Maintaining Client-Side Persistent Data using Caching
Non-cookie methods for distinguishing among web-server clients (browsers) use personalized information stored in the browser's cache. The information may be extracted by programs, such as JavaScript programs, executing at the client side; or by sending resource data to cause the client to report the personalized information to the server in conjunction with a resource request.
1 . A method comprising:
transmitting a personalized resource to be cached by a browser;
confirming that the personalized resource is stored in a cache of the browser; and
extracting personalization data from the personalized resource.
2 . The method of claim 1 , further comprising:
setting the personalization data as a session identifier.
3 . The method of claim 1 , further comprising:
reporting the personalization data from the browser to a server.
4 . The method of claim 3 , further comprising:
correlating a first session identifier and a second, different session identifier with each other using the personalization data.
5 . The method of claim 1 , further comprising:
comparing the personalization data to a session identifier.
6 . The method of claim 1 wherein the personalized resource is a main resource of a website.
7 . The method of claim 1 wherein the personalized resource is a common resource of a website.
8 . The method of claim 1 wherein the personalized resource is an image.
9 . The method of claim 1 , further comprising:
transmitting an executable program to the browser, the executable program to cause the browser to perform operations comprising:
requesting the personalized resource.
10 . The method of claim 1 wherein the personalized resource contains a unique nonce encoded into inconspicuous bits of an image.
11 . The method of claim 1 wherein the personalized resource contains a unique nonce encoded into an entry of a Cascading Style Sheet.
12 . The method of claim 1 wherein the personalized resource contains a unique nonce encoded into a portion of a Javascript program
13 . The method of claim 1 wherein the personalized resource contains a unique nonce encoded into a program that can execute on the browser.
14 . The method of claim 1 wherein the personalized resource contains a unique nonce encoded as a modification date of the personalized resource.
15 . The method of claim 1 wherein the personalized resource contains a unique nonce encoded as an entity tag of the personalized resource.
16 . A method comprising:
receiving a first original request from a first client, the first original request to obtain a resource;
altering the resource to produce a first personalized resource and sending the first personalized resource to the first client;
receiving a second original request from a second client, the second original request to obtain the resource;
altering the resource to produce a second personalized resource, different from the first personalized resource, and sending the second personalized resource to the second client.
17 . The method of claim 16 wherein sending a personalized resource to a client comprises sending information to cause the client to cache the personalized resource.
18 . The method of claim 16 , further comprising:
allocating a first session key to identify the first client;
sending the first session key to the first client; and
storing information to associate the first session key with the first personalized resource.
19 . The method of claim 16 wherein altering the resource to produce a personalized resource comprises:
selecting a false modification date to be sent with the personalized resource.
20 . The method of claim 16 wherein altering the resource to produce a personalized resource comprises:
encoding personalization information into a predetermined subset of bits of the resource.
21 . The method of claim 20 wherein the resource is a graphical image.
22 . The method of claim 20 wherein the resource is a Cascading Style Sheet (“CSS”) document.
23 . The method of claim 20 wherein the resource is a JavaScript program.
24 . The method of claim 20 wherein the resource is a program that can execute on the client.
25 . A method comprising:
transmitting executable instructions to a computer, the executable instructions to cause the computer to perform operations comprising:
a) issuing a request for a predetermined resource;
b) extracting personalization information from the predetermined resource; and
c) reporting the personalization information;
receiving a request for a resource, the request including a caching indicator but lacking a session key;
transmitting a resource-not-modified response to the request;
receiving personalization information from the computer;
correlating the personalization information with a previously-allocated session key; and
transmitting the previously-allocated session key to the computer.