Method and system for maintaining the integrity of a database providing persistent storage for objects

• US 6,029,177 A
• Filed: 01/30/1998
• Issued: 02/22/2000
• Est. Priority Date: 11/13/1997
• Status: Expired due to Term

• Current Assignee: Ent Services Development Corporation LP (DXC Technology Company)
• Original Assignee: Electronic Data Systems Corporation (Perspecta, Inc.)
• Inventors: Sadiq, Waqar, Cummins, Fred Arthur
• Primary Examiner(s): Alam, Hosain T.
• Application Number:
  US09/016,143
• Time in Patent Office: 753 Days
• Field of Search: 707/8, 707/201, 707/202, 707/203, 707/103, 709/101, 709/201, 709/205, 709/303
• US Class Current: 1/1
• CPC Class Codes: G06F 16/289 Object oriented databases
• CPC Class Codes: G06F 9/524 Deadlock detection or avoidance
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

One aspect of the invention is a method for updating a database providing persistent storage for a plurality of objects each comprising methods and instance variables, wherein a persistent record of each of the plurality of objects will experience a change in the context of a transaction if the transaction is allowed to commit. The method comprises sending a first prepare message to each of the plurality of objects, the plurality of objects sending their state to the database in response to the first prepare messages. A second prepare message is sent to the database if a prepared indicator was received in response to each of the first prepare messages. A commit message is sent to each of the plurality of objects and to the database if a prepared indicator was received in response to each of the first prepare messages and if a prepared indicator was received in response to the second prepare message.

Claims

1. A method for updating a database providing persistent storage for a plurality of objects each comprising methods and instance variables, wherein a persistent record of each of the plurality of objects will experience a change in the context of a transaction if the transaction is allowed to commit, the method comprising:

sending a first prepare message to each of the plurality of objects, the plurality of objects sending their state to the database in response to the first prepare messages;

sending a second prepare message to the database if a prepared indicator was received in response to each of the first prepare messages;

sending a commit message to each of the plurality of objects and to the database if a prepared indicator was received in response to each of the first prepare messages and if a prepared indicator was received in response to the second prepare message.

2. The method of claim 1, wherein the commit message is sent first to each of the plurality of objects and then to the database.

3. The method of claim 1, wherein sending a first prepare message further comprises:

sending a first prepare message to each of the plurality of objects;

establishing a connection with the database, the connection associated with the transaction;

registering the database connection with a transaction service, the registration being used by the transaction service to determine whether to send the second prepare message to the database; and

sending the state of each of the plurality of objects to the database.

4. The method of claim 1, wherein the second prepare message causes the database to be updated to reflect the state of the plurality of objects as changed by the transaction.

5. The method of claim 3, wherein the commit message is sent first to each of the plurality of objects and then to the database.

6. The method of claim 1, further comprising:

sending a validate message to ones of the plurality of objects; and

wherein the first prepare messages are sent if a valid indicator was received in response to each validate message.

7. The method of claim 6, wherein the commit message is sent first to each of the plurality of objects and then to the database.

8. The method of claim 6, wherein sending a first prepare message further comprises:

sending a first prepare message to each of the plurality of objects;

establishing a connection with the database, the connection associated with the transaction;

registering the database connection with a transaction service, the registration being used by the transaction service to determine whether to send the second prepare message to the database; and

sending the state of each of the plurality of objects to the database.

9. The method of claim 6, wherein the second prepare message causes the database to be updated to reflect the state of the plurality of objects as changed by the transaction.

10. The method of claim 6, wherein ones of the plurality of objects are operable to register for validation with the transaction service and wherein a validate message is sent to only those objects that register for validation with the transaction service.

11. The method of claim 1, further comprising:

rolling back the transaction if any of the plurality of objects fails to return a prepared indicator in response to the first prepare message; and

rolling back the transaction if the database fails to return a prepared indicator in response to the second prepare message.

12. A system for maintaining persistence in a distributed object environment comprising a plurality of objects each comprising methods and instance variables, wherein a persistent record of a first number of the plurality of objects will experience a change in the context of a transaction if the transaction is allowed to commit, the system comprising:

a transaction service running on at least one computer and operable to

send a first prepare message to each of the plurality of objects, at least one of the plurality of objects sending its state to a first database in response to the prepare message;

send a second prepare message to at least the first database if a prepared indicator was received in response to each of the first prepare messages;

send a commit message to each of the plurality of objects and to the first database if a prepared indicator was received in response to each of the first prepare messages and if a prepared indicator was received in response to each of the second prepare messages.

13. The system of claim 12, wherein the commit message is sent first to each of the plurality of objects and then to the first database.

14. The system of claim 12, wherein the transaction service is further operable to

receive a registration request from the first database;

registering the first database in response to the registration request; and

send a second prepare message to each database associated with the transaction from which a registration request was received if a prepared indicator was received in response to each of the first prepare messages.

15. The system of claim 12, wherein the second prepare message causes the first database to be updated to reflect the state of the first object as changed by the transaction.

16. The system of claim 12, wherein the transaction service is further operable to:

send a validate message to ones of the plurality of objects; and

wherein the first prepare messages are sent if a valid indicator was received in response to each validate message.

17. The system of claim 12, wherein ones of the plurality of objects are operable to register for validation with the transaction service and wherein a validate message is sent to only those objects that register for validation with the transaction service.

18. The system of claim 12, wherein the transaction service is further operable to:

roll back the transaction if any of the plurality of objects fails to return a prepared indicator in response to the first prepare message; and

roll back the transaction if the first database fails to return a prepared indicator in response to the second prepare message.

19. The system of claim 12, wherein at least one of the plurality of objects sends its state to a second database in response to the prepare message;

wherein the transaction service is further operable to send a second prepare message to the second database if a prepared indicator was received in response to each of the first prepare messages.

20. The system of claim 16, wherein the commit message is sent first to each of the plurality of objects and then to the first database;

and

wherein the transaction service is further operable to

receive a registration request from the first database;

registering the first database in response to the registration request; and

send a second prepare message to each database associated with the transaction from which a registration request was received if a prepared indicator was received in response to each of the first prepare messages.

21. The system of claim 12, wherein a first one of the plurality objects is related to a second one of the plurality of objects, wherein the second object'"'"'s persistent record comprises a system assigned key, and wherein the first object is operable to generate the first prepare message to the second object where the system assigned key for the second object has not been previously generated.

22. The system of claim 21, wherein the database is updated to reflect the state of the second object and retrieve the system assigned key in response to the first prepare message to the second object.