Web site access control system which queries server for URL category which is used to determine access and keeps cache of recent URL categories

摘要

Categorising URLs during internet access, wherein a specific URL is first checked against a local cache of categorised URLs to see if it is there, if not then a remote server is queried to obtain a category for that URL. The cache is preferably structured as: a hash array comprising one or more index elements, each index element comprising a host tree pointer and a hash key derived from a stored URL. The server searches in a similar manner. The server query including the URL is formed using UDP messages including sequence numbers for message identification and time stamps for retry time outs in case a query message is lost. Where the server only partially matches a URL a match length is provided. By keeping only a limited cache a low powered device may be used to implement the categorization system. The categorization of URLs may be used parental locks on web sites and similar access control.