Using mobile code to provide fault tolerance in tuple space based coordination languages

Abstract

Tuple space based coordination languages suffer from poor fault tolerance to agent failure. Traditionally, transaction type mechanisms have been adopted in them to provide this type of fault tolerance. However, transactions change the semantics of the tuple space access primitives performed within them and do not provide a sufficient level of flexibility. We propose using mobile coordination, which utilises mobile code, as an alternative mechanism for providing better fault tolerance to agent failure. The use of mobile code is transparent to the application programmer. Mobile coordination provides the same level of fault tolerance as transactions, but it also introduces the concept of agent wills. This allows coordination patterns to be performed in a fault tolerant manner which cannot be performed in a fault tolerant manner using transactions. Mobile coordination is described in detail. The API for a prototype centralised implementation is presented. It is shown that mobile coordination provides better support and better performance than the traditional approach of using transactions. Implementation strategies for a distributed implementation are also discussed.