Automatic data synchronization between a handheld and a host computer using pseudo cache including tags and logical data elements

• US 5,974,238 A
• Filed: 08/07/1996
• Issued: 10/26/1999
• Est. Priority Date: 08/07/1996
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Chase, Charlie David Jr.
• Primary Examiner(s): Maung, Zarni
• Assistant Examiner(s): Thomson, William D.
• Application Number:
  US08/689,304
• Time in Patent Office: 1,175 Days
• Field of Search: 395/200.78, 395/200.76, 395/821, 395/892, 395/893, 707/200, 707/203, 707/204
• US Class Current: 709/248
• CPC Class Codes: G06F 12/0815 Cache consistency protocols
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

An apparatus is disclosed for performing dynamic synchronization between data stored in a handheld computer and a host computer, each having a plurality of data sets including at least one common data set, each computer having a copy of the common data set. The handheld computer has a processor, a communication port, and a data synchronization engine. The data synchronization engine has a pseudo-cache and one or more tags connected to the pseudo cache. Data is synchronized whenever data is written to main memory and/or when the associated pseudo-cache tag is invalidated. By strict adherence to a set of protocols, data coherency is achieved because the system always knows who owns the data, who has a copy of the data, and who has modified the data. The data synchronization engine resolves any differences in the copies and allows the storage of identical copies of the common data set in the host computer and in the handheld computer.

Claims

1. A handheld computer adapted to communicate with a host computer, the host computer having a data set including logical data elements of a user database, the handheld computer comprising:

a processor;

a common data set which is a shared version of the host computer data set, the common data set including the logical elements of the user database;

a communication port coupled to said processor, said communication port adapted to link said processor with the host computer; and

a data synchronization engine coupled to said processor and said communication port, said data synchronization engine including;

one or more tags, each of said tags corresponding to one of the logical data elements in the user database, each of said tags including at least a modified flag; and

a pseudo cache engine coupled to the processor that maintains the states of each of said tags responsive to changes to corresponding ones of the logical data elements in the user database;

wherein said data synchronization engine initiates a synchronization of a logical data element with the host computer over the communication port when an associated one of the tags is modified in the pseudo cache.

2. The handheld computer of claim 1, wherein said communication port is a serial port.

3. The handheld computer of claim 2, wherein each of said tags points to an entry in said signature table and further points to an entry to said field mapping table.

4. The handheld computer of claim 1, wherein each of said tags has a signature table record and a field mapping table record.

5. The handheld computer of claim 1, further comprising an application programming interface coupled to said communication port.

6. The handheld computer of claim 1, each of said tags further including an exclusive flag and a deleted flag.

7. The handheld computer of claim 1, wherein each of said tags points to logical data elements that are associated with applications include a calendar, a phone list, a to-do list, a browser, a clock, and an electronic mail (E-mail).

8. An integrated information system, comprising:

a host computer comprising;

a data set including logical data elements of a user database; and

a handheld computer adapted to communicate with the host computer comprising;

a processor;

a common data set which is a shared version of the host computer data set, the common data set including the logical elements of the user database;

a communication port coupled to said processor, said communication port adapted to link said processor with the host computer; and

a data synchronization engine coupled to said processor and said communication port, said data synchronization engine including;

one or more tags, each of said tags corresponding to one of the logical data elements in the user database, each of said tags including at least a modified flag; and

a pseudo cache engine coupled to the processor that maintains the states of each said tags responsive to changes to corresponding ones of the logical data elements in the user database;

wherein said data synchronization engine initiates a synchronization of a logical data element with the host computer over the communication port when an associated one of the tags is modified in the pseudo cache.

9. The integrated information system of claim 8, further comprising a signature table and a field map table coupled to said tags.

10. The integrated information system of claim 9, wherein each of said tags points to an entry in said signature table and further points to an entry to said field mapping table.

11. The integrated information system of claim 8, wherein each of said tags has a signature table record and a field mapping table record.

12. The integrated information system of claim 8, further comprising an application programming interface coupled to said communication port.

13. The integrated information system of claim 8, each of said tags further including an exclusive flag and a deleted flag.

14. The integrated information system of claim 8, wherein each of said tags points to logical data elements that are associated with applications include a calendar, a phone list, a to-do list, a browser, a clock, and an electronic mail (E-mail).

15. A method for communicating data records between a handheld computer and a host computer, the handheld computer and host computer each having at least one common data set including logical data elements of a user database, each computer having copies of the common data set, the method comprising the steps of:

providing a pseudo cache having tag entries in the handheld computer corresponding to the logical data elements;

establishing a communication link between the handheld computer and the host computer in response to a change of a pseudo cache tag entry;

synchronizing data records stored by the handheld computer and the host computer, said synchronizing steps including;

searching tag entries of the pseudo cache for shared data records; and

modifying one or more o the tag entries coupled to said pseudo cache;

resolving any differences in the copies and storing identical copies of the common data set in the host computer and in the handheld computer.

16. The method of claim 15, further comprising the step of looking up a signature table record and a field map table record from each of the tag entries.

17. The method of claim 16, wherein said looking up steps further comprises the steps of indexing into an entry in the signature table and indexing into an entry to the field mapping table.

18. The method of claim 15, wherein each of the tag entries has a signature table and a field mapping table.

19. The method of claim 15, further comprising the step of interfacing with software on the host computer through an application programming interface.

20. The method of claim 15, further comprising the step of verifying a coherency protocol.

21. The method of claim 15, further comprising the step of storing one or more applications in a memory device.

22. The method of claim 21, wherein the applications have one or more data records and the host computer has corresponding data records, further comprising the step of synchronizing said data records with corresponding records on the host computer.

23. The method of claim 21, further comprising the step of executing one or more applications, including a calendar, a phone list, a to-do list, a browser, a clock, and an electronic mail (E-mail).

24. A desktop computer adapted to communicate with a handheld computer, the handheld computer having a data set including logical data elements in user database, the desktop computer comprising:

a processor;

a common data set which is a shared version of the handheld computer data set including the logical elements of the user database;

a communication port coupled to said processor, said communication port adapted to link said processor with the handheld computer; and

a data synchronization engine coupled to said processor and said communication port, said data synchronization engine including;

one or more tags each corresponding to one of the logical data elements in the user database;

wherein said data synchronization engine receives a synchronization of a logical data element within the host computer over the communication port when an associated one of the tags is written to a pseudo cache engine in the handheld computer with a set modified bit, the pseudo cache engine in the handheld computer maintaining the states of the associated ones of the tags in the handheld computer responses to changes to corresponding ones of the logical data elements in the user database in the handheld computer, and

wherein the synchronization of a logical data element reflects a change in the state of an associated one of the tags in the handheld computer.

25. The desktop computer of claim 24, wherein each of said tags points to logical data elements that are associated with applications include a calendar, a phone list, a to-do list, a browser, a clock, and an electronic mail (E-mail).