Method and apparatus for handling requests in a network

• US 7,069,325 B1
• Filed: 12/21/2001
• Issued: 06/27/2006
• Est. Priority Date: 12/21/2001
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Lu, Gang, O'Toole, James W. Jr.
• Primary Examiner(s): Najjar, Saleh
• Assistant Examiner(s): KOROBOV, VITALI A
• Application Number:
  US10/034,289
• Time in Patent Office: 1,649 Days
• Field of Search: 709203-208, 709213-219, 709/231, 709/232, 709/234, 709/239, 709/248, 709/235, 709/238, 709/223, 709/224, 709/226, 709/227
• US Class Current: 709/226
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 67/125 involving control of end-device applications over a network
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

The invention is directed to techniques for synchronizing a plurality of servers, receiving a client request from the client to access a server of the plurality of servers, generating a transmit identifier associated with the client request, the transmit identifier identifying an event upon the occurrence of which the plurality of synchronized servers each transmit a response to the client, forwarding the client request and the transmit identifier to each of the plurality of synchronized servers. The invention is also directed to techniques and mechanisms for receiving a client request associated with a client and receiving a transmit identifier identifying an event, generating a response to the client request, and transmitting the response to the client upon an occurrence of the event identified by the transmit identifier.

Claims

1. A method for responding to a client request, the method comprising the steps of:

synchronizing a plurality of servers;

receiving a client request from the client to access a server of the plurality of servers;

generating a transmit identifier associated with the client request, the transmit identifier identifying an event upon the occurrence of which the plurality of synchronized servers each transmit a response to the client, wherein said transmit identifier includes a timestamp reflecting an arrival time of the client request, wherein a predetermined delay is added to the timestamp to produce the transmit identifier, wherein the predetermined delay is greater than a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server and wherein the transmit identifier is associated with the client request; and

forwarding the client request and the transmit identifier to each of the plurality of synchronized servers.

2. The method of claim 1 wherein the step of synchronizing comprises the steps of:

synchronizing a clock mechanism in each of the plurality of servers.

3. The method of claim 1 wherein the step of associating the transmit identifier comprises the step of:

combining the transmit identifier into the client request.

4. The method of claim 1 wherein the step of obtaining the timestamp is performed upon receipt of the client request.

5. The method of claim 1 wherein the client request is received in a request queue, and wherein the step of obtaining the timestamp is performed at a time of processing the client request from the request queue.

6. The method of claim 1 wherein the transmit identifier identifies the event indicating a future time within each of the plurality of servers at which each of the plurality of servers responds to the client request;

and

wherein the future time is related to a predetermined delay associated with at least one of the plurality of servers.

7. The method of claim 1 wherein the step of generating the transmit identifier includes adding a predetermined delay to the timestamp to produce the transmit identifier, and combining the transmit identifier with the client request, wherein the client request is received in a request queue, wherein the step of obtaining the timestamp is performed at a time of processing the client request from the request queue, and wherein the transmit identifier identifies the event indicating a future time within each of the plurality of servers at which each of the plurality of servers responds to the client request, and wherein the future time is related to a predetermined delay associated with at least one of the plurality of servers.

8. A method for responding to a client request, the method comprising the steps of:

receiving a client request associated with a client and receiving a transmit identifier identifying an event, wherein said transmit identifier includes a timestamp reflecting an arrival time of the client request and wherein a predetermined delay is added to the timestamp to produce the transmit identifier, wherein the predetermined delay is greater than a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server and wherein the transmit identifier is associated with the client request;

generating a response to the client request; and

transmitting the response to the client upon an occurrence of the event identified by the transmit identifier.

9. The method of claim 8 further including the step of:

accepting a time synchronization signal; and

synchronizing a clock based on the synchronization signal.

10. A master server for handling content requests comprising:

a memory;

a communications interface;

a processor; and

an interconnection mechanism coupling the memory, the processor and the communications interface;

wherein the memory is encoded with a request handler application that when performed on the processor, produces a request handler process that causes the master server to provide a client request and transmit identifier in response to a client request such that the processor is configured to;

synchronize a plurality of servers;

receive a client request from the client to access a server of the plurality of servers;

generate a transmit identifier associated with the client request, the transmit identifier identifying an event upon the occurrence of which the plurality of synchronized servers each transmit a response to the client, and wherein said transmit identifier includes a timestamp reflecting an arrival time of the client request, wherein a predetermined delay is added to the timestamp to produce the transmit identifier, wherein the predetermined delay is greater than a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server and wherein the transmit identifier is associated with the client request; and

forward the client request and the transmit identifier to each of the plurality of synchronized servers.

11. The master server of claim 10 wherein, to synchronize a plurality of servers, the master server is configured to:

synchronize a clock mechanism in each of the plurality of servers.

12. The master server of claim 10 wherein, to associate the transmit identifier, the master server is configured to:

combine the transmit identifier into the client request.

13. The master server of claim 10 wherein the master server is configured to obtain the timestamp upon receipt of the client request.

14. The master server of claim 10 wherein the master server is configured such that the client request is received in a request queue, and wherein the master server obtains the timestamp at a time of processing the client request from the request queue.

15. The master server of claim 10 wherein the master server is configured such that the transmit identifier identifies the event indicating a future time within each of the plurality of servers at which each of the plurality of servers responds to the client request;

and

wherein the future time is related to a predetermined delay associated with at least one of the plurality of servers.

16. The master server of claim 10 wherein the master server is configured such that the predetermined delay is less than or equal to a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server.

17. A slave server for handling content requests comprising:

a memory;

a communications interface;

a processor; and

an interconnection mechanism coupling the memory, the processor and the communications interface;

wherein the memory is encoded with a request agent application that when performed on the processor, produces a request agent process that causes the slave server to provide content to a client, in response to a client request and a transmit identifier, such that the processor is configured to;

receive a client request associated with a client and receiving a transmit identifier identifying an event, and wherein said transmit identifier includes a timestamp reflecting an arrival time of the client request, wherein a predetermined delay is added to the timestamp to produce the transmit identifier, wherein the predetermined delay is greater than a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server and wherein the transmit identifier is associated with the client request;

generate a response to the client request; and

transmit the response to the client upon an occurrence of the event identified by the transmit identifier.

18. The slave server of claim 17 wherein, the slave server is further configured to:

accept a time synchronization signal; and

synchronize a clock based on the synchronization signal.

19. A system for identifying a server that provides the fastest response to a client request comprising:

a master server, which is configured to (i) receive a client request from the client to access a server of a plurality of slave servers, (ii) generate a transmit identifier associated with the client request, the transmit identifier identifying an event upon the occurrence of which the plurality of synchronized servers each transmit a response to the client, and wherein said transmit identifier includes a timestamp reflecting an arrival time of the client request, wherein a predetermined delay is added to the timestamp to produce the transmit identifier, wherein the predetermined delay is greater than a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server and wherein the transmit identifier is associated with the client request and (iii) forward the client request and the transmit identifier to each of the plurality of synchronized servers; and

a slave server, which is configured to (i) receive a client request associated with a client and receive a transmit identifier identifying an event (ii) generate a response to the client request, and transmit the response to the client upon an occurrence of the event identified by the transmit identifier.

20. A computer program product having a computer-readable medium including computer program logic encoded thereon that, when performed on a processor in a computerized device having a coupling of a memory, a processor, and at least one communications interface provides a method for providing a response to a client request by performing the operations of:

synchronizing a plurality of servers;

receiving a client request from the client to access a server of the plurality of servers;

generating a transmit identifier associated with the client request, the transmit identifier identifying an event upon the occurrence of which the plurality of synchronized servers each transmit a response to the client, and wherein said transmit identifier includes a timestamp reflecting an arrival time of the client request, wherein a predetermined delay is added to the timestamp to produce the transmit identifier, wherein the predetermined delay is greater than a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server and wherein the transmit identifier is associated with the client request; and

forwarding the client request and the transmit identifier to each of the plurality of synchronized servers.

21. An apparatus for responding to a client request comprising:

a memory;

a communications interface;

a processor; and

an interconnection mechanism coupling the memory, the processor and the communications interface;

wherein the memory is encoded with a request handler application that when performed on the processor, produces a means to enable the client request and transmit identifier to be forwarded to at least one slave server, such means including;

means for synchronizing a plurality of servers;

means for receiving a client request from the client to access a server of the plurality of servers;

means for generating a transmit identifier associated with the client request, the transmit identifier identifying an event upon the occurrence of which the plurality of synchronized servers each transmit a response to the client, and wherein said transmit identifier includes a timestamp reflecting an arrival time of the client request, wherein a predetermined delay is added to the timestamp to produce the transmit identifier, wherein the predetermined delay is greater than a maximum transmission delay for transmission of the client request to one of the plurality of servers from a master server and wherein the transmit identifier is associated with the client request; and

means for forwarding the client request and the transmit identifier to each of the plurality of synchronized servers.