Systems and Methods of Revalidating Cached Objects in Parallel with Request for Object

• US 20080229021A1
• Filed: 03/12/2007
• Published: 09/18/2008
• Est. Priority Date: 03/12/2007
• Status: Active Grant

• Current Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Original Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Inventors: Plamondon, Robert
• Granted Patent: US 7,783,757 B2
• Time in Patent Office: Days
• US Class Current: 711/125
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54
• CPC Class Codes: H04L 67/5681 Pre-fetching or pre-delivering data based on network characteristics
• CPC Class Codes: H04L 67/5682 Policies or rules for updating, deleting or replacing the stored data
• CPC Class Codes: H04L 69/04 Protocols for data compression, e.g. ROHC

Abstract

The present solution provides a variety of techniques for accelerating and optimizing network traffic, such as HTTP based network traffic. The solution described herein provides techniques in the areas of proxy caching, protocol acceleration, domain name resolution acceleration as well as compression improvements. In some cases, the present solution provides various prefetching and/or prefreshening techniques to improve intermediary or proxy caching, such as HTTP proxy caching. In other cases, the present solution provides techniques for accelerating a protocol by improving the efficiency of obtaining and servicing data from an originating server to server to clients. In another cases, the present solution accelerates domain name resolution more quickly. As every HTTP access starts with a URL that includes a hostname that must be resolved via domain name resolution into an IP address, the present solution helps accelerate HTTP access. In some cases, the present solution improves compression techniques by prefetching non-cacheable and cacheable content to use for compressing network traffic, such as HTTP. The acceleration and optimization techniques described herein may be deployed on the client as a client agent or as part of a browser, as well as on any type and form of intermediary device, such as an appliance, proxying device or any type of interception caching and/or proxying device.

Claims

1. A method for revalidating an object stored in cache while serving the object to a requester, the method comprising the steps of:

(a) receiving a request for an object from a requester;

(b) determining that the object exists in a cache;

(c) transmitting, responsive to the determination, the cached object to the requester in response to the request; and

(d) transmitting, responsive to the determination, a request to a remote object server to determine a status of the object.

2. The method of claim 1, wherein steps (c) and (d) occur substantially simultaneously.

3. The method of claim 1, wherein steps (c) and (d) occur in parallel.

4. The method of claim 1, wherein step (d) occurs prior to step (c).

5. The method of claim 1, comprising transmitting the cached object to the requester prior to receiving a response from the remote object server.

6. The method of claim 1, wherein step (d) comprises transmitting to a remote object server, responsive to the determination, a conditional request to retrieve the object.

7. The method of claim 6, comprising receiving a response to the conditional request indicating the object has not changed.

8. The method of claim 6, comprising receiving an updated version of the object from the remote object server in response to the conditional request.

9. The method of claim 8, comprising storing the updated version of the object in the local cache.

10. The method of claim 1, wherein step (a) comprises receiving, via a network, a request for an object from a requester.

11. The method of claim 1, wherein step (b) comprises determining (i) that the object exists in the local cache and (ii) that a status identifier associated with the object indicates that the object is valid.

12. The method of claim 1, wherein step (c) comprises transmitting via a network, responsive to the determination, the requested object from the cache to the requester.

13. The method of claim 1, wherein step (d) comprises transmitting to the remote object server, responsive to the determination, a request to retrieve an updated version of the object.

14. A system for revalidating an object stored in cache while serving the object to a requester, the system comprising:

(a) a cache manager in communication with a requester, a remote object server and a local cache storing an object, the cache manager receiving a first request for the object from the requester;

(b) wherein, in response to locating the object in the local cache, the cache manager transmits the object to the requester in response to the first request, and in response to locating the object in the local cache, transmits a second request to obtain a status of the object from the remote object server.

15. The system of claim 14, wherein the cache manager comprises one of software or hardware.

16. The system of claim 14, wherein the local cache comprises one of random access memory or disk storage.

17. The system of claim 14, wherein the remote object server comprises a web server.

18. The system of claim 14, wherein the cache manager communicates with the requester via a network.

19. The system of claim 14, wherein the cache manager transmits the object to requester and transmits the second request to the remote object server substantially simultaneously.

20. The system of claim 14, wherein the cache manager transmits the object to requester and transmits the second request to the remote object server in parallel.

21. The system of claim 14, wherein the cache manager transmits the cached object to the requester prior to receiving a response from the remote object server.

22. The system of claim 14, wherein the cache manager transmits to the remote object server, responsive to the determination, a conditional request to retrieve the object.

23. The system of claim 22, wherein the cache manager receives a response to the conditional request indicating the object has not changed.

24. The system of claim 22, wherein the cache manager receives an updated version of the object from the remote object server in response to the conditional request.

25. The system of claim 25, wherein the cache manager stores the updated version of the object in the local cache.

26. In a networked environment including a network appliance acting as a proxy between a client requesting objects and an object server responding to client requests, a method for revalidation objects cached by the appliance while also serving the objects to the client, the method comprising;

(a) intercepting, by an appliance, a request from a client for an object from a remote object server;

(b) determining, by the appliance, that the object exists in a cache of the appliance;

(c) transmitting by the appliance, responsive to the determination, the cached object to the client in response to the request; and

(d) transmitting by the appliance, responsive to the determination, a request to obtain a status of the object from the remote object server.

27. The method of claim 26, wherein the appliance comprises a transparent proxy.

28. The method of claim 26, wherein steps (c) and (d) occur substantially simultaneously.

29. The method of claim 26, wherein steps (c) and (d) occur in parallel.

30. The method of claim 26, wherein step (d) occurs prior to step (c).

31. The method of claim 26, comprising transmitting, by the appliance, the cached object to the client prior to receiving a response from the remote object server.

32. The method of claim 26, wherein step (d) comprises transmitting, by the appliance, a remote object server, responsive to the determination, a conditional request to retrieve the object.

33. The method of claim 32, comprising receiving, by the appliance, a response to the conditional request indicating the object has not changed.

34. The method of claim 33, comprising receiving, by the appliance, an updated version of the object.

35. The method of claim 34, comprising storing, by the appliance, the updated version of the object in the cache.

36. The method of claim 32, wherein step (b) comprises determining, by the appliance, (i) that the object exists in a local cache element and (ii) that a status identifier associated with the object indicates that the object is valid.

37. In a networked environment including a network appliance acting as a proxy between a client requesting objects and an object server responding to client requests, an appliance revalidating objects cached by the appliance while also serving the objects to the client, the appliance comprising:

(a) a packet processing engine intercepting a first request from a client for an object from a server;

(b) a cache manager in communication with the packet processing engine, the cache manager determining the object is stored in a cache of the appliance responsive to the packet processing engine;

(c) wherein, in response to locating the object in the cache, the appliance transmits the object to the client in response to the first request, and in response to locating the object in the cache, transmits a second request to the server to obtain a status of the object.

38. The appliance of claim 37, wherein the cache manager comprises one of software or hardware.

39. The appliance of claim 37, wherein the cache comprises one of random access memory or disk storage.

40. The appliance of claim 37, wherein the appliance transmits the object to the client and transmits the second request to the server substantially simultaneously.

41. The appliance of claim 37, wherein the appliance transmits the object to the client and transmits the second request to the server in parallel.

42. The appliance of claim 37, wherein the appliance transmits the cached object to the client prior to receiving a response to the second request from the server.

43. The appliance of claim 37, wherein the appliance transmits to the server, responsive to the determination, a conditional request to retrieve the object.

44. The appliance of claim 44, wherein the appliance receives a response to the conditional request indicating the object has not changed.

45. The appliance of claim 44, wherein the cache manager receives an updated version of the object from the server in response to the conditional request.

46. The appliance of claim 44, wherein the cache manager stores the updated version of the object in the local cache.