System and method for sticky routing of requests within a server farm

• US 20040024881A1
• Filed: 07/31/2002
• Published: 02/05/2004
• Est. Priority Date: 07/31/2002
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Oracle America, Inc. (Oracle Corporation)
• Inventors: Srinivasan, Arvind, Elving, Christopher H.
• Granted Patent: US 7,774,473 B2
• Time in Patent Office: Days
• US Class Current: 709/227
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing

Abstract

An upstream device, such as a load balancer or router within a server farm, may perform sticky routing of session requests to the servers handling those sessions by generating unique ID(s) identifying how requests may be routed through the server farm. Upstream devices through which travels a request that is not associated with a session on a server of the server farm may generate one or more unique IDs identifying how the request is routed through the server farm. The server handling the request may form a session ID and return that session ID and the unique ID(s) to the client that originated the new request and session. Clients may then send the session ID and unique IDs with clients requests for that session. Upon receiving requests corresponding to established sessions, the upstream devices may then identify routing information from the unique ID(s) and route the request accordingly.

Claims

1. A system, comprising:

an upstream device configured to receive client requests; and

a plurality of servers coupled to the upstream device and configured to store session information;

wherein for each client request not associated with an established session the upstream device is configured to select one of the plurality of servers and send that client request to that server with unique information identifying that server;

wherein, in response to each client requests not associated with an established session, each of the servers is configured to generate a session ID and send the session ID and the unique identifying information received from the upstream device to the client; and

wherein, in response to client requests associated with an established session, the upstream device is configured to send the client requests to the one of the plurality of servers indicated by the unique identifying information included with the client requests.

2. The system as recited in claim 1, wherein the upstream device comprises a load balancer configured to select one of the servers to send each client requests not associated with an established session according to a load of each server.

3. The system as recited in claim 1, wherein each of the plurality of servers comprises a web server, and wherein the client requests comprise requests received from web clients over the Internet, wherein the web servers are configured to respond to the requests from web clients.

4. The system as recited in claim 3, wherein each server is configured to store session state information for each session that server has established with a web client.

5. The system as recited in claim 1, wherein said unique identifying information is encrypted so as to not be available to clients sending the client requests.

6. The system as recited in claim 1, wherein said unique identifying information is encoded in each session ID and comprises a network address for the corresponding server.

7. The system as recited in claim 1, wherein said unique identifying information is generated by the upstream device.

8. The system as recited in claim 1, wherein, for client requests not associated with an established session, the upstream device is configured to modify a URI of the client request to include said unique identifying information and send the request to the corresponding server.

9. The system as recited in claim 1, wherein, for client requests not associated with an established session, the upstream device is configured to modify or insert a header in the client request to include said unique identifying information and send the request to the corresponding server.

10. The system as recited in claim 1, wherein, for client requests not associated with an established session, the upstream device is configured to modify a body of the client request to include said unique identifying information and send the request to the corresponding server.

11. The system as recited in claim 1, wherein said upstream device is comprised within a hierarchy of upstream devices configured to route the client requests to the servers;

wherein, for client requests not associated with an established session, the hierarchy of upstream devices is configured to generate said unique identifying information to identify each upstream device through which the client request was routed to the corresponding server.

12. The system as recited in claim 11, wherein, for client requests including a session ID, each upstream device is configured to examine the unique identifying information included with the client request to determine which upstream device or server the client request is to next be routed.

13. A method, comprising:

an upstream device receiving a client request; and

if the client request is not associated with an established session;

the upstream device selecting one of a plurality of servers and sending the client request to the server with unique information identifying the server; and

the server providing a session ID and the unique identifying information received from the upstream device in response to the client request not associated with a session ID and sending the session ID and the unique identifying information to the client;

if the client request is associated with an established session, the upstream device sending the client request associated with an established session to the one of the plurality of servers indicated by the unique identifying information associated with the request.

14. The method as recited in claim 13, wherein said selecting comprises selecting to balance the load of each server in the plurality of servers.

15. The method as recited in claim 13, wherein said server generating and sending comprises a web server responding to the client request, wherein the client is from a web client over the Internet.

16. The method as recited in claim 15, further comprising the server establishing a session with the web client and storing session state information for the session.

17. The method as recited in claim 13, further comprising encrypting said unique identifying information so as to not be available to a client sending the client request.

18. The method as recited in claim 17, wherein said unique identifying information is included in each session ID and comprises a network address for the corresponding server.

19. The method as recited in claim 13, further comprising the upstream device generating said unique identifying information.

20. The method as recited in claim 13, further comprising, for client requests not associated with an established session, the upstream device modifying a URI of the client request to include said unique identifying information.

21. The method as recited in claim 13, further comprising, for client requests not associated with an established session, the upstream device modifying or inserting a header in the client request to include said unique identifying information.

22. The method as recited in claim 13, further comprising, for client requests not associated with an established session, the upstream device modifying a body of the client request to include said unique identifying information.

23. The method as recited in claim 13, wherein the upstream device is comprised within a hierarchy of upstream devices configured to route the client requests to the servers.

24. The method as recited in claim 23, further comprising, for client requests not associated with an established session, the hierarchy of upstream devices generating said unique identifying information to identify each upstream device through which the client request was routed to the corresponding server.

25. A computer accessible medium comprising computer instructions configured to implement:

an upstream device receiving a client request; and

if the client request is not associated with an established session;

the upstream device selecting one of a plurality of servers and sending the client request to the server with unique information identifying the server; and

the server generating a session ID and providing the unique identifying information received from the upstream device in response to the client request not associated with a session ID and sending the session ID and the unique identifying information to the client;

if the client request is associated with an established session, the upstream device sending the client request associated with an established session to the one of the plurality of servers indicated by the unique identifying information with the request.

26. The computer accessible medium as recited in claim 25, wherein said selecting comprises selecting to balance the load of each server in the plurality of servers.

27. The computer accessible medium as recited in claim 25, wherein said server generating and sending comprises a web server responding to the client request, wherein the client is from a web client over the Internet.

28. The computer accessible medium as recited in claim 27, wherein the computer instructions are further configured to implement the server establishing a session with the web client and storing session state information for the session.

29. The computer accessible medium as recited in claim 25, wherein the computer instructions are further configured to implement encrypting said unique identifying information so as to not be available to a client sending the client request.

30. The computer accessible medium as recited in claim 29, wherein said unique identifying information is included in each session ID and comprises a network address for the corresponding server.

31. The computer accessible medium as recited in claim 25, further comprising the upstream device generating said unique identifying information.

32. The computer accessible medium as recited in claim 25, wherein the computer instructions are further configured to implement, for client requests not associated with an established session, the upstream device modifying a URI of the client request to include said unique identifying information.

33. The computer accessible medium as recited in claim 25, wherein the computer instructions are further configured to implement, for client requests not associated with an established session, the upstream device modifying or inserting a header in the client request to include said unique identifying information.

34. The computer accessible medium as recited in claim 25, wherein the computer instructions are further configured to implement, for client requests not associated with an established session, the upstream device modifying a body of the client request to include said unique identifying information.

35. The computer accessible medium as recited in claim 25, wherein the upstream device is comprised within a hierarchy of upstream devices configured to route the client requests to the servers.

36. The computer accessible medium as recited in claim 35, wherein the computer instructions are further configured to implement, for client requests not associated with an established session, the hierarchy of upstream devices generating said unique identifying information to identify each upstream device through which the client request was routed to the corresponding server.