System and methods for robust synchronization of datasets

• US 6,477,545 B1
• Filed: 12/08/1998
• Issued: 11/05/2002
• Est. Priority Date: 10/28/1998
• Status: Expired due to Term

• Current Assignee: Intellisync Corporation (Nokia Corporation)
• Original Assignee: Starfish Software, Inc. (Nokia Corporation)
• Inventors: LaRue, Chris
• Primary Examiner(s): Trammell, James P.
• Assistant Examiner(s): CHEUNG, MARY DA ZHI WANG
• Application Number:
  US09/208,815
• Time in Patent Office: 1,428 Days
• Field of Search: 707/8, 707/9, 707/10, 707/101, 707/102, 707/104, 707/200, 707/201, 707/202, 707/203, 707/204
• US Class Current: 707/625
• 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 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

Synchronization of databases is made to allows use of already-received changes in target datasets even if the synchronization session fails, and even before the failed synchronization session is re-performed or resumed to completion. Further, already-received changes received in a synchronization session are handled such that the need to re-send them in a subsequent synchronization session is minimized, even if the present synchronization should fail before completion. In synchronizing datasets to a reference dataset, after receipt of some number of changes from a dataset, changes are propagated into the reference dataset, to the extent that they can be reconciled with the reference dataset, without requiring that all changes from the dataset have already been received.

Claims

1. A method of synchronizing a first dataset with a second dataset, each of said first and second datasets comprising a plurality of corresponding records, wherein changes have been made to the records in the first dataset that have not yet been synchronized with the second dataset, the method comprising:

identifying a plurality of changes to the records in the first dataset to be synchronized with individual records of the second dataset in a synchronization session, wherein said plurality of changes have not yet been synchronized with the second dataset;

initiating a synchronization session to synchronize said plurality of changes from the first dataset to the second dataset;

sending a subset of one or more of said plurality of changes, but not all of said plurality of changes, from said first dataset to said second dataset;

receiving said subset of changes at said second dataset;

sending acknowledgment of receipt of said subset of changes from said second dataset to said first dataset;

receiving said acknowledgment of receipt of said subset of changes at said first dataset;

propagating said subset of changes into said second dataset; and

if there is no failure of said synchronization session, completing said synchronization by sending the remainder of said plurality of changes from said first dataset to said second dataset and propagating the remainder of said plurality of changes into said second dataset;

or, if there is a failure of said synchronization session before the remainder of the plurality of changes are received by said second dataset and propagated into said second dataset, making said subset of changes available to a user of said second dataset and making said subset of changes available for subsequent synchronizations between said second dataset and one or more other datasets before the remainder of the plurality of changes are received by said second dataset.

2. The method of claim 1, wherein if there is a failure of said synchronization session before the remainder of the plurality of changes are received by said second dataset and propagated into said second dataset, the method further comprises the steps of:

initiating a second synchronization session between said first and second datasets;

sending the remainder of said plurality of changes from said first dataset to said second dataset, but not sending any of said subset of changes;

receiving the remainder of said plurality of changes at said second dataset; and

propagating the remainder of said plurality of changes into said second dataset.

3. The method of claim 2, wherein, after the remainder of said plurality of changes has been sent from said first dataset and received at said second dataset, said second dataset sends changes to said first dataset, which are received at said first dataset and propagated into said first dataset.

4. The method of claim 3, wherein, after the changes from the second dataset are propagated into the first dataset, the first dataset sends new IDs to the second dataset for all new records received from the second dataset.

5. The method of claim 1, wherein said first dataset is a client dataset and said second dataset is a reference dataset of a synchronization engine.

6. The method of claim 5, wherein said first dataset is in a portable device and said second dataset resides on a server computer.

7. The method of claim 5, wherein said first dataset is in a portable device and said second dataset resides on a desktop computer.

8. The method of claim 1, wherein the first dataset and the second dataset contain PIM data.

9. The method of claim 8, wherein the plurality of changes include additions, updates and deletions of data records.

10. The method of claim 1, wherein said acknowledgment of receipt of said subset of changes includes an unambiguous identifier for each received change.

11. A method of synchronizing records of a client dataset with records of a reference dataset of a synchronization engine, the method comprising the steps of:

A) identifying a first plurality of changes to the records in the client dataset to be synchronized with the records of the reference dataset;

B) initiating a synchronization session between the client dataset and the reference dataset; and

C) communicating said first plurality of changes to the reference dataset and synchronizing said first plurality of changes into the records of the reference dataset, said step of communicating and synchronizing the first plurality of changes further comprising the steps of;

a) sending a subset of the first plurality of changes from the client dataset to the synchronization engine;

b) receiving the subset of the first plurality of changes at the synchronization engine;

c) synchronizing the subset of the first plurality of changes into the reference dataset and making the subset of the first plurality of changes available in said reference dataset for user access and for synchronization with another dataset before all of said first plurality of changes are received by said synchronization engine;

d) sending acknowledgements of the receipt of the subset of the first plurality of changes from the synchronization engine;

e) receiving the acknowledgements of the receipt of the subset of the first plurality of changes at the client dataset;

f) repeating steps a) to e) until all of the first plurality of changes are received at the synchronization engine, synchronized into the reference dataset and acknowledged back to the client dataset; and

g) if said synchronization session fails before all of said first plurality of changes are received by said synchronization engine, synchronized into the reference dataset and acknowledged back to the client dataset, initiating a subsequent synchronization session and continuing the step C), without resending from the client dataset any changes for which acknowledgements have already been received at the client dataset.

12. The method of claim 11, further comprising the steps of:

D) identifying a second plurality of changes in the reference dataset to be synchronized with the client dataset; and

E) communicating said second plurality of changes to the client dataset and synchronizing said second plurality of changes into the client dataset, said step of communicating and synchronizing the second plurality of changes further comprising the steps of;

a) sending a subset of the second plurality of changes from the synchronization engine to the client dataset;

b) receiving the subset of the second plurality of changes at the client dataset;

c) synchronizing the subset of the second plurality of changes into the client dataset;

d) sending acknowledgements of the receipt of the subset of the second plurality of changes from the client dataset;

e) receiving the acknowledgements of the receipt of the subset of the second plurality of changes at the synchronization engine;

f) repeating steps a) to e) until all of the second plurality of changes are received at the client dataset, synchronized into the client dataset and acknowledged back to the synchronization engine; and

g) if said synchronization session fails before all of said second plurality of changes are received by said client dataset, synchronized into the client dataset and acknowledged back to the synchronization engine, initiating a subsequent synchronization session and continuing the step E), without resending from the synchronization engine any changes for which acknowledgements have already been received at the synchronization engine.

13. The method of claim 12, wherein the substep c) of the step E) further comprises making the subset of the second plurality of changes available in said client dataset for user access and for synchronization with another dataset before all of said second plurality of changes are received by said client dataset.

14. The method of claim 12, wherein for substep d) of the step E), the acknowledgement from the client dataset to the synchronization engine includes a record ID for a new record in the client dataset when the change from the synchronization engine comprises an addition of a new record.

15. The method of claim 12, wherein for substep d) of the step C), the acknowledgments from the synchronization engine to the client dataset include an unambiguous identifier for each received change.

16. The method of claim 12, wherein for substep d) of the step E), the acknowledgments from the client dataset to the synchronization engine include an unambiguous identifier for each received change.

17. A method of synchronizing a first dataset with a second dataset, each of said first and second datasets comprising a plurality of corresponding records, wherein changes have been made to the records in the first dataset that have not yet been synchronized with the second dataset, the method comprising:

identifying a plurality of changes to the records in the first dataset to be synchronized with the records in the second dataset in a synchronization session, wherein said plurality of changes have not yet been synchronized with the second dataset;

initiating a synchronization session to synchronize said plurality of changes from the first dataset to the second dataset;

sending a subset of one or more of said plurality of changes, but not all of said plurality of changes, from said first dataset to said second dataset;

receiving said subset of changes at said second dataset;

updating a last synchronization time for each of the records affected by the subset of the plurality of changes;

propagating the subset of changes into said second dataset; and

if there is no failure of said synchronization session, completing said synchronization by sending the remainder of said plurality of changes from said first dataset to said second dataset, propagating the remainder of said plurality of changes into said second dataset and updating an overall last synchronization time;

or, if there is a failure of said synchronization session before the remainder of the plurality of changes are received by said second dataset and propagated into said second dataset, not updating the overall last synchronization time,

wherein the last synchronization times are used to determine changes that should be synchronized in subsequent synchronization sessions.

18. The method of claim 17, further comprising the steps of:

sending acknowledgment of receipt of said subset of changes from said second dataset to said first dataset; and

receiving said acknowledgment of receipt of said subset of changes at said first dataset.

19. The method of claim 17, wherein the last synchronization times are stored in a reference dataset of a synchronization engine.