Sustaining session connections

• US 7,962,623 B2
• Filed: 06/30/2004
• Issued: 06/14/2011
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Markaryan, Mark, Undery, James Evan
• Primary Examiner(s): Mesfin; Yemane
• Assistant Examiner(s): Gupta; Muktesh G
• Application Number:
  US10/881,251
• Publication Number:
  US 20060020707A1
• Time in Patent Office: 2,540 Days
• Field of Search: 709/227, 709/230, 370/431, 370/465
• US Class Current: 709/227
• CPC Class Codes: H04L 51/04 Real-time or near real-time messaging, e.g. instant messaging [IM]
• CPC Class Codes: H04L 51/23 Reliability checks, e.g. acknowledgments or fault reporting
• CPC Class Codes: H04L 65/1083 In-session procedures
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 67/145 avoiding end of session, e.g. keep-alive, heartbeats, resumption message or wake-up for inactive or interrupted session
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

In an embodiment, techniques for sustaining session connections are provided. The techniques send heartbeat messages when not sending a message may cause the session connection to close because of a timeout condition. Heartbeat messages are valid transport layer messages that will be ignored by protocols at higher levels of a data communications stack. As an example, the techniques may send a TCP message containing only a carriage return and line feed (“CRLF”) in its payload. Because the TCP layer considers a message containing only a CRLF to be a valid TCP message, intermediary computing devices such as proxy servers may not interpret heartbeat messages as “keep alive” messages, and may sustain session connections.

Claims

1. A method performed by a computing device for sustaining a session connection, comprising:

opening a session with a second computing device using a session initiation protocol, the session having a connection; and

sending a heartbeat message using a transport layer protocol, wherein the session initiation protocol is employed by a higher layer of a data communications stack than the second protocol, and wherein the heartbeat message is a valid message of the transport layer protocol and ignored by the session initiation protocol, and sending the heartbeat message sustains the session connection;

wherein the session is established and sustained between the computing device and a second computing device through a proxy server and wherein after transferring the heartbeat message from the computing device to the second computing device, the proxy server resets a message clock of the connection.

2. The method of claim 1 wherein the heartbeat message comprises a carriage return and line feed.

3. The method of claim 1 wherein the heartbeat message is sent prior to expiry of a message clock.

4. The method of claim 3 wherein the message clock measures time elapsed since a previous message was sent or received.

5. The method of claim 3 wherein the message clock relates to messages sent or received by a transport layer of a data communications stack.

6. The method of claim 1 wherein the second protocol is TCP/IP.

7. The method of claim 1 wherein the heartbeat message is sent periodically, wherein the periodicity is a function of a timeout value.

8. The method of claim 1 wherein the heartbeat message is sent in absence of a message of a session initiation protocol.

9. A computer-readable medium excluding transmission media, wherein computer-readable medium having stored thereon computer-executable instructions which, when executed, cause a computing system to perform a method comprising:

opening a session with a second computing device using a session initiation protocol, the session having a connection;

sending messages using the session initiation protocol, wherein the messages are segmented by a transport layer into a set of messages of a transport layer protocol; and

sending a heartbeat message using a second protocol, wherein the session initiation protocol is employed by a higher layer of a data communications stack than the transport layer protocol, and wherein the heartbeat message is a valid message of the transport layer protocol and is not provided to an application employing the session initiation protocol, and sending the heartbeat message sustains the session connection;

wherein the session is established and sustained between the computing device and a second computing device through a proxy server, and wherein after transferring the heartbeat message from the computing device to the second computing device, the proxy server resets a message clock of the connection.

10. The computer-readable medium of claim 9 wherein the heartbeat message is sent when a period of time elapses after a message is sent using the session initiation protocol.

11. The computer-readable medium of claim 9 wherein the heartbeat message is sent periodically, wherein the periodicity is a function of a timeout value.

12. The computer-readable medium of claim 9 wherein the heartbeat message comprises a carriage return and line feed.

13. The computer-readable medium of claim 9 wherein the heartbeat message is sent prior to expiry of a message clock.

14. The computer-readable medium of claim 13 wherein the message clock measures time elapsed since a previous message was sent or received.

15. The computer-readable medium of claim 13 wherein the message clock relates to messages sent or received by a transport layer of a data communications stack.

16. The computer-readable medium of claim 9 wherein the transport layer protocol is a TCP/IP.

17. The computer-readable medium of claim 9 wherein the heartbeat message is send in absence of a message of the session initiation protocol.

18. A system for sustaining a session connection, comprising:

a computing device including a processing unit and memory;

a component operating on the computing device that receives a message via a connection with a remote computing device; and

a component operating on the computing device that determines whether the received message is a heartbeat message, wherein the heartbeat message is a valid message of a lower level protocol and has no effect on a higher level protocol, and wherein the higher level protocol is a session initiation protocol and the lower level protocol is a transport layer protocol; and

when the received message is a heartbeat message, acknowledges the received message; and

when the received message is not a heartbeat message, forwards the message;

wherein the message is received from the remote computing device via a proxy server, and wherein after transferring the message, the proxy server resets a message clock of the session connection.

19. The system of claim 18 wherein the heartbeat message is received when a period of time elapses after a message of the higher level protocol is received, the period of time being less than a timeout value.

20. The system of claim 18 wherein the heartbeat message is received periodically, wherein the periodicity is a function of a timeout value.

21. The system of claim 18 wherein the heartbeat message comprises a carriage return and line feed.

22. The system of claim 18 wherein the heartbeat message is received prior to expiry of a message clock.

23. The system of claim 22 wherein the message clock measures time elapsed since a previous message was sent or received.

24. The system of claim 22 wherein the message clock relates to messages sent or received by a transport layer of a data communications stack.

25. The system of claim 18 wherein the lower level protocol is TCP/IP.

26. The system of claim 18 wherein the received message is forwarded to an application using the higher level protocol when it is not a heartbeat message.

27. The system of claim 18 wherein the heartbeat message comprises white space characters.

28. The system of claim 27 wherein a white space character is a linefeed.

29. The system of claim 27 wherein a white space character is a carriage return.