Traditional Client-server Architecture Research Articles

Managing Household Food Waste with the FoodSaveShare Mobile Application

It is estimated that European households are responsible for 55% of food waste generation. Key factors contributing to household food waste generation include food spoilage, confusion over expiration dates, overbuying, and inadequate shopping planning. Thus, food waste prevention at the household level depends heavily on food supplies monitoring and management. To this end, during the last decade, several consumer-oriented digital tools have been designed and launched. A literature review showed that currently accessible digital tools are scarce and cover a narrow range of functionalities. Here, we address these issues by designing and launching a decision support tool implemented in a smart mobile phone application (app), the FoodSaveShare Mobile App. The application development followed a traditional client–server architecture using state-of-the-art software and hardware technologies. Additionally, a survey of 340 individuals was conducted to better understand end-user motivation for and barriers against adopting this and similar apps. The developed application combines user-provided data with a retailer loyalty program to leverage the integrated features for tracking shopping activities. The app features a household shopping list populated by product barcode scanning and manual entry. Based on food and packaging type, food products are assigned approximate expiration dates to issue product expiration reminders. For products about to expire, suggestions for their utilization are provided, drawing from a list of over 7000 recipes. Additional functionality allows users to identify products that have either been consumed in time or that need to be discarded. Analytical tools, such as past purchase and resources discarded versus resources saved statistics, offer comprehensive insight and encourage improved shopping and consumption practices. The FoodSaveShare App was launched during the A2UFood Project, which allowed an organised campaign for its use. The app was tested under real customer data and conditions, and selected features have been adopted by the largest supermarket chain on the Island of Crete, Greece. The potential end-user survey results suggest that, provided personal data use issues are addressed, such apps can have a significant impact on reducing household food waste. Future work will focus on analysing the datasets produced by the application to assess its impact on household food waste management.

A formal pattern of information system design

A new design pattern intended for distributed cloud-based information systems is proposed. Pattern is based on the traditional client-server architecture. The server side is divided into three principal components: data storage, application server and cache server. Each component can be used to deploy parts of several independent information systems, thus realizing shared-resource approach. A strategy of separation of competencies between the client and the server is proposed. The strategy assumes that the client side is responsible for application logic and the server side is responsible for data storage consistency and data access control. Data protection is ensured by means of two particular approaches: at the entity level and at the transaction level. The application programming interface to access data is presented at the level of identified transaction descriptors.

MODEL OF INFORMATION INTERACTION BETWEEN ELEMENTS OF MULTILEVEL SYSTEM OF DIGITAL TWINS

One of the solutions to the problem of spatio-temporal data anisotropy is the use of a multilevel system of digital twins based on the corresponding industry models and the updated archive data base. The application of this approach has successfully proved itself in information systems for monitoring the parameters of the geomagnetic field and its variations, providing spatio-temporal interpolation of geomagnetic data with an accuracy of 0.81 nT in magnetically quiet periods. At the same time, the problem of information interaction between the levels of the system of digital twins remained unresolved, which is greatly aggravated by the constantly growing volume of data and their heterogeneous nature. The paper proposes a solution to the indicated problem by means of a formalized mechanism for packaging space-time information, in which the identification of data sources is performed on the basis of a hierarchical binary tokenization system. In addition, the proposed software implementation of such an approach is considered, a distinctive feature of which is the combination of traditional clientserver and innovative serverless architectures to implement a highly loaded reactive web application for working with analyzed data. The main stages of the implementation of information interaction are highlighted and programmatically formalized - from obtaining initial information from its sources to verifying data, analyzing them, processing and forming the output information flow of the system. The results of the computational experiments carried out on the example of the problem of monitoring the parameters of the Earth's magnetic field and its variations confirmed the effectiveness of the proposed solutions, expressed both in increasing the reactivity of web-based applications and in increasing the computational speed of formation and filling of information storages that aggregate information from distributed heterogeneous sources.

Score-based Incentive Mechanism (SIM) for live multimedia streaming in peer-to-peer network

A decentralized model is primarily used for communication and file transfer, the peer-to-peer network is based on this model. The field of real-time communication and media streaming has witnessed enormous growth in recent times owing to their use of peer-to-peer network. A significant part of Internet traffic is being created by the peer-to-peer network resulting in an increase in its demand. The rise in prominence of peer-to-peer network can be attributed to its properties like resource utilization and distributed nature. Resource utilization of peer-to-peer network is one foremost motive for selecting this network over the traditional client-server architecture. The availability of selfish peer or free riders affects the total resource utilization and degrades the performance of the network. So, there is a requirement of an incentive-based mechanism to motivate the selfish peer or free riders in the network to improve the performance of the network. In this paper, we will discuss a new score based incentive mechanism to improve the overall resource utilization. This approach is based on a reward-punishment based method, so the peers are encouraged or motivated to share more resources and chastise selfish peers. For calculating the score value of a peer, parameters like upload capacity, video quality, control packets, a time period for which peers stay in the network can be used. Different score values are assigned for different parameters. The simulation results presented in this paper verify the approach and illustrate that the quality of video and performance of network improves using our new score based incentive mechanism. The parameters used for calculating the performances are; end-to-end delay, playback delay, start-up delay, and frame redundancy etc.

Practical client-side replication

Client-side replication and direct client-to-client synchronization can be used to create highly available, low-latency interactive applications. Causal consistency, the strongest available consistency model under network partitions, is an attractive consistency model for these applications. This paper focuses on how client misbehaviour impacts causal consistency. We analyze the possible attacks to causal consistency and derive secure consistency models that preclude different types of misbehaviour. We propose a set of techniques for implementing such secure consistency models, which exhibit different trade-offs between the application guarantees, and the latency and communication overhead. Our evaluation shows that secure consistency models impose low overhead when compared with their insecure counterparts, while providing low user-to-user latency and server load compared with traditional client-server architectures. Secure consistency models can be used to enrich server-based architectures with fast and secure peer-to-peer interactions.

Distributed Caching via Rewarding: An Incentive Scheme Design in P2P-VoD Systems

Peer-to-peer (P2P) systems rely on peers' cooperation to provide a more robust and scalable service as compared to the traditional client-server architecture. However, the peers might be selfish in nature-they would like to receive services from others, but would not like to contribute their own resources by default. To conquer this problem, proper incentive schemes are needed so as to stimulate the peers' contributions. In particular, in P2P video-on-demand (VoD) systems, peers need to distributively cache the proper videos so as to mutually upload and help each other to acquire the required data. Content providers of P2P-VoD services want to incentivize peers to do so and alleviate the workload of the content server. In this paper, we design a practical mechanism to incentivize distributed caching in such systems, under which the peers are rewarded based on the popularity of the video they cache. We characterize the impact of this incentive scheme on peers' caching behaviors. In particular, we formulate an optimization framework to decide the optimal reward price for each video so as to keep enough replicas and minimize the content provider's operational cost. We first derive close form solutions in an asymptotic system, and then extend our results to be adaptive to various practical issues. Via extensive simulations, we validate the effectiveness and efficiency of our incentive scheme.

An Efficient Hybrid Push-Pull Based Protocol for VOD In Peerto-Peer network

Video-on-Demand is a service where movies are delivered to distributed users with low delay and free interactivity. The traditional client-server architecture experiences scalability issues to provide video streaming services. Peer-to-Peer (P2P) techniques for video on demand (VOD) have been shown to be a good enhancement to the traditional client/server methods when trying to reduce costs, increase robustness and solve the scalability issues. Various challenges arise when building a resilient P2P video on demand systems, such as long waiting time to receive the video segments and the quality of service. A new proposed data exchange schema is called Efficient Hybrid Push-Pull based Protocol (EHP3) can reduce the initial playback delay and improve the quality of service. The downstream peer has to accelerate the downloading process of the urgent segments, i.e. those missing segments which are near their playback time. The range of the urgent segments is referred to as the priority region. The upstream peers give a strict priority to segments within the priority region. If the downstream peer has sufficient download bandwidth, it should be able to completely receive these urgent segments before playback time. If there are no missing segments in the priority region, the downstream peer uses the pull protocol to download the missing segments which are outside the priority region. The simulation result shows that the proposed data exchange schema (EHP3) can reduce the initial play back delay and reduce the burden on the server side by increasing the number of caching segments in the playback buffer. Moreover, the proposed schema improves the quality of service by reducing the number of skipped segments during the playback.

A Local Resource Sharing Platform in Mobile Cloud Computing

Despite the increasing use of mobile computing, exploiting its full potential is difficult due to its inherent characteristics such as error-prone transmission channels, diverse node capabilities, frequent disconnections and mobility. Mobile Cloud Computing (MCC) is a paradigm that is aimed at overcoming previous problems through integrating mobile devices with cloud computing. Mobile devices, in the traditional client-server architecture of MCC, offload their tasks to the cloud to utilize the computation and storage resources of data centers. However, along with the development of hardware and software technologies in mobile devices, researchers have begun to take into consideration local resource sharing among mobile devices themselves. This is defined as the cooperation based architecture of MCC. Analogous to the conventional terminology, the resource platforms that are comprised of surrounding surrogate mobile devices are called local resource clouds. Some researchers have recently verified the feasibility and benefits of this strategy. However, existing work has neglected an important issue with this approach, i.e., how to construct local resource clouds in dynamic mobile wireless networks. This paper presents the concept and design of a local resource cloud that is both energy and time efficient. Along with theoretical models and formal definitions of problems, an efficient heuristic algorithm with low computational complexity is also presented. The results from simulations demonstrate the effectiveness of the proposed models and method.

</title> </titles> <publication_date> <month>12</month> <year>2011</year> </publication_date> <pages> <first_page>2081</first_page> <last_page>2081</last_page> </pages> <publisher_item> <item_number item_number_type='arNumber'>6082068</item_number> </publisher_item> <doi_data> <doi>10.1109/JPROC.2011.2174089</doi> <resource>http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6082068</resource> </doi_data> </journal_article> <journal_article> <titles> <title><![CDATA[Peer-to-Peer Media Streaming: Insights and New Developments

Internet media content delivery started to emerge roughly a decade ago, and it has subsequently had a major impact on network traffic and usage. Although traditional client-server systems were used initially for delivering media content, researchers and practitioners soon realized that peer-to-peer (P2P) systems, due to their self-scaling properties, had the potential to improve scalability compared with traditional client-server architectures. Consequently, various P2P media streaming systems have been deployed successfully, and corresponding theoretical investigations have been performed on such systems. The rapid developments in this field raise the need for up-to-date literature surveys to summarize them. In recent years, numerous technological discoveries have been achieved. The focus of this report is to survey and discuss these new findings, which include new technological developments, as well as new understandings of these developments and of the existing P2P streaming techniques, through both novel modeling methodologies and measurement-based studies.

A flexible content repository to enable a peer‐to‐peer‐based wiki

AbstractWikis—being major applications of the Web 2.0—are used for a large number of purposes, such as encyclopedias, project documentation, and coordination, both in open communities and in enterprises. At the application level, users are targeted as both consumers and producers of dynamic content. Yet, this kind of peer‐to‐peer (P2P) principle is not used at the technical level being still dominated by traditional client–server architectures. What lacks is a generic platform that combines the scalability of the P2P approach with, for example, a wiki's requirements for consistent content management in a highly concurrent environment. This paper presents a flexible content repository system that is intended to close the gap by using a hybrid P2P overlay to support scalable, fault‐tolerant, consistent, and efficient data operations for the dynamic content of wikis. On the one hand, this paper introduces the generic, overall architecture of the content repository. On the other hand, it describes the major building blocks to enable P2P data management at the system's persistent storage layer, and how these may be used to implement a P2P‐based wiki application: (i) a P2P back‐end administrates a wiki's actual content resources. (ii) On top, P2P service groups act as indexing groups to implement a wiki's search index. Copyright © 2009 John Wiley & Sons, Ltd.

Design Software for Application-Specific Microfluidic Devices

Microfluidics-based lab-on-a-chip systems, which feature miniaturization of biological separation and assay techniques, are rapidly transforming biochemical analysis and high-throughput screening. Microfluidic system design requires expertise in materials, chemistry, biology, and engineering, and understanding the complex interplay between variables that influence and limit system performance is difficult without computational assistance. Modeling approaches based on 3-dimensional numerical simulations provide detailed information regarding spatiotemporal variations of the field variables but are computationally very expensive for system-level analysis. Design-modeling tools are needed that rapidly simulate the complex underlying phenomena such as electroosmosis, electrophoresis, sample dispersion, mixing, and biochemical reactions without significantly compromising accuracy (1)(2)(3)(4)(5). In addition, these design tools must be easily usable by the microfluidic community, which comprises scientists and engineers from a variety of disciplines. To meet these challenges, we developed integrated design software that allows rapid layout of microfluidic channel networks, fast system performance simulation using a system solver, and the ability to easily reconfigure chip layout to meet specifications. We illustrate the application of the software to improve the design for an electrokinetic immunoassay chip. The software design follows a modified form of the traditional client-server architecture. The user interacts with a graphical user interface (GUI) front-end (client). Fig. 1⇓ shows a screenshot of the GUI. The microfluidic lab-on-a-chip system is represented as a network of interconnected components that can be assembled from a component library. The sequence of operations required for the creation of the microfluidic network, analysis, and visualization of results using the GUI is as follows: (1) Creation of the microfluidic network: The components (such as sample reservoirs, straight channels, bends, biosensors, and interconnects such as Y-, T-, and cross junctions) are selected from the component library and assembled into a network using a drag-and-drop method. (2) Problem …

A QoS-Aware and Energy-Conserving Transcoding Proxy Using On-Demand Data Broadcasting

Most research works in transcoding proxies in mobile computing environments are on the basis of the traditional client-server architecture and do not employ the data broadcast technique. In addition, the issues of QoS provision and energy conservation are also not addressed in the prior studies. In view of this, we design in this paper a QoS-aware and energy-conserving transcoding proxy by utilizing the on-demand broadcasting technique. We first propose a QoS-aware and energy-conserving transcoding proxy architecture, abbreviated as QETP, and model it as a queuing network consisting of three queues. By analyzing the queuing network, three lemmas are derived to estimate the load of these queues. We then propose a version decision policy and a service admission control scheme to provide QoS in QETP. The derived lemmas are used to guide the execution of the proposed version decision policy and service admission control scheme to achieve the given QoS requirement. In addition, we also propose a data indexing method to reduce the power consumption of clients. To measure the performance of the proposed architecture, three experiments are conducted. Experimental results show that the average access time reduction of the proposed scheme over the traditional client-server architecture ranges from 45 percent to 75 percent. Experimental results also show that the proposed scheme is more scalable than the traditional client-server architecture and is able to effectively control the system load to attain the given QoS requirements. In addition, the proposed scheme is able to greatly reduce the average tuning time of clients at the cost of a slight increase (around 5 percent in our experiments) in average access time.

Support for resilient Peer-to-Peer gaming

In areas such as Massively-Multiplayer Online Games (MMOGs), the conventional centralized server model does not scale with the sheer number of simultaneous clients that need to be supported. P2P architectures are increasingly being considered as replacements for traditional client-server architectures in MMOGs. A distributed P2P architecture that uses ''Coordinator'' nodes for handling smaller groups of players has been shown to be especially effective in supporting MMOGs. However, the drawback of moving from centralized to distributed architectures is the loss of control, and more specifically the increase in the vulnerability of the system as a whole to compromises. There has been no prior work on handling the specific case when the Coordinator itself is compromised and cheats, a scenario akin to cheating conducted by the network. We address this problem by proposing an architecture that is resilient to Coordinator compromises and demonstrate the effectiveness of this architecture. We believe that this is an essential step towards enabling a widespread deployment of P2P-based MMOGs.

Building an e-marketplace on a peer-to-peer infrastructure

Existing e-marketplaces, built on traditional client–server architectures, severely restrict the scope and dynamics of Business-to-Business (B2B) interactions. Peer-to-peer (P2P) architectures will provide far more decentralized infrastructures, while allowing a much wider range of business patterns to take place. On one hand, the interaction over a P2P network resembles the way real-world enterprises perform business with each other. On the other hand, a small set of simple services is enough to support complex business processes over a P2P infrastructure. Incidentally, most of the required technology is readily available, although it may be necessary to bring in an appropriate integration of different concepts. The paper discusses the implementation of essential services for P2P e-marketplaces, based on one of the leading P2P platforms, and illustrates its benefits by applying the P2P approach to a vendor of industrial equipment.

The Economics of Peer-to-Peer Networks

Peer-to-Peer (P2P) networks have emerged as a significant social phenomenon for the distribution of information goods and may become an important alternative to traditional client-server network architectures for knowledge sharing within enterprises. This paper reviews and synthesizes the relevant computer science and economics literatures as they relate to P2P networks, and raises important questions for researchers interested in studying the behavior of these networks from the perspective of the economics of information technology. With regard to the economic characteristics of these networks, we show that while the characteristics of services provided over P2P networks are similar to public goods and club goods, they have many important differences and hence there is a need for new theoretical models as well as empirical and experimental analysis to understand P2P user behavior. We then identify several important areas for study with regard to the economics of P2P networks and review recent academic papers in each area.

The Virtual Commons: Why Free-Riding Can Be Tolerated in File Sharing Networks

Peer-to-peer networks have emerged as a popular alternative to traditional client-server architectures for the distribution of information goods. Recent academic studies have observed high levels of free-riding in various peer-to-peer networks, leading some to suggest the imminent collapse of these communities as a viable information sharing mechanism. Our research develops an analytic model to analyze the behavior of P2P networks in the presence of free-riding. In contrast to previous predictions we find that P2P networks can operate effectively in the presence of significant free-riding. In future work we plan to explore how much peerto-peer network performance could be improved if free-riding were eliminated and discuss both the costs and benefits of managerial mechanisms to limit free-riding.

Dynamo: design, implementation, and evaluation of cooperative persistent object management in a local area network

In light of advances in processor and networking technology, especially the emergence of network attached disks, the traditional client-server architecture of persistent storage systems has become suboptimal for many computation/data intensive applications. In this paper, we introduce a revised architecture for persistent object management employing network attached storage: the dynamic object server environment (Dynamo). Dynamo introduces two main architectural innovations: (1) to provide high scalability, the object management functions are mainly performed cooperatively by the clients in the system. Furthermore, data is transferred directly to the client's cache from network-attached disks, thus avoiding copies from a disk to the server buffer and then over the network to the client. Other systems have an a priori assignment of ‘object management’ functions to specific nodes; (2) Dynamo uses a cooperative cache management which employs a decentralized lottery-based page replacement strategy with a novel technique which attempts to put a page replaced from one node into the cache of another node which is likely to access the page in the near future. We show via performance benchmarks run on the Dynamo system and simulation results how this architecture increases the system's adaptability, scalability and cost performance. Copyright © 2000 John Wiley & Sons, Ltd.