International Journal of Web and Grid Services (13 papers in press)
One Size Does Not Fit All: Logic-based Clustering for On-the-fly Web Service Composition and Verification
by Khai Huynh, Tho Quan, Thang Bui
Abstract: Recently, Web Service Composition (WSC) has been widely emerging since it is obviously hopeless to develop a specific web service which can single-handedly fulfill completely a requirement previously posed by clients. Moreover, as a WSC solution often needs to satisfy various kinds of constraints, its correctness is also required to be formally verified. However, composition and verification tasks always suffer from huge computational cost when applied in practice. It prompts the consideration of clustering approaches, which group similar web services into same clusters for further processing. Unfortunately, typical clustering techniques cannot ensure that all of the web services grouped into a cluster fulfill a certainly required constraint. Likewise, those techniques do not also guarantee that all of the web services fulfilling a constraint will be put into the same cluster. In other words, the existing web service clustering approaches accomplish neither the soundness nor completeness of a composition solution.
To overcome this problem, we propose a logic-based approach for clustering web services, where logic formulae are used for representing web services and their clusters. The clustering results are then further applied for WSC and verification in an on-the-fly manner. In the theoretical aspect, our approach achieves both soundness and completeness. In practice, the logic-based similarity used in our approach generates more reasonable clusters, resulting in significant performance improvement in experimentation.
Keywords: Logic-based Web Service Clustering; Logic-based Web Service Similarity; Web Service Clustering; Web Service Composition; Web Service Formal Definition.
G-OPTICS: Fast Ordering Density-based Cluster Objects using Graphics Processing Units
by Wookey Lee, Woong-Kee Loh
Abstract: Clustering is the process of forming groups or clusters of similar objects in the dataset and has been used as an important tool for many data mining applications including the web-based ones. While density-based clustering algorithms are widely adopted, their clustering result is highly sensitive to parameter values. The OPTICS algorithm presents a solution to this problem; it produces an ordering of objects that is equivalent to the clustering results for a wide range of thresholds e. In this paper, we propose an algorithm named G-OPTICS to significantly improve the performance of OPTICS using a Graphics Processing Unit (GPU). The experimental results using real and synthetic datasets demonstrated that G-OPTICS outperformed the previously fastest FOPTICS algorithm by up to 118.3 times (67.7 times on the average).
Keywords: ordering of objects; density-based clustering; graphics processing unit; parallel algorithm.
Implementation and Evaluation of Hybrid Broadcasting System for Webcasts
by Takeshi Ozaki, Yusuke Gotoh
Abstract: Due to the recent popularization of grid environments, streaming delivery using broadcast and telecommunication method systems is attracting great attention. In streaming delivery under hybrid broadcasting environments, clients concurrently receive such streaming data as music or movies from both broadcasting and telecommunication systems. Although these systems compensate for their respective the demerits, the waiting time is lengthened if the system does not deliver the data efficiently. To reduce this waiting time, many researches have proposed scheduling methods. However, since most scheduling methods use a computer simulation, they do not clearly show their the effectiveness. In this paper, we design and implement a hybrid broadcasting system to solve the problems of conventional methods. In our proposed system, we evaluate how efficiently they reduce waiting times using scheduling methods.
Keywords: Hybrid broadcasting; Continuous media data; Scheduling; Waiting time.
Blockchain Challenges and Opportunities: A Survey
by Zibin Zheng, Shaoan Xie
Abstract: Blockchain, the core mechanism in Bitcoin, has received extensive attentions recently. Blockchain serves as a public ledger and transactions stored in blockchain are nearly impossible to tamper. Blockchain has the key characteristics such as decentralization, persistency, anonymity and auditability. Blockchain help to improve efficiency and security. It could be applied into many fields including financial services, reputation system and public services. However, there are still a large number of technical challenges prohibiting the wide application of blockchain: scalability problem, privacy leakage etc. This paper presents a comprehensive survey on blockchain technology. In this paper, we present a comprehensive survey on the state-of-the-art research efforts on blockchain technology. In particular, we first give an overview on blockchain technology. The typical blockchain consensus algorithms are then introduced. We next present a survey on blockchain applications and technical challenges as well as recent advances. Finally, future research directions are also discussed.
Keywords: Blockchain; Decentralization; Consensus; Application.
Efficient Request Assignment Algorithm in Mobile Cloud Computing Environment
by Ao Zhou
Abstract: Recently, mobile applications have become increasingly computation-intensive. However, the energy and the computing capabilities of mobile devices, such as smartphones and tablets, are limited. Mobile cloud computing is becoming a powerful way to tackle this challenge. Offloading computation-intensive tasks to nearby cloudlets can significantly save energy and enhance the computation capabilities of mobile devices. However, determining how to assign task requests to cloudlets while minimizing the response time remains a challenging issue. The traditional approach cannot achieve the optimal effect since it ignores the task characteristics and the communication characteristic between the cloudlets. To address this challenge, in this paper, we provide an efficient algorithm for task request assignment that shortens the response time and reduces the network resource consumption. We first formulate the problem as a response time and network resource consumption minimization problem. To solve this problem, we then propose an optimized differential evolution algorithm. We finally evaluate the performance of the proposed task request assignment algorithm through experimental simulations. Simulation results demonstrate that the proposed algorithm is promising.
Keywords: Mobile cloud computing; Edge computing; Cloudlet; Request assignment.
A Compressed Graph Representation for Services Composition
by Jing Li, Yuhong Yan, Ming Zhu
Abstract: Service-oriented computing enhances business scalability and flexibility. Providers who expect to benefit from it may bring explosive growth of web services. As a result, the huge storage required in searching a composition solution may be too much to afford. In this paper, we apply a compressed data structure to tackle this challenging issue. We propose a system model to solve web service composition problem. In this model, we use a compressed tree to represent the search graph. This work innovatively solve the composition problem with compressed graph representation. The proposed model is verified through theoretical analysis and experimental study. The obtained experimental results show that this system may handle a large number of web services with small space requirement.
Keywords: web service composition; QoS optimization; graph compression.
pisodm: Building SOC Applications in the Presence of Non-Functional Requirements
by Khalid Belhajjame, Valeria De Castro, Javier Espinosa-Oviedo, Martin Musicante, Umberto Souza Da Costa, Placido Souza Neto, Genoveva Vargas-Solar, José-Luis Zechinelli-Martini
Abstract: Specifying non-functional requirements (NFRs) is a complex task, being usually addressed during the latter phases of the software development process.
The late inclusion of NFRs during the software development may compromise the quality of the resulting application.
This paper presents pisodm, a method and associated tools that
(i) allow the early specification of NFRs allowing users to them in an abstract way without having to care about low level details;
(ii) embraces the MDA philosophy, generating models (code) whenever possible for reducing the specification and programming effort of the business application logic and its associated NFRs.
Our solution has been used in the context of an industrial and real case study.
Keywords: MDA; Non-Functional Requirements; Service-based software process.
Cross-Lingual Analysis of English and Chinese Web Search
by Peiguang Lin, Tong Zhang, Menglong Xia, Jin Zhou, Peiyao Nie
Abstract: Edge Computing is pushing the frontier of computing applications, data, and services away from centralized nodes to the logical extremes of a network. It enables analytics and knowledge generation to occur at the source of the data. There is a growing number of the non-English Web during recent years and with an extra ordinary speed currently. Unfortunately, most of the works available on web search analysis are still English-based. Since the language-dependent and user-based search paradigms are becoming increasingly important for search engines; to understand the behavioural commonality and distinction of non-English users for conducting web search is essential and in urgent. Here we propose a framework for analysing the web search behaviours of users in a cross-lingual context. This framework is composed of ten factors, which can be applied at the query level, session level and corpus level respectively. The integral employment of these factors could help us with characterizing the user behaviour of web search, even in different languages, with regard to both statistical and semantic perspectives. As an application of this framework, we made a comparison of web search between English and Chinese users by mining their search engine query logs. This ten-factor containing framework shows a better efficiency not only in revealing the commonality and distinction of web search, but also in informing the design of search paradigms in a cross-lingual scenario.
Keywords: Edge Computing; Cross-Lingual Analysis; Web Search; hierarchical system.
Emerging issues and challenges for cloud data at the edge
by Kok-Seng Wong, Myung Ho Kim
Abstract: Due to advantages such as flexibility, mobility and cost-saving, the pushing of data storage and processing into the cloud has been a key trend in many enterprises. Recently, researchers have found that there is a growing limitation in the meeting of the computing and network bandwidths for the cloud when supported systems such as the Internet of Things (IoT) are used. Instead of establishing channels for the cloud storage and utilisation, edge-centric computing places some of the processes and resources near to the users; however, its utilisation has raised security concerns about the data usage, and the existing secure mechanisms in the cloud are no longer suitable for data protection at the edge. In this paper, the security issues of cloud data at the edge are studied. We present several challenges and opportunities for edge computing and demonstrate the impact of privacy leakage in IoT applications.
Keywords: data privacy protection; edge-centric computing; fog computing; IoT applications; secure data sharing.
Performance modelling and analysis for IoT services
by Jiwei Huang, Songyuan Li, Ying Chen, Junliang Chen
Abstract: With the growing popularity of Internet of Things (IoT) services on the internet, performance has become an important issue in the design and optimisation of IoT service systems. This paper proposes a theoretical approach of performance evaluation for IoT services, which is expected to provide a mathematical prediction on performance metrics at the design phase before system implementation. In specific, we first formulate an atomic service by a queueing system, and then an IoT system can be modelled by a queueing network. Detailed quantitative model analyses under different request arrival distributions are presented, and performance metrics are obtained. Furthermore, we briefly study two popular problems which are resource management and task scheduling in order to illuminate how the models and analytical results can be applied in the design and optimization of IoT systems. Finally, simulation experiments based on real-world data are conducted to validate the effectiveness of our approach.
Keywords: Internet of Things; IoT; IoT service; performance evaluation; quality of service; queueing model.
PSPO: a framework for cost-effective service placement optimisation during enterprise modernisation on hybrid clouds
by Ravikumar Ramadoss, N.M. Elango, A. Satheesh, Ching-Hsien Hsu
Abstract: An integrated cloud service model utilising both public and private cloud services to provide a holistic deployment of the enterprise applications is the need of the hour. Traditional existing applications getting modernised to meet the high business demands to serve end customers, by adapting technology enhancements towards big data and cloud to achieve the futuristic Service Level Agreements (SLA).Some efforts have been made to model with respect to cost and its impacts, yet the distinctive need is to get a holistic picture of the overall modernisation characteristics. In this paper, we propose a proactive cost optimisation model along with a proposed algorithm to solve some of the key issues towards service placement during enterprise modernisation. The proposed cost optimised algorithm is applied to different scenarios on multiple clouds with enterprise modernisation characteristics. Experimental results derived shown that the proposed work effectively optimises the service placement on multiple clouds.
Keywords: cost factors; enterprise modernisation; hybrid clouds; service migration.
Real-time adaptive QoS prediction using approximate matrix multiplication
by Adrian Satja Kurdija, Marin Silic, Sinisa Srbljic
Abstract: We introduce a novel QoS prediction model as a real-time support for the selection of atomic service candidates based on their QoS properties while constructing composite applications. The proposed approach satisfies the following requirements: (i) fast and accurate prediction of QoS values and (ii) adaptability with respect to environment changes. The model precomputes the similarities between users and services using approximate matrix multiplication to reduce the time complexity. When calculating a prediction for a user-service pair, the model considers similar users and services, but enhances the prediction accuracy by incorporating the number of observed records. Time complexity is further reduced by storing the lists of similar users and services which are updated in real-time. The model adapts to the changing environment: newer records are set to have greater influence on the predictions. The experiments conducted on relevant service-oriented datasets show advantages of the proposed model in accuracy and time performance.
Keywords: approximate matrix multiplication; QoS prediction; quality of service; real-time adaptability; service recommendation; web services.
Special Issue on: Security for Cloud Computing
Searchable Symmetric Encryption Based on the
Inner Product for Cloud Storage
by Jun Yang, Shujuan Li, Xiaodan Yan, Baihui Zhang, Baojiang Cui
Abstract: Searchable encryption enables the data owner to store their own data after
encrypting them in the cloud. Searchable encryption also allows the client to search over
the data without leaking any information about it. In this paper, we rst introduce a
searchable symmetric encryption scheme based on the inner product: it is more ecient
to compute the inner product of two vectors. In our construction, the parties can be Data
Owners, Clients or the Cloud Server. The three parties communicate with each other
through the inner product to achieve the goal that the client can search the data in the
cloud without leaking any information on the data the owner stored in the cloud. We then
perform a security analysis and performance evaluation, which show that our algorithm
and construction are secure and ecient.
Keywords: Searchable Encryption; Searchable Symmetric Encryption; Inner Product;
the Cloud Server; Security.