Abstract. A friendship system is introduced for modular static verification of object invariants. It extends a previous methodology, based on ownership hierarchy encoded in auxiliary state, to allow for state dependence across ownership boundaries. Friendship describes a formal protocol for a granting class to grant a friend class permission to express its invariant over fields in the granting class. The protocol permits the safe update of the granter’s fields without violating the friend’s invariant. The ensuing proof obligations are minimal and permit many common programming patterns. A soundness proof is sketched. The method is demonstrated on several realistic examples, showing that it significantly expands the domain of programs amenable to static verification. 0

Path logic programming is a modest extension of Prolog for the specification of program transformations. We give an informal introduction to this extension, and we show how it can be used in coding standard compiler optimisations, and also a number of obfuscating transformations. The object language is the Microsoft .NET intermediate language (IL).

A properly encapsulated data representation can be revised without affecting the correctness of client programs and extensions but encapsulation is difficult to achieve for heap based structures and object-oriented (OO) programs with reentrant callbacks. Building on a discipline that uses assertions and auxiliary fields to manage invariants and transferrable ownership, we give a rule for modular reasoning based on simulations. This representation independence result is proved for a sequential OO language with recursive, generic classes.

There are a number of distributed applications that use the Remote Procedure Call (RPC) paradigm to invoke remote tasks. When a large number of tasks are invoked, the performance of a distributed application may become unacceptably slow. This paper investigates whether or not a paradigm known as Remote Evaluation can be used as a replacement for RPC when the number of remote tasks invocations is high, and also when there are few tasks. This paper evaluates ways in which portable distributed applications can be written by utilizing standard interfaces in a selection of programming languages, on a variety of platforms. The interfaces are described in detail, and their performance is compared. This paper is targeted at application developers who wish to consider an alternative to RPC.

Recent progresses in the software development world has assisted a change in hardware from heavy mainframes and desktop machines to unimaginable small devices leading to the prophetic "third computing paradigm", Ubiquitous Computing. Still, this novel unnoticeable devices lack in various capabilities, like computing power, storage capacity and human interface. Connectivity associated to this devices is also considered an handicap which comes generally associated expensive and limited protocols like GSM and UMTS.

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Abstract. Security is a challenge in pervasive systems for several reasons. First, the large number of peers challenges the use of centralised security services like certificate authorities and reputation services. Second, a principal may be a physical object whose identity might not convey useful information for taking security decisions. Establishing a trusted channel depends more on a principal being able to demonstrate what is does, rather than who it is. Third, device mobility leads to the formation of ad hoc networks. Devices in these networks may be interacting for the first time so devices must carry sufficient information for them to establish mutual trust with other devices. This paper proposes a security model for pervasive systems, based on the idea of message quality. The model allows a principal to establish the intent of an adversary and to make the adversary prove its trustworthiness by furnishing proof of past behavior. 1