SYSTEMS AND METHODS FOR CACHING CONTENT WITH NOTIFICATION-BASED INVALIDATION

• US 20150100660A1
• Filed: 10/04/2013
• Published: 04/09/2015
• Est. Priority Date: 10/04/2013
• Status: Active Grant

• Current Assignee: Akamai Technologies, Inc.
• Original Assignee: Akamai Technologies, Inc.
• Inventors: Flack, Martin T., Steiner, Moritz M., Ludin, Stephen L., Hatala, Jozef
• Granted Patent: US 9,648,125 B2
• Time in Patent Office: Days
• US Class Current: 709/213
• CPC Class Codes: H04L 2209/76 Proxy, i.e. using intermediary entity to perform cryptographic operations network architectures or network communication protocols using hop-by-hop encryption H04L63/0464
• CPC Class Codes: H04L 63/0884 by delegation of authentication, e.g. a proxy authenticates an entity to be authenticated on behalf of this entity vis-à-vis an authentication entity
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04N 21/23106 involving caching operations prefetching while addressing of a memory level in which the access to the desired data or data block requires associative addressing means within memory systems or architectures G06F12/0862; caching at an intermediate stage in a data network H04L67/568

Abstract

Described herein are systems, devices, and methods for content delivery on the Internet. In certain non-limiting embodiments, a caching model is provided that can support caching for indefinite time periods, potentially with infinite or relatively long time-to-live values, yet provide prompt updates when the underlying origin content changes. In one approach, an origin server can annotate its responses to content requests with tokens, e.g., placing them in an appended HTTP header or otherwise. The tokens can drive the process of caching, and can be used as handles for later invalidating the responses within caching proxy servers delivering the content. Tokens may be used to represent a variety of kinds of dependencies expressed in the response, including without limitation data, data ranges, or logic that was a basis for the construction of the response.

Claims

1. A computer-implemented method operable in a server that has circuitry forming one or more processors and memory holding instructions for execution by the one or more processors, the method comprising:

receiving a client request;

in response to the client request, generating a forward request to a remote source;

receiving a response to the forward request from the remote source, the response comprising responsive content and at least one token;

locally caching the responsive content and the at least one token;

serving the responsive content to the client, in response to the client request;

receiving a message indicating that the at least one token is invalid; and

treating the cached responsive content as invalid to serve in response to a subsequent client request because the responsive content is associated with the at least one token that was indicated to be invalid in the message.

2. The method of claim 1, wherein the message comprises an explicit assertion that the at least one token is invalid.

3. The method of claim 1, wherein the message comprises an implicit assertion that the at least one token is invalid.

4. The method of claim 1, wherein the at least one token comprises a moniker and a serial number or timestamp, and the message indicates that the at least one token is invalid because the message includes the moniker and a different serial number or timestamp.

5. The method of claim 1, where the message is received from the remote source.

6. The method of claim 1, wherein the server is one of a plurality of nodes in a CDN and the message is received from a node in the CDN.

7. The method of claim 1, where the client request comprises a request for service from an application programmer interface (API), and the response is an API response.

8. The method of claim 1, where the remote source comprises one or more origin servers associated with a content provider.

9. The method of claim 1, where the server is a proxy server in a CDN.

10. The method of claim 1, wherein the at least one token corresponds to data in a database at the remote source that was used to construct the response.

11. The method of claim 1, wherein the at least one token corresponds to a primary key in a database at the remote source.

12. The method of claim 1, wherein the at least one token corresponds to a data selection or sorting function that was used by the remote source to select or sort data used in constructing the response.

13. The method of claim 1, wherein the token denotes a data structure at the source and the message is received following an update to data in the data structure.

14. The method of claim 1, wherein the at least one token corresponds to a file at the source that was used to construct the response.

15. The method of claim 1, wherein the at least one token corresponds to a key into a memory object caching system at the remote source.

16. The method of claim 1, further comprising

sending a plurality of other forward requests;

receiving a plurality of other responses, at least some of which comprise the at least one token;

caching the plurality of other responses;

following receipt of the message, treating each of the other responses that comprised the at least one token as invalid to serve in response to client requests.

17. The method of claim 1, wherein the at least one token comprises a moniker and an identification of a data range, and the message comprises the moniker and an identification of at least one particular data value within the data range.

18. The method of claim 1, wherein the response comprises responsive content and a header holding the at least one token.

18-1. An apparatus, comprising:

a microprocessor and memory storing computer-program instructions for execution by the one or more microprocessors, the execution of the computer-program instructions causing the apparatus to;

receive a client request;

in response to the client request, generate a forward request to a remote source;

receive a response to the forward request from the remote source, the response comprising responsive content and at least one token;

cache the responsive content and the at least one token in a cache local to the apparatus;

serve the responsive content to the client, in response to the client request;

receive a message indicating that the at least one token is invalid; and

treat the cached responsive data as invalid to serve in response to a subsequent client request because the responsive data is associated with the at least one token that was indicated to be invalid in the message.

19. A computer-implemented method operable in a server that has circuitry forming one or more processors and memory holding instructions for execution by the one or more processors, the method comprising:

receiving content having appended thereto one or more tokens;

caching the content and the one or more tokens;

receiving a client request for content;

determining that cached content is responsive to the request;

determining whether each of the cached one or more tokens are valid;

upon a determination that all of the one or more cached tokens are valid, serving the cached response to the client;

upon a determination that at least one of the one or more cached tokens are not valid, sending a forward request to a remote source for the content.

20. The method of claim 19, further comprising decorating the one or more tokens that were appended to the response before caching the one or more tokens.

21. The method of claim 19, wherein the determination of whether a given one of the one or more cached tokens that were received with the response is valid comprises:

comparing any of a timestamp and a serial number of the given token with a respective timestamp or serial number of a corresponding token stored in a cache of current tokens.

22. The method of claim 19, wherein the client request is directed to a URL and the determination that the cached content is responsive to the request is based on locating cached content corresponding to at least a portion of the URL.

23. The method of claim 19, wherein the client request is directed to a URL and the determination that the cached content is responsive to the request is based on locating cached content corresponding to at least a portion of the URL and another value extracted from the client request.

24. A system, comprising:

a plurality of distributed servers operated by a CDN service provider, the plurality of distributed servers receiving requests from clients for content accessible via an application programmer'"'"'s interface (API);

in response to the requests from clients, the plurality of distributed servers generating respective forward requests to at least one origin server associated with an API content provider;

the plurality of distributed servers receiving respective API responses from the at least one origin server, the respective API responses comprising responsive data and one or more tokens;

the plurality of distributed servers storing the respective API responses in respective local caches;

the at least one origin server generating an invalidation directed to at least one token of the one or more tokens and sending the invalidation to at least one machine operated by the CDN service provider;

the at least one machine sending the invalidation to the plurality of distributed servers;

wherein each of the plurality of distributed servers, as a result of receiving the invalidation, treats locally stored API responses that are associated with the at least one token as invalid to serve in response to subsequent client requests.

25. The system of claim 24, wherein the at least one origin server generates a given API response by obtaining data from a database and including one or more tokens that correspond to the data in the database from which the given API response was generated.

26. The system of claim 24, wherein the at least one origin server generates a given invalidation upon a change in given data in a database supporting the API, where the invalidation comprises a token corresponding to the data that changed.

27. The system of claim 24, where the plurality of distributed servers comprises a plurality of caching proxy servers.

28. The system of claim 24, wherein the at least one origin server generates a given API response by obtaining data from a database and including one or more tokens that correspond to a data selection or sorting function that was used by the at least one origin server to select or sort the responsive data in creating the given API response.