Agent for replicating data based on a client defined replication period

• US 5,884,324 A
• Filed: 07/23/1996
• Issued: 03/16/1999
• Est. Priority Date: 07/23/1996
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Wang, Shu-jen, Shen, HongHai, Cheng, Josephine M.
• Primary Examiner(s): Von Buhr, Maria N.
• Application Number:
  US08/684,011
• Time in Patent Office: 966 Days
• Field of Search: 707/1, 707/3, 707/10, 707/201, 395/200.33, 395/200.47-200.49, 711/141-146
• US Class Current: 1/1
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

A method, apparatus, and article of manufacture for replicating data stored in source database tables in a database management system implemented by a server at a remote client implemented on a client computer. The method comprises the steps of receiving a subscription message from the client computer, wherein the subscription message specifies a remote client database table and a data replication period, receiving a change log from the database management system at the data replication agent, generating a table of changed data by using the change log, data replication period, and source database table to reconstruct changes to the remote client database table, and transmitting the changed data table to the remote client.

Claims

1. A method of replicating data stored in one or more source database tables in a database management system, performed by both a server computer and a client computer, comprising the steps of:

receiving a subscription message from the client computer at a data replication agent performed by an agent computer, the subscription message comprising a data replication request message specifying one or more remote client database tables and a client defined data replication period, wherein the client defined replication period defines how often the replication process should proceed;

receiving a change log from the database management system at the data replication agent, the change log identifying changes to the source database table during the data replication period;

generating a table of changed data at the data replication agent, comprising the step of reconstructing changes to the remote client database table during the data replication period using the change log, the data replication period, and the source database table; and

transmitting the changed data from the data replication agent to a remote client.

2. The method of claim 1, further comprising the step of applying the changed data to the remote client database table.

3. The method of claim 1, wherein the data replication request message further comprises logical database operators.

4. The method of claim 1, wherein the step of transmitting the changed data to the remote client comprises the steps of:

transmitting a notify message to the remote client indicating that the table of changed data is generated;

receiving a data transmission message from the remote user, thereby establishing a communication link between the remote client and the data replication agent; and

transmitting the changed data to the remote client.

5. The method of claim 1, wherein the subscription message and the changed data are communicated between the client computer and the data replication agent via a daemon invoked at the client computer.

6. The method of claim 5, further comprising the steps of:

periodically querying the daemon at the remote client to determine if any changed data is present; and

applying the changed data to the remote client database table when changed data is present.

7. The method of claim 1, wherein the client computer further comprises a message queue associated with a trigger and a query browser to display the remote client database table, and the step of transmitting the changed data from the data replication agent to the remote client comprises the step of sending a message to the client computer to activate the trigger to invoke the query browser at the client computer.

8. An apparatus for replicating data stored in source database tables in a database management system, performed by both a server computer and a client computer, comprising:

an agent computer having a processor, a memory, and a data storage device;

means, performed by the agent computer, for receiving a subscription message from the client computer, the subscription message comprising a data replication request message specifying one or more user-selected remote client database tables and a client defined data replication period, wherein the client defined replication period defines how often the replication process should proceed;

means, performed by the agent computer, for receiving a change log from the database management system at the data replication agent, the change log identifying changes to the source database table during the data replication period;

means, performed by the agent computer, for generating a table of changed data at the data replication agent, comprising means for reconstructing changes to the remote client database table during the data replication period using the change log, the data replication period, and the source database table; and

means, performed by the agent computer, for transmitting the changed data from the data replication agent to a remote client.

9. The apparatus of claim 8, further comprising means, performed by the client computer, for applying the changed data to the remote client database table.

10. The apparatus of claim 8, wherein the data replication request message further comprises logical database operators.

11. The apparatus of claim 8, wherein the means for transmitting the changed data from the data replication agent to the remote client comprises:

means, performed by the agent computer, for transmitting a notify message to the remote client indicating that the table of changed data is generated;

means, performed by the agent computer, for receiving a data transmission message from the remote client, thereby establishing a communication link between the remote client and the data replication agent; and

means, performed by the agent computer, for transmitting the changed data to the remote client.

12. The apparatus of claim 8, wherein the subscription message and the changed data are communicated between the agent computer and the client computer via a daemon invoked at the client computer.

13. The apparatus of claim 12, further comprising:

means, performed by the client computer for periodically querying the daemon to determine if any changed data is present; and

means, performed by the client computer, for applying the changed data to the remote client database table when changed data is present.

14. The apparatus of claim 8, wherein the client computer further comprises a message queue associated with a trigger and a query browser to display the remote client database table, and the means for transmitting the changed data from the data replication agent to the remote client comprises means for sending a message to the client computer to activate the trigger to invoke the query browser at the client computer.

15. A program storage device, readable by a computer having a processor, a memory, and a data storage device, tangibly embodying one or more programs of instructions executable by the computer to perform method steps of replicating data stored in source database tables in a database management system, performed by both a server computer and a client computer, the method comprising the steps of:

receiving a subscription message from the client computer at a data replication agent executed by an agent computer, the subscription message comprising a data replication request message specifying one or more remote client database tables and a client defined data replication period, wherein the client defined replication period defines how often the replication process should proceed;

receiving a change log from the database management system at the data replication agent, the change log identifying changes to the source database table during the data replication period;

generating a table of changed data at the data replication agent, comprising the step of reconstructing changes to the remote client database table during the data replication period using the change log, the data replication period, and the source database table; and

transmitting the changed data from the data replication agent to a remote client.

16. The program storage device of claim 15, wherein the method steps further comprise the step of applying the changed data to the remote client database table.

17. The program storage device of claim 15, wherein the data replication request message further comprises logical database operators.

18. The program storage device of claim 15, wherein the method step of transmitting changed data to the remote client comprises the method steps of:

transmitting a notify message to the remote client indicating that the table of changed data is generated;

receiving a data transmission message from the remote client, after establishing a communication link between the remote client and the data replication agent; and

transmitting the changed data to the remote client.

19. The program storage device of claim 15, wherein the subscription message and the changed data are communicated between the client computer and the data replication agent via a daemon invoked at the client computer.

20. The program storage device of claim 19, wherein the method steps further comprise the step of applying the changed data to the remote client database table when changed data is present.

21. The program storage device of claim 15, wherein the client computer comprises a message queue associated with a trigger and a query browser to display the remote client database table, and the method step of transmitting the changed data from the data replication agent to the remote client comprises the method step of sending a message to the client computer to activate the trigger to invoke the query browser at the client computer.