JP2000227869A - Method and system for synchronously updating data base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous data base updating system capable of obtaining complete security without using an expensive firewall at all and without requiring the special knowledge of a protocol such as the firewall when updating a data base, which is stored in file servers integrated in two different LAN, with automatic synchronism. SOLUTION: A first personal computer PC1 connected to a first LAN reads out change data in a first data base 10 and temporarily stores these read change data in an intermediate data storage device such as hard disk. Continuously, the data storage device is switched to a second PC2 and the change data in the first data base 10 are written in a data base 20 of a second LAN to which the second PC2 is connected. This operation is automatically repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to two separate LAs.
The present invention relates to a system for updating a database stored in a file server incorporated in N while automatically synchronizing.

[0002]

2. Description of the Related Art An organization using a database separates in-house data that should be kept secret from general data that can be disclosed, protects the company (organization) from data leakage, and protects in-house data by hackers and the like. Various measures have been taken to prevent tampering.

When a database is used on a LAN, a protocol or data filtering is usually performed by software called a "firewall" as a security protection device. A “firewall” is a barrier set on a bridge, router, or gateway, and the type of packet (TCP / IP or IP
X, etc.) or packets that pass based on the destination address.

[0004]

[Problems to be solved by the invention] "Firewall"
Is relatively low in the OSI hierarchy (closer to the machine)
Since filtering is performed, general-purpose use regardless of the type of application is possible. Also, since the data transmission time is so small that it can be ignored, it can be regarded as the same LAN, and a complete real-time system can be constructed. However, firewalls have the problem of being relatively expensive.

[0005] Further, although different LANs are physically and visually connected to each other even though they are through a firewall, there is a problem that a real feeling of a firewall is poor.
There is a problem that it cannot be completely denied that it is broken in any way.

The present invention provides a database stored in a file server incorporated in two separate LANs,
Automatically synchronize and update without having to use expensive firewalls at all and without the need for specialized knowledge of protocols such as firewalls. It is intended to provide a system.

[0007]

According to the present invention, a first LAN is provided.
A first personal computer connected to the first database reads out the change data in the first database, temporarily stores the read out change data in an intermediate data storage device such as a hard disk, and subsequently, The storage device is connected to a second personal computer, and the operation of writing the changed data in the first database to the database of the second LAN to which the second personal computer is connected is automatically repeated.

In this case, the database structure of the second LAN needs to be exactly the same as that of the first LAN.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a database synchronous updating system 100 according to one embodiment of the present invention.

[0010] The database synchronous update system 100
The database of its own server is copied to the database of another LAN under the shadow of the application.

Further, the database synchronous updating system 10
0 is the internal server 10 as the first server,
Personal computer PC1 as a computer, an internal LAN, and an external server 20 as a second server
And an external personal computer PC2 as a second computer
, An external LAN, an external storage device 30, and a SCSI bus switching device 40.

Further, the database synchronous updating system 10
0, the in-house server 10 and the in-house personal computer PC1
Are connected by the first LAN, and the external server 20
And the external personal computer PC2 are connected by the second LAN, and the data in the database stored in the internal server 10 and the data in the database stored in the external server 20 are updated so as to match each other. Database synchronization update system.

The internal server 10 stores an internal database, and the external server 20 stores an external database. External storage device 30
Is used to temporarily hold changed data among the data in the database stored in the internal server 10, and is used to temporarily store changed data in the database stored in the external server 20. , And temporarily stores changed data.

The SCSI bus switching device 40 is an example of a switching device for switching the connection between the external storage device 30 and the internal personal computer PC1 or the external personal computer PC2.

The personal computer PC1 is an example of change data extracting means for extracting changed data from a database stored in the in-house server 10. An external storage device 30 is connected to the in-house personal computer PC1. Is an example of a write control unit that writes the extracted change data to the external storage device 30 when the change device is outside the personal computer PC2 after the writing to the external storage device 30 is completed. In the case where the change data is stored in the external storage device 30 and the external storage device 30 is connected to the external personal computer PC2, the change data is stored in the external storage device. 30 is an example of changed data reading means for reading data from the external server 30; Access the over scan, are also examples of change data updating means for updating the data corresponding to the changed data in the corporate server with the changed data.

That is, the database synchronous update system 1
00, the first server and the first computer are connected by the first LAN, the second server and the second computer are connected by the second LAN, and are stored in the first server. In a database synchronous update system for updating data in a database to match data in a database stored in a second server, an external storage device storing changed data of data in the database, and an external storage A switching device for switching the connection between the device and the first computer or the second computer; a change data extracting means for extracting changed change data from a database stored in the first server; and an external storage device. When connected to the first computer, the extracted change data is transferred to the change data in the first server. Writing control means for writing the data to the external storage device, and switching control means for switching the switching device to the second computer after the writing to the external storage device is completed; change data stored in the external storage device; When the storage device is connected to the second computer, a change data reading means for reading change data from the external storage device and a database stored in the second server are accessed, and the change in the first server is changed. 1 is an example of a database synchronous update system having a change data update unit that updates data corresponding to data with change data.

The in-house personal computer PC1 is an example of a switching state detecting means for detecting the switching state of the switching device 40, and a change indicating that data in the database stored in the in-house server 10 has been changed. This is storage control means for storing information in the in-house server 10.

The change information indicating that the data in the databases stored in the servers 10 and 20 has been changed is an index file having a change flag.

Further, when the database stored in the external server 20 has update availability information and the external personal computer PC2 accesses the database stored in the external server 20, the update is performed. If the update is not possible by referring to the availability information, updating the change data stored in the external server 20 to the change data stored in the internal server 10 is prohibited.

FIG. 2 is a circuit diagram showing an outline of the SCSI bus switching device 40 in the above embodiment.

The SCSI bus switching device 40 includes data selection ICs 41 and 42, a first port connector 43, a second port connector 44, a hard disk port connector 45 connected to the external storage device 30, and an IC 41 or 42. A signal control circuit 45 for controlling signals, a first button B1 for manual switching, and a die 2 button B for manual switching
2 and control terminals SW1-S, SW-1R, SW2-S,
SW2-R.

FIG. 3 is an explanatory diagram showing the connection relationship between the SCSI bus switching device 40 and the personal computers PC1 and PC2 in the above embodiment.

Next, the operation of updating the database in the above embodiment will be described. In the following,
The update operation of the database will be described focusing on the device on the first LAN side (the in-house server 10 side).

FIG. 4 is a flowchart showing the operation of the above embodiment. Note that the processing operation shown in FIG. 4 is a processing operation only inside the company, and actually, a processing operation similar to the processing operation shown in FIG. 4 is performed outside the company.

First, an internal LAN or an external LAN is connected to the external storage device 30 via the switching device 40. Therefore, the in-house personal computer PC1 determines whether or not the in-house LAN is connected to the external storage device 30 (S1). If the in-house LAN is connected to the external storage device 30, the number of the database that has been checked to determine whether data has been changed is checked (S2). If the number of the database for which the data has been changed is less than a predetermined number (for example, 100), it is determined whether or not a change flag has been set in the in-house database stored in the in-house server 10. The personal computer PC1 makes a determination (S3). In this case, if there is a change in the data in the database, a change flag is set (the change flag becomes "1"), and this change flag is provided in the index file in the database.

If an in-house LAN is connected to the external storage device 30 and it is determined that the data in the database has changed based on the change flag, the in-house personal computer PC
1 detects a record that has been changed based on the index file (S4). That is, the in-house personal computer PC1 reads out the changed data in the in-house database stored in the in-house server 10. Then, the read change data is stored in the first folder of the external storage device 30 (S5).

Thereafter, the in-house personal computer PC1 switches and connects the external storage device 30 to the out-of-office personal computer PC2 via the switching device 40 (S6). Then, the changed data in the in-house database is written to the database of the out-of-office server 20 connected to the out-of-office LAN to which the out-of-office personal computer PC2 is connected (S9). However, when the database stored in the external server 20 has the update permission / inhibition information, and the external personal computer PC2 accesses the database of the external server 20, the update permission / inhibition information is referred to (S7), and the update is disabled. If so, updating the change data stored in the external server 20 to the change data stored in the internal server 10 is prohibited (S8).

Then, the in-house personal computer PC1 switches and connects the external storage device 30 to the in-house personal computer PC1 via the switching device 40 (S10), selects the next database (S11), and returns to step S2. Then, the above processing (S3 to S11) is repeated until the number of the database for which it has been checked whether or not the data has changed becomes 100.

Here, if the number of the database examined to determine whether or not the data has changed becomes 100 or more (S
2) The external storage device 30 is switched and connected to the external LAN via the switching device 40 (S12).

If the switching device 40 has been switched to the in-house LAN side (S1), a change record is marked. In other words, the application on the in-house LAN side is
At the same time as updating the corresponding field in the corresponding record in the database, the fact that the change has been made is also written in the “index file”. The “key value” of the record is written in the “index file”.
When operating in the “flag detection mode”, the application writes “1” in the “change flag” field.

When a change record is detected (S4), the registered database is always
Monitor the "index file" field or the "change flag" field, and if the "change record" exists in the index file, read out the "key value", and based on the read out key value, The read change record is read out to the buffer memory.

When a record in which the "change flag" field is "1" is found while operating in the "flag detection mode", the same applies to the above, and the record is read out to the buffer memory. Then, a change record is written (S5). That is, the change record read into the buffer memory in this manner is immediately transmitted to the first LA in the external storage device 30 such as a hard disk.
N is written to the folder corresponding to N. Since the file name of the intermediate data to be written includes the original database file name, it is possible to target a plurality of databases. The range to be written is all the fields of the changed record, which are written out in text mode.

When the intermediate data is written to the external storage device 30, the record in the index file is deleted, or "0" is written in the "change flag" field of the application database. Then, the search in the reverse direction is performed. That is, after all the registered databases are detected, the update operation in the reverse direction is performed, that is, the change data written by the outside company device is detected from the folder corresponding to the external LAN in the external storage device 30. If there is data written by the outside company device (updated portion of the outside company database), the key content is read, and the corresponding record in the inside company database is read. However, this directory is always free if it is set to update only in one direction.

By the way, when updating in the reverse direction, the changed data is written in a database inside the company in units of records. However, it is not written in the field for which “write right” is set. If the writing is successful, the external storage device 3
After deleting 0 records and updating all records,
The intermediate data file itself stored in the external storage device 30 is deleted. Then, the bus switching device 40 is controlled. That is, when a series of operations is completed, a signal is sent to the bus switching device 40, and the bus switching device 40 is switched to a company outside device.

FIG. 5 is a diagram showing an example of a database and an example of an index file in the above embodiment.

The database shown in FIG. 5 is provided with four fields (items) of "product number", "product name", "product type", and "unit price". Among these fields, a field (unique field) having no duplication in the product number is treated as a key. The field treated as a key need not be limited to one field, and a field constituting one product number by a plurality of data may be used as a field treated as a key. The key thus set may be used as a field treated as a key.

FIG. 6 is a diagram showing an example of text data output to the external storage device 30 in the above embodiment.

In the example shown in FIG. 6, if the four fields of “product number”, “product name”, “product type” and “unit price” are changed on the in-house LAN side, these four fields are changed. Is changed and updated on the external LAN side for all of the above. However, even if the field of “unit price” is changed on the external LAN side, the internal LAN
Side data update is prohibited.

Next, the operation of the SCSI switching device 40 will be described in more detail.

First, the in-house personal computer PC1 is an LA connected to the external storage device 30 and the in-house personal computer PC1.
N (for example, an in-house server) exchanges change data. When this is completed, the terminal of the printer port (that is, S
(W2-SW lead), a negative logic pulse of about 100 milliseconds is transmitted.

When the switching device 40 switches the bus, a switching confirmation signal (also negative logic) is output to the SW2-R of the switching device 40 (that is, the 11th terminal of the printer port of the personal computer PC2). , PC for external use
C2 learns that it has been switched, and
And exchanges change data with a LAN (for example, external server 20) to which the external personal computer PC2 is connected.

When the work of the external personal computer PC2 is completed,
To switch the SCSI bus to the other side (inside the company) as in the first case, a negative logic pulse of about 100 milliseconds is also sent to the terminal of the printer port outside the company (that is, the SW1-S lead).

The SCSI switching device 40 switches the bus to the inside of the company this time, and a switching confirmation signal appears on the SW1-R lead (that is, the 11th terminal of the printer port of the personal computer PC1). Knowing that it was switched, perform the first action. Thus, a series of operations returns to the beginning.

A database stored in a physically separated LAN can only distribute data through a removable medium such as an MO. By using the system of the above embodiment, mutual updating of data is possible without compromising security at all.

Since the in-house LAN and the out-of-office LAN are physically separated from each other, usually, the in-house personal computer PC1 connected to the in-house LAN can access only the in-house database. The external personal computer PC2 connected to the external LAN can access only the external database. However, if the in-house personal computer PC1 can use one common local medium (for example, the external storage device 30) by switching over time as in the above-described embodiment, the data can be mutually updated.

In the above embodiment, the databases of the two LANs are copied bidirectionally. Therefore,
If the data of the copy source and the data of the copy destination are changed almost at the same time, inconsistency such as that the data returns to the original occurs. Even if this cannot be essentially solved, in the above embodiment, "write right" can be set in the field, thereby protecting the field from being written back.

According to the above embodiment, both LANs are completely physically and electrically separated without using an expensive firewall at all and without requiring specialized knowledge of a protocol such as a firewall. So the security is perfect.

In the above embodiment, the changed record is recorded in a method of adding a "change flag" to the application database and a separate database of only "key value" and "change flag" is provided as an index file. There is a method, but a method that can be easily changed on the application side can be selected during operation.

As a method of removing the mark from the index file after the data update is completed, a method of returning the "change flag" to "0" and a method of deleting the record of the index file itself are considered. Then, the record itself of the index file is deleted.

[0050]

According to the present invention, when updating a database stored in a file server incorporated in two separate LANs while automatically synchronizing, an expensive firewall is not used at all. In addition, there is an effect that complete security can be obtained without requiring specialized knowledge of a protocol such as a firewall.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a database synchronous update system 100 according to one embodiment of the present invention.

FIG. 2 shows a SCSI bus switching device 40 in the embodiment.
FIG. 2 is a circuit diagram showing an outline of the embodiment.

FIG. 3 shows a SCSI bus switching device 40 in the embodiment.
FIG. 4 is an explanatory diagram showing a connection relationship between a personal computer PC1 and a personal computer PC2.

FIG. 4 is a flowchart showing the operation of the embodiment.

FIG. 5 is a diagram showing an example of a database and an example of an index file in the embodiment.

FIG. 6 is a diagram showing an example of text data output to the external storage device 30 in the embodiment.

[Explanation of symbols]

 100: Database synchronous update system 10: Internal server as first server PC1: Internal personal computer as first computer 20: External server as second server PC2: Second computer PC for external use, 30 ... external storage device, 40 ... SCSI bus switching device.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Haruya Takei 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Wataru Matsubara 3- 19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Joe Musashi 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo F-Term within Nippon Telegraph and Telephone Corporation (reference) 5B082 EA05 GB02

Claims (8)

[Claims] 1. A first server and a first computer are connected by a first LAN, and a second server and a second computer are connected by a second LAN and stored in the first server. In a database synchronous updating system for updating data in the database that has been stored and data in the database stored in the second server so that they match each other, an external storage that stores changed data of the data in the database A device that switches the connection between the external storage device and the first computer or the second computer; and a change that extracts changed data from a database stored in the first server. Means for extracting data; when the external storage device is connected to the first computer, Writing control means for writing the changed data to the external storage device; switching control means for switching the switching device to the second computer after writing to the external storage device is completed; Change data reading means for storing the change data and reading the change data from the external storage device when the external storage device is connected to the second computer; storing the change data in the second server And a change data updating means for accessing a database that has been set and updating data corresponding to the change data in the first server to the change data. 2. A switching state detecting means for detecting a switching state of the switching device, wherein the change information indicating that data in a database stored in the first server has been changed is transmitted to the switching server. Storage control means for storing the data in the first server; 3. The database synchronization update according to claim 2, wherein the change information indicating that data in the database stored in the server has been changed is an index file having a change flag. system. 4. The database according to claim 1, wherein the database stored in the second server is:
When the second computer accesses a database stored in the second server, the database refers to the update permission / inhibition information. A database synchronous updating system, wherein updating of change data stored in a server to change data stored in the first server is prohibited. 5. A first server and a first computer are connected by a first LAN, and a second server and a second computer are connected by a second LAN and stored in the first server. In the database synchronization updating method of updating the data in the first database and the data in the second database stored in the second server so as to match, the first personal computer includes: A change data reading step of reading the change data in the first database; a change data storage step of storing the read change data in a predetermined data storage device; and, following the change data storage step, A connection switching step of switching and connecting a data storage device to the second personal computer; and Database synchronization update method characterized by having: a change data writing step writes change data. 6. The switching device according to claim 5, wherein a switching state detecting step of detecting a switching state between the predetermined data storage device and the first LAN or the second LAN; And a storage control step of storing, in the first server, change information indicating that the database has been changed. 7. The database synchronization update according to claim 6, wherein the change information indicating that data in the database stored in the server has been changed is an index file having a change flag. Method. 8. The system according to claim 5, wherein the second database has update availability information, and when the second computer accesses the second database, the second database refers to the update availability information and updates the information. If it is not possible, updating of the change data stored in the second server to change data stored in the first server is prohibited.