Change notification query multiplexing

• US 20060195456A1
• Filed: 02/28/2005
• Published: 08/31/2006
• Est. Priority Date: 02/28/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Fang, Lijiang, Yuan, Hua
• Granted Patent: US 7,805,422 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27

Abstract

In order to efficiently handle change notification requests to a storage system based on a database data store and a database engine, the change notification requests are multiplexed. This can be done by issuing a query which refers, for information about what changes are being tracked, to a data structure. The information about what changes to track for each request to be multiplexed is stored in the data structure. Additionally, information about the request can be stored in the data structure. By adding information to the data structure, the query can be altered without needing to directly modify or reissue the query.

Claims

1. A storage platform comprising:

a database engine;

a data store implemented on the database engine for storing data therein; and

an application programming interface that enables application programs to issue requests for notification of a change to one or more specified elements stored in the data store,

wherein, if more than one of said requests are issued, at least two of said requests are multiplexed and a combined query is used to query the database engine to service said multiplexed requests for notification.

2. The storage platform of claim 1, wherein a data structure stores information identifying one or more elements of the data stored in the data store as the subject of at least one of said multiplexed requests, and wherein said combined query references said data structure.

3. The storage platform of claim 2, wherein said data structure stores, for each such element of the data identified as the subject of at least one of said multiplexed requests, information identifying a type of change to said subject element for which notification has been requested.

4. The storage platform of claim 2, where said combined query comprises reference information identifying said data structure.

5. The storage platform of claim 2, wherein if an additional request for notification of a change to one or more specified elements stored in the data store is received, additional information is added to said data structure, said additional information identifying one or more elements of the data stored in the data store as the subject of said additional request.

6. The storage platform of claim 2, wherein said data structure further stores, for each of said multiplexed requests, requestor information identifying a requestor for said multiplexed request, and wherein, when a change is returned by said query relevant to one of said multiplexed requests, said requestor information is used to return information to a corresponding requestor.

7. The storage platform of claim 1, where said storage platform implements a security scheme to govern access to the data store, and wherein said multiplexing of requests occurs only for requests which are similar with respect to their access available to said data store under said security scheme.

8. The storage platform of claim 1,

further comprising at least one additional data store;

wherein said application programming interface enables application programs to issue requests for notification of a change to one or more specified elements stored in any of said data stores; and

wherein said multiplexing of requests occurs only for requests directed at the same data store.

9. A method for handling a first change notification request for notification of a first change to data in a data store and a second change notification request for notification of a second change to data in a data store, comprising:

receiving said first change notification request;

issuing a query to said data store, said query calculated to indicate the occurrence of said first change;

receiving said second change notification request; and

altering said query so that said query is calculated to indicate the occurrence of said first change or said second change.

10. The method of claim 9, where said query comprises a reference to a data structure, where said data structure comprises at least one query parameter describing said first change for notification, and where said step of altering said query comprises adding at least one query parameter concerning said second change to said data structure.

11. The method of claim 9, where said query comprises a reference to a data structure, where said data structure comprises at least one query parameter describing said first change for notification, and where said step of altering said query consists of adding at least one query parameter concerning said second change to said data structure.

12. The method of claim 9, further comprising:

receiving an additional change notification request for notification of an additional change to data in a data store; and

altering said query so that said query is calculated to indicate the occurrence of said first change, said second change, or said additional change.

13. The method of claim 9, where said step of altering said query comprises:

determining that said first change notification request and said second notification request are directed towards the same data store.

14. The method of claim 9, where said step of altering said query comprises:

determining a first security level for an issuer of said first change notification request;

determining a second security level for an issuer of said second change notification request; and

determining that said first security level and said second security level are compatible.

15. A computer-readable medium having instructions stored thereon for causing a computer to perform a method of handling a first change notification request for notification of a first change to data in a data store and a second change notification request for notification of a second change to data in a data store, said method comprising:

receiving said first change notification request;

issuing a query to said data store, said query calculated to indicate the occurrence of said first change;

receiving said second change notification request; and

altering said query so that said query is calculated to indicate the occurrence of said first change or said second change.

16. The computer-readable medium of claim 15, where said query comprises a reference to a data structure, where said data structure comprises at least one query parameter describing said first change for notification, and where said step of altering said query comprises adding at least one query parameter concerning said second change to said data structure.

17. The computer-readable medium of claim 15, where said query comprises a reference to a data structure, where said data structure comprises at least one query parameter describing said first change for notification, and where said step of altering said query consists of adding at least one query parameter concerning said second change to said data structure.

18. The computer-readable medium of claim 15, said method further comprising:

receiving an additional change notification request for notification of an additional change to data in a data store; and

altering said query so that said query is calculated to indicate the occurrence of said first change, said second change, or said additional change.

19. The computer-readable medium of claim 15, where said step of altering said query comprises:

determining that said first change notification request and said second notification request are directed towards the same data store.

20. The method of claim 15, where said step of altering said query comprises:

determining a first security level for an issuer of said first change notification request;

determining a second security level for an issuer of said second change notification request; and

determining that said first security level and said second security level are compatible.