JPH1125057A - Inter-subsystem time correction system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire properly corrected system time without changing a calendar clock in a subsystem itself. SOLUTION: A system time informing means 13 built in a main system 1 periodically acquires current system time from a calendar clock 12 and informs respective subsystems 2 of the current system time. A time correction means 22 built in each subsystem 2 acquires a local calendar clock 21 to be corrected and stores a system time correction value consisting of a difference from the system time informed by the main system 1 in a shared table 25. A system time acquiring means 27 built in the subsystem 2 acquires the local calendar clock 21 at the time of receiving a time acquiring request from an operation program 26, and while taking account of the system time correction value stored in the table 25, provides the corrected time as a current system time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer network system operating in synchronization with a system time, and more particularly to a time correction method between subsystems.

[0002]

2. Description of the Related Art Conventionally, the only absolute time in a system system which is owned by a main system (hereinafter, referred to as a system time).
Synchronizing and operating multiple subsystems in
This has been realized by updating the local calendar clock held in each subsystem as needed based on a time notification distributed from the main system at regular intervals (Japanese Patent Application Laid-Open Nos. 3-25582 and 2-156758). Gazette).

[0003]

In the above-mentioned prior art, since the calendar clock in the subsystem is changed, in the business system in which the system time can be arbitrarily set (for evaluation or the like), the calendar clock is not used. This causes inconsistency of other programs (including the operating system) that refer to, and in the worst case, there is a risk of causing a serious failure such as a system stop.

In addition, since the calendar clock is not always accurate, it is necessary to always set the time when performing offline work such as file maintenance while being disconnected from the main system. In such a case, the date (time stamp) of the created file or the like becomes inaccurate, which may cause a serious problem in file management.

An object of the present invention is to operate synchronously while maintaining a certain error between the main system providing the system time and the subsystem provided (as long as there is no significant difference in clock accuracy). Focusing on the fact that the subsystem that provides the system time keeps the error as the system time correction value, so that the time corrected system time can be obtained without changing its own calendar clock To provide a time correction method between subsystems.

[0006]

According to the present invention, there is provided a system for correcting time between subsystems, comprising: a main system for measuring only the system time in a system; and a subsystem for performing business processing in synchronization with the system time of the main system. In the computer network system having the following, when the system time is corrected by the business program in each subsystem by regularly transmitting the system time synchronization message from the main system, a local system held for each subsystem is provided. The system time can be corrected without changing the calendar clock.

[0007] A time correction method between subsystems according to the present invention is a computer comprising a main system for measuring only the system time in a system, and a subsystem for performing business processing in synchronization with the system time of the main system. In the network system, a system time notification unit provided in the main system and periodically notifying the current system time to each subsystem, and a local calendar clock provided in the subsystem and to be corrected, A time correction unit that holds a system time correction value, which is a difference from the system time notified from the main system, on a shared table; and a local time correction unit that is provided in the subsystem and that responds to a time acquisition request from a business program. Get the calendar clock and keep it in the shared table It was by adding the system time correction value and a system time acquisition means for providing a system time at that time. A message transmission timing generator for periodically generating a transmission timing of a system time synchronization message by a timer interrupt; and acquiring a system time from a calendar clock based on the transmission timing from the message transmission timing generator. And a system time synchronization message transmitting unit that creates a system time synchronization message and transmits it to the subsystem. Also, the time correction means may include a system time synchronization message receiving unit that receives a system time synchronization message, and a difference between a system time in the system time synchronization message received by the system time synchronization message receiving unit and a local calendar clock. And a system time correction value calculation unit that calculates the system time correction value and stores it in the shared table. Further, the system time obtaining means may be a subroutine linked to a business program and called at irregular intervals. Thus, in the main system, the system time serving as a correction reference can be notified to each subsystem in the same system system by the system time notifying unit. On the other hand, in each subsystem, the difference between the time of the calendar clock in the own system and the system time notified from the main system is obtained by the time correction means, and the difference is stored in the shared table as a system time correction value. At this time, the calendar clock was not changed. Further, the system time obtaining means operates when a notification of the system time is requested from the business program, and adds the system time correction value on the shared table to the local calendar clock at that time, thereby obtaining the simultaneous time. The system time can be easily obtained.

On the other hand, the recording medium of the present invention comprises a program for causing a computer of a main system to function as a system time notifying means for periodically notifying each subsystem of the current system time, and a computer of each subsystem. A time correction unit that obtains a local calendar clock to be corrected, and stores a system time correction value, which is a difference from the system time notified from the main system, in a shared table, and a time acquisition request from a business program. A program for acquiring a local calendar clock, and taking into account the system time correction value held in the shared table, and providing a program for functioning as system time acquisition means for providing the system time at that time. .

Further, the recording medium of the present invention records a program for causing a computer to function as a system time notifying means for periodically notifying each subsystem of the current system time.

Further, in the recording medium of the present invention, the computer acquires a local calendar clock to be corrected and holds a system time correction value, which is a difference from the system time notified from the main system, on a shared table. And a system for acquiring a local calendar clock in response to a time acquisition request from a business program, and providing the system time at that time taking into account the system time correction value held in the shared table. A program for functioning as time acquisition means is recorded.

[0011]

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

FIG. 1 is a block diagram showing a configuration of a computer network system to which an inter-subsystem time correction method according to a first embodiment of the present invention is applied. The main part of this computer network system is composed of a main system 1 for measuring the system time and a subsystem 2 having a business program 26 operating in synchronization with the system time.

The main system 1 and the subsystem 2
It is directly connected by the communication line 3. In order to increase the accuracy of the corrected system time, it is desirable to use a communication means with a high speed as much as possible, and when there is a large amount of communication due to business processing or the like, it is necessary to install a dedicated communication line for time synchronization. .

FIG. 2 is a diagram showing an example of a system time synchronization message M transmitted from the main system 1 to the subsystem 2 via the communication line 3. The system time synchronization message M includes a header portion including a transmission destination identifier, a transmission source identifier, and a data length, and a message ID (ID
and a message portion including a message.

The main system 1 includes an interrupt timer 11
An operating system (hereinafter abbreviated as OS) 10 including a calendar clock 12 and a system time notifying unit 13 including a message transmission timing generation unit 14 and a system time synchronization message transmission unit 15 are mounted.

The system time notifying means 13 includes a message transmission timing generator 14 for periodically generating the transmission timing of the system time synchronizing message M in response to an interrupt from the interrupt timer 11, a system time from the calendar clock 12, and a system time. And a system time synchronization message transmitting unit 15 for generating a synchronization message and transmitting it to the subsystem 2.

When the main system 1 is started, first, a logical communication path between the system time synchronization message transmitting unit 15 and the system time synchronization message receiving unit 23 is established in the system time synchronization message transmitting unit 15. If the establishment is successful, the system time synchronization message transmission unit 1
5 acquires the system time at that time from the calendar clock 12, creates a system time synchronization message M, and transmits it to each subsystem 2 (first transmission).

On the other hand, a message transmission timing generator 1
4 continuously gives the transmission timing of the system time to the system time synchronization message transmitting unit 15 regularly based on the interrupt from the interrupt timer 11 from the time of initial startup.

System time synchronization message transmission section 15
Obtains the current system time from the calendar clock 12 in accordance with the transmission timing from the message transmission timing generator 14, and sends the system time synchronization message M to the subsystem 2 in which the logical communication path is established.
Send This enables continuous correction of the system time of the entire computer network system.

The transmission timing (interval) provided by the message transmission timing generator 14 is an evaluation value determined by the accuracy of the system time required for the computer network system, the accuracy of the local calendar clock of the subsystem 2, and the like. .

It should be noted that the system time synchronization message transmitting section 15 needs to be provided with a retry process when the establishment of the logical communication path has failed. This is the same on the subsystem 2 side.

The subsystem 2 includes a calendar clock 21
, A time correction unit 22, a shared table 25, and a business program 26 including a system time acquisition unit 27.

The time correction means 22 comprises a system time synchronization message receiving section 23 for receiving the system time synchronization message M, and a system time correction value calculating section 24 for calculating the system time correction value and storing it in the shared table 25. Have been.

The business program 26 is linked with a system time acquisition means 27 which is a subroutine called at irregular intervals.

The shared table 25 is used for sharing the correction value between the system time correction value calculation unit 24 and the system time acquisition unit 27.

When the subsystem 2 is started, similarly to the main system 1, the system time synchronization message receiving unit 2
In 3, a logical communication path is established with the main system 1. After the establishment, the reception state is always maintained, and each time the system time synchronization message M is received, a reception notification is sent to the system time correction value calculation unit 24.

The system time correction value calculation section 24 secures the shared table 25 at the time of initial startup. Shared table 2
5 stores a system time correction value which is a difference between the local calendar clock 21 and the system time.
Until the system time is received from the main system 1, its value is 0.

The system time correction value calculation unit 24 obtains the current time from the calendar clock 21 of the own subsystem 2 in response to the reception completion notification from the system time synchronization message reception unit 23, and calculates the difference from the notified system time. Ask for. At this point, the obtained difference is simply stored in the shared table 25 as the system time correction value.

The system time acquisition means 27 is a service which is called when the system time is needed in the business program 26 to which it is linked, and realizes a function of notifying the request source of the current system time. It is a program. At the time of an irregular call from the business program 26, first, the current time is obtained from the local calendar clock 21, and a value obtained by adding the system time correction value of the shared table 25 to the current time is returned to the requesting business program 26 as the system time.

When there are a plurality of business programs 26 requiring the system time in FIG. 1, each of them needs to link the system time acquisition means 27.

Referring to FIG. 3, the process of the message transmission timing generator 14 is a sleep step A for a fixed time.
001 and transmission request message creation step A002
And an event notification step A003.

Referring to FIG. 4, the processing of the system time synchronization message transmitting unit 15 is performed in a logical communication channel opening step A.
101, a sleep step A102 for a fixed time, a common transmission processing step A103, an event waiting step A104, and a common transmission processing step A105.

Referring to FIG. 5, the common transmission processing step A103 further includes a calendar time acquisition step A1.
11, a relative time conversion step A112, and a message transmission step A113.

Referring to FIG. 6, the processing of the system time synchronization message receiving unit 23 is a logical communication channel establishment step A.
201, a predetermined time sleep step A202, a message reception waiting step A203, a system time retrieval step A204, and an event notification step A20.
5

Referring to FIG. 7, the processing of the system time correction value calculating section 24 is performed in a shared table securing step A301.
, An event reception waiting step A302, a calendar time acquisition step A303, and a relative time conversion step A3.
04 and a system time correction value storage step A305.

Referring to FIG. 8, the processing of the business program 26 includes a business processing step A401, a system time acquisition requesting step A402, and a business processing step A403.
Consists of

Referring to FIG. 9, the processing of the system time obtaining means 27 includes a calendar time obtaining step A501,
Relative time conversion step A502, system time relative time calculation step A503, calendar system time conversion step A504, system time return step A50
5

FIG. 10 is a timing chart showing the relationship between the system time and the subsystem local time in the first embodiment.

Next, the operation of the time correction method between subsystems according to the first embodiment configured as described above will be described with reference to FIGS.

The message transmission timing generator 14
Sleep for a certain period of time immediately after the initial startup (Step A00)
1) At the time of expiration, a transmission request message for the system time synchronization message M is created (step A002), and an event is notified to the system time synchronization message transmission unit 15 (step A003). After the notification, the message transmission timing generator 14 returns the control to step A001 again.

Further, the system time synchronization message transmitting section 15 establishes a logical communication path with the subsystem 2 at the time of initial startup (step A101). If the establishment has failed, the system sleeps for a certain period of time to retry (step A102). If the establishment is successful, the system time synchronization message transmission unit 15 performs a common transmission process (step A103). That is, the system time synchronization message transmission unit 15 acquires the current time T _s from the calendar clock 12 to provide the OS10 at that time (step A111), we negotiated it uniquely within the system based,
Into a relative time Delta] t _s from arbitrary time T ₀ of the past (Step A 112), system time synchronization message M
To the subsystem 2 (step A11).
3). The reason for converting the system time T _s into a relative time Δt _s from an arbitrary time T ₀ in the past is to facilitate calculations for time correction in the subsystem 2.

After the initial processing, the system time synchronizing message transmitting section 15
(Step A104). When the transmission request event is received from the message transmission timing generator 14, the system time synchronization message transmitter 15 executes steps A111 to A113 of the common transmission processing as in the case of the initial processing (step A105).

System time synchronization message receiving section 23
Opens a logical communication path with the main system 1 at the time of initial startup (step A201). If the establishment fails, sleep for a certain period of time to retry (step A
202). If the establishment is successful, the system time synchronization message receiving section 23 starts the main system 1
(Step A203). When receiving the system time synchronization message M from the main system 1, the system time synchronization message receiving unit 23 extracts the relative time ΔT _s of the system time therefrom (step A20).
4), and notifies the system time correction value calculation unit 24 (step A205). After the notification, the system time synchronization message receiving unit 23 continues to wait for the message reception again (step A203).

The system time correction value calculation unit 24 secures a shared table 25 for storing the system time correction value Δt at the time of the initial startup, and makes the system table obtainable by the system time acquisition unit 27 (step A301). afterwards,
The system time correction value calculation unit 24 waits in a state of waiting for a time reception notification from the system time synchronization message reception unit 23 (step A302). Upon receiving the time reception notification from the system time synchronization message receiving part 23, the system time correction value calculation unit 24 obtains the current time T ₁ from the calendar clock 21 OS20 is provided (step A303), the main system Just like in step 1,
After it is converted into a relative time Δt ₁ from time T ₀ uniquely decided in the system (step A304), a system time correction value Δt = Δt _s −Δt ₁ is obtained and stored in the shared table 25 (step A304). A305). After the storage, the system time correction value calculation unit 24 waits again for a time reception notification (step A302).

When the system time is required by the business program 26 during the business process (step A401),
The business program 26 calls the system time acquisition unit 27 (Step A402).

The called system time correction means 27
Reads (step A 501) the current time T _2, from the calendar clock 21 to first OS20 is provided, to convert again the relative time Delta] t ₂ from time T ₀ (step A5
02), relative time of system time Δt _s = Δt ₂ + Δt
(Step A503). Finally, the system time correction means 27, converts it to calendar time T _s (step A 504), and returns to the requestor (step A50
5).

Thereafter, the business program 26 resumes business processing (step A403).

Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 11, the time correction method between subsystems according to the second embodiment of the present invention is different from the time correction method between subsystems according to the first embodiment shown in FIG. A recording medium 4 in which a system time notification program corresponding to the system time notification means 13 is recorded, and a recording medium 5 in which a time correction program corresponding to the time correction means 22 and a system time acquisition program corresponding to the system time acquisition means 27 are recorded. Is provided.

The system time notification program is read from the recording medium 4 into the main system 1 and controls the operation of the main system 1. The operation of the main system 1 under the control of the system time notification program is the same as that of the first system shown in FIG.
The operation is the same as that of the main system 1 in the inter-subsystem time correction method according to the embodiment, and thus the detailed description is omitted.

The time correction program and the system time acquisition program are transmitted from the storage medium 5 to the subsystem 2.
To control the operation of the subsystem 2. The operation of the subsystem 2 under the control of the time correction program and the system time acquisition program is exactly the same as the operation of the subsystem 2 in the inter-subsystem time correction method according to the first embodiment shown in FIG. I omit the detailed explanation.

[0052]

Next, an embodiment of the time correction method between subsystems according to the first embodiment will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 12 shows the overall configuration of a computer network system to which the time correction method between subsystems according to the present embodiment is applied.
And subsystems FEP01, FEP02 and FEP
03 is connected by a bus-type LAN as the communication line 3.

The program constituting the system time notifying means 13 of the main system CPU01 includes a task TFP
Task TCP that gives the transmission timing of the system time to the
And each subsystem FEP0 connected by a bus type LAN
1, a task TFP for performing data link control with FEP02 and FEP03 and transmitting system time.

On the other hand, each subsystem FEP01, FEP
Time correction means 2 which operates in common with FEP02 and FEP03
2 include main system CPU 0
l, a task HDP for performing data link control with the system l and a process for receiving the system time, and a system time correction value calculated based on a notification from the task HDP, and a shared table
1 is stored in the task NCP.

The task AP for performing business processing includes G
A subroutine that is a library function provided as etSystemTime () is linked.

Further, a shared table commtb1 that can be commonly referred to by the task NCP and the task AP is secured.

Next, the operation of the time correction method between subsystems according to the present embodiment will be described with reference to FIGS.

First, two parameters p1 and p2 necessary for explaining the processing will be described.

The parameter p1 is a past time serving as a reference point for correcting the system time uniquely determined in the computer network system.
It is 00:00:00 on the first day of the month. The parameter p2 is a correction interval of the system time, and its value is 3600 [seconds].
It is.

FIG. 13 is a flowchart showing the flow of processing of the task TCP in the main system CPU01.

After the initial startup, the task TCP immediately sleeps for the time of the parameter p2 (a function provided by the OS 10 whose sleep is released by interruption after a lapse of a specified time) (step B001). When the sleep mode is released, the task TCP creates a system time transmission request (step B002), notifies the task TFP of the request (step B003), and sleeps again for the time of the parameter p2 (step B001). Task TCP
Continues this operation until the system stops.

FIG. 14 is a flowchart showing the flow of processing of task TFP in main system CPU 01.

The task TFP performs processing asynchronously for each data link with each subsystem 2. That is, events occurring in a plurality of data links can be waited for in a multiplex manner, and processing is defined for each occurred event (event driving).

At the time of initial startup, the task TFP first sets up the parameter pl (step B101).
Thereafter, a data link open request is made to each of the subsystems FEP01, FEP02, and FEP03 (step B102), and an event is waited for (step B103). The open request performs 30 retries (asynchronous processing by the OS 10) at one second intervals. If the data link open fails, the task TFP
After a minute, a timer value is set to retry (step B105), and an open retry timer is started (step B106). This operation continues until the subsystem is opened.

For the subsystem that has been successfully opened, the task TFP performs the time transmission process shown in FIG. 15 at this point (step B107).

More specifically, the task TFP starts with the OS1
Current time c_tim from calendar clock 11 of 0
e (step B201), and the relative time s_tim from the parameter p1 determined in the system.
e (step B202). This conversion involves O
Using the function provided by S10 (CNV (x,
y)). The obtained relative time s_time is set in the transmission message area (step B203), and a message header (address of the partner station, own station address, message length, message ID) is further added to the message and transmitted to the subsystem (step B203). Step B204).

The main system CPU01 operates the two tasks TCP and TFP to operate the respective subsystems FEP01, FEP02 and FE in the system.
The system time can be continuously transmitted to P03 at regular intervals.

On the other hand, FIG.
It is a flowchart which shows the flow of the process of the task HDP in (subsystem FEP02 and FEP03 are the same).

After the initial startup, the task HDP issues a data link open request to the main system CPU 01 (step C001). An open request retries 30 times at 1 second intervals, and fails if it fails.
A retry is performed after a sleep period of minutes (step C003). This operation is continued until the main system CPU01 is opened (permanent retry).

When the data link is opened, the task HDP waits for a message from the main system CPU 01 (step C002). Upon receiving the message, the task HDP examines the message header part, and if it is an invalid message, disconnects the data link (step C005) and starts again from the open operation.

If the message is normal, the task HDP
Extracts the system time (relative time) from the information (step C004), creates a system time reception notification, and passes it to the task NCP (step C006). Task H
The DP repeats this receiving operation until the system stops.

FIG. 17 is a diagram showing a similar configuration of the subsystem FEP01.
3 is a flowchart showing a flow of a process of a task NCP in FIG.

When the task NCP is initially started, the task AP
Initialize (secure) the shared table commtb1, which is a shared area with the server (step C101), and write the initial value “0” of the system time correction value therein (step C10).
2). Next, the task NCP waits for a reception event from the task HDP (step C103). Task HD
At the time of notification of reception of the system time from P, the task NCP first determines the current time c_
time is acquired (step C104), and the parameter p
Is converted to a relative time l_time from 1 (step C
105). This conversion also uses the CNV function. Subsequently, the task NCP subtracts the relative time l_time from the system time s_time (step C106) of the main system CPU01 that has just received, and stores the result in the shared table commtb1 (step C10).
7). This is the system time correction value in the subsystem FEP01. This value is the value of another calendar clock 21
This is naturally different in subsystems FEP02 and FEP03 having

FIG. 18 is a flowchart showing the flow of the processing of the task AP in the subsystem FEP01. In this example, it is assumed that the task AP performs a process of outputting a form with the system time added.

In the form creation processing (step C201), the task AP is assigned the library function GetSystem.
Time () is called (step C202).
This library function GetSystemTime ()
Is a service program provided as a part of the system time correction function, and upon a request from the task AP,
The processing shown in FIG. 19 is performed.

More specifically, the library function GetSyst
emTime () first obtains the current time c_time from the calendar clock 21 of the OS 20 (step C).
501), relative time l_time from parameter p1
(Step C502). Next, the library function GetSystemTime () calculates the relative time l_t.
A function (EXT) for converting the time s_time (step C504) obtained by adding the system time correction value stored in the shared table commtb1 to the calendar notation into the calendar notation
(X, y)) to obtain a final system time e_time (step C505), and return it to the task AP as a return value (step C506).

Task A that has obtained system time e_time
P adds this in the form output process (step C203) and prints out.

[0079]

The first effect is that the system time can be obtained without changing the calendar clock in the subsystem. This has the effect of preventing unstable operation of the system due to unexpected changes in the calendar clock. The reason is that the difference from the system time held by the main system is held as a system time correction value on the subsystem side, and the system time is obtained when necessary.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a computer network system to which an inter-subsystem time correction method according to a first embodiment of the present invention is applied.

FIG. 2 is a diagram showing a configuration of a system time synchronization message used in an inter-subsystem time correction method according to the first embodiment.

FIG. 3 is a flowchart showing a processing flow of a message transmission timing generator in FIG. 1;

FIG. 4 is a flowchart showing a processing flow of a system time synchronization message transmitting unit in FIG. 1;

FIG. 5 is a flowchart showing the common transmission processing in FIG. 4 in further detail;

FIG. 6 is a flowchart showing a processing flow of a system time synchronization message receiving unit in FIG. 1;

FIG. 7 is a flowchart showing a processing flow of a system time correction value calculation unit in FIG. 1;

FIG. 8 is a flowchart showing a flow of processing of a business program in FIG. 1;

FIG. 9 is a flowchart showing a processing flow of a system time acquisition unit in FIG. 1;

FIG. 10 is a timing chart illustrating a relationship between a system time and a subsystem local time according to the first embodiment.

FIG. 11 is a block diagram illustrating a configuration of a computer network system to which an inter-subsystem time correction method according to a second embodiment of the present invention is applied.

FIG. 12 is a block diagram illustrating an example of a method of correcting time between subsystems according to the first embodiment.

FIG. 13 is a flowchart showing a flow of processing of a task TCP in FIG.

FIG. 14 is a flowchart showing a processing flow of a task TFP in FIG. 12;

15 is a flowchart showing the time transmission process in FIG. 14 in more detail.

FIG. 16 is a flowchart showing a processing flow of a task HDP in FIG. 12;

FIG. 17 is a flowchart showing a process flow of a task NCP in FIG. 12;

FIG. 18 is a flowchart showing a processing flow of a task AP in FIG.

19 is a flowchart showing GetSystemTime in FIG. 18 in more detail.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main system 2 Subsystem 3 Communication line 4, 5 Recording medium 10 Operating system 11 Interrupt timer 12 Calendar clock 13 System time notification means 14 Message transmission timing generation part 15 System time synchronization message transmission part 22 Time correction means 23 System time synchronization message Reception unit 24 System time correction value calculation unit 25 Shared table 26 Business program 27 System time acquisition means AP, TCP, TFP, HDP, NCP Task commtbl Shared table CPU01 Main system FEP01, FEP02, FEP03 Subsystem GetSystemTime Library function M System time synchronization message

Claims (8)

[Claims] 1. A computer network system comprising: a main system that measures only the system time in a system; and a subsystem that performs business processing in synchronization with the system time of the main system. System time synchronization message, the system time can be corrected without changing the local calendar clock owned by each subsystem when the system time is corrected by the business program in each subsystem. A time correction method between subsystems. 2. A computer network system comprising: a main system that measures only the system time within a system; and a subsystem that performs business processing in synchronization with the system time of the main system. System time notification means for periodically notifying each subsystem of the current system time, and a local calendar clock provided in the subsystem, which is to be corrected, and obtained from the system time notified by the main system. A time correction unit that stores a system time correction value, which is a difference, on a shared table; and a local calendar clock that is provided in the subsystem and that obtains a local calendar clock in response to a time acquisition request from a business program, and stores the local calendar clock in the shared table. Taking into account the system time correction value And a system time obtaining means for providing the system time as the system time. 3. A system according to claim 1, wherein said system time notifying means generates a system time synchronization message transmission timing periodically by a timer interrupt, and a calendar clock based on the transmission timing from said message transmission timing generation section. 3. The inter-subsystem time correction system according to claim 2, further comprising: a system time synchronization message transmitting unit that acquires a system time from the system, creates a system time synchronization message, and transmits the system time synchronization message to the subsystem. 4. The system time synchronization message receiving unit for receiving a system time synchronization message, wherein the time correction means includes a system time synchronization message received by the system time synchronization message reception unit and a local calendar clock. 3. The time correction system between subsystems according to claim 2, further comprising a system time correction value calculation unit that calculates a system time correction value that is a difference from the system time and stores the system time correction value in a shared table. 5. The time correction method between subsystems according to claim 2, wherein said system time acquisition means is a subroutine linked to a business program and called at irregular intervals. 6. A program for causing a computer of a main system to periodically function as a system time notifying means for notifying each subsystem of a current system time, and a computer of each subsystem being provided with a local computer to be corrected. Time correction means for acquiring a calendar clock, and holding a difference from the system time notified from the main system on a shared table; and acquiring a local calendar clock in response to a time acquisition request from a business program, A recording medium which stores a program for functioning as a system time acquisition unit that provides a system time at that time in consideration of a system time correction value held in a shared table. 7. A recording medium on which a program for causing a computer to function as a system time notifying means for periodically notifying each subsystem of a current system time is recorded. 8. A time correction unit that obtains a local calendar clock to be corrected by a computer and stores a difference from a system time notified from a main system on a shared table, and a time obtaining request from a business program. Recording a program for functioning as a system time obtaining means for obtaining a local calendar clock, providing the system time at that time in consideration of the system time correction value held in the shared table, Medium.