A self-organising awareness system for distributed software engineering

Software engineers and other collaborative disciplines rely on informal "out-of-band" communication for ef- fective coordination of their activities, especially in agile methods. This type of communication is lost when development is distributed, with consequent deleterious effects on engineer effectiveness. In order to effectively support distributed software engineering, a replacement for this informal communication must be found. Much previous research focussed on either synchronous awareness such as radar views and shared editors, where participants were distributed in space not time, or asynchronous awareness such as change notification, which did not explicitly support concurrent activities. A unified approach is necessary to support software engineering. Furthermore, requiring co-location of engineering teams is not possible in today's marketplace where development is often outsourced, consequently a definite requirement for awareness tools to replace informal communication exists. To implement an awareness tool capable of providing awareness of activities distributed both in time (asyn- chronous awareness) and space (synchronous awareness). The tool will not rely on a centralised reflector; instead information will be distributed over a peer-to-peer network arranged using a self-organisation algorithm. Consequently awareness information need not travel more than a few hops from its originating peer, reducing network load and increasing relevance of information received. Unlike reflector-based CSCW systems, the network will scale and will not have a single point of failure in the reflector. Furthermore, without the need to setup a reflector, there is the capability for ad-hoc awareness, using low-complexity peer discovery by local broadcast for example. The tool will be integrated with the Eclipse development environment. The files a user is currently editing will determine the data they are interested in and fuzzy similarity metrics will be used to compare the collections of each peer in the network in order to drive the self-organisation process. To evaluate the success of self-organisation, a simulation approach will be used before deploying the algorithms in the wild. To evaluate the effectiveness of the awareness provision, initial deployment and controlled experiments will be conducted within the Distributed Software Engineering group at the University of Lincoln and a later version of the tool will be trialled with existing Eclipse user

A group membership algorithm with a practical specification

Presents a solvable specification and gives an algorithm for the group membership problem in asynchronous systems with crash failures. Our specification requires processes to maintain a consistent history in their sequences of views. This allows processes to order failures and recoveries in time and simplifies the programming of high level applications. Previous work has proven that the group membership problem cannot be solved in asynchronous systems with crash failures. We circumvent this impossibility result building a weaker, yet nontrivial specification. We show that our solution is an improvement upon previous attempts to solve this problem using a weaker specification. We also relate our solution to other methods and give a classification of progress properties that can be achieved under different models

Process membership in asynchronous environments

The development of reliable distributed software is simplified by the ability to assume a fail-stop failure model. The emulation of such a model in an asynchronous distributed environment is discussed. The solution proposed, called Strong-GMP, can be supported through a highly efficient protocol, and was implemented as part of a distributed systems software project at Cornell University. The precise definition of the problem, the protocol, correctness proofs, and an analysis of costs are addressed

Possibilistic Information Flow Control for Workflow Management Systems

In workflows and business processes, there are often security requirements on both the data, i.e. confidentiality and integrity, and the process, e.g. separation of duty. Graphical notations exist for specifying both workflows and associated security requirements. We present an approach for formally verifying that a workflow satisfies such security requirements. For this purpose, we define the semantics of a workflow as a state-event system and formalise security properties in a trace-based way, i.e. on an abstract level without depending on details of enforcement mechanisms such as Role-Based Access Control (RBAC). This formal model then allows us to build upon well-known verification techniques for information flow control. We describe how a compositional verification methodology for possibilistic information flow can be adapted to verify that a specification of a distributed workflow management system satisfies security requirements on both data and processes.Comment: In Proceedings GraMSec 2014, arXiv:1404.163

DataWarp: Building Applications which Make Progress in an Inconsistent World

The usual approach to dealing with imperfections in data is to attempt to eliminate them. However, the nature of modern systems means this is often futile. This paper describes an approach which permits applications to operate notwithstanding inconsistent data. Instead of attempting to extract a single, correct view of the world from its data, a DataWarp application constructs a collection of interpretations. It adopts one of these and continues work. Since it acts on assumptions, the DataWarp application considers its recent work to be provisional, expecting eventually most of these actions will become definitive. Should the application decide to adopt an alternative data view, it may then need to void provisional actions before resuming work. We describe the DataWarp architecture, discuss its implementation and describe an experiment in which a DataWarp application in an environment containing inconsistent data achieves better results than its conventional counterpart

The Helpful Environment: distributed agents and services which cooperate

The University of Edinburgh and research sponsors are authorised to reproduce and distribute reprints and on-line copies for their purposes notwithstanding any copyright annotation hereon. The views and conclusions contained herein are the author’s and shouldn’t be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of other parties.Imagine a future environment where networks of agents - people, robots and software agents - interact with sophisticated sensor grids and environmental actuators to provide advice, protection and aid. The systems will be integral to clothing, communications devices, vehicles, transportation systems, buildings, and pervasive in the environment. Vehicles and buildings could assist both their occupants and those around them. Systems would adapt and respond to emergencies whether communication were possible or not. Where feasible, local help would be used, with appropriate calls on shared services facilitated whenever this is both possible and necessary. Through this framework requests for assistance could be validated and brokered to available and appropriate services in a highly distributed fashion. Services would be provided to individuals or communities through this network to add value and give all sorts of assistance beyond emergency response aspects. In emergency situations, the local infrastructure would be augmented by the facilities of the responder teams at any level from local police, ambulance and fire response, all the way up to international response. An emergency zone’s own infrastructure could be augmented when necessary by laying down temporary low cost sensor grids and placing specialized devices and robotic responders into the disaster area. These would form the basis for a distributed, adaptable, and resilient “helpful environment” for every individual and organisation at personal, family, business, regional, national and international levels

Design of a shared whiteboard component for multimedia conferencing

This paper reports on the development of a framework for multimedia applications in the domain of tele-education. The paper focuses on the protocol design of a specific component of the framework, namely a shared whiteboard application. The relationship of this component with other components of the framework is also discussed. A salient feature of the framework is that it uses an advanced ATM-based network service. The design of the shared whiteboard component is considered representative for the design as a whole, and is used to illustrate how a flexible protocol architecture utilizing innovative network functions and satisfying demanding user requirements can be developed