JPH1145201A - Computer system, data access processing method and recording medium in the system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a computer system suitable for realizing a network computer for mobile use, which can avoid data inconsistency caused by access conflict when a plurality of client computers try to update the same server resource. provide. When an attempt is made to access the same resource on a server from a network computer, even if the access includes an update, the access contention avoidance unit operates the data. Can be prevented from occurring, and consistency between the plurality of client computers 12 and 13 and the server 11 with respect to the data to be updated can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer system suitable for realizing a network computer usable in a mobile environment, and more particularly to an improvement so as to avoid contention for access to resources on a server and a mobile computer. The present invention relates to a computer system which allows a user to perform processing using files managed by a server computer without being aware of necessary files, securing synchronization, and being aware of a connection state with the server computer.

[0002]

2. Description of the Related Art In recent years, instead of a personal computer, a network computer (NC: Network) has been used.
A new computer architecture, called Computer, has begun to be developed.

[0003] This network computer is premised on the use of a network, and all programs and data required for data processing are downloaded from a server computer via the network. As a result, each client computer functioning as a network computer does not need to have programs and data, so that it is possible to flexibly cope with an update of an operating system (OS) or an application program, and as a result, a machine management cost. Drastic alleviation is possible.

[0004] However, the network computer is premised on operation through a network connection as described above, and is not normally considered for use in a mobile environment. For this reason, development of a new network computer capable of performing the same business as in the online state connected to the network even in the offline state not connected to the network is desired.

[0005]

In order to realize a network computer usable in a mobile environment as described above, a local storage for holding a copy of server resources required for work in an offline state is provided in the network computer. It is necessary to provide a network computer using the local storage.

[0006] In this case, in order to be able to perform the same job in both the offline state and the online state, the server resources must be synchronized with the resources in the local storage. For this reason, it is necessary to download and upload resources between the server and the network computer to ensure the consistency of the data contents of each other.

However, when accessing the same resource on the server from a plurality of network computers, if the access includes an update, a problem arises that data inconsistency occurs.

[0008] Particularly, in the case of a network computer configured to be operable even in a mobile environment by using resources in a local storage, the network computer may be used for a long time in an off-line state without being connected to a network, and may be connected later. It is likely that resources such as data on the server are updated by another network computer or the like before the synchronization process is performed. In this case, if the synchronization processing is performed as it is, data consistency between network computers will be lost.

[0009] Conventionally, as a method for supporting a mobile environment, a file synchronization technique called a briefcase method has been known in personal computers and the like.

In this briefcase system, files managed centrally by, for example, a desktop personal computer are transferred to a personal computer (hereinafter referred to as a mobile computer) which is easy to carry and has a communication function while maintaining the consistency of contents. It is used when it is used.

However, in this briefcase system, a user explicitly copies a file (or a list of files to be copied) on a copy source computer (in the above case, a desktop personal computer).
Is stored in a delivery area called a briefcase,
In addition, after updating the data on the mobile computer, it is necessary to explicitly instruct the integrity of the file in order to match the contents of the file on the source computer with the contents of the file on the mobile computer.

For this reason, in the briefcase method, for example, when using a mobile computer placed on the road, each user must always keep track of all necessary files. In addition, there is a problem that each user must always keep track of the state of the file on the mobile computer and the state of the file on the source computer in order to maintain the consistency of the file.

On the other hand, in the above-described network computer, generally, necessary files and programs are appropriately assigned to each user by an administrator of the server computer so that each user does not need to be aware of it. Since the preparation is made, in the online state, the user can automatically bring necessary files and programs from the server computer and execute it using a computer connected to the network. However, this method is based on the premise that a network computer is always connected to a server via a network, and is not suitable for a network computer for mobile use.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and enables a computer system suitable for realizing a network computer for mobile use, and a data system used in the system. It is an object to provide an access processing method and a recording medium.

Further, the present invention performs a process using a file managed by the server computer without grasping the necessary files and securing synchronization, and making the user aware of the connection state with the server computer. It is an object of the present invention to provide a computer system which can be operated.

[0016]

In order to solve the above-mentioned problems, the present invention provides a server computer and a plurality of clients which operate by downloading programs and data necessary for data processing from the server computer via a network. In a computer system including a computer, a conflict that avoids data inconsistency caused by an access conflict when a plurality of client computers try to update the same resource on the server computer and ensures the consistency of the data to be updated It is characterized by having avoidance means.

In this computer system, when an attempt is made to access the same resource on the server from a plurality of network computers, even if the access includes an update, the contention is avoided by the action of the conflict avoiding means. It is possible to prevent occurrence of a situation such as occurrence of inconsistency, and it is possible to ensure consistency of data to be updated between a plurality of client computers and server computers.

Particularly, in the case of a network computer that can operate in a mobile environment by using resources in a local storage, it may be used for a long time in an offline state without being connected to a network. It is easy for resources such as data on the server to be updated by other network computers before processing is performed. However, by using conflict avoidance means, synchronous processing can be performed without causing data inconsistency. Therefore, the same business can be continuously performed in both the offline state and the online state.

The conflict avoiding means manages whether or not there is a client computer which downloads and uses the resource on the server computer, and stores the data on the used resource to another client computer. It is characterized by including means for prohibiting download for the purpose of updating. In this way, the in-use resource is set in a so-called locked state, and by prohibiting download for the purpose of updating data to another client computer, it is possible to reliably prevent data inconsistency due to contention.

The conflict avoiding means is provided on the server computer and manages the data update time of each resource. The conflict avoiding means is provided on each of the client computers and is provided when the resource is downloaded from the server computer. Based on the data update time and the current data update time managed on the server computer, determine whether the resources on the server computer have been updated by another client computer after the download, and The information processing apparatus further comprises means for controlling an update process for a resource on the server computer based on the determination result.

According to this configuration, control using the data update time becomes possible, and the occurrence of data inconsistency due to contention can be reliably prevented without locking the resources in use.

According to the present invention, in order to achieve the second object described above, a briefcase holding a list of files to be copied to a mobile computer is provided for a user set by a mobile computer user. hand,
This is a new one provided for the manager set by the file manager of the server computer. The two briefcases for the user and the administrator are provided as a pair corresponding to each user.

That is, in the present invention, by setting a briefcase for an administrator by a file administrator, it is not necessary for each user to be conscious of program files and data files necessary for his / her own business. On the other hand, for some experienced users,
By setting up a briefcase for the user,
Additional customization is possible.

Further, the present invention provides a method for ensuring the consistency of files indicated by a file list held in a briefcase for an administrator and a user when a server computer and a mobile computer are connected. Synchronous processing is performed, and when the server computer and the mobile computer are connected,
Synchronous processing for ensuring consistency of the files indicated in the file list held in the briefcases for the administrator and the user at predetermined time intervals or upon request It is.

That is, in the present invention, there is no need to make the user aware of ensuring synchronization between the file managed by the server computer and the file copied to the mobile computer.

According to the present invention, when the server computer and the mobile computer are not connected, a file copied to the mobile computer is used instead of a file managed on the server computer. is there.

That is, in the present invention, in order to make no difference in the operation between the state where the server computer is connected and the state where the server computer is not connected,
It does not make the user aware of the connection status with the server computer.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
1 shows a system configuration of a network computer according to an embodiment.

Network computer (NC) 12
Operates by downloading all programs and data necessary for data processing such as an operating system and application programs from a server computer 11 via a network such as a LAN 10 or a public network. The (NC) 12 is used while connected to the LAN 10 (office mode). Also, when you go out,
The network computer (NC) 12 is basically used in a state of being disconnected from the server computer 11 (mobile mode).
PP (Point to Point Protocol)
1) remote connection to the server computer 11 is also possible (PPP mode).

The server computer 11 is a network computer (NC) serving as its client machine.
12 are provided with resources such as programs and data, and these resources are stored and managed in the disk device 21.

Network computer (NC) 12
In order to be able to work offline,
A local storage 23 is provided. The local storage 23 stores a replica which is a copy of resources such as programs and data on the server computer 11. Which resources are downloaded as replicas to the network computer (NC) 12 is managed by a synchronization list on the server computer 11.

Here, the synchronization list manages files to be subjected to data synchronization processing performed to maintain data consistency between the server computer 11 and the local storage 23 of the network computer (NC) 12. It is described for each target network computer, and the synchronization list manages file names and the like that need to be synchronized for each network computer. The synchronization list corresponding to each network computer has an administrator synchronization list and a user synchronization list. The administrator writes a list of files to be given to the user on the administrator synchronization list, and the user of the network computer writes files to be synchronized by himself on the user synchronization list.

When a replica is downloaded to the network computer (NC) 12, a replica list, which is a copy of the synchronization list, is also downloaded and stored in the local storage 23. By using the replica on the local storage 23, the network computer (NC) 12 can operate without server access. As the local storage 23, a flash memory card, a hard disk, or the like is used.

The OS downloaded from the server computer 11 to the network computer (NC) 12 includes a connected processing function for controlling the network computer (NC) 12 in a normal network operation mode operating with server access, and a local storage. In addition, a disconnected processing function is provided which enables business operations to be performed in an offline state by using the H.23.

Further, in the OS, a synchronization processing unit 24 for performing a synchronization process and an access conflict avoidance processing unit 25 are provided. The synchronization processing unit 24 is connected to the network computer (N
C) In order to allow the same business to be continuously performed on the server 12, the server resources are synchronized with the resources in the local storage 23 by downloading / uploading the resources to and from the server computer 11. This synchronization process is executed when the network computer (NC) 12 logs in or logs out.

The access conflict avoiding processing unit 25 cooperates with the access conflict avoiding processing unit 22 of the server computer 22 in response to an access conflict when a plurality of network computers try to update the same resource on the server computer 11. A collision avoidance process for avoiding the resulting data inconsistency is performed. The access conflict avoiding processing unit 25 is provided in all network computers in the present system. Thereby, even if access from a plurality of network computers including an update request for the same server resource conflicts, it is possible to prevent data inconsistency from occurring, and to prevent the inconsistency of data between each network computer and the server computer 11. Data consistency can be ensured.

The desktop network computer (desktop NC) 13 is used only in a network-connected environment, and is different from the network computer (NC) 12 in that it has no local storage. This desktop network computer (desktop NC) 13 also has
The above-described access conflict avoidance processing unit is provided.

Next, the basic operation mode of the network computer (NC) 12 of the present embodiment will be described.

The network operation mode premised on the operation in the online state includes a LAN mode (office mode),
PPP (Point to Point Protocol)
ol) mode. PPP mode is for telephone networks,
Server 11 via a public network such as an ISDN network or a PHS network
Used for remote access to.

On the other hand, the disconnect operation mode on the premise of the operation in the offline state is for supporting the above-mentioned mobile mode, and is based on the use of the replica of the server resource. The storage area of the local storage 23 where the replica used in the mobile mode is recorded is called a daypack. That is, the daypack is a storage area for programs and data that are in the local storage 23 and necessary for the user to use the network computer (NC) 12 in the mobile mode.

By replicating necessary programs and data in the mobile mode from the server computer 11 to the daypack in advance, the network operation mode (office mode or PP) can be used.
The operation performed in the P mode) can be continuously performed even if the operation is shifted to the disconnect operation mode.

As described above, even in the network operation mode, the daypack may be used for prefetching programs and data in preparation for shifting to offline work. The download operation for the prefetch is executed as an initial process of the synchronization process.

Therefore, the following four operation modes of the network computer (NC) 12 can be considered.

(1) LAN & daypack mode (2) LAN mode (daypack is not used) (3) Daypack mode (4) PPP & daypack mode (5) PPP mode (daypack is not used) (2). When going out, (3) to (5) can be used, but usually only (3) or (4) is used, and (5) is not used.

FIG. 2 shows the transition of these connection modes.

When the power of the network computer (NC) 12 is turned on from the power-off state or is reset in the power-on state, an initialization process (system start) by the OS is started. During a log-in process for the network computer (NC) 12 to acquire an environment necessary for its operation from the server 11, a log-in dialog is displayed on the screen of the network computer (NC) 12, and the log-in dialog is used. The operation mode is selected. The operation modes used are broadly classified into the "office mode" and the "mobile mode".

The "office mode" is a mode for use in an office where LAN can be used. If "Office Mode" is selected, the connection mode will be LAN
Mode or LAN & daypack mode is transited.

The "mobile mode" is a mode in which use of the LAN is impossible and is assumed to be used outside. When the “mobile mode” is selected, the connection mode transits to the daypack mode or the PPP & daypack mode.

The mechanism for the state transition and the selection of the use mode are incorporated in the OS initialization processing.

Hereinafter, the transition of the connection mode will be specifically described.

(A) Use of Day Pack in LAN Mode In the LAN mode, if there is a day pack that the user owns, the LAN & day pack mode is automatically set. Despite the presence of a daypack that the user owns, there is no LAN mode.

In the LAN mode, the ownership of the daypack can be obtained or abandoned.

Release of Ownership of Day Pack In the LAN & day pack mode, the ownership of the day pack can be released at any time. If the ownership of the daypack is abandoned, the mode shifts to the LAN mode.

Acquisition of Daypack Ownership In the LAN mode, if there is a daypack that no one owns, ownership of that daypack can be acquired. If the ownership of the daypack is obtained, the mode shifts to the LAN & daypack mode.

(B) Use of PPP in Day Pack Mode In the day pack mode, use of PPP can be started at any time. When you start using PPP, PPP &
Move to daypack mode.

Conversely, in the PPP & daypack mode, the use of PPP can be terminated at any time. When the use of the PPP ends, the mode shifts to the daypack mode.

(C) The PPP mode is not used.

The PPP mode is not used.

To establish a PPP connection, various setting information for dial-up is required. To enter the PPP mode, this information must be entered directly by the operator.

On the other hand, in the case of the PPP & day pack mode, since the transition is made from the day pack use mode, dial-up setting information can be stored in the day pack. This information can be set in the server in advance.

In consideration of mobile applications, it is considered that there is no problem in using PPP even if it is limited to a daypack.

(D) Mode transition at the time of login At the time of login, either the LAN use mode or the day pack use mode can be selected. When the LAN use mode is selected, if there is a day pack to which the user has the right to use, the mode shifts to the LAN & day pack mode.

In the day pack use mode, it is possible to shift to the PPP & day pack mode.

The selection of the LAN use mode at the time of login assumes that the user is in an office where a LAN can be used, and is therefore called “office mode”. On the other hand, selecting the daypack mode is referred to as “mobile mode” because it is assumed that the LAN is unavailable and that the user is going out.

At the time of login, the operator selects "office mode" or "mobile mode" as a use mode, and starts use.

(E) Reset and power-off It is possible to reset and power-off from all modes. The reset initializes the data section of the OS and executes a system initialization routine. The power-off is a hardware power-off.

Next, referring to the flowchart of FIG.
The flow of processing when the OS is started will be described.

When the power of the network computer 12 is turned on or an operation for rebooting the network computer 12 is performed, a boot program stored in the ROM of the network computer 12 starts. First, the boot program of the ROM checks whether or not the OS is stored in the local storage 23 composed of a flash memory or the like (step S101).

When the OS is stored in the local storage 23, the local storage 121
S is booted (step S102). On the other hand, if the OS is not stored in the local storage 23, R
The boot program of OM is DHCP (Dynamic
Host Configuration Proto
col), the OS name, the IP address, and the minimum required boot environment for starting the OS are stored in the server computer 11.
From TFTP (Trivial Fi
le Transfer Protocol)
A boot loader is loaded from the server computer 11 and control is passed to the boot loader (steps S103 and S103).
104).

The boot loader is an NFS (Network)
The OS is loaded from the server computer 11 and booted (Step S105). Thereby, the initialization processing of the OS is started (step S106). In this initialization process, the OS
The settings of the network environment used by are set.

After the environment setting process is performed in this way, a use mode selection process (step S107) is performed.

In the use mode selection process, first, the OS
Thus, the presence / absence of a daypack for which ownership is set, the determination of whether the LAN 10 can be used, and the like are performed, and the default value of the use mode is determined based on the result,
The default value is Network Computer (NC)
12 are displayed on the login dialog screen. In this use mode selection processing, first, it is checked whether or not a local storage including a daypack for which ownership is set exists. If there is a local storage including a daypack for which ownership has been set, the default value of the use mode is set to “mobile mode”. Next, DHCP
Broadcasts a DISCOVER packet, and determines whether or not an OFFER packet has been received.
It is checked whether the use of the LAN is possible. When the OFFER packet is received, it is determined that the environment is such that the LAN can be used, and the default value of the use mode is switched to “office mode”. Thus, if there is a local storage that can be used as a daypack,
"Mobile mode" or "office mode" is displayed as a default value in the login dialog depending on whether or not AN can be used. When the user explicitly changes the setting of the use mode on the login dialog, the mode is changed to the mode instructed by the user. Then, when the OK button on the login dialog is pressed, the current mode is determined, and processing for setting the mode is started. Then, an indicator indicating the use mode is displayed on the screen. On the other hand, if the local storage does not exist, or if the local storage does exist but the ownership is not set for the daypack, the default mode is not determined and the L mode is not determined.
It is checked whether the use of the AN is possible. If it is determined that the environment is such that the LAN can be used, the default value of the use mode is set to “office mode”. Then, “office mode” is displayed on the login dialog as a default value, and “mobile mode” is invalidated. As described above, if the local storage does not exist, or if the local storage exists but the ownership is not set for the daypack, the “office mode” is basically selected.

When the use mode is selected in the use mode selection process, a user authentication process is performed based on the user name and password input in the login dialog (steps S108, S110). When the user authentication process is successful, if the “office mode” is selected, the connection mode is set to L based on the presence or absence of the daypack.
The mode is set to the AN mode or the LAN & daypack mode (step S109). On the other hand, when the “mobile mode” is selected, a transition is made between the daypack mode and the PPP & daypack mode in accordance with the user's PPP connection operation and disconnection operation.

Next, a basic operation form of the network computer system shown in FIG. 1 will be described.

In the network computer system shown in FIG. 1, necessary resources such as an operating system and application programs are centrally managed by a server 11 and necessary resources are transferred from the server 11 to a network computer via a network such as a LAN 10 or a public network when necessary. It downloads to 12 and 13 and operates. When updating data, the processing result is uploaded to the server 11 side. Therefore, these network computers 1
Normally, as shown in FIG. 4, the devices 2 and 13 are assumed to be used in an environment where they are always connected to a network and can communicate with a server.

On the other hand, when used in a mobile environment, it is conceivable that it is not connected to a network such as a LAN or a public network. Therefore, the network computer (NC) 1 used for mobile applications
2 is provided with a local storage 23 composed of a flash memory card or a hard disk as described above, and downloads necessary resources from the server 11 as shown in FIG. Create a replica in. As a result, it is possible to perform the same processing as in the online state even when shifting to the offline state with no network connection. Further, in order to be able to continue the same processing in both the offline state and the online state, the synchronization between the server resource and the replica must be established. For this synchronization processing, download / upload of resources is performed by the synchronization processing unit 24.

Here, the problem with downloading / uploading is that when a plurality of network computers access the same server resource at the same time,
This is a problem of data inconsistency due to data update collision. Here is an example.

As shown in FIG. 6, a certain resource X on the server 11 is transferred to the desktop NC (NC-A) 1.
Suppose that 3 tried to update and downloaded. Another NC 12 (NC-B) downloads the same resource X, also trying to update. In this case, these NC1
Server 11 depending on the order of upload by
The data content of X above is determined. That is, the data uploaded later remains.

The data inconsistency due to the access conflict is not limited to the download / upload by the NC. As shown in FIG. 7, when the resources used by the NC are operated by the program on the server 11, The same problem occurs when operating from another computer.

In the present embodiment, as shown in FIG.
And each network computer 1
2 and 13 are also provided with an access conflict avoiding unit 25, thereby preventing occurrence of data inconsistency due to access conflict.

Hereinafter, a specific example of the access conflict avoiding unit will be described.

The access conflict avoiding function described below is merely one embodiment, and the present invention is not limited to this embodiment.

1. Locking / Unlocking Data When updating data, as shown in FIG. 9A, the data is locked before downloading. For locked data, another N
C / Software cannot be accessed. The lock mechanism may be implemented by using a semaphore mechanism of the OS or by marking an area that manages data (for example, an area on a disk that manages a file) as being locked.

When the data update is completed, FIG.
Unlock as shown in FIG. After unlocking, other NC / software can access.

In this method, if unlocking is not performed, there is a possibility that the locked state will be kept forever. In order to avoid this, it is more preferable to employ a means such as providing a fixed time limit for the lock.

FIG. 10 is a flowchart showing a process on the client side when a semaphore is used for the access conflict avoiding unit 22 of the server 11 as a method of the lock process.

In this case, in the case of the desktop type network computer 13, the procedure shown in FIG. 10 is incorporated in the resource download mechanism as the above-mentioned access conflict avoiding unit, and the network computer (NC) 1
In the case of 2, the procedure of FIG. 10 is incorporated into the synchronization processing unit 24 as the access conflict avoiding unit 25 described above.

When downloading a resource from the server 11 for the purpose of updating data, each network computer first issues a lock request for the resource to the server 11 (step S201).

When the lock request is normally received by the server 11 and the data lock succeeds (step S202), the network computer downloads the locked data and performs a process using the data (steps S204 and S205). ). Thereafter, the data contents changed by the data processing are uploaded to the server 11 to update the data on the server 11 (step S206), and an unlock request for the updated data is issued to the server 11 (step S20).
7).

On the other hand, if the lock request has not been normally accepted by the server 11 and the lock has not succeeded, a lock unavailable time processing routine (step S203) is performed, where an error is notified to the user and the user is notified. For example, a retry may be performed with the intention of the user, or the process from the lock may be retried after waiting for a certain time.

In the case of the network computer 12 having the local storage 23, since it is not always connected to the network, it temporarily shifts to the offline state after downloading the data and performs data processing in that state. It is also conceivable to upload the data for the synchronization process when the online state is changed again.

Next, the processing on the server 11 side will be described with reference to the flowcharts of FIG. 11 and FIG.

[0094] In the server 11, semaphores corresponding to individual data are prepared. This semaphore may be prepared statically when the data is created. It is also possible to use a method of dynamically creating data when a lock request is received and deleting it when unlocking.

As shown in FIG. 11, the server 11
Upon receiving the lock request, the semaphore first finds the semaphore corresponding to the relevant data, and performs a P operation for shifting the semaphore to the locked state (step S30).
1, S302). Here, control in the no-wait mode is used, and an error is immediately returned for an access request or a lock request for locked data.

When the P operation is completed normally, the server 11
Notifies the network computer that issued the lock request of the lock success (steps S303 and S30).
4) If the P operation has not been performed normally, the server 11 notifies the network computer that has issued the lock request that the lock has been disabled (step S30).
3, S305).

When receiving the unlock request, as shown in FIG. 12, the server 11 first finds a semaphore corresponding to the data requested to be unlocked,
A V operation for unlocking the semaphore is performed (steps S401, S402). Then, the network computer that has issued the unlock request is notified of the unlock success (step S403).

As described above, the in-use resource is locked and the download for the purpose of updating the data to another client computer is prohibited, so that the occurrence of the data inconsistency due to the conflict can be surely prevented.

2. Checking by Data Update Date and Time When each network computer downloads data, it also downloads the data update date and time (usually the file update date and time). When uploading data, the data update date and time when downloading and the server 1
1 is compared with the latest data update date and time. If the two match, the data downloaded by the user is the latest data, and the data has not been updated thereafter. Therefore, in this case, as long as the user uploads his / her data, the data consistency is maintained. On the other hand, if the two do not match, the other
1 means that the corresponding data has been updated,
You cannot upload your own data to ensure data consistency, but there are various ways to do this at this time. To give some examples, such a situation is communicated to the user to inquire whether or not to upload, or to instruct the user to upload to another file.

FIG. 13 shows a state of control using such a data update time.

As shown in FIG. 13A, the same data on the server 11 is transferred to the network computer (N).
(CA) 13 and (NC-B) 12 download.
At this time, the data update time (12:00) managed on the server 11 is also downloaded at the same time.

Thereafter, as shown in FIG. 13B, the network computer (NC-A) 13 performs data processing using the downloaded data, and attempts to upload the updated data to the server 11. ,
Data update time when downloading, and server 11
Compare with the latest data update time managed above,
Check whether the two match. Here, since the two match, the update data is uploaded as usual. By this upload, the corresponding data on the server 11 is updated, and the data update time is also changed to the latest value (13:00).

Thereafter, as shown in FIG. 13 (C), the network computer (NC-B) 12 attempts to upload the updated data, The time is compared with the latest managed data update time, and whether or not the two coincide with each other is checked. Here, since the two do not match, as described above, control is performed such as inquiring the user whether or not to upload, or instructing the user to upload to another file.

FIG. 14 shows a processing flow on the client side when the check based on the data update date is used.

In this case, in the case of the desktop network computer 13, the resource download /
The procedure of FIG. 14 is incorporated in the upload mechanism as the above-described access conflict avoiding unit. In the case of the network computer (NC) 12, the procedure of FIG. Will be incorporated. The server 11 has a function of managing the data update time of each data and a function of notifying the data update time in response to a request from the network computer.

Each network computer first downloads data from the server 11 and updates the data update time (update-time) corresponding to the data.
A) is obtained from the server 11 (steps S501, S501)
502). Thereafter, data processing using the downloaded data is performed (step S503). When the data is updated in this manner, the network computer firstly updates the latest data update time (upda
te-timeB), and compares the latest data update time (update-timeB) with the data update time (update-timeA) obtained at the time of download (steps S504 and S505). If they match, update data is uploaded (steps S506 and S507), and if they do not match, data update collision processing (step S508) is performed. In the process at the time of data update collision, control such as inquiring of the user whether or not to upload or instructing the user to upload to another file is performed as described above.

If a computer program for executing the procedure of the synchronization process and the access conflict avoidance process in the system of the first embodiment is recorded on a recording medium,
Just apply the computer program to a normal client / server model computer system,
The same effect as in the present embodiment can be obtained.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described.

FIG. 15 is a functional block diagram of a mobile computing system according to the second embodiment of the present invention.

As shown in FIG. 15, in this mobile computing system, a network computer (N
C) 101, if necessary, server computer 120
Is connected via the network 140.

The network computer 101 controls the entire system by an operating system 104. Under the operating system 104, the briefcase management applet 102 and the browser 103
And other desktop environment applications work.
Further, the network computer 101 includes a nonvolatile storage device 112, and a file (prefetch file 11) copied (prefetched) from the server computer 120 is stored in the nonvolatile storage device 112.
3) is stored. This prefetch file 113
This corresponds to the replica of the first embodiment.

The operating system 104 is downloaded from the server computer 120 and has a cache management unit 105 to operate regardless of the connection state with the server computer 120. This cache management unit 105 stores the cache Nfs
(Network file system) Client 106, Cache Http (Hyper tex)
t transfer protocol) client 107, a Web cache management unit 108, a prefetch update management unit 109, and a nonvolatile storage device management unit 110. The nonvolatile storage device management unit 110 further includes a URL (U
a resource management locator (niform resource locator) 111. The feature of the embodiment on the network computer 101 side is that the prefetch update management unit 109
The point is that the synchronization of the prefetch file 113 is ensured without making the user aware at the time of connection with the.

On the other hand, the server computer 120 manages the shared file 122 and the non-shared (or read-only) file 123. The briefcase 130 indicating a list of files to be prefetched by the network computer 101 is set by the administrator. The user 127 and the user setting 128 are managed as a pair corresponding to each user. This briefcase 130 corresponds to the synchronization list of the first embodiment.

The server computer 120 includes an archive tool 121, a conflict resolution tool 124,
It comprises a daemon 125, an Nfs daemon 126, and a briefcase management server 129. The feature of this embodiment on the server computer 120 side is that an administrator setting 127 is added as the briefcase 130 (this allows the user to recognize program files and data files necessary for work). You don't have to).

Further, a feature of the entire system of this embodiment is that the conflict resolution tool 124 is
It is provided only on the 20 side (this makes it possible to reduce the processing load on the network computer 101 side and system resources such as programs).

In the mobile computing system of this embodiment, when the network computer 101 and the server computer 120 are connected (hereinafter, referred to as a “connect state”), the network computer 101 determines that the cache Nfs client 106 has N
Access the file by communicating with the fs daemon 126. The cache HTTP client 107 displays a Web page by communicating with the HTTP daemon 125.

Hereinafter, the operation principle of the mobile computing system of this embodiment will be described step by step.

(1) Preparation In the server computer 120, the administrator cuts out a non-shared portion or a read-only file 123 for each user from the shared file 122 in advance. In addition, the administrator archives HTTP and applet files required for work and the like in a meaningful unit using the archive tool 121.

(2) Registration The administrator stores the link information to the file to be given to the user in the administrator setting 12 provided for the user.
Register in Briefcase 7 Further, the user inputs the link information to the file to be used by the briefcase management server 1 using the briefcase management applet 102.
Via 29, the user is registered in a user setting 128 briefcase provided for the user.

(3) Prefetch The prefetch update management unit 109 of the network computer 101 sets the administrator setting 12
Briefcase 1 consisting of 7 and 128 for user setting
30 is scanned, and if there is a file that has not been reflected in the nonvolatile storage device 112, the cache Nfs client 1
06, the file is read, and the nonvolatile storage device 1
12 (prefetch file 113). In addition, the URL name and the name on the nonvolatile storage device 112 are
The association is made by the RL name management unit 111. Then, when synchronization between the nonvolatile storage device 112 and the briefcase 130 is established, the network computer 101 is in a disconnectable state (Owned Clean). At this point, disconnection may be explicitly instructed from outside.

(4) Disconnected Operation In the disconnected state, the network computer 101 sends the cache Nfs client 106 and the cache HTTP client 107 to the network 1
Before flowing data to 40, the nonvolatile storage device 112 is tried under the control of the cache management unit 105. Also, U
The RL name (including the Nfs file name) and the name on the nonvolatile storage device 112 are associated by the URL name management unit 111. It should be noted that URL names correspond to http
A simulation of the daemon 125 is also involved.

(5) Ensuring Synchronization (Consistency) of Updated Files When the network computer 101 is reconnected, the prefetch update manager 109 updates the prefetch file 113 of the non-volatile storage device 112 by updating the briefcase. It is determined whether the file is not newer than the file of the link destination of 130, and if it is, the prefetch file 113 of the non-volatile storage device 112 is written to the link of the briefcase 130. Then, the nonvolatile storage device 112 and the briefcase 1
When the consistency is ensured by the synchronization process with 30,
The network computer 101 is in a disconnectable state (Owned Clean).

(6) Ensuring Consistency for New Creation and Deletion When a newly created (or deleted) file or directory exists in the network computer 101, the prefetch update management 109 sets the file or directory as a link destination of the briefcase 130. Create (or delete)

As described above, in the mobile computing system of the present embodiment, the administrator registers the files required by each user in the briefcase 130 of the administrator setting 127, so that the user can There is no need to recognize program files and data files necessary for business. Also, at the time of connection, the prefetch update management unit 109 sets the prefetch file 113
The user does not need to be aware of the consistency of the file because the synchronization between the file and the file linked by the briefcase 130 is performed. Further, at the time of disconnection, the cache management unit 105 sets the cache Nfs client 1
06 and a proxy function for proxying processing using the non-volatile storage device 112 in response to various requests from the HTTP client 107, so that the user can perform operations without being aware of the connection state with the server computer 120. Will be.

Note that (2) registration, (5) synchronization for ensuring consistency of updated files, and (6) synchronization of new creation and deletion can be executed in parallel. In order to reduce the processing load on the network computer 101 and system resources such as programs, the shared file 122 and the non-shared (or read-only) file 1
Resolution of the conflict with the application 23 is performed by a conflict resolution tool 124 depending on the application. The activation of the conflict resolution tool 124 is appropriately performed by the server administrator.
Alternatively, it is automatically performed by the server at a predetermined timing.
This collision resolution tool corresponds to the access conflict avoiding unit of the first embodiment.

FIG. 16 shows an example of a message when a directory is registered in briefcase 130. As shown in FIG. 16, when registering a directory in the briefcase 130, the following three types can be selected. Also, regarding this selection, the user and the administrator can give a default value as a system attribute, so that the inquiry can be omitted.

(1) Registration of the directory only (only the first layer) (2) Registration including the contents of the subdirectory (3) Registration of only the name space of the directory Also, in FIG. An example of a message at the time of registration is shown. As shown in FIG. 17, when registering a file in the briefcase 130, the following two types can be selected. Also,
Regarding this selection, the user and the administrator may give a default value as a system attribute, so that the inquiry can be omitted.

(1) Registering only the relevant file (2) Registering the relevant file and the name space of its directory FIG. 18 shows the file attributes stored in the briefcase 130, and FIG. Indicates the file attribute to be used.

Next, with reference to FIGS. 20 to 22, a procedure for moving the prefetch update management unit 109 of this embodiment will be described.

When network computer 101 is connected to server computer 120, prefetch update management section 109 waits until a predetermined operation timing comes or an operation request is received (step C1 in FIG. 20). ), When an operation timing arrives or an operation request is received, an automatic synchronization process is executed (FIG. 20).
Step C2). When these operations are completed, the prefetch update management unit 109 waits again for the next operation timing or operation request.

FIG. 21 is a flowchart showing the operation of the automatic synchronization process. Here, the consistency of the files directly registered in the briefcase is taken.

The prefetch update management unit 109 extracts all the files located at the highest position in the nonvolatile storage device (LS) 112. In addition, all files registered in the briefcase (BC) are extracted (step A1 in FIG. 21). For all extracted files, a non-volatile storage device (L
S) The file status on the top and the briefcase destination (BC
Based on the state of the file of (1), the following divided processing is performed.

(1) A file exists on the nonvolatile storage device (LS), but the corresponding file is not registered in the briefcase (BC) or the destination of the briefcase (BC)
If the file does not exist in the non-volatile storage device (L
S) to delete the file (step A in FIG. 21).
2).

(2) If a file exists at the briefcase destination (BC destination) but does not exist on the nonvolatile storage device (LS), the file at the briefcase destination (BC destination) is transferred to the non-volatile storage device (LS). (Step A3 in FIG. 21).

(3) If the file at the briefcase destination (BC destination) is newer than the file on the nonvolatile storage device (LS), the file at the briefcase destination (BC destination) is downloaded to the nonvolatile storage device (LS) ( Step A4 in FIG. 21).

(4) If the file at the briefcase destination (BC destination) is older than the file on the nonvolatile storage device (LS), the file on the nonvolatile storage device (LS) is uploaded to the briefcase destination (BC destination). (Step A5 in FIG. 21).

Similarly, the prefetch update management unit 109
All the directories located at the highest level in the nonvolatile storage device (LS) 112 are extracted. Also briefcase (BC)
Is extracted (step A6 in FIG. 21). For all extracted directories,
From the state of the directory on the non-volatile storage device (LS) and the state of the directory at the briefcase destination (BC destination),
The following separated processing is performed.

(1) If a directory exists on the nonvolatile storage device (LS), but the corresponding directory is not registered in the briefcase (BC) or the directory at the briefcase destination (BC destination) does not exist, The directory and the directories below the directory are deleted from the storage device (LS) (step A7 in FIG. 21).

(2) If a directory exists at the briefcase destination (BC destination) but does not exist on the nonvolatile storage device (LS), the directory is created in the nonvolatile storage device (LS) (FIG. 21). Step A
8) Then, the directory is designated, and the automatic matching process of the designated directory is performed (step A9 in FIG. 21).

(3) In other cases, the extracted directory is specified and the specified directory is automatically matched (step A9 in FIG. 21).

FIG. 22 is a flowchart showing the operation of the automatic synchronization process for the designated directory. Here, the consistency of the files registered indirectly is obtained by directory registration in the briefcase.

The prefetch update management section 109 stores the specified directory (dir) in the nonvolatile storage device (LS) 112.
Extract all files in. In addition, briefcase point (B
Then, all the files in the specified directory (dir) of (C destination) are extracted (step B1 in FIG. 22). Based on the state of the file on the non-volatile storage device (LS) and the state of the file at the briefcase destination (BC destination), the following divided processing is performed on all the extracted files.

(1) If a file exists on the nonvolatile storage device (LS) but does not exist on the briefcase destination (BC destination), the file on the nonvolatile storage device (LS) is transferred to the briefcase destination (BC destination). ) (Step B2 in FIG. 22).

(2) When a file exists at the briefcase destination (BC destination) but does not exist on the nonvolatile storage device (LS), the file at the briefcase destination (BC destination) is transferred to the non-volatile storage device (LS). (Step B3 in FIG. 22). However, if the specified directory (dir) exists in the briefcase and DirName
In the case of the attribute, only the file information is downloaded and the file entity is not downloaded.

(3) If the file at the briefcase destination (BC destination) is newer than the file on the nonvolatile storage device (LS), the file at the briefcase destination (BC destination) is downloaded to the nonvolatile storage device (LS) ( Step B4 in FIG. 22). However, if the specified directory (dir) exists in the briefcase and has the DirName attribute, only the file information is downloaded and the file entity is not downloaded.

(4) If the file at the briefcase destination (BC destination) is older than the file on the nonvolatile storage device (LS), the file on the nonvolatile storage device (LS) is uploaded to the briefcase destination (BC destination). (Step B5 in FIG. 22).

Similarly, the prefetch update management unit 109
All subdirectories in the designated directory (dir) on the nonvolatile storage device (LS) 112 are extracted. In addition, the directory (di) specified for the briefcase destination (BC destination)
Extract all subdirectories in r) (step B6 in FIG. 22). For each of the extracted subdirectories, the following processing is performed based on the status of the subdirectory on the nonvolatile storage device (LS) and the status of the subdirectory ahead of the briefcase (BC).

(1) Although a subdirectory exists on the nonvolatile storage device (LS), a briefcase destination (BC destination)
If no subdirectory exists, a subdirectory is created at the briefcase destination (BC destination) (step B7 in FIG. 22). After that, the specified directory (dir)
Is not a Dir attribute present in the briefcase,
The automatic synchronization process of the designated directory is performed recursively by designating the subdirectory (step B in FIG. 22).
8).

(2) If a subdirectory exists at the briefcase destination (BC destination) but does not exist on the nonvolatile storage device (LS), a subdirectory is created in the nonvolatile storage device (LS) (FIG. 22 Step B9). Thereafter, if the designated directory (dir) is not a Dir attribute existing in the briefcase, the subdirectory is designated and recursively performs automatic matching processing of the designated directory (step B8 in FIG. 22).

(3) In other cases, if the designated directory (dir) is not a Dir attribute existing in the briefcase, the extracted directory is designated and the designated directory is automatically recursively synchronized (FIG. 22). Step B8).

As described above, the prefetch update management unit 10
9 appropriately updates and manages the prefetch file 113 based on the briefcase consisting of the administrator setting 127 and the user setting 128, so that the user can
There is no need to know which file is needed, and no need to be aware of its consistency.

Note that the file synchronization securing method applied to the mobile computing system described in the second embodiment stores a program which can be executed by a computer in a recording medium such as a magnetic tape, an optical disk, and a semiconductor memory. It is possible to distribute.

Further, it goes without saying that the techniques of the first and second embodiments can be used in an appropriate combination.

[0154]

As described above, according to the present invention,
It is possible to prevent occurrence of a situation in which data inconsistency occurs due to contention of access involving updating of the same data, and it is possible to provide a computer system suitable for realizing a network computer for mobile use.

Further, according to the present invention, it is unnecessary for each user who uses a network computer or the like as a mobile computer to be conscious of program files and data files necessary for his / her business. It is not necessary to be aware of the synchronization between the file managed by the PC and the file copied to the mobile computer. Furthermore, the operation does not differ between when connected to the server computer and when it is not connected, so that the user is not conscious of the connection state with the server computer.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration of a network computer system according to a first embodiment of the present invention.

FIG. 2 is an exemplary view showing a transition of an operation mode of a network computer provided in the system of the first embodiment.

FIG. 3 is an exemplary flowchart for explaining the operation of the network computer provided in the system of the first embodiment when the OS is started;

FIG. 4 is a block diagram showing an example of a basic operation of the system according to the first embodiment;

FIG. 5 is a block diagram showing another example of the basic operation of the system according to the first embodiment;

FIG. 6 is an exemplary view showing an example of access conflict in the system of the first embodiment.

FIG. 7 is an exemplary view showing another example of access conflict in the system of the first embodiment.

FIG. 8 is a diagram showing a state in which an access conflict avoidance function is incorporated in the system of the first embodiment.

FIG. 9 is an exemplary view for explaining the principle of an access conflict avoidance function applied to the system according to the first embodiment;

FIG. 10 is an exemplary flowchart showing the processing procedure of the network computer when the access conflict avoidance function using a semaphore is applied to the system of the first embodiment;

FIG. 11 is an exemplary flowchart showing the locking processing procedure of the server computer in the system of the first embodiment.

FIG. 12 is an exemplary flowchart showing an unlocking processing procedure of a server computer in the system of the first embodiment.

FIG. 13 is an exemplary view for explaining the principle of an access conflict avoidance function based on data update time applied to the system of the first embodiment;

FIG. 14 is an exemplary flowchart showing the procedure of data download / upload processing executed by the network computer of the system of the first embodiment.

FIG. 15 is a functional block diagram of a mobile computing system according to a second embodiment of the present invention.

FIG. 16 is an exemplary view showing an example of a message when the directory of the second embodiment is registered in the briefcase.

FIG. 17 is an exemplary view showing an example of a message when a file of the second embodiment is registered in a briefcase.

FIG. 18 is an exemplary view showing file attributes held in a briefcase according to the second embodiment;

FIG. 19 is a view showing file attributes held in a nonvolatile storage device according to the second embodiment;

FIG. 20 is a flowchart illustrating a main operation procedure of a prefetch update management unit according to the second embodiment.

FIG. 21 is an exemplary flowchart for explaining the operation procedure of a prefetch update management unit relating to a file directly specified in the briefcase according to the second embodiment;

FIG. 22 is an exemplary flowchart for explaining an operation procedure of a prefetch update management unit relating to a file indirectly designated as a briefcase according to the second embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Server computer 12 ... Network computer for mobile use 13 ... Desktop network computer 21 ... Disk device 22 ... Access conflict avoiding part 23 ... Local storage 24 ... Synchronization processing part 25 ... Access conflict avoiding part 101 ... Network computer 102 ... Briefcase management Applet 103 Browser 104 Operating system 105 Cache management unit 106 Cache Nfs client 107 Cache HTTP client 108 Web cache management unit 109 Prefetch update management unit 110 Nonvolatile storage device management unit 111 URL name management unit 112 Non-volatile storage device 113 Prefetch file 120 Server computer 121 Archive tool 122 Existence file 123 ... Non-shared (or read-only) file 124 ... Conflict resolution tool 125 ... HTTP daemon 126 ... Nfs daemon 127 ... Administrator briefcase 128 ... User briefcase 129 ... Briefcase management server 130 ... Briefcase 140 …network.

Claims (26)

[Claims] 1. A computer system comprising: a server computer; and a plurality of client computers that operate by downloading programs and data required for data processing from the server computer via a network. A computer system comprising: conflict avoiding means for avoiding data inconsistency caused by access conflict when a plurality of client computers try to update, and ensuring consistency of the data to be updated. 2. The conflict avoiding means manages whether or not there is a client computer that downloads and uses a resource on the server computer, and transmits to another client computer about a resource that is being used. 2. The computer system according to claim 1, further comprising means for prohibiting download for the purpose of updating the data. 3. The conflict avoiding means is provided on the server computer and manages a data update time of each resource. The conflict avoiding means is provided on each of the client computers and downloads the resource from the server computer. Based on the data update time and the current data update time managed on the server computer, determine whether the resources on the server computer have been updated by another client computer after the download, and 2. The computer system according to claim 1, further comprising means for controlling an update process for a resource on the server computer based on a result of the determination. 4. The plurality of client computers download a program and data necessary for data processing from a server computer via a network,
A mobile network computer configured to operate without access to the server computer by using a local storage device that stores a part of the downloaded program and data; A computer for downloading resources from the server computer and for updating data on the server computer to the server computer for ensuring synchronization of resource contents between the server computer and the local storage device; 2. The computer system according to claim 1, further comprising a synchronous processing unit for uploading a resource. 5. The server computer manages an update time for each resource, wherein the synchronization processing means performs a data update time when a resource is downloaded from the server computer when uploading the resource; Based on the current data update time managed on the server computer, determine whether resources on the server computer have been updated by another client computer after downloading, and based on the determination result, 5. The computer system according to claim 4, wherein the updating of resources on the server computer is controlled. 6. The plurality of client computers include a first client computer connected to the server computer via a LAN, and a second client computer connected to the server computer via a public network. The computer system according to claim 1, wherein: 7. A computer system including a server computer and a plurality of network computers that operate by downloading programs and data required for data processing from the server computer via a network, wherein the same resources on the server computer are used. A computer system comprising: conflict avoidance means for avoiding data inconsistency caused by access conflict when a plurality of network computers try to update, and ensuring consistency of the data to be updated. 8. The plurality of network computers download programs and data required for data processing from a server computer via a network,
A mobile network computer configured to operate without access to the server computer by using a local storage device for storing a part of the downloaded program and data is included. Item 7. The computer system according to Item 7. 9. The plurality of network computers include a first network computer connected to the server computer via a LAN, and a second network computer connected to the server computer via a public network. 8. The computer system according to claim 7, wherein: 10. A data access processing method in a computer system including a server computer and a plurality of client computers that operate by downloading programs and data necessary for data processing from the server computer via a network, Manage resources on the server computer and control access to the data to be updated so that data conflict does not occur due to access competition when a plurality of client computers try to update the same resource on the server computer. Thereby ensuring the consistency of the data to be updated. 11. A resource management system for managing whether or not there is a client computer which downloads and uses a resource on the server computer, and updates a resource being used for updating data to another client computer. 11. The data access processing method according to claim 10, wherein prohibited downloading is performed. 12. A data update time of each resource is managed on the server computer, and when a resource is uploaded from the client computer to the server computer, the data is updated when the resource is downloaded from the server computer. By comparing the time with the current data update time managed on the server computer, it is determined whether or not the corresponding resource on the server computer has been updated by another client computer after its download. Controlling an update process for a resource on the server computer based on a result of the determination.
0, a data access processing method. 13. A data access processing method in a computer system including a server computer and a plurality of network computers that operate by downloading programs and data required for data processing from the server computer via a network, Managing resources on the server computer and controlling access to the data to be updated so that data conflict does not occur due to access competition when a plurality of network computers try to update the same resource on the server computer. Thereby ensuring the consistency of the data to be updated. 14. The plurality of network computers download a program and data necessary for data processing from a server computer via a network,
A mobile network computer configured to operate without access to the server computer by using a local storage device for storing a part of the downloaded program and data is included. Item 14. The data access processing method according to item 13. 15. A computer program for use in a computer system including a server computer and a plurality of client computers that operate by downloading programs and data required for data processing from the server computer via a network are recorded. A recording medium, wherein the computer program manages resources on the server computer so that data conflict does not occur due to access competition when a plurality of client computers try to update the same resource on the server computer. And a control unit that controls access to the data to be updated, thereby ensuring consistency of the data to be updated. 16. The computer program according to claim 1, further comprising: a step of managing whether or not there is a client computer which downloads and uses a resource on said server computer; 16. A recording medium according to claim 15, further comprising a step of prohibiting download for the purpose of updating data to the storage medium. 17. The computer program, comprising: a step of managing a data update time of each resource on the server computer; and a step of uploading a resource from the client computer to the server computer; By comparing the data update time when downloaded from the server with the current data update time managed on the server computer, the corresponding resource on the server computer is updated by another client computer after the download. 16. The recording medium according to claim 15, further comprising: a step of determining whether or not the update has been performed, and controlling an update process for a resource on the server computer based on a result of the determination. 18. A computer program for use in a computer system including the server computer and a plurality of network computers operating by downloading programs and data necessary for data processing from the server computer via a network is recorded. The recording medium, wherein the computer program stores resources on the server computer so that data conflict does not occur due to access competition when a plurality of network computers try to update the same resource on the server computer. A recording medium, which manages and controls access to the data to be updated, thereby ensuring consistency of the data to be updated. 19. A mobile computer system in which files managed by a server computer are used by being copied to individual mobile computers, wherein the server computer has a briefcase that holds a list of files to be copied to the mobile computer. A mobile computer system, wherein a pair is provided for a manager of the file and for a user of the mobile computer so as to correspond to each of the mobile computers. 20. When the server computer and the mobile computer are connected to each other, the server computer and the mobile computer relate to the files indicated in the file list held in the administrator and user briefcases. 20. The image processing apparatus according to claim 19, further comprising a synchronization processing unit for ensuring consistency between the two.
The described mobile computer system. 21. The manager and the user briefer according to a predetermined period or in response to a request when the server computer and the mobile computer are connected to each other. 20. The mobile computer system according to claim 19, wherein the mobile computer system performs a synchronization process for ensuring consistency between the server computer and the mobile computer regarding the files indicated in the file list held in the case. 22. The file list held by the briefcase includes a directory, and the directory may be copied to the mobile computer only in a namespace of a directory, only the directory, or all subdirectories. 2. A method according to claim 1, wherein any one of the following is set to be identifiable.
22. The mobile computer system according to 9, 20, or 21. 23. A file proxy means for using a file copied to the mobile computer instead of a file managed on the server computer when the server computer and the mobile computer are not connected. The mobile computer system according to claim 19, 20, 21 or 22, wherein the mobile computer system comprises: 24. The mobile computer system according to claim 19, wherein said server computer is provided with a collision resolving means for resolving a conflict relating to a file update. 25. A mobile computer system in which files managed by a server computer are used by being copied to individual mobile computers, wherein the server server computer holds a list of files to be copied to the mobile computer. In the method of ensuring file consistency applied to a mobile computer system in which a briefcase is provided for each of the mobile computers in a pair for a manager of the file and for a user of the mobile computer, the server computer When the mobile computer is connected to the server, the consistency between the server computer and the mobile computer regarding the files indicated in the file list held in the administrator and user briefcases Performing a synchronization process for securing; and when the server computer and the mobile computer are connected, for each of predetermined periods or upon request, the briefs for the administrator and the user Performing a synchronization process for ensuring consistency between the server computer and the mobile computer regarding the files indicated in the file list held in the case. . 26. A file managed by a server computer is copied to an individual mobile computer for use, and a briefcase holding a list of files copied to the mobile computer is provided to the server computer by an administrator of the file. A program for performing a synchronization process for ensuring file consistency on a mobile computer system provided in correspondence with each of the mobile computers in a pair for the user of the mobile computer and the server computer. And when the mobile computer is connected, ensure synchronization between the server computer and the mobile computer for the files indicated in the file list held in the administrator and user briefcases, The server When the computer and the mobile computer are connected to each other, for a predetermined period of time, or upon request, the files indicated in the file list held in the administrator and user briefcases are displayed. A computer-readable recording medium storing a program for operating the mobile computer system so as to ensure synchronization between the server computer and the mobile computer.