An application programming interface layer for devices, such as handheld computers, personal digital assistants, Internet enabled phones, laptops, and desktop computers or the like, that provides device independence so applications may run on any of such devices without specific programming for device specific dependencies. The retroflector 12 comprises a substantially spherical graded refractive index lens 16 and a reflective part 18 for reflecting the incident beam of radiation passing through the lens. Database group registry tracks client classification and provides adaptive context mapping according to set attribute relative to targeted on-line transaction. Internet Protocol addresses associated with the candidate domain names are retrieved from the DNS resource records of the candidate domain names.