International Journal of Web and Grid Services (9 papers in press)
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.
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.
Towards the Optimality of QoS-aware Web Service Composition with Uncertainty
by Sen Niu, Guobing Zou, Yanglan Gan, Yang Xiang, Bofeng Zhang
Abstract: QoS-aware web service composition has recently become one of the most challenging research issues. Although much work has been investigated to solve the problem, they mainly focus on certain QoS of web services, while QoS with uncertainty exposes the most important characteristic in real and highly dynamic environment on the Internet. In this paper, with the consideration of uncertain service QoS and user's preferences, we model the issue of uncertain QoS-aware web service composition via interval number and translate it into a multi-objective optimization problem with global QoS constraints of user's preferences. The encoded optimization problem is solved by an non-deterministic multi-objective evolutionary algorithm, which takes advantage of new genetic encoding schema, the strategy of crossover and uncertain interval Pareto comparison. To validate the feasibility of our proposed approach, large-scale experiments have been conducted on our simulated datasets. The experimental results demonstrate that our proposed approach can effectively and efficiently help an active user find optimum composite service solutions set with satisfactory convergence.
Keywords: web services;uncertain QoS;web service composition;multi-objective optimization.
A Semantic Approach for Generating Government Processes
by Cherouana Amina, Bellatreche Ladjel, Mahdaoui Latifa, Medjahed Brahim
Abstract: In the last years, governments embraced business process management practices to improve their interactions and services with various stakeholders such as citizens, businesses, and other government agencies. Nevertheless, current government process management solutions are still very limited at the semantic level, leading to challenges in dealing with legal, social, organizational, political and economic constraints, collectively referred to as Context. In this paper, we introduce SGPM, a Semantic Government Process Management approach for the design and deployment of legally compliant government processes. The developed solution is mainly articulated around an ontological framework, with a high level of abstraction, allowing the explicit representation of legal context associated with government processes. It is connected to a defined legal meta-model that acts as legal context extraction guidelines and knowledge source. Moreover, this framework is substantiated by a legal features model allowing the semantic representation of structural relationships and dependencies between processes, sub-processes, as well as activities. The ontological framework is implemented as software assets, using OWL-DL, that constitute the kernel from which BPEL executable government processes are automatically generated.
Keywords: E-government; Government Process Management; Meta-modeling; Ontology; Legal Context; Compliance.
SAW-Q: A dynamic composition approach of REST services based on queue model
by Jesus Bellido, Rosa Alarcon, Cesare Pautasso, Carla Vairetti
Abstract: Service composition is one of the principles of service-oriented architecture; it enables reuse and allows developers to combine existing services in order to create new services that in turn can be part of another composition. Dynamic composition requires that service components are chosen from a set of services with equal or similar functionality at runtime, and possibly automatically. The adoption of the REST services in the industry has led to a growing number of services of this type, many with similar functionality. The existing dynamic composition techniques are method-oriented whereas REST is resource-oriented, and consider only traditional (WSDL/SOAP) services. We propose SAW-Q, an extension of Simple Additive Weighting (SAW), as a novel dynamic composition technique that follows the principles of the REST style. Additionally, SAW-Q models quality attributes as a function of the actual service demand instead of the traditional constant values. Our model is much more accurate when compared to real implementation, positively improving the quality of dynamic service compositions.
Keywords: SOA; REST services; dynamic composition; quality attributes.
Planning Operators of Concurrent RDF Stream Processing Queries
by Sejin Chun, Seungjun Yoon, Jooik Jung, Kyong-Ho Lee
Abstract: RDF Stream Processing(RSP), which aims to query data streams and Linked Data sets using common data model and query languages extended from RDF and SPARQL, is gaining popularity. However, most of the existing RSP engines do not provide any optimization techniques for shared join operators among query plans from concurrent queries. Many number of shared join operators can incur the waste of a lot of CPU resources like a processing memory. Moreover, queries on shared operators cause a slow response time because they must be re-evaluated without reusing intermediate results. To solve these problems, we propose an efficient method of optimizing query plans on multiple queries. First, the proposed method evicts some data that get notified from the streams in order to maintain an efficient memory usage. Second, the proposed method optimizes query plans to maximize the reuse of shared join results. Experimental results show that the proposed method has significant improvements in terms of memory consumption and latency, compared to the state-the-of-art methods.
Keywords: RDF; SPARQL; Stream processing; Distributed processing; Operator planning; Semantic Web.
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.