MADServer: An Architecture for Opportunistic Mobile Advanced Delivery

Rapid increases in cellular data traffic demand creative alternative delivery vectors for data. Despite the conceptual attractiveness of mobile data offloading, no concrete web server architectures integrate intelligent offloading in a production-ready and easily deployable manner without relying on vast infrastructural changes to carriers’ networks. Delay-tolerant networking technology offers the means to do just this. We introduce MADServer, a novel DTN-based architecture for mobile data offloading that splits web con- tent among multiple independent delivery vectors based on user and data context. It enables intelligent data offload- ing, caching, and querying solutions which can be incorporated in a manner that still satisfies user expectations for timely delivery. At the same time, it allows for users who have poor or expensive connections to the cellular network to leverage multi-hop opportunistic routing to send and receive data. We also present a preliminary implementation of MADServer and provide real-world performance evaluations

Using protocol analysis to explore the creative requirements engineering process

Protocol analysis is an empirical method applied by researchers in cognitive psychology and behavioural analysis. Protocol analysis can be used to collect, document and analyse thought processes by an individual problem solver. In general, research subjects are asked to think aloud when performing a given task. Their verbal reports are transcribed and represent a sequence of their thoughts and cognitive activities. These verbal reports are analysed to identify relevant segments of cognitive behaviours by the research subjects. The analysis results may be cross-examined (or validated through retrospective interviews with the research subjects). This paper offers a critical analysis of this research method, its approaches to data collection and analysis, strengths and limitations, and discusses its use in information systems research. The aim is to explore the use of protocol analysis in studying the creative requirements engineering process.<br /

Total order in opportunistic networks

Opportunistic network applications are usually assumed to work only with unordered immutable messages, like photos, videos, or music files, while applications that depend on ordered or mutable messages, like chat or shared contents editing applications, are ignored. In this paper, we examine how total ordering can be achieved in an opportunistic network. By leveraging on existing dissemination and causal order algorithms, we propose a commutative replicated data type algorithm on the basis of Logoot for achieving total order without using tombstones in opportunistic networks where message delivery is not guaranteed by the routing layer. Our algorithm is designed to use the nature of the opportunistic network to reduce the metadata size compared to the original Logoot, and even to achieve in some cases higher hit rates compared to the dissemination algorithms when no order is enforced. Finally, we present the results of the experiments for the new algorithm by using an opportunistic network emulator, mobility traces, and Wikipedia pages.Peer ReviewedPostprint (author's final draft

The role of structural embeddedness in an IT outsourcing network

The design of governance to safeguard against a vendor's opportunistic behaviour is one of the critical issues in information technology outsourcing (ITO) since this behaviour causes cost escalation and service debasement. The roles of structural embeddedness underlying network governance have been gaining its importance as complementary or substitutable governance in ITO. Our research attempts to reveal how structural embeddedness can affect the decision-makings of clients and vendors and their resulting outcomes in an ITO network and how these effects are moderated by various ITO network structures according to outsourced IT services. An agent-based simulation and game-theoretic approach are adopted to build a simulation model to describe ITO networks with various structures and ITO transactions between clients and vendors. Finally, the future research directions are discussed

The relative clinical effectiveness and cost-effectiveness of three contrasting approaches to partner notification for curable sexually transmitted infections: a cluster randomised trial in primary care

Since 1998 there has been a substantial increase in reported cases of sexually transmitted infection (STI), most strikingly in the 16–24 years age group.1 Across genitourinary medicine (GUM) clinics in the UK in 2007, young people accounted for 65% of chlamydia cases, 50% of cases of genital warts and 50% of gonorrhoea infections.1 Chlamydia is the most common STI in under-25s. Since 1998, the rate of diagnosed chlamydia has more than doubled in the 16–24 years age group (from 447 per 100,000 in 1998 to 1102 per 100,000 in 2007). This may be because of a combination of a higher proportion of young people testing, improved diagnostic methods and increased risk behaviour.1 Chlamydia infection can frequently go undetected, particularly in women, as it is often asymptomatic.1 If left untreated, chlamydia can lead to pelvic inflammatory disease and infertility in women. This highlights the importance of testing this higher-risk age group to ensure prompt diagnosis and treatment. It is estimated that 11–12% of 16- to 19-year-olds presenting at a GUM clinic with an acute STI will become reinfected within a year.2 In order to minimise reinfection, preventative measures are required, including effective methods of notifying partners to ensure rapid diagnosis and treatment and reduce the likelihood of index patients being reinfected from the same source

Opportunistic Sensing in Train Safety Systems

Train safety systems are complex and expensive, and changing them requires huge investments. Changes are evolutionary and small. Current developments, like faster - high speed - trains and a higher train density on the railway network, have initiated research on safety systems that can cope with the new requirements. This paper presents a novel approach for a safety subsystem that checks the composition of a train, based on opportunistic sensing with a wireless sensor network. Opportunistic sensing systems consist of changing constellations sensors that, for a limited amount of time, work together to achieve a common goal. Such constellations are selforganizing and come into being spontaneously. The proposed opportunistic sensing system selects a subset of sensor nodes from a larger set based on a common context.We show that it is possible to use a wireless sensor network to make a distinction between carriages from different trains. The common context is acceleration, which is used to select the subset of carriages that belong to the same train out of all the carriages from several trains in close proximity. Simulations based on a realistic set of sensor data show that the method is valid, but that the algorithm is too complex for implementation on simple wireless sensor nodes. Downscaling the algorithm reduces the number of processor execution cycles as well as memory usage, and makes it suitable for implementation on a wireless sensor node with acceptable loss of precision. Actual implementation on wireless sensor nodes confirms the results obtained with the simulations