RULE BASED CACHE PROCESSING IN APPLICATION DELIVERY CONTROLLER FOR LOAD BALANCING

• US 20160285992A1
• Filed: 03/26/2015
• Published: 09/29/2016
• Est. Priority Date: 03/26/2015
• Status: Active Grant

• Current Assignee: Fortinet Inc.
• Original Assignee: Fortinet Inc.
• Inventors: Katsev, Sergey
• Granted Patent: US 10,560,543 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/1014 based on the content of a request
• CPC Class Codes: H04L 67/535 Tracking the activity of the user network monitoring arrangements H04L43/00; recording of computer activity G06F11/34
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 67/5682 Policies or rules for updating, deleting or replacing the stored data

Abstract

Methods and systems for improving performance of an HTTP cache are provided. According to one embodiment, an HTTP request is received by an ADC for a resource associated with a server on behalf of which the ADC is performing load balancing. The ADC determines based on a local HTTP cache whether it can service the request. The request is parsed to identify a header. The existence or non-existence of locally cached content matching the request is identified by comparing portions of the identified header with corresponding portions of header information of cached content based on a vary rule defining when two headers are meaningfully different. Therefore, the identified header need not exactly match an entirety of the cached information for a cache hit to be found. Responsive to a cache hit, the ADC responds to the request with an HTTP response containing the identified locally cached content.

Claims

1. A method comprising:

receiving, by an Application Delivery Controller (ADC), a Hypertext Transfer Protocol (HTTP) request from a client device for a resource associated with at least one of a plurality of servers on behalf of which the ADC is performing load balancing;

determining, by the ADC, with reference to an HTTP cache of the ADC whether the HTTP request can be serviced by the ADC by;

parsing, by the ADC, the HTTP request to identify a header contained therein; and

identifying existence or non-existence of locally cached content matching the HTTP request by comparing appropriate portions of the identified header with corresponding appropriate portions of a plurality of headers of content cached within the HTTP cache based on a vary rule automatically generated by the ADC or configured by an administrator of the ADC that defines when two headers are meaningfully different, whereby the identified header is not required to exactly match up with an entirety of one of the plurality of headers for a cache hit to be found; and

when a result of said determining indicates the HTTP request can be serviced by the ADC, then responding to the HTTP request, by the ADC, with an HTTP response containing the identified locally cached content.

2. The method of claim 1, further comprising when the result indicates the HTTP request cannot be serviced by the ADC, then selecting a server of the plurality of servers to service the HTTP request.

3. The method of claim 1, wherein the identified header comprises a cookie header, wherein the vary rule is configured to define conditions under which the cookie header matches a cached cookie header stored in the HTTP cache, and wherein the cookie header contains an identifier of a server of the plurality of servers that previously processed at least one HTTP request from the client device.

4. The method of claim 1, wherein the vary rule is used in conjunction with a Vary header in the HTTP cache.

5. The method of claim 1, wherein the vary rule is in a form of one or more of a string with one or more wildcards and a regular expression.

6. The method of claim 1, wherein the result is based on one or more of information regarding a server of the plurality of servers that processed prior HTTP requests by the client device and field values of one or more vary fields that the server defined in connection with responding to the prior HTTP requests.

7. A load balancing system comprising:

a Hypertext Transfer Protocol (HTTP) request receiving module configured to receive, from a client device, an HTTP request;

an HTTP request parsing module configured to parse, at an application delivery controller (ADC), the HTTP request to identify one or more headers;

a cache search module configured to enable searching, by the ADC, to determine whether a resource requested in the HTTP request is present in a local HTTP cache, wherein when the resource is not present in the local HTTP cache, load balancing is performed to allocate the HTTP request to one of a plurality of servers;

a rule-based cache hit determination module configured to execute a vary rule on the one or more headers to determine whether a cache hit is found, wherein the vary rule is formed to evaluate whether the cached response is eligible to be sent back to the client device such that if eligibility is confirmed, the cached response is sent back to the client device.

8. The system of claim 7, wherein in case said cache hit is not found, load balancing is performed to allocate said HTTP request to a server.

9. The system of claim 7, wherein said rule is configured to match cookie information of at least one of said one or more headers with cookie information stored in said cache, and wherein said cookie information pertains server identifier that had processed at least one prior HTTP request from said client device.

10. The system of claim 7, wherein said rule forms part of vary field of header information.

11. The system of claim 7, wherein header of said one or more headers of said HTTP request that stores the persistence information is a cookie header.

12. The system of claim 7, wherein said eligibility is confirmed based on information selected from one or a combination of server that processed prior requests, and field values of one or more vary fields that a server had defined while responding to said HTTP request.

13. The system of claim 7, wherein said rule matches any or a combination of full string match, substring match, semantic match, list match, and regular expression match.