Systems and methods of dynamically checking freshness of cached objects based on link status

• US 8,037,126 B2
• Filed: 03/12/2007
• Issued: 10/11/2011
• 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
• Primary Examiner(s): Jean; Frantz B
• Application Number:
  US11/685,139
• Publication Number:
  US 20080229024A1
• Time in Patent Office: 1,674 Days
• Field of Search: 709/203, 709/219, 709/218, 709/249, 709/227, 709/228
• US Class Current: 709/203
• 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

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 dynamically determining whether to check a status of a cached object based on an operational characteristic of a connection to a remote object server, the method comprising the steps of:

(a) receiving, by a device intermediary to a requestor and a server, an object transmitted from the server to the requestor via a transport layer connection between the device and the server, the device storing the object in a cache;

(b) detecting, by the device, that an operational characteristic of the transport layer connection between the device and the server is within a predetermined threshold; and

(c) determining, by the device in response to the detection, to transmit a request to the server to check a freshness of the object stored in the cache.

2. The method of claim 1, wherein step (a) comprises forwarding, by the device, the object to the requestor.

3. The method of claim 1, wherein step (b) comprises detecting, by the device, available bandwidth via the transport layer connection to the server is not within the predetermined threshold.

4. The method of claim 1, wherein step (c) comprising determining, by the device in response to the detection, to not transmit the request to the server.

5. The method of claim 1, wherein step (b) comprises detecting, by the device, a speed of the transport layer connection to the server is not within the predetermined threshold.

6. The method of claim 5, wherein step (c) comprising determining, by the device in response to the detection, to not transmit the request to the server.

7. The method of claim 1, wherein step (b) comprises detecting, by the device, a roundtrip time of the transport layer connection to the server is not within the predetermined threshold.

8. The method of claim 7, wherein step (c) comprising determining, by the device in response to the detection, to not transmit the request to the server.

9. The method of claim 1, wherein step (b) comprises detecting, by the device, one of the server is not available via the transport layer connection or the transport layer connection is not operational.

10. The method of claim 1, wherein step (c) comprising determining, by the device in response to the detection, to not transmit the request to the server.

11. The method of claim 1, wherein step (b) comprises detecting, by the device, an operational characteristic of the transport layer connection to the server is within the predetermined threshold for freshening the object in the cache.

12. The method of claim 11, wherein step (c) comprising transmitting, by the device in response to the detection, the request to the server to obtain the status of the object.

13. The method of claim 12, comprising transmitting, by the device, the request to the server prior to a user requesting the object from the page.

14. The method of claim 12, comprising transmitting, by the device, a conditional request for the object to the server.

15. The method of claim 12, comprising receiving, by the device, an updated version of the object from the server, and storing the object in the cache.

16. The method of claim 12, comprising receiving, by the device, the status of the object indicating the object in the cache is stale, and in response to the status, transmitting a second request for the object to the server.

17. The method of claim 1, wherein step (b) comprises detecting, by the device, that the transport layer connection to the server has available bandwidth greater than a predetermined bandwidth threshold, and wherein step (c) comprising transmitting, by the device, the request to the server in response to the detection.

18. The method of claim 1, wherein the device comprises one of a client or an appliance intercepting and forwarding communications between the client and the server.

19. In a networked environment including a network appliance acting as a proxy between a client requesting pages and a server responding to client requests, an appliance for dynamically determining whether to check a status of a cached object based on an operational characteristic of a connection to the server, the appliance comprising:

means for intercepting, by a device intermediary to a client and a server, an object transmitted from the server to the client via a transport layer connection between the device and the server and storing the object in a cache;

means for detecting that an operational characteristic of the transport layer connection between the device and the server is within a predetermined threshold; and

means for determining, in response to the detection, to transmit a request to the server to check freshness of the object stored in the cache.

20. The appliance of claim 19, wherein the appliance forwards the object to the client.

21. The appliance of claim 19, comprising means for detecting available bandwidth via the transport layer connection to the server is not within the predetermined threshold.

22. The appliance of claim 21, comprising means for determining, in response to the detection, to not transmit the request to the server.

23. The appliance of claim 19, comprising means for detecting a speed of the transport layer connection to the server is not within the predetermined threshold.

24. The appliance of claim 23, comprising means for determining, in response to the detection, to not transmit the request to the server.

25. The appliance of claim 19, comprising means for detecting a round-trip time of the transport layer connection to the server is not within the predetermined threshold.

26. The appliance of claim 25, comprising means for determining, in response to the detection, to not transmit the request to the server.

27. The appliance of claim 19, comprising means for detecting one of the server is not available via the transport layer connection or the transport layer connection is not operational.

28. The appliance of claim 27, comprising means for determining, in response to the detection, to not transmit the request to the server.

29. The appliance of claim 19, comprising means for detecting an operational characteristic of the transport layer connection to the server is within the predetermined threshold for freshening the object in the cache.

30. The appliance of claim 29, comprising means for transmitting, in response to the detection, the request to the server to obtain the status of the object.

31. The appliance of claim 19, comprising means for transmitting the request to the server prior to a user requesting the object from the page.

32. The appliance of claim 19, where the appliance transmits a conditional request for the object to the server.

33. The appliance of claim 32, comprising a cache manager for receiving an updated version of the object from the server, and storing the object in the cache.

34. The appliance of claim 32, comprising means for receiving the status of the object indicating the object in the cache is stale, and in response to the status, transmitting a second request for the object to the server.

35. The appliance of claim 19, comprising means for detecting that the transport layer connection to the server has available bandwidth greater than a predetermined bandwidth threshold, and transmitting the request to the server in response to the detection.

36. A system comprising a device deployed between a client and a server, the system determining whether to check a status of a cached object based on an operational characteristic of a transport layer connection between the device and the server, the system comprising:

a device deployed between a client and a server receiving from the server a page transmitted by the server to the client via a transport layer connection between the device and the server, the page identifying a first object, the device storing the first object in a cache;

a detector of the device detecting whether available network bandwidth of the transport layer connection between the device and the server is greater than a predetermined bandwidth threshold; and

wherein the device determines, in response to the detector detecting that the available network bandwidth of the transport layer connection between the device and the server is greater than the predetermined bandwidth threshold, to transmit a first request to the server via the transport layer connection to obtain a first status of the first object from the server for the first object stored in the cache of the device; and

wherein the device determines not to request a status of a second object stored in the cache of the device while the detector detects that the available network bandwidth of the transport layer connection is below the predetermined bandwidth threshold.