Methods, systems and computer program products for resuming SNA application-client communications after loss of an IP network connection

• US 20020103909A1
• Filed: 01/31/2001
• Published: 08/01/2002
• Est. Priority Date: 01/31/2001
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Devine, Wesley McMillan, Trottman, Douglas Alan, Huang, Sue L.
• Granted Patent: US 7,089,311 B2
• Time in Patent Office: Days
• US Class Current: 709/227
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/163 In-band adaptation of TCP data exchange; In-band control procedures
• CPC Class Codes: H04L 69/169 Special adaptations of TCP, UDP or IP for interworking of IP based networks with other networks protocols for interworking, protocol conversion H04L69/08
• CPC Class Codes: H04L 69/327 in the session layer [OSI layer 5]
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

Systems, methods and computer program products are provided for preserving a session between an SNA application and a TN3270E server after loss of an IP network connection between the TN3270E server and a TN3270E client that is communicating with the SNA application via the SNA session.

Claims

1. A method for preserving a session between an SNA application and a TN3270E server after loss of an Internet protocol (“

IP”

) connection between the TN3270E server and a TN3270E client that is associated with the session, the method comprising;

reestablishing the IP connection between the TN3270E server and the TN3270E client; and

then

forwarding a screen refresh request to the SNA application.

2. The method of claim 1, wherein the method further comprises:

receiving a screen refresh from the SNA application; and

forwarding the screen refresh to the TN3270E client over the reestablished IP connection.

3. The method of claim 2, wherein the step of forwarding a screen refresh request to the SNA application comprises sending an LUSTAT message to the SNA application.

4. The method of claim 2, wherein the method further comprises:

receiving a user logon screen from the SNA application in response to the LUSTAT message;

forwarding the user logon screen to the TN3270E client;

receiving logon information from the TN3270E client;

checking the authenticity of the received logon information; and

forwarding the screen refresh to the TN3270E client over the reestablished IP connection only if the received logon information is authentic.

5. The method of claim 2, wherein the screen refresh received from the SNA application and forwarded to the TN3270E client comprises a last data screen that was forwarded from the SNA application and acknowledged as received by the TN3270E client.

6. The method of claim 1, wherein the method further comprises:

receiving a user logon screen from the SNA application in response to the screen refresh request;

forwarding the user logon screen to the TN3270E client;

receiving logon information from the TN3270E client;

checking the authenticity of the received logon information; and

resuming the session if the received logon information is authentic.

7. The method of claim 4, wherein the steps of forwarding a screen refresh request to the SNA application, receiving a screen refresh from the SNA application and forwarding the screen refresh to the TN3270E client over the reestablished IP connection are performed by the TN3270E server.

8. The method of claim 2, wherein the IP connection comprises a TCP/IP connection.

9. A method for reestablishing a TCP/IP connection between a TN3270E client and a TN3270E server after loss of a first TCP/IP connection between the TN3270E client and the TN3270E server in which the TN3270E client connected to the TN3270E server under a first Logical Unit (“

TLU”

) name, the method comprising;

receiving a connection request, wherein the connection request specifies the first LU name;

transmitting a query addressed to the TN3270E client over the first TCP/IP connection;

establishing a second TCP/IP connection in response to the connection request if a response to the query is not received within a specified time period; and

resuming communications over the second TCP/IP connection.

10. The method of claim 9, wherein the query comprises a query to which the TN3270E client automatically responds.

11. The method of claim 9, wherein the query comprises a timemark request.

12. The method of claim 9, further comprising the step of authenticating the identity of the TN3270E client prior to resuming communications with the TN3270E client over the second TCP/IP connection.

13. The method of claim 12, wherein the authenticating step comprises:

receiving an X.509 certificate over the second TCP/IP connection; and

verifying that the X.509 certificate corresponds to the TN3270E client.

14. The method of claim 13, wherein the step of transmitting a query is only performed if the X.509 certificate corresponds to the TN3270E client.

15. The method of claim 9, wherein the method further comprises forwarding a screen refresh request to the SNA application over the second TCP/IP connection.

16. The method of claim 15, wherein the method further comprises:

receiving a screen refresh from the SNA application; and

forwarding the screen refresh to the TN3270E client over the second TCP/IP connection.

17. The method of claim 16, wherein the step of forwarding a screen refresh request to the SNA application comprises sending an LUSTAT message to the SNA application.

18. The method of claim 16, wherein the method further comprises:

receiving a user logon screen from the SNA application in response to the LUSTAT message;

forwarding the user logon screen to the TN3270E client;

receiving logon information from the TN3270E client;

checking the authenticity of the received logon information; and

forwarding the screen refresh to the TN3270E client over the second TCP/IP connection only if the received logon information is authentic.

19. A system for preserving a session between an SNA application and a TN3270E server after loss of an Internet protocol (“

IP”

) connection between the TN3270E server and a TN3270E client that is associated with the session, comprising;

means for reestablishing the IP connection between the TN3270E server and the TN3270E client; and

means for forwarding a screen refresh request to the SNA application.

20. A system for reestablishing a TCP/IP connection between a TN3270E client and a TN3270E server after loss of a first TCP/IP connection between the TN3270E client and the TN3270E server in which the TN3270E client connected to the TN3270E server under a first Logical Unit (“

LU”

) name, comprising;

means for receiving a connection request, wherein the connection request specifies the first LU name;

means for transmitting a query addressed to the TN3270E client over the first TCP/IP connection;

means for establishing a second TCP/IP connection in response to the connection request if a response to the query is not received within a specified time period; and

means for resuming communications over the second TCP/IP connection.

21. A computer program product for preserving a session between an SNA application and a TN3270E server after loss of an Internet protocol (“

IP”

) connection between the TN3270E server and a TN3270E client that is associated with the session, the computer program product comprising a computer usable storage medium having computer readable program code means embodied in the medium, the computer readable program code means comprising;

computer readable program code means for reestablishing the IP connection between the TN3270E server and the TN3270E client; and

computer readable program code means for forwarding a screen refresh request to the SNA application.

22. A computer program product for reestablishing a TCP/IP connection between a TN3270E client and a TN3270E server after loss of a first TCP/IP connection between the TN3270E client and the TN3270E server in which the TN3270E client connected to the TN3270E server under a first Logical Unit (“

LU”

) name, the computer program product comprising a computer usable storage medium having computer readable program code means embodied in the medium, the computer readable program code means comprising;

computer readable program code means for receiving a connection request, wherein the connection request specifies the first LU name;

computer readable program code means for transmitting a query addressed to the TN3270E client over the first TCP/IP connection;

computer readable program code means for establishing a second TCP/IP connection in response to the connection request if a response to the query is not received within a specified time period; and

computer readable program code means for resuming communications over the second TCP/IP connection.