Abstract: A system and method provides secondary resource files in response to a request for a web page from a client device. In response to the request, a server provides an HTML file which identifies a secondary resource file, such as a javascript file, and the current version value of the secondary resource. The HTML file may be associated with a header which prevents the file from being cached. If there is no locally-cached version of the secondary resource file, the file is requested from the server. The server will transmit the secondary resource file with a header indicating that the file is to be stored indefinitely. If there is a locally-cached version of the secondary resource file, the client device compares the version value of the locally-cached version to the received current version value. If the values are different, the client requests the differences between the files.

Abstract: Methods and systems are described for computing shortest paths among a set of locations. A small set of landmarks is chosen and the distance between each location and each landmark is computed and stored. Given source and destination locations, the landmark distances are used to compute lower-bound estimates of distances from locations to the destination. The estimates are then used with a heuristic search to find the shortest path from source to destination.