Method, intermediate device and computer program code for maintaining persistency

• US 9,106,606 B1
• Filed: 11/16/2008
• Issued: 08/11/2015
• Est. Priority Date: 02/05/2007
• Status: Active Grant

• Current Assignee: F5 Networks, Inc. (F5 Incorporated)
• Original Assignee: F5 Networks, Inc. (F5 Incorporated)
• Inventors: Hasson, Uri, Shoolman, Yiftach
• Primary Examiner(s): Elfervig, Taylor
• Application Number:
  US12/271,903
• Time in Patent Office: 2,459 Days
• Field of Search: 709/228, 709/203, 709/219, 709/223, 709/246
• US Class Current: 1/1
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/1004 Server selection for load balancing
• CPC Class Codes: H04L 67/1006 with static server selection, e.g. the same server being selected for a specific client
• CPC Class Codes: H04L 67/1014 based on the content of a request
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing
• CPC Class Codes: H04L 67/141 Setup of application sessions admission control or resource allocation in data switching networks H04L47/70
• CPC Class Codes: H04L 67/142 Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms
• CPC Class Codes: H04L 67/146 Markers for unambiguous identification of a particular session, e.g. session cookie or URL-encoding
• CPC Class Codes: H04L 67/34 involving the movement of software or configuration parameters network booting or remote initial program loading [RIPL] G06F9/4416
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

A method for maintaining server persistency, including: (a) receiving, by an intermediate entity, a first session request from client to receive a service from a server out of a plurality of servers that are connected to the intermediate entity; (b) selecting a server out of the plurality of servers and directing to the selected server information indicative of the first session request; (c) receiving a response of the selected server to the information indicative of the first session request; (d) analyzing the response of the selected server, to provide an analysis result indicative whether the response includes code to be executed by the client and includes at least one instruction that facilitates sending, by the client, another request, to receive a service from a server out of the plurality of servers; (e) modifying, based on the analysis result, the code by adding information that will cause the client to send a selected server identifier in association to the sending of the other request; and (f) sending a modified response to the client, wherein the modified response includes the modified code.

Claims

1. A method for maintaining server persistency, comprising:

receiving, by an intermediate entity, a first session request from client to receive a service from a server out of a plurality of servers that are coupled to the intermediate entity;

selecting a server out of the plurality of servers and directing to the selected server information indicative of the first session request;

receiving a response of the selected server to the information indicative of the first session request;

analyzing, by an analyzer of the intermediate entity, the response of the selected server, to provide an analysis result indicative whether the response comprises code to be executed by the client and comprises at least one instruction that facilitates sending, by the client, another request to receive a service from a server out of the plurality of servers;

wherein the analyzing comprises analyzing the response of the selected server to locate browser code to be executed by a browser of the client;

modifying, by a modifier of the intermediate entity, in response to the analysis result, the browser code by adding information to each call in the browser code that will cause the client to send a selected server identifier in association to the sending of the other request, wherein the browser code is parsed and marked at each location where each call is made to an operating system of the client for sending each request, and wherein the information added at each marked location for each call includes a unique HTTP header that includes the selected server identifier independent of a dedicated HTTP cookie; and

sending a modified response to the client, wherein the modified response comprises the modified browser code.

2. The method according to claim 1 wherein the method is executed without using dedicated HTTP cookies.

3. The method according to claim 1 comprising analyzing the response of the selected server to locate at least one instruction that is executed by a browser of the client and comprises a call to an entity to enable sending the other request, wherein the entity is selected from a group consisting of an operating system of the client and an API layer between the browser code and the operating system of the client.

4. The method according to claim 1 comprising adding the HTTP

header for each call instruction of the code, wherein each HTTP header comprises the selected server identifier, if the other request and the modified response are associated with a same site.

5. The method according to claim 1 comprising:

receiving, by the intermediate node, the other request from the client;

removing the selected server identifier to provide a modified other request; and

sending to the selected server information indicative of the modified other request.

6. The method according to claim 1 comprising:

receiving a selected server response that comprises compressed code;

de-compressing the compressed code to provide de-compressed code;

wherein the analyzing comprises analyzing the de-compressed code;

wherein the modifying comprises modifying, in response to the analysis result, the decompressed code by adding information that will cause the client to send the selected server identifier in association to the sending of the other request;

compressing the modified de-compressed code to provide a compressed modified code; and

sending a modified response to the client, wherein the modified response comprises the compressed modified code.

7. The method according to claim 1 comprising:

receiving a selected server response that comprises encrypted code;

decrypting the encrypted code to decrypted code;

wherein the analyzing comprises analyzing the decrypted code;

wherein the modifying comprises modifying, in response to the analysis result, the decrypted code by adding information that will cause the client to send the selected server identifier in association to the sending of the other request;

encrypting the modified decrypted code to provide an encrypted modified code; and

sending a modified response to the client, wherein the modified response comprises the encrypted modified code.

8. The method according to claim 1 comprising modifying, in response to the analysis result, the code by adding information that will cause the client to send the selected server identifier in association to the sending of the other request if the other request and the modified response are associated with a same site.

9. An intermediate device, comprising:

a client interface receiving a first session request from a client to receive a service from a server out of a plurality of servers;

a server selector selecting a server out of the plurality of servers;

a server interface, coupled to the plurality of servers, directing to the selected server information indicative of the first session request and to receive a response of the selected server to the information indicative of the first session request;

an analyzer analyzing the response of the selected server, to provide an analysis result indicative whether the response comprises code to be executed by the client and comprises at least one instruction that facilitates sending, by the client, another request to receive a service from a server out of the plurality of servers;

a modifier modifying, in response to the analysis result, browser code by adding information to each call in the browser code that will cause the client to send a selected server identifier in association to the sending of the other request, wherein the browser code is parsed and marked at each location where each call is made to an operating system of the client for sending each request, and wherein the information added at each marked location for each call includes a unique HTTP header that includes the selected server identifier independent of a dedicated HTTP cookie;

wherein the analyzer analyzes the response of the selected server to locate the browser code to be executed by a browser of the client; and

wherein the client interface further sends a modified response to the client, wherein the modified response comprises the modified browser code.

10. The intermediate device according to claim 9 does not utilize dedicated HTTP cookies.

11. The intermediate device according to claim 9 wherein the analyzer analyzes the response of the selected server to locate at least one instruction that is executed by a browser of the client and comprises a call to an entity to enable sending the other request, wherein the entity is selected from a group consisting of an operating system of the client and an API layer between the browser code and the operating system of the client.

12. The intermediate device according to claim 9 wherein the modifier adds the HTTP header for each call instruction of the code, if the other request and the modified response are associated with a same site, wherein each added HTTP header comprises the selected server identifier.

13. The intermediate device according to claim 9 wherein the client interface receives, by the intermediate node, the other request from the client;

wherein the modifier removes the selected server identifier to provide a modified other request; and

the client interface sends to the selected server information indicative of the modified other request.

14. The intermediate device according to claim 9 comprising a decompressor and a compressor;

wherein the server interface receives a selected server response that comprises compressed code;

wherein the de-compressor de-compresses the compressed code to provide decompressed code;

wherein the compressor compresses decompressed modified code received from the modifier to provide a compressed modified code; and

wherein the client interface sends a modified response to the client, wherein the modified response comprises the compressed modified code.

15. The intermediate device according to claim 9 comprising a decryptor and an encryptor;

wherein the server interface receives a selected server response that comprises encrypted code;

wherein the decryptor decrypts the encrypted code to provide decrypted code;

wherein the encryptor decrypts decrypted modified code received from the modifier to provide an encrypted modified code; and

wherein the client interface sends a modified response to the client, wherein the modified response comprises the encrypted modified code.

16. The intermediate device according to claim 9 wherein the modifier modifies, in response to the analysis result, the code by adding information that will cause the client to send the selected server identifier in association to the sending of the other request if the other request and the modified response are associated with a same site.

17. A computer program product that comprises a non-transitory computer readable medium that stores instructions for:

receiving, by an intermediate entity, a first session request from client to receive a service from a server out of a plurality of servers that are coupled to the intermediate entity;

selecting a server out of the plurality of servers and directing to the selected server information indicative of the first session request;

receiving a response of the selected server to the information indicative of the first session request;

analyzing, by an analyzer of the intermediate entity, the response of the selected server, to provide an analysis result indicative whether the response comprises code to be executed by the client and comprises at least one instruction that facilitates sending, by the client, another request to receive a service from a server out of the plurality of servers;

wherein the analyzing comprises analyzing the response of the selected server to locate browser code to be executed by a browser of the client;

modifying, by a modifier of the intermediate entity and in response to the analysis result, the browser code by adding information to each call in the browser code that will cause the client to send a selected server identifier in association to the sending of the other request and sending a modified response to the client, wherein the browser code is parsed and marked at each location where each call is made to an operating system of the client for sending each request, and wherein the modified response comprises the modified browser code, and wherein the information added at each marked location for each call includes a unique HTTP header that includes the selected server identifier independent of a dedicated HTTP cookie;

wherein the computer readable medium stores instructions for analyzing the response of the selected server to locate browser code to be executed by a browser of the client.

18. The computer program product according to claim 17 comprising a non-transitory computer readable medium that stores instructions for receiving, analyzing, modifying and sending without using dedicated HTTP cookies.

19. The computer program product according to claim 17 comprising a non-transitory computer readable medium that stores instructions for analyzing the response of the selected server to locate at least one instruction that is executed by a browser of the client and comprises a call to an operating system of the client to enable sending the other request.

20. The computer program product according to claim 17 comprising a non-transitory computer readable medium that stores instructions for adding the HTTP header for each call instruction of the code, if the other request and the modified response are associated with a same site, wherein each HTTP header comprises the selected server identifier.

21. The computer program product according to claim 17 comprising a non-transitory computer readable medium that stores instructions for:

receiving, by the intermediate node, the other request from the client;

removing the selected server identifier to provide a modified other request; and

sending to the selected server information indicative of the modified other request.

22. The computer program product according to claim 17 comprising a non-transitory computer readable medium that stores instructions for:

receiving a selected server response that comprises compressed code;

de-compressing the compressed code to provide de-compressed code;

analyzing the de-compressed code;

modifying, in response to the analysis result, the de-compressed code by adding information that will cause the client to send the selected server identifier in association to the sending of the other request;

compressing the modified de-compressed code to provide a compressed modified code; and

sending a modified response to the client, wherein the modified response comprises the compressed modified code.

23. The computer program product according to claim 17 comprising a non-transitory computer readable medium that stores instructions for:

receiving a selected server response that comprises encrypted code;

decrypting the encrypted code to decrypted code;

analyzing the decrypted code;

modifying, in response to the analysis result, the decrypted code by adding information that will cause the client to send the selected server identifier in association to the sending of the other request;

encrypting the modified decrypted code to provide an encrypted modified code; and

sending a modified response to the client, wherein the modified response comprises the encrypted modified code.

24. The computer program product according to claim 17 comprising a non-transitory computer readable medium that stores instructions for modifying, in response to the analysis result, the code by adding information that will cause the client to send the selected server identifier in association to the sending of the other request if the other request and the modified response are associated with a same site.