determined according to the transfer conditions, and therefore it is possible to determine whether the data are divided and transferred in accordance with the operating conditions of the computer and, if divided and transferred, to set various conditions. 
     According to the invention, there is provided a computer-readable recording medium having stored therein a computer program which causes a computer having an operating data storage unit for storing data to be used for the operation of the particular computer to receive the transferred data to be used by the computer from other computers and to store the data in the operating data storage unit, wherein the computer program includes program code means for causing the computer to determine according to predetermined conditions whether the divide transfer of the data from other computers is possible, program code means for causing the computer to split and transfer the data from other computers in the case where it is determined that the data can be divided and transferred, program code means for causing the computer to sequentially accumulate and store the data divided and transferred from other computers, and program code means for causing the computer to store the stored data in the operating data storage unit. 
     In this way, a computer is realized in which each program code means stored in the recording medium according to the invention is read by the computer, so that the data from other computers is divided and transferred to, at appropriate timing, and accumulated in the data storage unit, and at the time point when all the data are completely transferred and stored as one complete data, the data are stored in the operating data storage unit and becomes available for use. 
     Also, the recording medium according to the invention having the configuration described above further comprises program code means for causing the computer to read at least one of the predetermined conditions including the possibility of divide transfer, the presence or absence of the designation of preferential transfer, the presence or absence of the designation of the due date of transfer completion, the presence or absence of the limitation of the number of times to divide the data, the presence or absence of the limitation of the amount of the data transferred at a time, related to the data to be transferred from other computers, and the presence or absence of the limitation due to the own load. 
     In this way, a computer is realized, which is caused to read the program code means stored in the recording medium according to this invention and determine whether the data can be divided and transferred in accordance with the read conditions. 
     The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing an example configuration of a computer network system according to the invention. 
     FIG. 2 is a flowchart showing the steps of the update processing of the computer network system according to the invention. 
     FIG. 3 is a flowchart showing the steps of determination of divide/collective downloading in the computer network system according to the invention. 
     FIG. 4 is a flowchart showing the steps of divide downloading of the data in the computer network system according to the invention. 
     FIG. 5 is a block diagram showing a computer network system according to another embodiment of the invention. 
     FIG. 6 is a schematic diagram showing a configuration example of a general-purpose computer according to the invention. 
     FIG. 7 is a schematic diagram showing the contents of the computer program recorded in a recording medium according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail below with reference to the diagrams showing embodiments thereof. FIG. 1 is a block diagram showing an example configuration of a computer network system according to the invention. A client/server system is shown as an example of the computer network system. 
     In FIG. 1, reference numeral  100  designates a LAN, numeral  1  designates a sever computer (hereinafter referred to as the server unit), and numeral  2  designates client computers (hereinafter referred to as the client units). These component parts are connected to the LAN  100  and constitute a client/server system as a network system. To one LAN is connectable a plurality of the server units  1  and the client units  2 . In the case under consideration, however, one server unit  1  and two client units  2  are connected to the LAN  100 . Nevertheless, a computer system can be configured in which only one server unit  1  and only one client unit  1  are connected. 
     Also, the client unit  2  is a computer according to the invention, and by being caused to read the program code from a recording medium according to the invention to be described later, functions as a client unit  2  connected to the client/server system constituting a computer network system according to the invention. 
     The server unit  1  and the client unit  2  are each a general-purpose personal computer having such hardware units as a CPU, a memory, a disk unit (hard disk, flexible disk, etc.), a printer, a display unit, a keyboard, a mouse, and the like. Each unit is connected with large capacity storage media  10 ,  20  using the hardware such as a hard disk, a magnetic tape etc., and installed with the OS (operating system) and various software. 
     The storage medium  10  of the server unit  1  has stored therein the information in files such as a server system file  11 , a backup file  12 , an update information file  13  and an update data file  14 . 
     The server system file  11  has filed and stored therein the OS and various application software required for the operation of the server unit  1 . When these software are executed by the server unit  1 , the server system file  11  functions as an operating unit  111 . Also, backup data for each client  2  is stored in the backup file  12 . 
     The update information file  13  has stored therein various information on the update data registered in the update data file  14 . The various information include not only the unique information such as the size of individual update data but also the conditions for downloading to the client unit  2 , including whether divide downloading or only collective downloading is possible, whether immediate (preferential) downloading is required or normal downloading will do, whether the due date of downloading completion is designated, whether the number of times is designated for the divide downloading, the amount of transfer data for each session of the divide downloading, and the client load conditions permitting the downloading. These conditions are registered in advance as download conditions. 
     The update data file  14  has stored therein the update data. The update data are read from outside or from other computers through the LAN  100  as required by the operating unit  111  of the server unit  1  and stored in the update data file  14 . 
     The storage medium  20  of the client unit  2  has stored therein an operating system file  21 , a master log file  22 , a self-maintenance system file  23 , an update data file  24 , and other information in the form of a file. 
     The operating system file  21  has stored therein the OS and various application software as a file required for a particular client unit  2 . In the case where these software are executed by the client unit  2 , the operating system file  21  functions as an operating unit  211 . The operating unit  211  executes these functions in the case where the ordinary application software such as the word processor or the spread sheet stored in the operating system file  21  are executed by the client unit  2 . 
     The master log file  22  holds the operation history of the client unit  2  and is referred to at the time of self-maintenance. 
     Also, the self-maintenance system file  23  has stored therein various software as a file required for the self-maintenance of the client unit  2 . In the case where these software are executed by the client unit  2 , the self-maintenance system file  23  functions as a self-diagnosis/auto-recovery unit  212 , an update processing unit  213  and an update processing determination unit  214 . 
     The update data file  24  stores temporarily therein the update data downloaded in divide form or collectively from the server unit  1 . The update data downloaded collectively is transferred to the operating system file  21  from the update data file  24  and installed at the time of self-maintenance, and thus becomes available for use. Also, at the time of divide downloading, the update data file  24  sequentially accumulates the downloaded data portions until the whole of one update data is completely downloaded. Once the whole of one update data is completely downloaded, they are collectively installed in the operating system file  21  from the update data file  24  at the time of self-maintenance, and then becomes available for use. 
     The self-diagnosis/auto-recovery unit  212  executes the self-diagnosis of the client unit  2  itself at an appropriate timing such as when an instruction is received from the user or power is turned on, determines whether a file to be recovered by the backup data exists or not, and in the case where such a file is registered, recovers it by reading the required file from the backup file  12  of the server unit  1 . 
     Also, the update processing unit  212  functions as an update data transfer processing unit, and referring to the contents of the update information file  13  of the server unit  1 , determines the necessity of the update processing at an appropriate timing such as when an external input is discontinued for a predetermined length of time. The update processing determination unit  214  determines whether the update data from the server unit  1  are to be downloaded collectively or in divide form when the update processing unit  213  executes the update processing. 
     In this client/server system, when the power supply of the client unit  2  is turned on to start up, the self-diagnosis/auto-recovery unit  212  is activated by the self-diagnosis software stored in the self-maintenance system file  24  of the particular client unit  2 . Then, the self-diagnosis of the client unit  2  is executed by the self-diagnosis/auto-recovery unit  212 . A similar self-maintenance can be executed, however, by the user issuing an instruction at an arbitrary time point when the maintenance processing is possible to execute, as well as when power is turned on. 
     Once the self-diagnosis is executed by the self-diagnosis/auto-recovery unit  212 , the contents of the operating system file  21  and the master log file  22  are compared with each other, and it is determined whether the system environment of the client unit  2 , i.e. the folder/file of software, etc. are modified or newly prepared. In the case where there are data (folder/file) requiring recovery, the backup data are read from the backup file  12  of the server unit  1  and reinstalled in the operating system file  21 , thus making it possible to recover the portions necessary to be recovered. 
     In normal case, the client unit  2  becomes available for operation in this way. At the time of self-maintenance of the client unit  2  or at an appropriate timing of subsequent normal operation such as when an external input is discontinued for a predetermined length of time, however, the update processing unit  213  performs the update processing, i.e. the downloading of the update data registered in the update data file  14  to the update data file  24 . 
     FIG. 2 is a flowchart showing the steps of the update processing of the computer network system according to the invention. With reference to this flowchart of FIG. 2, the steps of the update processing executed by the server unit  1  and the client unit  2  will be explained below. 
     The server unit  1  determines the presence or absence of the update data from the contents of the update information file  13  of the server unit  1  at an appropriate timing as described above (step S 11 ). In the case where the update data is not registered (NO in step S 11 ), the state at that time point, i.e. the operating state or the execution of the self-maintenance processing state is continued while executing the processing of step S 11  again at the next appropriate timing. 
     In the case where the update data is registered (YES in step S 11 ), on the other hand, the update processing unit  213  determines whether the client unit  2  is in operation or not, or specifically, whether the self-maintenance processing is not being executed or being executed (step S 12 ). If the client unit  2  is not in operation (NO in step S 12 ), i.e. in the case where the self-maintenance processing is being executed, the update processing unit  213  determines whether the downloading of some of the update data indicated by the contents of the update information file  13  is already completed or not (step S 13 ). 
     In the case where there are some update data of which the downloading is completed, such data are stored in the update data file  24 . Thus, the update processing unit  213  performs the application process for installing the particular update data in the operating system file  21  from the update data file  24  and rendering it available for use (step S 14 ), and executing the processing of step S 11  again at the next appropriate timing, determines whether other update data are registered in the update data file  14  of the server unit  1  or not. 
     In the case where there is no update data completely downloaded in step S 13  (NO in step S 13 ), or in the case where the client unit  2  has started the operation in step S 12  (YES in step S 12 ), the update processing unit  213  causes the update processing determination unit  214  to determine the update processing for the update data registered in the server unit  1  (step S 15 ). 
     FIG. 3 is a flowchart showing the steps of determining the divide or collective downloading in the computer network system according to the invention. This update processing is executed by the update processing determination unit  214 . 
     First, in accordance with the contents of the update information file  13  of the server unit  1 , the update processing determination unit  214  determines whether the divide downloading of the update data registered in the update data file  14  of the server unit  1  is already started or not (step S 51 ). Specifically, it is determined whether the divide downloading of the update data registered in the update data file  24  of the server unit  1  to the client unit has been executed several times but not the whole downloading sessions have not yet been completed. 
     In the case where the divide downloading has been already executed several times (YES in step S 51 ), the update processing determination unit  214  reads the transfer situation of the particular update data from the update information file  13  (step S 52 ), and determines whether the update data includes the due date designation or not (step S 53 ). In the case where the due date is not designated (NO in step S 53 ), the update processing determination unit  214  determines from the contents of the update information file  13  of the server unit  1  whether the number of times is designated for dividing the particular update data (S 54 ). In the case where the number of times for the dividing is not designated (NO in step S 54 ), the divide downloading of the particular update data is designated (step S 55 ) and the process returns to the main routine. 
     In the case where the due date is designated in step S 53  (YES in step S 53 ), on the other hand, the update processing determination unit  214  reads the designated due date from the update information file  13  of the server unit  1 , and determines whether the designated due date is within a predetermined number of days from the present date (step S 56 ). In the case where the designated due date is not within the predetermined number of days from the present date (NO in step S 56 ), the process proceeds to step S 54 , while in the case where the designated due date is within the predetermined number of days from the present date (YES in step S 56 ), in contrast, there is not enough time for divide downloading, and therefore the update processing determination unit  214  designates the collective downloading of the update data (step S 58 ) and the process returns to the main routine. 
     In the case where the number of times to divide the update data is designated in step S 54  (YES in step S 54 ), the update processing determination unit  214  determines whether the designated number of times to divide the update data is not more than a predetermined number (step S 57 ). In the case where the designated number of times to divide the update data is not more than a predetermined number (YES in step S 57 ), the process proceeds to step S 55  described above, while in the case where the designated number of times to divide the update data is more than a predetermined number (NO in step S 57 ), on the other hand, the update processing determination unit  214  designates the collective downloading of the particular update data (step S 58 ) and the process returns to the main routine. The reason for collective downloading in the case where the designated number of times to divide the update data for downloading is more than a predetermined number set in each client unit  2  is to avoid an excessive load being imposed on the client unit  2  by the execution of the divide downloading the predetermined number of times or more. 
     In the case where it is determined in step S 51  that the divide downloading is not started (NO in step S 51 ), on the other hand, it is not yet clear whether the particular update data can be downloaded in divide form or not, and therefore the update processing determination unit  214  makes the following determination. First, the update processing determination unit  214  acquires the information on the update data from the update information file  13  of the server unit  1  (step S 61 ), and determines whether the collective downloading is designated or not (step S 62 ). In the case where the collective downloading is designated (YES in step S 62 ), the update processing determination unit  214  designates the collective downloading of the particular update data (step S 58 ), and the process returns to the main routine. 
     In the case where the collective downloading is not designated (NO in step S 62 ), on the other hand, the update processing determination unit  214  determines from the contents of the update information file  13  of the server unit  1  whether the immediate downloading is designated or not (step S 63 ). In the case where the immediate downloading is designated (YES in step S 63 ), the update processing determination unit  214  designates the collective downloading for immediately downloading the update data (step S 58 ), and the process returns to the main routine. In the case where the immediate downloading is not designated (NO in step S 63 ), on the other hand, the process proceeds to step S 53  described above. 
     After the determination of the update processing in step S 15  or specifically after the determination of the divide downloading or the collective downloading, the process is returned to the main routine shown in FIG.  2 . In the case where the divide downloading is designated (YES in step S 16 ), on the other hand, the divide downloading is executed once (step S 17 ). 
     The processing of step S 17  will be explained below. FIG. 4 is a flowchart showing the steps of the process for divide downloading in the computer network system according to the invention. 
     First, the update processing unit  213  of the client unit  2  reads the transfer situation of the update data from the update information file  13  of the server unit  1 , or specifically, the past transfer situation of the update data to be downloaded in divide form (step S 71 ). Then, in accordance with the transfer situation read from the update information file  13 , the update processing unit  213  reads the update data of the update data file  14  of the server unit  1 , from the top portion thereof in the case where no transfer is made in the past or from the following portion of the update file  14  in the case where several sessions of divide downloading are made in the past. Thus, the data transfer to the update data file  24  of the client unit  2  is started (step S 72 ). 
     Once the transfer of the update data is started to the backup file  23  of the client unit  2  from the update data file  14  of the server unit  1  in this way, the update processing unit  213  checks whether the system situation, the transfer amount, the due date and the number of times are not more than the threshold values (step S 72 ) and the presence or absence of the instruction for termination (step S 74 ) while continuing to transfer the data until the data transfer amount reaches a predetermined amount set for a single session of divide downloading (YES in step S 75 ). 
     In the case where any one of the system situation, the transfer amount, the due date and the number of times exceeds the threshold value (NO in step S 73 ), the update processing unit  213  determines whether the divide downloading can be continued or not (step S 78 ), and in the case where the divide downloading is impossible to continue (NO in step S 78 ), the collective downloading is designated (step S 79 ) and the process is returned to the main routine. In the case where the divide downloading is possible to continue (YES in step S 78 ), on the other hand, the update processing unit  213  ends the data transfer temporarily (step S 76 ), and writes the past data transfer situation up to the particular time point in the update information file  13  of the server unit  1  as the update data transfer situation (step S 77 ) and the process is returned to the main routine. 
     In the case where an instruction to terminate the process is given from the server unit  1  or the client unit  2  (YES in step S 74 ) or in the case where the data transfer amount reaches the predetermined value (YES in step S 75 ), as in the preceding case, the process of steps S 76  and S 77  is executed and then the process is returned to the main routine. 
     In the case where the collective downloading is designated in the above-mentioned step S 79 , whether the collective downloading is designated or not is determined in step S 19  after the process returns to the main routine shown in FIG. 2, and therefore the process proceeds to step S 18  for executing the collective downloading. 
     After executing one session of divide downloading in this way, the process of S 11  and subsequent steps is repeated at the next appropriate timing during the operation of the client unit  2 . Thus, one update data is sequentially divided and downloaded and sequentially accumulated in the update data file  24  of the client unit  2 , until the whole of one update data is downloaded from the update data file  14  of the server unit  1  to the update data file  24  of the client unit  2  is completed. In this case, when the next self-maintenance is executed in the client unit  1 , the process of steps S 12 , S 13 , S 14  is executed, and therefore the update data completely downloaded and accumulated in the update data file  24  is installed in the operating system file  21  and thus becomes available for use. 
     Also, in the case where the collective downloading is designated in step S 15  (NO in step S 16 ) or in the case where the collective downloading is designated during the processing operation of step S 17  (YES in step S 19 ), the collective downloading is executed (step S 18 ). As a result, one update data is immediately downloaded collectively and stored in the update data file  24  of the client unit  2 . In this case, when executing the next self-maintenance processing in the client unit  2 , the process of steps S 12 , S 13 , S 14  is executed, and therefore the update data completely downloaded and accumulated in the update data file  24  is installed in the operating system file  21  and becomes available for use. 
     FIG. 5 is a block diagram showing a computer network system according to another embodiment of the present invention. In this example, the update information file  13  and the update data file  14  included in the files of the server unit  1  shown in FIG. 1 are stored as an update information file  25  and an update data file  26 , respectively, in a large capacity storage medium  20 - 1  connected to a client for management, different from the client unit  2  to be diagnosed, for example, unit  200  used by the manager for system management. Also, the client unit  200  for system management includes an operating unit  211  for the operation of the client unit  200  and a management unit  220  for system management. 
     In the computer network system shown in FIG. 5, the update data can be registered in the update data file  26  of the client unit  200  for management, and therefore various conditions for the update data registered in the update data file  26  can be easily set in the update information file  25  by the manager through the client unit  200 . 
     The client unit  2  as a computer according to this invention described above can be realized by causing a general-purpose computer such as a personal computer to read and install a software program recorded in the recording medium. 
     FIG. 6 is a schematic diagram showing a configuration example of a general-purpose computer making up a computer of the present invention. This general-purpose computer (personal computer) PC includes a flexible disk drive  205  for reading from a flexible disk  205 M the code of the program PG recorded therein for providing the function of the client unit  2  as the computer according to the invention and/or a CD-ROM drive  206  for reading from the CD-ROM  206 M the code of the processing program PG described above. 
     Reference numeral  201  designates a display unit such as a CRT display, numeral  203  a pointing device such as a mouse, and numeral  204  an input device such as a keyboard. 
     The code of the program PG read from the flexible disk  205 M by the flexible disk drive  205  or the code of the program PG read from the CD-ROM  206 M by the CD-ROM drive  206  is installed, in the recording medium  20  ( 10 ) using the hard disk, for example, and as described above, functions as various functional parts. 
     Although the flexible disk and/or the CD-ROM is shown as a recording medium in the figure, the invention is not limited to them but the magnetic tape, the magneto-optical disk, etc., can of course be used in combination with an appropriate drive (read means). 
     Reference numeral  100  designates a LAN for connecting other computers (server units) or the management center with the personal computer PC. Thus, the processing program PG can be installed from other computers or the management center through this LAN  100 . 
     FIG. 7 is a schematic diagram showing the contents of the computer program recorded in the recording medium according to the invention. Specifically, this diagram shows the contents of the program PG, i.e. the program code for realizing the function of the client unit  2  as the computer PC according to the invention recorded in the flexible disk  205 M as an example of the recording medium. 
     The flexible disk  205 M shown in FIG. 7 is a computer readable recording medium with a computer program being stored, whereby the client unit  2  having the operating system file  21  storing the data used for its own operation is caused to receive the update data to be used by itself transferred from the server unit  1  connected through the LAN  100  and store it in the operating system file  21 . 
     The specific contents of the computer program include a program code PC 11  used for determining in accordance with predetermined conditions whether the divide transfer of the update data from the server unit  1  is possible or not, a program code PC 12  used for dividing and transferring the update data from the server unit  1  in the case where it is determined that the divide transfer is possible, a program code PC 13  used for sequentially accumulating the update data divided and transferred from the server unit  1  and storing them as the update data in the update data file  24 , and a program code PC 14  used for storing the update data stored in the update data file  24 , in the operating system file  21 . 
     The computer program further includes a program code PC 15  used for causing the computer to read from the server unit  1  at least one of a plurality of predetermined conditions including the possibility of divide transfer, the presence or absence of the designation of preferential transfer, the presence or absence of the designated due date of transfer completion, the presence or absence of the limitation of the number of times to divide the update data the presence or absence of the limitation of the amount of data to be transferred each time, related to the update data to be transferred from the server unit  1 , and the presence or absence of the limitation due to the load of the client unit  2 . 
     The program PG recorded in the flexible disk  205 M as an example of this type of recording medium is read by a general-purpose computer, thereby providing the function of the client unit  2  according to the invention as described above. 
     As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.