Caching pagelets of structured documents

1. A method comprising:

receiving, by a server computing system, a request for a web page from a client computing device;

identifying, by the server computing system, one or more resource portions stored in a cache, each resource portion corresponding to a portion of a structured document for use by the client computing device to render the requested web page;

determining, by the server computing system, whether the client computing device has requested the web page within a predetermined time threshold since a previous request for the web page;

if the client computing device has requested the web page within the predetermined time threshold,

instructing, by the server computing system, the client computing device to render the requested web page using the one or more resource portions stored in the cache, and

refreshing the one or more resource portions, comprising:

generating difference data, if any, for the one or more resource portions, wherein the difference data for the one or more resource portions indicates changes to be made to the one or more resource portions;

instructing the client computing device to, in parallel with the generation of the difference data, render the one or more resource portions;

sending the difference data to the client computing device; and

instructing the client computing device to, based on the difference data, update the resource portions stored in the cache and render the updated resource portions; and

if the client computing device has not requested the web page within the predetermined time threshold,

regenerating, by the server computer system, the one or more resource portions, and

instructing, by the server computer system, the client computing device to render the requested web page using the regenerated one or more resource portions and cache the regenerated one or more resource portions.

2. The method of claim 1 , further comprising determining if a user event has occurred affecting a state of the one or more resource portions since the one or more resource portions were last stored in the cache, and

if the user event has occurred, regenerating the one or more resource portions to be stored in the cache based on the user event affecting the state of the one or more resource portions.

3. The method of claim 1 , wherein the cache is stored in a persistent storage of the client computing device.

4. The method of claim 3 , wherein the one or more resource portions are stored in the cache in an encrypted format, and rendering the requested web page using the one or more resource portions stored in the cache comprises decrypting the one or more resource portions.

5. The method of claim 3 , further comprising erasing the cache in response to a user event.

6. The method of claim 5 , wherein the user event comprises logging off from a web site from which the web page has been requested.

7. One or more computing devices associated with server computing system, the computing devices comprising:

one or more processors; and

one or more computer-readable non-transitory storage media embodying software that is configured when executed by one or more of the processors to:

receive, by the server computing system, a request for a web page from a client computing device;

identify, by the server computing system, one or more resource portions stored in a cache, each resource portion corresponding to a portion of a structured document for use by the client computing device to render the requested web page;

determine, by the server computing system, whether the client computing device has requested the web page within a predetermined time threshold since a previous request for the web page;

if the client computing device has requested the web page within the predetermined time threshold,

instruct, by the server computing system, the client computing device to render the requested web page using the one or more resource portions stored in the cache, and

refresh the one or more resource portions, comprising:

generating difference data, if any, for the one or more resource portions, wherein the difference data for the one or more resource portions indicates changes to be made to the one or more resource portions;

instructing the client computing device to, in parallel with the generation of the difference data, render the one or more resource portions;

sending the difference data to the client computing device; and

instructing the client computing device to, based on the difference data, update the resource portions stored in the cache and render the updated resource portions; and

if the client computing device has not requested the web page within the predetermined time threshold,

regenerate, by the server computer system, the one or more resource portions, and

instruct, by the server computer system, the client computing device to render the requested web page using the regenerated one or more resource portions and cache the regenerated one or more resource portions.

8. The computing devices of claim 7 , wherein the software is further configured to determine if a user event has occurred affecting a state of the one or more resource portions since the one or more resource portions were last stored in the cache, and

if the user event has occurred, regenerate the one or more resource portions to be stored in the cache based on the user event affecting the state of the one or more resource portions.

9. The computing devices of claim 7 , wherein the cache is stored in a persistent storage of the client computing device.

10. The computing devices of claim 9 , wherein the one or more resource portions are stored in the cache in an encrypted format, and the software is further configured to render the requested web page using the one or more resource portions stored in the cache by decrypting the one or more resource portions.

11. The computing devices of claim 9 , wherein the software is further configured to erase the cache in response to a user event.

12. The computing devices of claim 11 , wherein the user event comprises logging off from a web site from which the web page has been requested.

13. One or more computer-readable non-transitory storage media embodying software that is configured when executed to:

receive, by a server computing system, a request for a web page from a client computing device;

identify, by the server computing system, one or more resource portions stored in a cache, each resource portion corresponding to a portion of a structured document for use by the client computing device to render the requested web page;

determine, by the server computing system, whether the client computing device has requested the web page within a predetermined time threshold since a previous request for the web page;

if the client computing device has requested the web page within the predetermined time threshold,

instruct, by the server computing system, the client computing device to render the requested web page using the one or more resource portions stored in the cache, and

refresh the one or more resource portions, comprising:

generating difference data, if any, for the one or more resource portions, wherein the difference data for the one or more resource portions indicates changes to be made to the one or more resource portions;

instructing the client computing device to, in parallel with the generation of the difference data, render the one or more resource portions;

sending the difference data to the client computing device; and

instructing the client computing device to, based on the difference data, update the resource portions stored in the cache and render the updated resource portions; and

if the client computing device has not requested the web page within the predetermined time threshold,

regenerate, by the server computer system, the one or more resource portions, and

instruct, by the server computer system, the client computing device to render the requested web page using the regenerated one or more resource portions and cache the regenerated one or more resource portions.

14. The media of claim 13 , wherein the software is further configured to determine if a user event has occurred affecting a state of the one or more resource portions since the one or more resource portions were last stored in the cache, and

if the user event has occurred, regenerate the one or more resource portions to be stored in the cache based on the user event affecting the state of the one or more resource portions.

15. The media of claim 13 , wherein the cache is stored in a persistent storage of the client computing device.

16. The media of claim 15 , wherein the one or more resource portions are stored in the cache in an encrypted format, and the software is further configured to render the requested web page using the one or more resource portions stored in the cache by decrypting the one or more resource portions.

17. The media of claim 15 , wherein the software is further configured to erase the cache in response to a user event.

18. The media of claim 17 , wherein the user event comprises logging off from a web site from which the web page has been requested.