Resource invalidation in a content delivery network

• US 20080215735A1
• Filed: 10/31/2007
• Published: 09/04/2008
• Est. Priority Date: 02/10/1998
• Status: Active Grant

• Current Assignee: Level 3 Communications LLC (Lumen Technologies, Inc.)
• Original Assignee: Level 3 Communications LLC (Lumen Technologies, Inc.)
• Inventors: Greer, Richard E., Farber, David A., Swart, Andrew D., Balter, James A.
• Granted Patent: US 8,060,613 B2
• Time in Patent Office: Days
• US Class Current: 709/226
• CPC Class Codes: G06F 16/957 Browsing optimisation, e.g. caching or content distillation
• CPC Class Codes: G06F 9/505 considering the load
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/10015 Access to distributed or replicated servers, e.g. using brokers
• CPC Class Codes: H04L 67/1006 with static server selection, e.g. the same server being selected for a specific client
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/101 based on network conditions
• CPC Class Codes: H04L 67/1012 based on compliance of requirements or conditions with available server resources
• CPC Class Codes: H04L 67/1019 Random or heuristic server selection
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs
• CPC Class Codes: H04L 67/1025 Dynamic adaptation of the criteria on which the server selection is based
• 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 67/2895 Intermediate processing functionally located close to the data provider application, e.g. reverse proxies
• CPC Class Codes: H04L 67/561 Adding application-functional data or data for application control, e.g. adding metadata
• CPC Class Codes: H04L 67/563 Data redirection of data network streams
• CPC Class Codes: H04L 67/564 Enhancement of application control based on intercepted application data
• CPC Class Codes: H04L 67/5682 Policies or rules for updating, deleting or replacing the stored data
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A repeater server in a content delivery network (CDN) maintains a list of resources that are no longer valid. When the server gets a request for a resource, it checks whether that resource is on the list, and, if so, it replicates the resource from a content provider'"'"'s content source such as an origin server. Otherwise the repeater server tries to serve a copy of the requested resource or to obtain a copy from another location in the CDN.

Claims

1. A method, in a system in which a plurality of content providers provide multiple resources to multiple clients, wherein each content provider provides at least some resources via one or more content sources associated with that content provider, and wherein at least some of said resources are to be served to clients from a shared content delivery network (CDN) formed by a plurality of repeater servers, the method comprising, at a particular repeater server in said CDN:

(A) receiving an indication that at least one resource is no longer valid, and, in response to said receiving, causing said at least one resource to be invalidated;

(B) responsive to a request of the particular repeater server to serve a particular resource of a particular content provider to a particular client, determining whether said particular resource has been invalidated, and

(C1) if the particular resource has been invalidated, then attempting to replicate an updated copy of the particular resource on the particular repeater server from at least one content sources associated with the content provider, and then serving the updated copy of the particular resource to the particular client; and

(C2) if the particular resource has not been invalidated, then

(c21) if a copy of the particular resource is not available on the particular repeater server, attempting to replicate a copy of the particular resource on the particular repeater server from another location in the system, and then serving the copy of the particular resource to the particular client, said another location in the system being another server in the CDN or at least one content sources associated with the content provider;

otherwise

(c22) if a copy of the particular resource is available on the particular repeater server, serving the copy of the particular resource to the particular client.

2. A method as recited in claim 1, wherein said indication that said at least one resource is no longer valid is determined from a resource invalidation message identifying said at least one resource that is no longer valid.

3. A method as recited in claim 2, wherein said message identifies said at least one resource that is no longer valid using an identifier of the at least one resource.

4. A method as recited in claim 2, wherein said message identifies said at least one resource that is no longer valid using one or more patterns

5. A method as recited in claim 2, further comprising:

sending an acknowledgement message for said resource invalidation message.

6. A method as recited in claim 2, further comprising:

causing said resource invalidation message to propagate to other repeater servers in said CDN.

7. A method as recited in claim 1, wherein a resource is no longer valid if the resource is stale.

8. A method as recited in claim 1, wherein a resource is no longer valid if the resource has changed.

9. A method as recited in claim 1, further comprising:

deleting at least some of said resources that are no longer valid prior to any request for said at least some of said resources.

10. A method, in a system in which a plurality of content providers provide multiple resources to multiple clients, wherein each content provider provides at least some resources via one or more content sources associated with that content provider, and wherein at least some of said resources are to be served to clients from a shared content delivery network (CDN) formed by a plurality of repeater servers, the method comprising:

(A) receiving a message identifying at least one resource that is stale; and

then

(B) responsive to the a request of a repeater server to serve the at least one resource that has been identified as stale, the request being the first request for said at least one resource that is received after said message has been received, attempting to replicate an updated copy of the particular resource on the repeater server from at least one content source associated with the content provider, and then attempting to serve the updated copy of the particular resource to the client.

11. A method as recited in claim 10, wherein said message is received at a first server in said CDN, the method further comprising:

responsive to said step of receiving, said first server propagating said message to other servers in said CDN.

12. A method as recited in claim 10, wherein said message identifies said at least one resource that is stale using an identifier of the at least one resource.

13. A method as recited in claim 10, wherein said message identifies said at least one resource that is stale using one or more patterns.

14. A method, in a system in which a plurality of content providers provide multiple resources to multiple clients, wherein each content provider provides at least some resources via one or more content sources associated with that content provider, and wherein at least some of said resources are to be served to clients from a shared content delivery network (CDN) formed by a plurality of repeater servers, the method comprising, at a particular repeater server in said CDN:

(A) obtaining a resource invalidation request message, said message identifying at least one resource of said multiple resources that is no longer valid; and

(B) causing said resource invalidation request message to be sent to others of said plurality of repeater servers in said CDN.

15. A method as recited in claim 14, further comprising:

(C) waiting for said others of said plurality of repeater servers to acknowledge the resource invalidation request message.

16. A method as recited in claim 14, further comprising:

if a repeater server in said CDN fails to acknowledge the resource invalidation request message within a given period, disconnecting said repeater server.

17. A method as recited in claim 16, further comprising:

when said repeater server reconnects, instructing said repeater server to flush its entire cache.

18. A method as recited in claim 15, further comprising:

if a repeater server in said CDN fails to acknowledge the resource invalidation request message within a given period, then instructing said repeater server to flush at least some of its cache.

19. A method as recited in claim 18, wherein said repeater server is instructed to flush its entire cache.

20. A method as recited in claim 15, further comprising:

when all repeater servers have either acknowledged the resource invalidation request message or have timed out,

broadcasting a second invalidation request to all repeaters servers to cause the repeater servers to remove the corresponding resource identifiers from the list of resource identifiers pending invalidation.

21. A method as recited in claim 15, further comprising:

when all repeater servers have either acknowledged the resource invalidation request message or have timed out,

broadcasting a second invalidation request to all repeaters servers to cause the repeater servers to remove the corresponding resource identifiers from the list of resource identifiers pending invalidation and further causes repeater servers receiving the second invalidation request to request a new copy of the invalidated resource.

22. A method, in a system in which a plurality of content providers provide multiple resources to multiple clients, wherein each content provider provides at least some resources via one or more content sources associated with that content provider, and wherein at least some of said resources are to be served to clients from a shared content delivery network (CDN) formed by a plurality of repeater servers, the method comprising:

(A) sending to at least one of said repeater servers in said CDN a first resource invalidation request message, said first message identifying at least one resource that is no longer valid, said first message causing at least some of the repeater servers in the CDN to mark the corresponding content as stale and pending invalidation; and

(C) responsive to at least some of said repeater servers acknowledging said first resource invalidation request message, causing a second resource invalidation request message to be sent to said plurality of repeater servers in said CDN, said second message causing at least some of the repeater servers to remove the corresponding resource identifiers from the list of resource identifiers pending invalidation.

23. A method, in a system in which a plurality of content providers provide multiple resources to multiple clients, wherein each content provider provides at least some resources via one or more content sources associated with that content provider, and wherein at least some of said resources are to be served to clients from a shared content delivery network (CDN) formed by a plurality of repeater servers, the method comprising:

(A) receiving a message identifying at least one resource that is no longer valid; and

then

(B) responsive to the next request of a repeater server to serve the at least one resource that has been identified as stale, obtaining an updated copy of the particular resource on the repeater server from at least one content sources associated with the content provider.

24. A method as recited in claim 23, further comprising:

after said updated copy of said particular resource has been obtained, serving the updated copy of the particular resource to the client.