How replicated data management in the cloud can benefit from a data grid protocol - the Re:GRIDiT Approach

Cloud computing has recently received considerable attention both in industry and academia. Due to the great success of the first generation of Cloud-based services, providers have to deal with larger and larger volumes of data. Quality of service agreements with customers require data to be replicated across data centers in order to guarantee a high degree of availability. In this context, Cloud Data Management has to address several challenges, especially when replicated data are concurrently updated at different sites or when the system workload and the resources requested by clients change dynamically. Mostly independent from recent developments in Cloud Data Management, Data Grids have undergone a transition from pure file management with read only access to more powerful systems. In our recent work,we have developed the Re:GRIDiT protocol for managing data in the Grid which provides concurrent access to replicated data at different sites without any global component and supports the dynamic deployment of replicas. Since it is independent from the underlying Grid middleware, it can be seamlessly transferred to other environments like the Cloud.In this paper, we compare Data Management in the Grid and the Cloud, briefly introduce the Re:GRIDiT protocol and show its applicability for Cloud Data Management

Coordination-Free Byzantine Replication with Minimal Communication Costs

State-of-the-art fault-tolerant and federated data management systems rely on fully-replicated designs in which all participants have equivalent roles. Consequently, these systems have only limited scalability and are ill-suited for high-performance data management. As an alternative, we propose a hierarchical design in which a Byzantine cluster manages data, while an arbitrary number of learners can reliable learn these updates and use the corresponding data. To realize our design, we propose the delayed-replication algorithm, an efficient solution to the Byzantine learner problem that is central to our design. The delayed-replication algorithm is coordination-free, scalable, and has minimal communication cost for all participants involved. In doing so, the delayed-broadcast algorithm opens the door to new high-performance fault-tolerant and federated data management systems. To illustrate this, we show that the delayed-replication algorithm is not only useful to support specialized learners, but can also be used to reduce the overall communication cost of permissioned blockchains and to improve their storage scalability

Developing parasite control strategies in organic systems

This report was presented at the UK Organic Research 2002 Conference. Organic farmers have taken a lead in attempting to reduce dependence on pharmaceutical control of parasites in farmed livestock. Focussing on management and nutrition, the objective of this research is to further develop control strategies, which can support and increase the flexibility of clean grazing systems for sheep and cattle. The approach has been to combine on-farm epidemiological studies, with replicated experiments, in order to develop and demonstrate better systems of control applicable to UK organic farms. Preliminary data from the first years' epidemiological studies are presented in this paper

Small Grain Forage Trial: Nitrogen Fertility x Harvest Date

Cool season annual forages, such as cereal grains, can provide early season grazing as well as high quality stored feed. However, it is unclear if quality and yield of these forages could be improved through better nitrogen (N) management. Improved quality of homegrown forages can help to reduce expensive grain purchases. The goal of this project was to determine yield and quality of an annual cool season forage harvested at various stages of maturity and under different organic N fertility regimes. The data presented here is from one replicated research trial in Vermont. Crop performance data from additional tests in different locations and often over several years, should be compared before you make decisions about planting small grains

Distributed match-making

In many distributed computing environments, processes are concurrently executed by nodes in a store- and-forward communication network. Distributed control issues as diverse as name server, mutual exclusion, and replicated data management involve making matches between such processes. We propose a formal problem called distributed match-making as the generic paradigm. Algorithms for distributed match-making are developed and the complexity is investigated in terms of messages and in terms of storage needed. Lower bounds on the complexity of distributed match-making are established. Optimal algorithms, or nearly optimal algorithms, are given for particular network topologies

Small Grain Forage Trial Nitrogen Fertility and Harvest Date

Cool season annual forages, such as cereal grains, can provide early season grazing as well as high quality stored feed. However, it is unclear if quality and yield of these forages could be improved through better fertility management. Improved quality of homegrown forages can help to reduce expensive grain purchases. In addition, production of high quality forage can improve the level of beneficial fats (i.e. Omege-3) in the milk. In order to produce forage with the highest levels of beneficial fats management practices may need to be modified. It is unclear if nitrogen management will impact the level of beneficial fats in the forages. The goal of this project was to determine yields, quality, and fatty acid (FA) levels of annual cool season forage harvested at various growth stages and under different fertility regimes. The data presented here is from one replicated research trial in Vermont. Crop performance data from additional tests in different locations and often over several years, should be compared before you make decisions about planting small grains. Support for this project came from the Organic Valley Farmers Advocating for Organics fund

Concurrent Computing with Shared Replicated Memory

The behavioural theory of concurrent systems states that any concurrent system can be captured by a behaviourally equivalent concurrent Abstract State Machine (cASM). While the theory in general assumes shared locations, it remains valid, if different agents can only interact via messages, i.e. sharing is restricted to mailboxes. There may even be a strict separation between memory managing agents and other agents that can only access the shared memory by sending query and update requests to the memory agents. This article is dedicated to an investigation of replicated data that is maintained by a memory management subsystem, whereas the replication neither appears in the requests nor in the corresponding answers. We show how the behaviour of a concurrent system with such a memory management can be specified using concurrent communicating ASMs. We provide several refinements of a high-level ground model addressing different replication policies and internal messaging between data centres. For all these refinements we analyse their effects on the runs such that decisions concerning the degree of consistency can be consciously made.Comment: 23 page

An open database of productivity in Vietnam's social sciences and humanities for public use

This study presents a description of an open database on scientific output of Vietnamese researchers in social sciences and humanities, one that corrects for the shortcomings in current research publication databases such as data duplication, slow update, and a substantial cost of doing science. Here, using scientists’ self-reports, open online sources and cross-checking with Scopus database, we introduce a manual system and its semi-automated version of the database on the profiles of 657 Vietnamese researchers in social sciences and humanities who have published in Scopus-indexed journals from 2008 to 2018. The final system also records 973 foreign co-authors, 1,289 papers, and 789 affiliations. The data collection method, highly applicable for other sources, could be replicated in other developing countries while its content be used in cross-section, multivariate, and network data analyses. The open database is expected to help Vietnam revamp its research capacity and meet the public demand for greater transparency in science management

Exploiting replication in distributed systems

Techniques are examined for replicating data and execution in directly distributed systems: systems in which multiple processes interact directly with one another while continuously respecting constraints on their joint behavior. Directly distributed systems are often required to solve difficult problems, ranging from management of replicated data to dynamic reconfiguration in response to failures. It is shown that these problems reduce to more primitive, order-based consistency problems, which can be solved using primitives such as the reliable broadcast protocols. Moreover, given a system that implements reliable broadcast primitives, a flexible set of high-level tools can be provided for building a wide variety of directly distributed application programs