Method and apparatus for persistent access to Web resources using relative time-stamps

Abstract

A method and apparatus are disclosed for providing persistent storage of Web resources. Uniform Resource Locators (“URLs”) that identify Web resources are augmented to include a time stamp. A web browser and a web server are disclosed that accommodate a time stamp parameter and allow a user to refer to any Web address with a precise target date. The disclosed Web browser can optionally include a mechanism to facilitate the specification of the desired date and time, or the user can manually append the time stamp to the URL indicated in the “Location” window of the browser. The persistent Web servers (i) receive URLs containing a time stamp or relative time-stamp, (ii) extract the time stamp, (iii) retrieve the appropriate Web page corresponding to the time-stamp, and (iv) return the appropriate page to the client. The persistent Web servers include a persistent archive for storing all of the versions of Web resources that will be persistently available to Web users.

I claim:  
     
         1 . A method for providing an electronic document, said electronic document having multiple versions, each of said versions having a time-stamp indicating a creation time of said corresponding version, said method comprising the steps of: 
 receiving a request for one of said versions of said electronic document, said request including a relative time-stamp indicating a time offset from a predefined time; and    transmitting said version of said electronic document corresponding to said relative time-stamp.    
     
     
         2 . The method according to  claim 1 , further comprising the step of storing a pointer to a previous version of said electronic document when said previous version of said electronic document is substantially identical.  
     
     
         3 . The method according to  claim 1 , wherein an address identifying said electronic document includes said time-stamp.  
     
     
         4 . The method according to  claim 3 , wherein said address is a Uniform Resource Locator (“URL”).  
     
     
         5 . The method according to  claim 4 , wherein said Uniform Resource Locator (“URL”) has an associated request header for indicating said time stamp.  
     
     
         6 . The method according to  claim 1 , wherein said request is specified using a browser.  
     
     
         7 . The method according to  claim 1 , further comprising the step of transmitting the version of said electronic document with the most recent time-stamp preceding the requested time-stamp when a version of said electronic document does not exist with the requested relative time-stamp.  
     
     
         8 . A system for storing an electronic document having multiple versions, said system comprising: 
 a memory for storing said multiple versions of said electronic document in an archive of electronic documents; and    a processor operatively coupled to said memory, said processor configured to: 
 receive a request for one of said versions of said electronic document, each of said multiple versions having a time-stamp indicating a creation time of said corresponding version, said request including a relative time-stamp indicating a time offset from a predefined time; and  
 transmit said version of said electronic document corresponding to said relative time-stamp.  
   
     
     
         9 . The system according to  claim 8 , wherein said processor is further configured to store a pointer to a previous version of said electronic document when said previous version of said electronic document is substantially identical.  
     
     
         10 . The system according to  claim 8 , wherein an address identifying said electronic document includes said time-stamp.  
     
     
         11 . The system according to  claim 10 , wherein said address is a Uniform Resource Locator (“URL”).  
     
     
         12 . The system according to  claim 11 , wherein said Uniform Resource Locator (“URL”) has an associated request header for indicating said time stamp.  
     
     
         13 . The system according to  claim 8 , wherein said request is specified using a browser.  
     
     
         14 . The system according to  claim 8 , wherein said processor is further configured to transmit the version of said electronic document with the most recent time-stamp preceding the requested time-stamp when a version of said electronic document does not exist with the requested relative time-stamp.  
     
     
         15 . An article of manufacture for accessing an electronic document identified by an address and having multiple versions, said article of manufacture comprising: 
 a computer readable medium having computer readable program code means embodied thereon, said computer readable program code means comprising program code means for causing a computer to: 
 receive a request for one of said versions of said electronic document, each of said versions having a time-stamp indicating a creation time of said corresponding version, said request including a relative time-stamp indicating a time offset from a predefined time; and  
 transmit said version of said electronic document corresponding to said relative time-stamp.