Distributed cache for state transfer operations

• US 7,720,975 B2
• Filed: 10/29/2007
• Issued: 05/18/2010
• Est. Priority Date: 02/13/2001
• Status: Expired due to Fees

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Aventail LLC
• Inventors: Erickson, Rodger D.
• Primary Examiner(s): Lim; Krisna
• Application Number:
  US11/927,350
• Publication Number:
  US 20080104686A1
• Time in Patent Office: 932 Days
• Field of Search: 709201-203, 709214-229, 709/248
• US Class Current: 709/227
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/10015 Access to distributed or replicated servers, e.g. using brokers
• CPC Class Codes: H04L 67/1034 Reaction to server failures by a load balancer
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/148 Migration or transfer of sessions
• CPC Class Codes: H04L 67/288 Distributed intermediate devices, i.e. intermediate devices for interaction with other intermediate devices on the same level
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A network arrangement that employs a cache having copies distributed among a plurality of different locations. The cache stores state information for a session with any of the server devices so that it is accessible to at least one other server device. Using this arrangement, when a client device switches from a connection with a first server device to a connection with a second server device, the second server device can retrieve state information from the cache corresponding to the session between the client device and the first server device. The second server device can then use the retrieved state information to accept a session with the client device.

Claims

1. A method of maintaining session based communications with a client, the method comprising:

conducting a session with a client from a primary server;

obtaining state information corresponding to the session between the primary server and the client; and

transmitting portions of the state information for the session between the client and the primary server to a plurality of secondary servers for caching, whereby the client may establish a new session with any one of the servers from the plurality of secondary servers if the session between the primary server and the client terminates, and whereby the server from the plurality of secondary servers may be provided a necessary portion of state information from another server from the plurality of secondary servers if the necessary portion of the state information is not present at the server from the plurality of secondary servers having established a new session with the client, the plurality of secondary servers collectively maintaining a complete copy of the state information.

2. The method of claim 1, wherein the state information is credential information.

3. The method of claim 2, wherein the credential information includes a Secure Sockets Layer (SSL) session identifier.

4. The method of claim 2, wherein the credential information includes authentication information.

5. The method of claim 1, wherein the state information includes data segment information for controlling the transmission of a data segment between the primary server and the client.

6. The method of claim 1, wherein the state information includes Transmission Control Protocol/Internet Protocol header information.

7. The method of claim 1, wherein the state information includes purchase information.

8. The method of claim 7, wherein the purchase information includes items selected for purchase.

9. The method of claim 7, wherein the purchase information includes financial transaction information.

10. The method of claim 7, wherein the purchase information includes a billing addresses.

11. The method of claim 1, wherein the state information is simultaneously transmitted to the plurality of secondary servers.

12. The method of claim 1, wherein the state information is transmitted to the plurality of secondary servers concurrent with caching of the state information at the primary server.

13. The method of claim 1, wherein the state information is consecutively transmitted to the plurality of secondary servers.

14. The method of claim 1, wherein the state information is transmitted to the plurality of secondary servers utilizing a broadcast transmission.

15. The method of claim 1, wherein the state information is transmitted to the plurality of secondary servers utilizing a multicast transmission.

16. The method of claim 1, wherein the state information is transmitted to the plurality of secondary servers utilizing a unicast transmission.

17. The method of claim 1, further comprising receiving an acknowledgement from the plurality of secondary servers with respect to receipt of the state information from the primary server by the plurality of secondary servers.

18. The method of claim 1, further comprising hashing the state information prior to storage of the state information in cache memory at the primary server.

19. The method of claim 18, wherein the state information is hashed utilizing the BUZhash algorithm.

20. A method of sharing state information among a plurality of server computers, comprising:

receiving first state information from a first server computer, the first state information reflecting a first communication session between the first server computer and a first client computer;

storing the first state information;

receiving second state information from a second server computer, the second state information reflecting a second communication session between the second server computer and a second client computer;

storing the second state information;

receiving a request for the first state information from a third server computer; and

transmitting the first state information to the third server computer, such that the third server computer can employ the first state information to reestablish the first communication session with the first client computer.

21. The method of claim 20, further comprising:

receiving a request for the second state information from a fourth server computer; and

transmitting the second state information to the fourth server computer, such that the fourth server computer can employ the second state information to reestablish the second communication session with the second client computer.

22. The method of claim 20, wherein the first state information is credential information.

23. The method of claim 22, wherein the credential information includes a Secure Sockets Layer (SSL) session identifier.

24. The method of claim 22, wherein the credential information includes authentication information.

25. The method of claim 20, wherein the first state information is data segment information for controlling transmission of a data segment between the first server computer and the first client computer.

26. The method of claim 20, wherein the first state information is Transmission Control Protocol/Internet Protocol header information.

27. The method of claim 20, wherein the first state information is purchase information.