Cache method

• US 20030055889A1
• Filed: 08/26/2002
• Published: 03/20/2003
• Est. Priority Date: 08/27/2001
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Ho, Chi-Fan, Chen, Meng-Cheng
• Application Number:
  US10/227,673
• Publication Number:
  US 20030055889A1
• Time in Patent Office: Days
• US Class Current: 709/203
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2340/02 Handling of images in compressed format, e.g. JPEG, MPEG
• CPC Class Codes: G09G 2360/121 using a cache memory
• CPC Class Codes: G09G 5/14 Display of multiple viewports
• CPC Class Codes: H04N 21/643 Communication protocols network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP], H04L65/65

Abstract

A method of transmitting update-display data (1) from a thin server device to a thin client device, the method comprising the steps of: generating a (short) key representing new update-display data (1) to be transmitted; comparing a newly generated key to a key or keys previously generated; compiling a message to be transmitted to the client device; the message comprising a header and code words representing the update-display data, wherein the header is set in dependence upon the result of the comparison step to identify to the client whether the update-display data is already cached, to be cached or not to be cached.

Preferably DCT coding is used.

A thin client server system using this method is faster and more efficient.

Claims

1. A method of transmitting update-display data from a thin server device to a thin client device, the method comprising the steps of:

generating a key (6) representing new update-display data (1) to be transmitted;

comparing a newly generated key to a key or keys previously generated; and

compiling a message to be transmitted to the client device,

wherein the message is set in dependence upon the result of the comparison step to identify to the client device whether the update-display data (1) is already cached, to be cached or not to be cached.

2. A method according to claim 1, wherein the message comprises a header (20) which comprises a cache instruction field (21) and a sequence identity field (22).

3. A method according to claim 2, wherein the cache instruction field contains an instruction corresponding to one of the commands:

“

cache”

, “

no cache” and

“

cached”

, and the sequence identity field (22) comprises a cache address.

4. A method according to claim 3, wherein the cache address is the address of the matching key when the command is “

cached”

.

5. A method according to claim 3, wherein the cache address is a new address when the command is “

cache”

.

6. A method according to claim 1, wherein the key is generated by transform coding of the update-display data (1).

7. A method according to claim 6, wherein the key comprises the combined length of all code words of the encoded update-display data (1).

8. A method according to claim 2, further comprising the initial step of checking the size of the update-display data (1) and setting the cache instruction field to “

no cache”

if the size of the update-display data (1) is less than a predetermined value.

9. A method according to claim 1, wherein the comparison step further comprises first comparing the size of the new update-display data (1) to the size of cached update-display data.

10. A method according to claim 8,wherein the size of the update-display data (1) comprises a width and a height of the data (1).

11. A method according to claim 1, further comprising the step of comparing code words of new update-display data (1) with cached update-display data if more than one matching key is identified in the cache data.

12. A method according to claim 2, wherein the client device sends a transmit code word message to the server if the sequence identity field (22) flags data lost from the client memory.

13. A thin client server computer system adapted for performing the method of claim 1.

14. Computer software for enabling a processor to carry out the method of claim 1.

15. A data carrier comprising the computer software according to claim 14.

16. A computer system comprising a server device having:

a cache memory;

a sequence identity generator to identify cache memory addresses;

a source data encoder;

a key generator for generating a key representing encoded source data;

a comparator for comparing a generated key to one or more cached keys;

a message generator linked to the comparator for generating different messages depending upon the output of the comparator;

a transmitter for sending the message to a client device;

the client device having;

a receiver for receiving the message from the server;

a cache memory;

a message reader; and

a display.