Method and system for recovering system resources used by an inactive Telnet client

• US 6,330,607 B1
• Filed: 05/04/1999
• Issued: 12/11/2001
• Est. Priority Date: 03/30/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Chmielewski, Paul Richard, Murphy, Thomas Edwin Jr., Stevens, Jeffrey Scott, Rieth, Paul Francis
• Primary Examiner(s): Harrell, Robert B
• Application Number:
  US09/305,216
• Time in Patent Office: 952 Days
• Field of Search: 709/200, 709/223, 709/226, 709/227, 709/237, 709/248
• US Class Current: 709/227
• CPC Class Codes: H04L 67/08 specially adapted for terminal emulation, e.g. Telnet
• CPC Class Codes: H04L 69/32 Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A computer executing a Telnet application manages usage of a system resource by issuing through a transport layer directed to a specific client a DO TIMING MARK command. Responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from the specific client, the Telnet application calculates a WAIT time; and responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from the specific client within said WAIT time, the Telnet application causes release of system resource used by the client.

Claims

1. Method for managing usage of a system resource at a server by each of a plurality of clients in a communications system, comprising the steps of:

tailoring a wait period for each specific client of said plurality of clients, including

issuing through a transport layer a DO TIMING MARK command to each specific client;

responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said specific client, calculating said period for said specific client; and

responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said specific client within said WAIT time, releasing said system resource.

2. The method of claim 1, said wait period being calculated at an application layer as

wait period=n*((y*AVG_RTT)+((1− y)*NEW_RTT_SAMPLE;

where AVG_RTT is the average wait time, NEW_RTT_SAMPLE is the most recently measured wait time between issuing said DO TIMING MARK and receiving said WILL TIMING MARK or WONT TIMING MARK response, y is a parameter set between 0 and 1 for selectively weighting the significance of said NEW_RTT_SAMPLE, and n≧

1.

3. The method of claim 1, said wait period being calculated periodically for each said specific client during each session by issuing a plurality of said DO TIMING MARK commands and receiving a plurality of said WILL TIMING MARK or WONT TIMING MARK responses.

4. Method for managing usage of a system resource in computer executing a Telnet application, comprising the steps of:

issuing through a transport layer directed to a specific client a DO TIMING MARK command;

responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said specific client, calculating a WAIT_time as

WAIT _time=n*((y*AVG_RTT)+((1−

y)*NEW_RTT_SAMPLE;

where AVG_RTT is the average wait time, NEW_RTT_SAMPLE is the most recently measured wait time between issuing said DO TIMING MARK and receiving said WILL TIMING MARK or WONT TIMING MARK response, y is a parameter set between 0 and 1 for selectively weighting the significance of said NEW_RTT_SAMPLE, and n≧

1; and

responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said specific client within said WAIT_time, releasing said system resource.

5. System for managing usage of a system resource in a computer executing a Telnet application, comprising:

means for issuing through a transport layer directed to a specific client a DO TIMING MARK command;

means responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said specific client for calculating a WAIT_time as

WAIT_time=n*((y*AVG_RTT)+((1−

y)*NEW_RTT__SAMPLE;

where AVG_RTT is the average wait time, NEW_RTT_SAMPLE is the most recently measured wait time between issuing said DO TIMING MARK and receiving said WILL TIMING MARK or WONT TIMING MARK response, y is a parameter set between 0 and 1 for selectively weighting the significance of said NEW_RTT_SAMPLE, and n≧

1; and

means responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said specific client within said WAIT_time, releasing said system resource.

6. System for managing usage of a system resource at a server by each of a plurality of clients in a communications system, comprising:

means for tailoring a wait period for each specific client of said plurality of clients, including

means for issuing through a transport layer a DO TIMING MARK command to each specific client;

means responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said specific client for calculating said period for said specific client; and

means responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said specific client within said WAIT time for releasing said system resource.

7. A program storage device readable by a machine, tangibly embodying a program of instructions executable by a machine to perform method steps for managing usage of a system resource in a computer executing a Telnet application, said method steps comprising:

tailoring a wait period for each specific client of said plurality of clients, including

issuing through a transport layer a DO TIMING MARK command to each specific client;

responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said specific client, calculating said period for said specific client; and

responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said specific client within said WAIT time, releasing said system resource.

8. An article of manufacture comprising:

a computer usuable medium having computer readable program code means embodied therein for managing usage of a system resource in a computer executing a Telnet application, the computer readable program means in said article of manufacture comprising;

computer readable program code means for causing a computer to effect tailoring a wait period for each specific client of said plurality of clients, including

issuing through a transport layer a DO TIMING MARK command to each specific client;

responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said specific client, calculating said period for said specific client; and

computer readable program code means for causing a computer to effect responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said specific client within said WAIT time, releasing said system resource.

9. Method for managing usage of a plurality of application user terminal devices used for reading and updating information stored at a host system, comprising the steps of:

establishing at a host server a virtual display device for a first terminal device;

issuing through a transport layer directed to a said first terminal device a DO TIMING MARK command;

responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said first terminal device, calculating a WAIT time; and

responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said first terminal device within said WAIT time, releasing said virtual display device.

10. System for managing usage of a plurality of application user terminal devices used for reading and updating information stored at a host system, comprising the steps of:

means for establishing at a host server a virtual display device for a first terminal device;

means for issuing through a transport layer directed to a said first terminal device a DO TIMING MARK command;

means responsive to receiving a WILL TIMING MARK or WONT TIMING MARK response from said first terminal device for calculating a WAIT time; and

means responsive to receiving no WILL TIMING MARK or WONT TIMING MARK response from said first terminal device within said WAIT time for releasing said virtual display device.