Real-time database update transaction with disconnected relational database clients

• US 7,287,044 B2
• Filed: 08/15/2005
• Issued: 10/23/2007
• Est. Priority Date: 07/01/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wilmot, Gerald J.
• Primary Examiner(s): Wassum; Luke S
• Application Number:
  US11/204,836
• Publication Number:
  US 20060010178A1
• Time in Patent Office: 799 Days
• Field of Search: None
• 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: G06F 16/275 Synchronous replication
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method and system for performing real-time database update transactions with disconnected database clients includes a disconnected client server (DCS) and disconnected client extensions (DCE). The DCS formats the database cell, its key, any associated database cells, and a timestamp and sends them to a disconnected database client by email. The timestamp indicates the last time the database cell or associated database cells was changed. The disconnected database client sends a reply email with the update of the database cell and the timestamp. Upon receipt of the reply email, the DCS compares the received timestamp to a current timestamp for the database cell. If they match, then the database cell is updated according to the received update. If they do not match, then the update is based on outdated information and is rejected. In this manner, reliable real-time update transactions are provided between a disconnected database client and the database.

Claims

1. A method for performing real-time update transactions between a database system and remote database clients, the method comprising:

the database system sending to a remote database client an update request to update data in the database system, the update request comprising

a first timestamp indicating a last time the data in the database system was previously modified as of a time of the update request; and

a first checksum value corresponding to a state of the data in the database system as of the time of the update request;

responsive to the remote database client receiving the update request, the remote database client sending to the database system a reply to the update request, the reply including

a new value for the data in the database system;

the first timestamp corresponding to a state of the data in the database system as of the time of the update request; and

the first checksum value corresponding to the state of the data in the database system as of the time of the update request;

the database system determining whether the first timestamp matches a second timestamp indicating a last time the data in the database system was previously modified as of a time that the database system received the reply, the database system further determining whether the first checksum value matches a second checksum value corresponding to the state of the data in the database system as of the time that the database system received the reply; and

responsive to the first timestamp matching the second timestamp and the first checksum value matching the second checksum value, updating the data in the database system with the new value for the data, otherwise rejecting the reply.

2. The method of claim 1, wherein the remote database client and the database system communicate via an email server.

3. The method of claim 2, wherein each of the update request and the reply is comprised in an email.

4. The method of claim 2, wherein:

the database system sending to a remote database client an update request comprises the database system

formatting the update request into an email request; and

the method further includes the email server sending the email request to the remote database client.

5. A computer readable medium with program instructions for performing real-time update transactions between a database system and remote database clients, the program instructions comprising instructions for:

the database system sending to a remote database client an update request to update data in the database system, the update request comprising

a first timestamp indicating a last time the data in the database system was previously modified as of a time of the update request; and

a first checksum value corresponding to a state of the data in the database system as of the time of the update request;

responsive to the remote database client receiving the update request, the remote database client sending to the database system a reply to the update request, the reply including

a new value for the data in the database system;

the first timestamp corresponding to a state of the data in the database system as of the time of the update request; and

the first checksum value corresponding to the state of the data in the database system as of the time of the update request;

the database system determining whether the first timestamp matches a second timestamp indicating a last time the data in the database system was previously modified as of a time that the database system received the reply, the database system further determining whether the first checksum value matches a second checksum value corresponding to the state of the data in the database system as of the time that the database system received the reply; and

responsive to the first timestamp matching the second timestamp and the first checksum value matching the second checksum value, updating the data n the database system with the new value for the data, otherwise rejecting the reply.

6. The computer readable medium of claim 5, wherein the remote database client and the database system communicate via an email server.

7. The computer readable medium of claim 6, wherein each of the update request and the reply is comprised in an email.

8. The computer readable medium of claim 6 wherein:

the instructions for the database system sending to a remote database client an update request comprise instructions for the database system to format the update request into an email; and

the computer readable medium further comprises instructions for the email server to send the email request to the remote database client.

9. A method for performing an update transaction in a database system, the method comprising:

sending to a remote database client an update request to update data in a database system, the update request comprising

a first timestamp indicating a last time the data in the database system was previously modified as of a time of the update request; and

a first checksum value corresponding to a state of the data in the database system as of the time of the update request;

responsive to sending the update request to the remote database client, receiving a reply from the remote database client, the reply including

a new value for the data in the database system;

the first timestamp corresponding to a state of the data in the database system as of the time of the update request; and

the first checksum value corresponding to the state of the data in the database system as of the time of the update request;

determining whether the first timestamp matches a second timestamp indicating a last time the data in the database system was previously modified as of a time that the reply was received, the database system further determining whether the first checksum value matches a second checksum value corresponding to the state of the data in the database system as of the time that the reply was received; and

responsive to the first timestamp matching the second timestamp and the first checksum value matching the second checksum value, updating the data in the database system with the new value for the data, otherwise rejecting the reply.

10. The method of claim 9, wherein each of the update request and the reply is comprised in an email.

11. A computer readable medium with program instructions for performing an update transaction in a database system, the program instructions comprising instructions for:

sending to a remote database client an update request to update data in a database system, the update request comprising

a first timestamp indicating a last time the data in the database system was previously modified as of a time of the update request; and

a first checksum value corresponding to a state of the data in the database system as of the time of the update request;

responsive to sending the update request to the remote database client, receiving a reply from the remote database client, the reply including

a new value for the data in the database system;

the first timestamp corresponding to a state of the data in the database system as of the time of the update request; and

the first checksum value corresponding to the state of the data in the database system as of the time of the update request;

determining whether the first timestamp matches a second timestamp indicating a last time the data in the database system was previously modified as of a time that the reply was received, the database system further determining whether the first checksum value matches a second checksum value corresponding to the state of the data in the database system as of the time that the reply was received; and

responsive to the first timestamp matching the second timestamp and the first checksum value matching the second checksum value, updating the data in the database system with the new value for the data, otherwise rejecting the reply.

12. The computer readable medium of claim 11, wherein each of the update request and the reply is comprised in an email.

13. A system comprising:

database system configured to send to a remote database client an update request to update data in the database system, the update request comprising

a first timestamp indicating a last time the data in the database system was previously modified as of a time of the update request; and

a first checksum value corresponding to a state of the data in the database system as of the time of the update request;

responsive to the remote database client receiving the update request, the remote database client being configured send to the database system a reply to the update request, the reply including

a new value for the data in the database system;

the first timestamp contending to a state of the data in the database system as of the time of the update request; and

the first checksum value corresponding to the state of the data in the database system as of the time of the update request,

wherein the data the database system is further configured to determine whether the first timestamp matches a second timestamp indicating a last time the data in the database system was previously modified as of a time that the database system received the reply, the database system further configured to determine whether the first checksum value matches a second checksum value contending to the state of the data in the database system as of the time that the database system received the reply; and

wherein responsive to the first timestamp matching the second timestamp and the first checksum value matching the second checksum value, the database system is configure to update the data in the database system with the new value for the data, otherwise the database system is configured to reject the reply.

14. The system of claim 13, wherein each of the update request and the reply is comprised in an email.