Signature Based Map Caching

• US 20120173606A1
• Filed: 12/29/2010
• Published: 07/05/2012
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: Environmental Systems Research Institute Incorporated
• Original Assignee: Environmental Systems Research Institute Incorporated
• Inventors: Becker, Peter
• Granted Patent: US 8,880,589 B2
• Time in Patent Office: Days
• US Class Current: 709/203
• CPC Class Codes: G01C 21/3667 Display of a road map G01C21/3614 takes precedence; guidance using 3D or perspective road maps G01C21/3635
• CPC Class Codes: G01C 21/3878 Hierarchical structures, e.g. layering
• CPC Class Codes: G01C 21/3881 Tile-based structures
• CPC Class Codes: G09B 29/004 Map manufacture or repair; Tear or ink or water resistant maps; Long-life maps printing processes for maps B41M3/02; by permanently attaching map sections to sheets B42B7/00

Abstract

Systems, methods, and computing devices for building, operating and using map systems with signature-based map caches are disclosed. Based on the desired map properties included in a formatted map request, a map signature can be generated. The map signature can be used to access a signature based map cache to determine whether a map with identical map properties has been previously generated and stored in cache or otherwise available for retrieval. If the map signature exists in the map cache, the corresponding map can be delivered to a map client. If the map signature does not exist in the map cache, then a map can be generated or rendered based on the map properties in the map request. Once the map is generated, it can be saved to the map cache along with associated map signature for future retrieval.

Claims

1. A method for operating a map server comprising a processor, a cache memory and a network interface, the method comprising:

receiving a map request from a map client over the network interface using the processor;

obtaining a map signature based on the map request using the processor;

accessing the cache memory using the processor;

determining if the cache memory includes the map signature using the processor;

if the cache memory includes the map signature, then retrieving a map associated with the map signature from the cache memory using the processor.

7. The method of claim 1 wherein obtaining the map signature comprises applying a hash function to at least some map properties in the map request.

8. The method of claim 1 wherein receiving the map request comprises converting the map request from a first map request format to a second map request format.

9. The method of claim 1 wherein receiving the map request comprises generating a plurality of map tile requests based on the received map request.

10. The method of claim 9 wherein obtaining a map signature comprises generating a plurality of map tile signatures based on the generated map tile requests and determining if the cache memory includes the map signature comprises determining if the cache memory includes at one of the generated map tile signatures.

11. The method of claim 10 wherein obtaining the plurality of map tile signatures comprises applying a hash function to the plurality of map tile requests.

12. The method of claim 11 wherein the hash function is an MD5 hash function.

13. The method of claim 9 wherein generating the map signature comprises applying a hash function to the map request in the second map request format.

2. The method of 1 wherein if the cache memory does not include the map signature, then generating a map in response to the map request using the processor.

3. The method of claim 2 further comprising associating the generated map with the map signature;

and

storing the generated map and the map signature to the cache memory.

4. The method of claim 3 wherein storing the generated map and the map signature to the cache memory comprises sending the generated map and the map signature to a cache manager server computer.

5. The method of claim 4 further comprising receiving cache updates from the map server computer.

6. The method of claim 3 further comprising sending the retrieved or generated map associated with the map signature over the network interface to the map client.

14. A map server comprising:

a network interface configured to communicate with an external network;

a processor coupled to the network interface; and

a cache memory coupled to the processor;

wherein the processor is configured to execute computer readable code to;

receive a map request message from a map client over the network interface;

obtain a map signature based on the map request message;

access the cache memory;

determine if the cache memory includes the map signature;

if the cache memory includes the map signature, then retrieve a map associated with the map signature from the cache memory.

15. The map server of claim 14 wherein the processor is further configured to execute computer readable code to send the retrieved map associated with the map signature to the map client over the network interface.

16. The map server of claim 14 wherein the processor is further configured to execute computer readable code to generate a map in response to the map request message.

17. The map server of claim 15 wherein the processor is further configured to execute computer readable code to send the map associated with the map signature to the map client over the network interface.

18. The map server of claim 16 wherein the processor is further configured to execute computer readable code to send the retrieved or generated map associated with the map signature over the network interface to the map client.

19. The map server of claim 18 wherein the processor is further configured to execute computer readable code to associate and store the generated map and the map signature in the cache memory.

20. The map server of claim 19 wherein the processor is further configured to execute computer executable code to send updates to and receive updates from a cache manager.