the invention provides for flexible , convenient , and dynamic url mapping methods and systems by providing generalized approaches which specify patterns in term of recognizable syntax . the recognizable syntax can be defined by one or more rules . the rules are used and applied to an input url string which is provided by a client to map the input url string to an output url string which is used by a rendering engine to provide a requested resource . embodiments of the invention provide for a rule cache or internal store in which rules are kept . the rule cache allows for rules to be added , deleted , or modified as desired , without the need to stop and re - start the web service . the rule cache can be populated dynamically at run time . in addition , embodiments of the invention conveniently group rules into rule groups . individual rule groups can be selectively applied to an input url string . furthermore , reverse mapping is supported by embodiments of the invention simply through the use of suitable rule additions or rule group additions in the rule cache , as may be appropriate .