Polling Protocol for Automatic Load Limiting

• US 20120078996A1
• Filed: 09/24/2010
• Published: 03/29/2012
• Est. Priority Date: 09/24/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Shah, Shital
• Granted Patent: US 8,510,374 B2
• Time in Patent Office: Days
• US Class Current: 709/203
• CPC Class Codes: H04L 43/0817 by checking functioning
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/62 Establishing a time schedule for servicing the requests

Abstract

A client-specific or client-independent polling interval is provided to each client dynamically based on server load. The polling interval can be provided in the server polling response sent in response to a client polling request. The polling interval can be determined using a feedback control system or using a Bucket Reservation Method. The server uses a next polling interval and a flag that indicates if the previous polling request was ignored. Using these two parameters the server can continuously control the polling frequency from the client to achieve optimal performance.

Claims

1. A system comprising:

a processor and a memory; and

a module configured to cause the processor to repeatedly adapt rate of polling by a plurality of clients on a server based on current utilization of the server by;

calculating a next polling interval for a client of the plurality of clients; and

sending the calculated next polling interval to the client in a server polling response sent by the server to the client.

2. The system of claim 1, wherein the next polling interval for the client sent by the server is recalculated for each server polling response sent to the client.

3. The system of claim 1, wherein the next polling interval is calculated by a bucket reservation mechanism in which a first request received by the server from the plurality of clients is assigned a first bucket of a plurality of buckets and a second request is assigned a second bucket of the plurality of buckets, wherein each bucket of the plurality of buckets is associated with a time interval such that when the plurality of buckets are fully utilized, a desired refresh rate is maintained regardless of number of client requests received by the server.

4. The system of claim 1, wherein the rate of polling is dynamically adjusted for each polling request to tune the rate of polling of the server to current operating conditions of the server.

5. The system of claim 1, wherein the server polling response comprises a value that indicates a client polling request was ignored by the server in response to receiving a client request disregarding the calculated next polling interval for the client.

6. The system of claim 1, wherein the calculated next polling interval for the client is calculated on the server based on a feedback control mechanism that varies polling intervals for each of the plurality of clients to achieve a desired server polling rate.

7. The system of claim 6, wherein a filter implemented using exponential averaging is applied to at least one of the next polling interval or a rate of polling requests made on the server.

8. A method comprising:

receiving by a server module executing on a server computer a request from a client executing on a client computer;

calculating a next polling interval for a plurality of clients polling the server computer, to continuously adapt a rate of polling requests received on the server computer based on current server utilization; and

sending the next polling interval for a client of the plurality of clients to the client computer in a server polling response.

9. The method of claim 8, further comprising:

calculating the next polling interval for a client using a bucket reservation mechanism in which a first request received on the server from the plurality of clients is assigned a first bucket and a second request from the plurality of clients is assigned a second bucket of a plurality of buckets, the plurality of buckets associated with a time interval such that when the plurality of buckets are fully utilized, a desired refresh rate is maintained.

10. The method of claim 8, further comprising:

calculating the next polling interval using a feedback control mechanism in which polling interval is varied for each of the plurality of clients to achieve a desired server polling rate.

11. The method of claim 10,

wherein the next polling interval is calculated by applying an exponential averaging filter to a previous client polling interval.

12. The method of claim 10,

wherein the next polling interval is calculated by applying an exponential averaging filter to a rate of polling requests made on the server.

13. The method of claim 8,

wherein the server polling response comprises a value that indicates a client polling request was ignored by the server computer in response to receiving a client request disregarding the calculated next polling interval for the client.

14. The method of claim 8, wherein the next polling interval for the client sent by the server is recalculated for each server polling response sent to the client.

15. A computer-readable storage medium comprising computer-executable instructions which when executed cause at least one processor to:

continuously adapt rate of polling of a server based on current utilization of the server by;

calculating a next polling interval for a client of the plurality of clients;

sending the calculated next polling interval to the client in a server polling response sent by the server to the client.

16. The computer-readable storage medium of claim 15, comprising further computer-executable instructions, which when executed cause the at least one processor to:

calculate the next polling interval using a bucket reservation mechanism in which a first client of the plurality of clients is assigned a first bucket of a plurality of buckets and a second client of the plurality of clients is assigned a second bucket of the plurality of buckets, the plurality of buckets associated with an interval of time such that when the plurality of buckets are fully utilized, a desired refresh rate is maintained regardless of number of the plurality of clients making requests on the server.

17. The computer-readable storage medium of claim 15, comprising further computer-executable instructions, which when executed cause the at least one processor to:

calculate the next polling interval for the client based on a feedback control mechanism that varies polling intervals for each of its clients to achieve a desired server polling rate.

18. The computer-readable storage medium of claim 17, comprising further computer-executable instructions, which when executed cause the at least one processor to:

calculate the next polling interval by applying a filter implemented using exponential averaging to at least one of the next polling interval or a rate of polling requests made on the server.

19. The computer-readable storage medium of claim 15, comprising further computer-executable instructions, which when executed cause the at least one processor to:

indicate that a client polling request was ignored by the server in response to the client disregarding the calculated next polling interval for the client.

20. The computer-readable storage medium of claim 15, comprising further computer-executable instructions, which when executed cause the at least one processor to:

tune the rate of polling to current server operating conditions by dynamically adjusting the polling interval for each polling request received by the server.