This paper presents the design and implementation of the Intentional Naming System (INS), a resource discovery and service location system for dynamic and mobile networks of devices and computers. Such environments require a naming system that is (i) expressive, to describe and make requests based on specific properties of services, (ii) responsive, to track changes due to mobility and performance, (iii) robust, to handle failures, and (iv) easily configurable. INS uses a simple language based on attributes and values for its names. Applications use the language to describe what they are looking for (i.e., their intent), not where to find things (i.e., not hostnames). INS implements a late binding mechanism that integrates name resolution and message routing, enabling clients to continue communicating with end-nodes even if the name-to-address mappings change while a session is in progress. INS resolvers self-configure to form an application-level overlay network, which they use to discover new services, perform late binding, and maintain weak consistency of names using soft-state name exchanges and updates. We analyze the performance of the INS algorithms and protocols, present measurements of a Java-based implementation, and describe three applications we have implemented that demonstrate the feasibility and utility of INS.

systems and fault tolerance at no cost, but do not support service discovery and therefore are not useful for truly open system such as the web. Service discovery could be realised through regular search engines. However, current engines limit themselves to plain text when indexing and cannot make use of other formats. Search engines of the future may overcome this problem. The Agora [Sea98] and Webtrader [Vas99] project are two such efforts. In the Webtrader system, servers advertise their services on XML pages containing keywords, metadata (such as QoS) and the service interface. Keywords and metadata help the trader to match services against client requests; the interface allows the client to use the service. While this approach requires servers to advertise in the required XML format, Agora aims to trade existing components, which are already online. Similar to classical search engines, which parse HTML pages for indexing, Agora parses Java class files and indexes them. With suc