Apparatus, method, and article of manufacture for client-side optimistic locking in a stateless environment

• US 6,401,103 B1
• Filed: 08/06/1999
• Issued: 06/04/2002
• Est. Priority Date: 08/06/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ho, Shyh-Mei, Watts, Vern Lee
• Primary Examiner(s): Breene, John
• Assistant Examiner(s): Ali, Mohammad
• Application Number:
  US09/369,943
• Time in Patent Office: 1,033 Days
• Field of Search: 707/3, 707/503, 707/101-104, 707/201-203, 709/224, 709/223, 709/231, 709/204, 709/103, 709/229, 717/11, 717/5, 705/35, 711/13
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2315 Optimistic concurrency control
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: G06F 16/972 Access to data in other repository systems, e.g. legacy data or dynamic Web page generation
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

The invention is an optimistic locking mechanism which allows Internet access to a database while maintaining data integrity in a stateless web environment. One embodiment of the invention incorporates a conventional IMS residing on a host computer and includes a generic transaction module which retrieves original data segments from the an IMS database in response to a search request from a web user. This embodiment of the invention further includes a server-side interface module for duplicating the original data segment into identical lines of data segments. One data segment may be updated by a web user whereas the other data segment remains constant and serves as a reference of the original state of the data segment. Both data segments are transmitted to a web user who may make changes to one data segment but not the other. Both data segments are returned, and the generic transaction module compares the state data segment to a current data segment to determine if the web user updates were based on the current state. If so, the IMS is updated to reflect the web user updates. If the web user updates were not based on the current state, the data segments are updated to reflect the current state and are then retransmitted to the web user. In this manner, a web user is allowed to update only data segments which are current, thereby maintaining integrity of the database.

Claims

1. An apparatus for allowing a user at a remote site to update data stored in a database while maintaining the integrity of the data using a client-side optimistic lock, the apparatus comprising:

a processor for executing instructions; and

a memory device storing modules executable by the processor, the modules comprising;

a transaction manager module configured to retrieve an original data segment from the database in response to a search request from the user;

a data segment duplicator module configured to generate two copies of the original data segment, a modifiable data segment to be modified at the remote site and a state data segment to be unaltered for transmission to the remote site; and

a comparison module configured to receive an updated modifiable data segment and the state data segment from the remote site and compare the state data segment with a current data segment to determine equivalence thereof and to lock and update the current data segment to reflect the updated modifiable data segment upon a determination of equivalence.

2. The apparatus of claim 1, further comprising a server adapted to effect communications between the data segment duplicator module and the remote site and wherein the data segment duplicator module comprises a server-side interface module configured to interact with the server to deliver and receive data segments.

3. The apparatus of claim 2, further comprising an IMS for managing the data stored in the database, and wherein the server-side interface module operates within the IMS.

4. The apparatus of claim 2, wherein the server-side interface module is further configured to generate the state data segment into a non-displayable format.

5. The apparatus of claim 3, wherein the server-side interface module is further configured to generate the modifiable and state data segments into HTML format.

6. The apparatus of claim 1, wherein the comparison module is further configured to compare the state and current data segments to determine non-equivalence, and to update the modifiable and state data segments to reflect the current data segment upon non-equivalence.

7. The apparatus of claim 6, wherein each data segment comprises data attributes and the comparison module is further configured to determine equivalence and non-equivalence based on a comparison of the data attributes of the state and current data segments.

8. The apparatus of claim 6, wherein the transaction manager module is further configured to lock the current data segment during comparison of the state and current data segments by the comparison module.

9. A method for accessing a database across a network and updating data stored on the database while maintaining data integrity via a client-side optimistic lock, the method comprising:

retrieving an original data segment in response to a search request received from a remote sire on the Internet;

generating two copies of the original data segment, a modifiable data segment to be modified at the remote site and a state data segment to be unaltered;

transmitting the modifiable data segment and the state data segment to the remote site;

receiving an updated modifiable data segment and the state data segment from the remote site; and

comparing the state data segment with a current data segment in the database.

10. The method of claim 9 further comprising updating the current data segment to reflect the updated modifiable data segment upon a determination that the state data segment and the current data segment are equivalent.

11. The method of claim 9 further comprising:

updating the modifiable and state data segments to reflect the current data segment upon a determination that the state data segment and current data segment are non-equivalent; and

retransmitting the modifiable and state data segments to the remote site.

12. The method of claim 9, further comprising:

updating, at the remote site, the modifiable data segment to reflect user preferences; and

maintaining the state data segment constant.

13. The method of claim 9, wherein each data segment comprises data attributes and wherein comparing the state data segment with the current data segment further comprises comparing the data attributes of the state data segment and the data attributes of the current data segment.

14. The method of claim 9 further comprising locking the current data segment during the step of comparing the state data segment with the current data segment.

15. The method of claim 9, wherein transmitting the modifiable data segment and the state data segment to the remote site comprises transmitting the modifiable data segment and the state data segment over the Internet.

16. A method for accessing a database across a network and updating data stored on the database while maintaining data integrity comprising:

retrieving an original data segment in response to a search request received from a remote site on the Internet;

generating a modifiable data segment and a state data segment based on the original data segment;

transmitting the modifiable data segment and the state data segment to the remote site, wherein transmitting the modifiable data segment and the state data segment to the remote site further comprises formatting the modifiable data segment and the state data segment into HTML;

receiving an updated modifiable data segment and the state data segment from the remote site; and

comparing the state data segment with a current data segment in the database.

17. A method for accessing a database across a network and updating data stored on the database while maintaining data integrity comprising:

retrieving an original data segment in response to a search request received from a remote site on the Internet;

generating a modifiable data segment and a state data segment based on the original data segment;

formatting the state data segment into a non-displayable format;

transmitting the modifiable data segment and the state data segment to the remote site;

receiving an updated modifiable data segment and the state data segment from the remote site; and

comparing the state data segment with a current data segment in the database.

18. A computer readable medium having stored thereon computer executable instructions for performing a method for accessing a database and updating data on the database in a stateless network environment while maintaining data integrity, the method comprising:

retrieving an original data segment in response to a search request using a stateless protocol received from a remote site on the network;

generating two copies of the original data segment, a modifiable data segment to be modified at the remote site and a state data segment to be unaltered;

transmitting the modifiable data segment and the state data segment to the remote site using a stateless protocol;

receiving an updated modifiable data segment and the state data segment from the remote site; and

comparing the state data segment with a current data segment in the database.

19. The computer readable medium of claim 18 wherein the method further comprises updating the current data segment to reflect the updated modifiable data segment upon a determination that the state data segment and the current data segment are equivalent.

20. The computer readable medium of claim 18 wherein the method further comprises:

updating the modifiable and state data segments to reflect the current data segment upon a determination that the state data segment and current data segment are non-equivalent; and

retransmitting the modifiable and state data segments to the remote site.

21. The computer readable medium of claim 18 wherein transmitting the modifiable data segment and the state data segment to the remote site further comprises formatting the modifiable data segment and the state data segment into HTML.

22. The computer readable medium of claim 18 wherein the method further comprises formatting the state data segment into a non-displayable format.

23. The computer readable medium of claim 18 wherein the method further comprises:

updating, at the remote site, the modifiable data segment to reflect user preferences; and

maintaining the state data segment constant.

24. The computer readable medium of claim 18 wherein each data segment comprises data attributes and wherein comparing the state data segment with the current data segment further comprises comparing the data attributes of the state data segment and the data attributes of the current data segment.

25. The computer readable medium of claim 18 wherein the method further comprises locking the current data segment during the step of comparing the state data segment with the current data segment.

26. The method of claim 18 wherein transmitting the modifiable data segment and the state data segment to the remote site comprises transmitting the modifiable data segment and the state data segment over the Internet.

27. A method for database update in a stateless environment that allows updates without locking the database or tracking update requests by the database management system, comprising:

sending, to a client-portion of a requestor, two copies of state data, one to be modified and the other left unaltered, over a communications network, the state data reflecting the state of the data in the database when sent;

receiving, from the requester, modified data and the state data, the modified data being modified state data and to be used to update the database; and

if the state data is equivalent to the current data in the database, updating the database to reflect the modified data.

28. A method as recited in claim 27 wherein sending is accomplished using HTML pages transported according to the Hyper-Text Transport Protocol.

29. A method as recited in claim 27 wherein the client-portion of a requestor is a web browser processing HTML pages, sending is accomplished using HTML pages transported according to the Hyper-Text Transport Protocol, and sending the two copies of state data comprises sending one to be modified that is viewable on the browser and the other left unaltered that is hidden from view on the browser.

30. A method as recited in claim 27 wherein the current data is locked while being compared to state data for equivalence and if equivalent, updating the database.

31. A method as recited in claim 27 further comprising:

if the state data is not equivalent to the current data, sending, to the requestor, the current data as the new state data.

32. An article of manufacture comprising a computer program carrier embodying one or more instructions that, when used by a computer, causes the computer to perform the method as recited in claim 27.