Implementing Network Protocols as Distributed Logic Programs

Declarative networking [2, 4, 3, 1] is an application of database query-language and processing techniques to the domain of networking. Declarative networking is based on the observation that network protocols deal at their core with computing and maintaining distributed state (e.g., routes, sessions, performance statistics) according to basic information locally available at each node (e.g., neighbor tables, link measurements, local clocks) while enforcing constraints such as local routing policies. Recursive query languages studied in the deductive database literature [6] are a natural fit for expressing the relationship between base data, derived data, and the associated constraints. Simple extensions to these languages and their implementations enable the natural expression and efficient execution of network protocols. Declarative networking aims to accelerate the process of specifying, implementing, experimenting with and evolving designs for network architectures. Declarative networking can reduce program sizes of distributed protocols by orders of magnitude relative to traditional approaches. In addition to serving as a platform for rapid prototyping of network protocols, declarative networking also open up opportunities for automatic protocol optimization and hybridization, program checking and debugging. This paper presents an introduction to declarative networking using a simple routing protocol example. For more details on declarative networking related projects, refer to the NetDB@Penn website [5], and the RapidNet [7] declarative networking engine

Easing software development for pervasive computing environments

textIn recent years pervasive computing has enjoyed an amazing growth in both research and commercial fields. Not only have the number of available techniques and tools expanded, but the number of actual deployments has been underwhelming. With this growth however, we are also experiencing a divergence of software interfaces, languages, and techniques. This leads to an understandably confusing landscape which needlessly burdens the development of applications. It is our sincere hope that through the use of specialized interfaces, languages, and tools, we can make pervasive computing environments more approachable and efficient to software developers and thereby increase the utility and value of pervasive computing applications. In this dissertation, we present a new method for creating and managing the long-term conversations between peers in pervasive computing environments. The Application Sessions Model formally describes these conversations and specifies techniques for managing them over their lifetimes. In addition to these descriptions, this dissertation presents a prototype implementation of the model and results from its use for realistic scenarios. To address the Application Sessions Model's unique needs for resource discovery in pervasive computing environments, we also present the Evolving Tuples Model. This model is also formally defined in this dissertation and practical examples are used to clarify its features. A prototype for both sensor hardware and software simulation of this model is described along with results characterizing the behavior of the model. The models, prototypes, and evaluations of both models presented here form the basis of a new and interesting line of research into support structures for pervasive computing application development.Electrical and Computer Engineerin

Linux XIA: an interoperable meta network architecture to crowdsource the future Internet

With the growing number of proposed clean-slate redesigns of the Internet, the need for a medium that enables all stakeholders to participate in the realization, evaluation, and selection of these designs is increasing. We believe that the missing catalyst is a meta network architecture that welcomes most, if not all, clean-state designs on a level playing field, lowers deployment barriers, and leaves the final evaluation to the broader community. This paper presents Linux XIA, a native implementation of XIA [12] in the Linux kernel, as a candidate. We first describe Linux XIA in terms of its architectural realizations and algorithmic contributions. We then demonstrate how to port several distinct and unrelated network architectures onto Linux XIA. Finally, we provide a hybrid evaluation of Linux XIA at three levels of abstraction in terms of its ability to: evolve and foster interoperation of new architectures, embed disparate architectures inside the implementation’s framework, and maintain a comparable forwarding performance to that of the legacy TCP/IP implementation. Given this evaluation, we substantiate a previously unsupported claim of XIA: that it readily supports and enables network evolution, collaboration, and interoperability—traits we view as central to the success of any future Internet architecture.This research was supported by the National Science Foundation under awards CNS-1040800, CNS-1345307 and CNS-1347525

Supporting Cyber-Physical Systems with Wireless Sensor Networks: An Outlook of Software and Services

Sensing, communication, computation and control technologies are the essential building blocks of a cyber-physical system (CPS). Wireless sensor networks (WSNs) are a way to support CPS as they provide fine-grained spatial-temporal sensing, communication and computation at a low premium of cost and power. In this article, we explore the fundamental concepts guiding the design and implementation of WSNs. We report the latest developments in WSN software and services for meeting existing requirements and newer demands; particularly in the areas of: operating system, simulator and emulator, programming abstraction, virtualization, IP-based communication and security, time and location, and network monitoring and management. We also reflect on the ongoing efforts in providing dependable assurances for WSN-driven CPS. Finally, we report on its applicability with a case-study on smart buildings

Supporting Context-Aware Application Development in Ad Hoc Mobile Networks

Some of the most dynamic systems being built today consist of physically mobile hosts and logically mobile agents. Such systems exhibit frequent configuration changes and a great deal of resource variability. Applications executing under these circumstances need to react continuously and rapidly to changes in operating conditions and must adapt their behavior accordingly. Applications with these capabilities are referred to as context-aware. Much of the current work on context-aware computing relies on information directly available to an application via context sensors on its local host, e.g., user profile, host location, time of day, resource availability, and quality of service measurements. The work reported in this dissertation starts by building a new perspective on context-awareness, in which the context includes, in principle, any information available in the ad hoc network but is restricted, in practice, to specific projections of the overall context. This work reports on the design and implementation of a middleware model that brings this notion of context to the application programmer. Another important aspect of the software engineering process is the ability to reason formally about the programs we create. This dissertation details initial steps to create formal reasoning mechanisms dedicated to the needs of context-aware applications. The results of this work simplify application development in ad hoc mobile networks from a design and implementation perspective and through formal reasoning

It's about THYME: On the design and implementation of a time-aware reactive storage system for pervasive edge computing environments

This work was partially supported by Fundacao para a Ciencia e a Tecnologia (FCT-MCTES) through project DeDuCe (PTDC/CCI-COM/32166/2017), NOVA LINCS UIDB/04516/2020, and grant SFRH/BD/99486/2014; and by the European Union through project LightKone (grant agreement n. 732505).Nowadays, smart mobile devices generate huge amounts of data in all sorts of gatherings. Much of that data has localized and ephemeral interest, but can be of great use if shared among co-located devices. However, mobile devices often experience poor connectivity, leading to availability issues if application storage and logic are fully delegated to a remote cloud infrastructure. In turn, the edge computing paradigm pushes computations and storage beyond the data center, closer to end-user devices where data is generated and consumed, enabling the execution of certain components of edge-enabled systems directly and cooperatively on edge devices. In this article, we address the challenge of supporting reliable and efficient data storage and dissemination among co-located wireless mobile devices without resorting to centralized services or network infrastructures. We propose THYME, a novel time-aware reactive data storage system for pervasive edge computing environments, that exploits synergies between the storage substrate and the publish/subscribe paradigm. We present the design of THYME and elaborate a three-fold evaluation, through an analytical study, and both simulation and real world experimentations, characterizing the scenarios best suited for its use. The evaluation shows that THYME allows the notification and retrieval of relevant data with low overhead and latency, and also with low energy consumption, proving to be a practical solution in a variety of situations.publishersversionpublishe

Unifying Static And Runtime Analysis In Declarative Distributed Systems

Today’s distributed systems are becoming increasingly complex, due to the ever-growing number of network devices and their variety. The complexity makes it hard for system administrators to correctly configure distributed systems. This motivates the need for effective analytic tools that can help ensure correctness of distributed systems. One challenge in ensuring correctness is that there does not exist one solution that works for all properties. One type of properties, such as security properties, are so critical that they demand pre-deployment verification (i.e., static analysis) which, though time-consuming, explores the whole execution space. However, due to the potential problem of state explosion, static verification of all properties is not practical, and not necessary. Violation of non-critical properties, such as correct routing with shortest paths, is tolerable during execution and can be diagnosed after errors occur (i.e., runtime analysis), a more light-weight approach compared to verification. This dissertation presents STRANDS, a declarative framework that enables users to perform both pre-deployment verification and post-deployment diagnostics on top of declarative specification of distributed systems. STRANDS uses Network Datalog (NDlog), a distributed variant of Datalog query language, to specify network protocols and services. STRANDS has two components: a system verifier and a system debugger. The verifier allows the user to rigorously prove safety properties of network protocols and services, using either the program logic or symbolic execution we develop for NDlog programs. The debugger, on the other hand, facilitates diagnosis of system errors by allowing for querying of the structured history of network execution (i.e., network provenance) that is maintained in a storage-efficient manner. We show the effectiveness of STRANDS by evaluating both the verifier and the debugger. Using the verifier, we prove path authenticity of secure routing protocols, and verify a number of safety properties in software-defined networking (SDN). Also, we demonstrate that our provenance maintenance algorithm achieves significant storage reduction, while incurring negligible network overhead

Engineering Pervasive Service Ecosystems: The SAPERE approach

Emerging pervasive computing services will typically involve a large number of devices and service components cooperating together in an open and dynamic environment. This calls for suitable models and infrastructures promoting spontaneous, situated, and self-adaptive interactions between components. SAPERE (Self-Aware Pervasive Service Ecosystems) is a general coordination framework aimed at facilitating the decentralized and situated execution of self-organizing and self-adaptive pervasive computing services. SAPERE adopts a nature-inspired approach, in which pervasive services are modeled and deployed as autonomous individuals in an ecosystem of other services and devices, all of which interact in accord to a limited set of coordination laws, or eco-laws. In this article, we present the overall rationale underlying SAPERE and its reference architecture. We introduce the eco-laws--based coordination model and show how it can be used to express and easily enforce general-purpose self-organizing coordination patterns. The middleware infrastructure supporting the SAPERE model is presented and evaluated, and the overall advantages of SAPERE are discussed in the context of exemplary use cases

The Prom Problem: Fair and Privacy-Enhanced Matchmaking with Identity Linked Wishes

In the Prom Problem (TPP), Alice wishes to attend a school dance with Bob and needs a risk-free, privacy preserving way to find out whether Bob shares that same wish. If not, no one should know that she inquired about it, not even Bob. TPP represents a special class of matchmaking challenges, augmenting the properties of privacy-enhanced matchmaking, further requiring fairness and support for identity linked wishes (ILW) – wishes involving specific identities that are only valid if all involved parties have those same wishes. The Horne-Nair (HN) protocol was proposed as a solution to TPP along with a sample pseudo-code embodiment leveraging an untrusted matchmaker. Neither identities nor pseudo-identities are included in any messages or stored in the matchmaker’s database. Privacy relevant data stay within user control. A security analysis and proof-of-concept implementation validated the approach, fairness was quantified, and a feasibility analysis demonstrated practicality in real-world networks and systems, thereby bounding risk prior to incurring the full costs of development. The SecretMatch™ Prom app leverages one embodiment of the patented HN protocol to achieve privacy-enhanced and fair matchmaking with ILW. The endeavor led to practical lessons learned and recommendations for privacy engineering in an era of rapidly evolving privacy legislation. Next steps include design of SecretMatch™ apps for contexts like voting negotiations in legislative bodies and executive recruiting. The roadmap toward a quantum resistant SecretMatch™ began with design of a Hybrid Post-Quantum Horne-Nair (HPQHN) protocol. Future directions include enhancements to HPQHN, a fully Post Quantum HN protocol, and more