It is assumed that the reader is already familiar with the Internet, Uniform Resource Locators[1], and the World-Wide Web. There are now a large number of elementary texts which introduce these concepts, for example[2].
This report discusses problems arising from the current usage of URLs on the Internet, and introduces some possible solutions to these problems. It introduces two new Uniform Resource Identifiers which are intended to complement the URL - the Uniform Resource Characteristic[3] and the Uniform Resource Name[4]. URNs and URCs are being developed under the auspices of the Internet Engineering Task Force, the group which oversees Internet protocol development and standardization.
An alternative approach which has not been considered in the current work on URIs would be to use multicast technology[5]. Multicasting is a technique which allows a computer to send a single message to any number of other computers simultaneously. By constrast, existing unicast networking technologies only provide for communication with one computer at a time. Multicast is currently widely used in the Internet community for tele-conferencing[6] - notably of the meetings of the IETF[7].
This report considers the use of the SIMPLE DISCOVERY PROTOCOL[8] in implementing the proposed scenarios for URNs and URCs. SDP is an experimental multicast resource discovery protocol developed by the author. The rationale behind it is discussed further in[9].