Predictive predownload of templates with delta encoding
Techniques for predictive predownload of templates with delta caching are used to substantially minimize the time needed to send objects from a server to a client. A template builder generates templates for each web page. A prediction engine maintains a prediction map, responsive to web pages and other objects, the objects including the templates for web pages. The prediction engine selects objects likely to be requested by the client making the particular request, such as a next page or an object referenced by a page. A delta encoder for a page determines a delta between a current version of that page, and a template for that page, and encodes the page for delivery to the client using template information and delta information. The client is able to present the web page in response to the template information (which is likely already present at the client) and the delta information.
1. A method of predictive predownloading of next objects with delta encoding, including steps of:
receiving from a client a request for an object;
updating a prediction map in response to the request and a referring page that indicates an object just previously requested by the client, the prediction map associating the requested object with next objects likely to be requested;
maintaining a stored set of templates for the requested object, each template comprising a selected portion of the requested object that is unchanging between instances of the requested object;
calculating delta information for one particular template of the stored set of templates, delta information comprising selected portions of the requested object that vary between instances of the requested object; and
sending to the client (i) a hint that includes a suggestion to download a next object based on the prediction map embedded in a response message with (ii) delta information for the requested object that specifies the particular template.
2. The method of claim 1 wherein the requested object comprises a web page.
3. The method of claim 1 wherein the hint comprises information to be stored in a client cache.
4. The method of claim 1 wherein the sending step comprises sending to the client the next object.
5. The method of claim 1 wherein the maintaining step comprises conditionally building a new template when the delta information exceeds a selected threshold.
6. The method of claim 1 wherein the maintaining step comprises determining a number of changes made to a set of selected objects and conditionally building a new template when the number of changes exceeds a selected threshold.
7. The method of claim 6 wherein the selected threshold includes a reference to one or more of the following: object age, object size, object type and operator selection.
8. An apparatus for predictive predownloading of templates with delta encoding, including:
a delta encoder configured to calculate delta information for a requested web page responsive to a stored set of templates, each template comprising a selected portion of the requested web page that is unchanging between instances of the requested web page, delta information comprising selected portions of the requested web page that vary between instances of the requested web page;
a template builder configured to build a new template for the requested web page if the delta information for the requested web page exceeds a threshold value; and
a predictor configured to determine a set of next web pages likely to be requested in response to the requested web page and a referring page that indicates a web page just previously requested, the predictor also interacts with the template builder to build a template for at least one of the set of next web pages.
9. The apparatus of claim 8 wherein the threshold value includes a reference to one or more of the following: object age, object size, object type and operator selection.
10. The apparatus of claim 8 wherein the template builder builds the at least one template of the set of next web pages.
11. The apparatus of claim 8 wherein the predictor generates a hint that hint includes suggestions to a client what next object to download.
12. The apparatus of claim 11 wherein the hint includes URLS of templates for likely next pages.
13. The apparatus of claim 11 wherein the hint includes information to be stored in a client cache.
14. The apparatus of claim 11 further including a message generator configured to send to a client (i) the hint and (ii) delta information for the requested web page.
15. The apparatus of claim 14 wherein the message generator is configured to send to a client the next object identified by the hint.