System and method for maintaining a network connection

• US 7,426,569 B2
• Filed: 02/25/2004
• Issued: 09/16/2008
• Est. Priority Date: 02/25/2004
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Dunk, Craig Allan
• Primary Examiner(s): DUONG, OANH L
• Application Number:
  US10/784,984
• Publication Number:
  US 20050188098A1
• Time in Patent Office: 1,665 Days
• Field of Search: 709/203, 709/218, 709223-225, 709227-228, 709/232, 709/250
• US Class Current: 709/232
• CPC Class Codes: H04L 67/04 specially adapted for terminals or networks with limited capabilities; specially adapted for terminal portability
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066

Abstract

A system and method for maintaining a persistent connection is provided. In an embodiment, a system includes a client that connects to a web-server via a physical link that is bandwidth-constrained. The physical link also includes at least one network address translation (“NAT”) router that is configured to terminate idle connections between the client and the web-server. The client is configured to send keep-alive packets to the web-server in order to reduce the likelihood of the NAT router terminating the connection. The keep-alive packets are sent on a variable basis that is intended to reduce bandwidth consumption while ensuring that the NAT router does not deem the connection idle and terminate the connection.

Claims

1. A system for maintaining a persistent connection, the system comprising:

an electronic device including a network interface for communicating with another device via a network connection carried over physical link that includes an equipment;

the equipment for terminating said network connection if said network connection remains idle for a predetermined time-out criterion of said equipment;

wherein said electronic device is configured to send keep-alive signals on said network connection;

wherein said electronic device is configured to send said keep-alive signals according to a plurality of different time intervals to determine said predetermined time-out criterion of said equipment;

wherein said electronic device determines said predetermined time-out criterion by;

loading an initial default time period into said electronic device;

sending at least one of said keep-alive signals to said another device at said initial default time period;

increasing said initial default time period if said initial default time period does not cause said network connection to be dropped by said equipment;

repeating said sending step and increasing step until said increased initial default time period causes said network connection to be dropped;

maintaining a last-known good time period when said increased initial default time period causes said network connection to be dropped, wherein said last-known good time period is less than and closest to said increased initial default time period that causes said network connection to be dropped;

reestablishing said network connection; and

thereafter,

sending subsequent keep-alive signals to said another electronic device at said last-known good time period.

2. The system of claim 1, wherein said electronic device is further configured to determine when one of said time intervals results in said equipment terminating said connection thereby determining said predetermined time-out criterion of said equipment.

3. The system according to claim 2, wherein said electronic device is configured to request an HTTP (Hyper Text Transfer Protocol) web-page via said connection of said another device and said keep-alive signal is a no-op signal.

4. The system of claim 1, wherein said equipment is a NAT (Network Address Translator) router.

5. The system of claim 1, wherein said predetermined time-out criterion is a predetermined time period.

6. The system according to claim 1, wherein said electronic device is a client, said another device is a web-server and at least a portion of said link includes the Internet.

7. The system according to claim 6, wherein said client is battery operated and said initial default time period are increased more quickly as said battery life is depleted to thereby reduce battery consumption while determining said predetermined time-out criterion.

8. The system according to claim 7, wherein said client is a wireless device and at least a portion of said link includes a wireless connection from said wireless device to the Internet.

9. A method of maintaining a network connection, the method comprising the steps of:

loading a time-out period into a first electronic device of an initial default value;

establishing a connection from said first electronic device to a second electronic device via a physical link that includes an equipment for terminating said connection if said connection remains idle for a predetermined timeout period;

sending keep-alive signals from said first electronic device to said second electronic device via said equipment according to said time-out period;

increasing said time-out period and repeating said sending step if said time-out period does not cause said connection to be terminated by said equipment;

repeating said increasing step until said connection is terminated by said equipment in order to determine said predetermined time-out period of said equipment;

adjusting said time-out period to a value less than and closest to said determined predetermined time-out period of said equipment; and

thereafter

sending said keep-alive signals using said adjusted time-out period.

10. The method according to claim 9, wherein said adjusting step is performed by iteratively decreasing said determined predetermined time-out period until said connection is no longer terminated by said equipment.

11. The method according to claim 9 wherein said connection carries an HTTP web-page requested by said first electronic device of said second electronic device and said keep-alive signal is a no-op signal.

12. The method according to claim 9 wherein said equipment is a NAT router.

13. The method according to claim 9, wherein said first electronic device is a client, said second device is a web-server and at least a portion of said link includes the Internet.

14. The method according to claim 9, wherein said first electronic device is battery operated and said increasing step is based on larger intervals when said battery life is approaching depletion.

15. The method according to claim 14, wherein said first electronic device is a wireless device and at least a portion of said link includes a wireless connection from said wireless device to the Internet.

16. A computer-readable storage medium containing a set of programming instructions, when executed by a first electronic device, for performing a method comprising the steps of:

loading a time-out period into said first electronic device of an initial default value;

establishing a connection from said first electronic device to a second electronic device via a physical link that includes an equipment for terminating said connection if said connection remains idle for a predetermined time-out period;

sending keep-alive signals from said first electronic device to said second electronic device according to said time-out period;

increasing said predetermined time-out period and repeating said sending step if said time-out period does not cause said connection to be terminated by said equipment; and

,

repeating said increasing step until said connection is terminated by said equipment in order to determine said pre-determined time-out period of said equipment;

adjusting said time-out period to a value less than and closest to said determined predetermined time-out period of said equipment; and

thereafter

sending said keep-alive signals using said adjusted time-out period.