Safe Tuplespace-based Coordination in Multiagent Systems

Linda is a high-level coordination model that allows agents to interact via shared tuplespaces without knowing each other's identities and without having to arrange for a definite rendezvous. This high level of abstraction would make Linda particularly suitable for use as a coordination model for heterogeneous distributed systems, if it were not for the fact that the Linda communication is unsafe. In order to enhance the safety of tuplespaces, this article introduces a mechanism for establishing security policies that regulate agent access to tuplespaces. This mechanism is based on a previously published concept of law-governed interaction. It makes a strict separation between the formal statement of a policy, which one calls a “law,” and the enforcement of this law, which is carried out by a set of policy-independent trusted controllers. A new policy under this scheme is created basically by formulating its law, and can be easily deployed throughout a distributed system. Two example policies are discussed here in detail: one ensures a secure bidding policy; the other prevents denial of service, by regulating the flow of requests sent to the tuplespaces.