Position summary: the Lana approach to wireless computing

The goal of the Lana project is to develop system support for short-distance wireless applications. We chose a language-based approach: mechanisms like scoping and typing are used to enforce system properties. The Lana language is strongly influenced by Java-it contains interfaces, packages, single inheritance etc.-though is designed with support for disconnected operation, coordination and security. Lana supports concurrent programs. The language semantics states that all memory locations transitively reachable from a program object must be moved along with the program. Further, the set of programs is organized into a hierarchy. When a program moves between nodes then all of its sibling programs are moved along with it. This feature is used by applications to specify hoarding policies: all related programs and objects are grouped under a common umbrella program which is moved. Method calls between programs are asynchronous; thus, a caller is never blocked awaiting a reply that might never come. Each method call generates a unique key object that is used by a program to locate the reply message or exception if ever the program momentarily leaves the network. Return messages-or security or mobility exceptions provoked by the call-have this key value bound to them. Any program that is delegated the key by the caller may therefore service the reply message. Thus a node may leave a network yet safely delegate its pending jobs to other nodes.