Service-based Applications Research Articles

An aspect-oriented model-driven approach for building adaptable context-aware service-based applications

Context-aware service-based applications development has been considered among the most studied research fields in the last decade. The objective was to accompany the rapid technology evolution of mobile computing devices by providing customized services able to interact with different contextual situations of a pervasive environment. For this purpose, many research works have advocated Model-Driven Development (MDD) for building context-aware service-based applications. However, the proposed approaches have presented specific methodologies without using development standards, which may be followed by developers. In addition, most of them have ignored the dynamic adaptation aspect at runtime that should characterize such kind of applications and no adaptation strategy was considered in their proposals. The current paper aims to propose a generic model-driven approach for context-aware service-based applications engineering with a software development methodology including a reconfiguration loop to achieve the dynamic adaptation of these applications. This approach focuses on the combination of MDD and Aspect Oriented Modelling (AOM) to take advantage of their benefits. AOM encapsulates different context-awareness logics separately in aspect models called ContextAspect that can be easily woven into the service's business logic according to the changing context over time. The proposed development methodology includes four phases (modelling, composition, transformation and adaptation) which act in conformance with the MDA technology. The main results gained by using the present approach are the possibility to combine the MDA technology with the aspect-oriented paradigm in a generic development methodology for context-aware service-based applications, and the handling of their dynamic adaptation at execution time according to the changes in the context. The development of context-aware applications is a complex, cumbersome, and time-consuming task. However, the experience reached by implementing the proposed methodology leads us to believe that the involvement of MDD and AOM is significantly beneficial to overcome some recognised shortcomings of several existing approaches and to make this task simpler, easier and faster.

A Highly Accurate Prediction Algorithm for Unknown Web Service QoS Values

Quality of service (QoS) guarantee is an important component of service recommendation. Generally, some QoS values of a service are unknown to its users who has never invoked it before, and therefore the accurate prediction of unknown QoS values is significant for the successful deployment of web service-based applications. Collaborative filtering is an important method for predicting missing values, and has thus been widely adopted in the prediction of unknown QoS values. However, collaborative filtering originated from the processing of subjective data, such as movie scores. The QoS data of web services are usually objective, meaning that existing collaborative filtering-based approaches are not always applicable for unknown QoS values. Based on real world web service QoS data and a number of experiments, in this paper, we determine some important characteristics of objective QoS datasets that have never been found before. We propose a prediction algorithm to realize these characteristics, allowing the unknown QoS values to be predicted accurately. Experimental results show that the proposed algorithm predicts unknown web service QoS values more accurately than other existing approaches.

An Efficient Algorithm for the Bursting of Service-Based Applications in Hybrid Clouds

Enterprises are more and more using hybrid cloud environments to deploy and run applications. This consists in providing and managing software and hardware resources within the enterprise and getting additional resources provided externally by public clouds whenever this is needed. In this later case, deployment of new applications consists in choosing a placement of some components in the private cloud and some others in the public cloud. To tackle this NP-hard problem, we have proposed in a previous work an approximate approach based on communication and hosting costs induced by the deployment of components in the public cloud. In this paper, we go further and propose a new efficient algorithm adapted for service-based applications modelled that can be not only described as behavior-based but also as architecture-based compositions of services.

A replicas placement approach of component services for service-based cloud application

Placement of component service replicas for service-based application (SBA) in cloud environments has become increasingly important. A SBA is usually communication topology-aware, and component service replicas possess stronger data dependency than data replicas; therefore, there are huge amounts of communication between the computer nodes that are used to place component service replicas. Because the conventional methods do not consider the communication topology of component services and the relations between computer nodes, they are not appropriate for placing component service replicas. In this paper, we propose a topological matching-based component service replicas placement method that takes into account not only the topology of SBAs but also the communication performance between different computing nodes. This method first discovers the communication topology of a SBA via multi-scale graph clustering then acquires the topology of computer nodes through spectral clustering. It then places the component service replicas by matching the above two topological structures. Comprehensive experiments are conducted by comparing the performance of our method with those of other methods based on CloudSim simulation software. The results show the effectiveness of our method for improving the performance of SBAs.

An improved security framework for Web service-based resources

Web service-based application has become one of the dominative ones of the Internet. This trend brings more and more security challenges in reliability, condentiality, and data nonrepudiation, especially in some systems that have massive diversied resources. An improved framework for secure accesses of Web resources is presented and implemented by extending and enhancing the Spring Security framework. It improves the security level of systems for identity authentication, authorized access, and secure transmission. The highly safe authentication is based on the integration of an improved authentication module of Spring Security with a U-key method and a RSA algorithm. For authorized access, the Spring Security's ACL (access control list) mechanism is improved by optimizing the domain object-level access control. For secure transmission, a compromising method is presented to take both the security level and the speed of data transmission into account by means of mixing the RSA and DES algorithms. In addition, the security interceptor of Spring Security is extended and a series of securitylters are added to keep Web attacks away. The above improved security framework has been applied to an online virtual experiment platform named VeePalms. The experimental results show that most security problems with high severity in the system have been solved and medium-low severe problems decreased dramatically. Moreover, VeePalms has been used in practice for about 2 years, which has proved the effectiveness of the security framework.

MT4WS: an automated metamorphic testing system for web services

The use of web services has been growing significantly, with increasingly large numbers of applications being implemented through the web. A difficulty associated with this development is the quality assurance of these services, specifically the challenges encountered when testing the applications - amongst other things, testers may not have access to the source code, and the correctness of the output may not be easily ascertained known as the oracle problem. Metamorphic testing MT has been introduced as a technique to alleviate the oracle problem. MT makes use of properties of the software under test, known as metamorphic relations, and checks whether or not these relations are violated. Since MT does not require source code to generate the metamorphic relations, it is suitable for testing web services-based applications. We have designed an XML-based language representation to facilitate the formalisation of metamorphic relations, the generation of follow-up test cases, and the verification of the test results. Based on this, we have also developed a tool to support the automation of MT for web service applications. This tool has been used in an experiment to test web services, the evaluation of which is reported in this paper.

Semantic Web Service Search: A Brief Survey

Scalable means for the search of relevant web services are essential for the development of intelligent service-based applications in the future Internet. Key idea of semantic web services is to enable such applications to perform a high-precision search and automated composition of services based on formal ontology-based representations of service semantics. In this paper, we briefly survey the state of the art of semantic web service search.

Rapid Development of Service-based Cloud Applications

Cloud application platforms gain popularity and have the potential to alter the way service-based cloud applications are developed involving utilisation of platform basic services. A platform basic service provides certain functionality and is usually offered via a web API. However, the diversification of the services and the available providers increase the challenge for the application developers to integrate them and deal with the heterogeneous providers' web APIs. Therefore, a new approach of developing applications should be adopted in which developers leverage multiple platform basic services independently from the target application platforms. To this end, the authors present a development framework assisting the design of service-based cloud applications. The objective of the framework is to enable the consistent integration of the services, and to allow the seamless use of the concrete providers. The optimal service provider each time can vary depending on criteria such as pricing, quality of service and can be determined based upon Big Data analysis approaches.

Event Pattern Discovery in Multi-Cloud Service-Based Applications

The adoption of Cloud computing in the Service Oriented Architecture (SOA) world is continuously increasing. However, as developers try to optimize their application deployment cost and performance, they may also deploy application parts redundantly on different VMs. In such heterogeneous and distributed environments, it is important to have a clear view of the system's state and its components' interrelationships. This paper aims at proposing a novel monitoring and adaptation framework for Service-based Applications (SBAs) deployed on multiple Clouds. The main functionality of this framework is the discovery of critical event patterns within monitoring event streams, leading to specific Service Level Objective (SLO) violations. Furthermore, two main meta-models are proposed for describing the SBA's components and their dependencies, and the supported adaptation actions in a specific context respectively. The proposed approach is empirically evaluated based on a real-world traffic management application.

Designing service-based applications in the presence of non-functional properties: A mapping study

ContextThe development of distributed software systems has become an important problem for the software engineering community. Service-based applications are a common solution for this kind of systems. Services provide a uniform mechanism for discovering, integrating and using these resources. In the development of service based applications not only the functionality of services and compositions should be considered, but also conditions in which the system operates. These conditions are called non-functional requirements (NFR). The conformance of applications to NFR is crucial to deliver software that meets the expectations of its users. ObjectiveThis paper presents the results of a systematic mapping carried out to analyze how NFR have been addressed in the development of service-based applications in the last years, according to different points of view. MethodOur analysis applies the systematic mapping approach. It focuses on the analysis of publications organized by categories called facets, which are combined to answer specific research questions. The facets compose a classification schema which is part of the contribution and results. ResultsThis paper presents our findings on how NFR have been supported in the development of service-based applications by proposing a classification scheme consisting in five facets: (i) programming paradigm (object/service oriented); (ii) contribution (methodology, system, middleware); (iii) software process phase; (iv) technique or mathematical model used for expressing NFR; and (v) the types of NFR addressed by the papers, based on the classification proposed by the ISO/IEC 9126 specification. The results of our systematic mapping are presented as bubble charts that provide a quantitative analysis to show the frequencies of publications for each facet. The paper also proposes a qualitative analysis based on these plots. This analysis discusses how NFR (quality properties) have been addressed in the design and development of service-based applications, including methodologies, languages and tools devised to support different phases of the software process. ConclusionThis systematic mapping showed that NFR are not fully considered in all software engineering phases for building service based applications. The study also let us conclude that work has been done for providing models and languages for expressing NFR and associated middleware for enforcing them at run time. An important finding is that NFR are not fully considered along all software engineering phases and this opens room for proposing methodologies that fully model NFR. The data collected by our work and used for this systematic mapping are available in https://github.com/placidoneto/systematic-mapping_service-based-app_nfr.

Recent research advances in cloud computing and big data

Recent research advances in cloud computing and big data

Semantics, knowledge and grids

Summary Semantics, knowledge and grids represent three streams of studying humans and cyberspace that humans create and interact. Relevant research concerns all areas of computing, especially web semantics, artificial intelligence, and advanced computing infrastructures. This special issue selected eight papers reporting relevant research and applications from the 9th International Conference on Semantics, Knowledge and Grids. Copyright © 2015 John Wiley & Sons, Ltd.

Development of telemedical solutions based on the electronic case record (EFA)

Efficient communication among doctors who cooperatively support their patients is a prerequisite for implementing effective intersectoral treatment processes. In order to achieve this, IT is becoming increasingly important. With IT systems doctors want to exchange information concerning a patient's case (e.g. doctors' letters, medication prescriptions, etc.). Furthermore, more and more IT-based applications that support the treatment process between patient and doctor (e.g. telemedicine solutions) are being developed. The development of the electronic case record (elektronische FallAkte) has yielded concepts and solutions for a structured case-based information exchange. Furthermore, it has led to infrastructure solutions that support service-based applications for telemedical applications. The "elektronische FallAkte" is an initiative of health institutions that have been organized into the association "Verein elektronische FallAkte". In this paper, concepts and realizations of the "elektronische FallAkte", as well as service-based applications on that infrastructure are described.

Dynamic Test Reconfigurationfor Composite Web Services

This paper introduces a testing strategy that is suitable for testing service-based applications. We describe an architecture that responds to changes of service operation, operation arguments and service composition changes. Our proof-of-concept test system performs runtime testing on our model atomic and composite web services using a random testing technique. A novel change identification method was developed to capture changes at the service interface. The test system is able to identify changes that occur in service operations and operational arguments in a service description of a test candidate. Our approach uses a new method to detect changes in a service inventory. Automated reconfiguration is used to support the continuous operation of the testing systems during a test candidate change.

A Novel Approach to Identify Sullied Terms in Service Level Agreement

level agreement (SLA) is simply a file relating the level of service expected by a customer from a dealer laying out the metrics by which that examination is calculated, and the remedies or penalty, if any, must agreed-upon levels not be absolute. Typically, SLAs are between companies and external suppliers, but they may also be among two departments within a company. Service Level Agreements (SLAs) are typically used to specify regulations about the utilization of services that are agreed between the providers of the Service-Based Applications (SBAs) and their consumers. An SLA includes a list of conditions that contain the guarantees that must be fulfilled during the provisioning and use of the services. While the abuse of such guarantees may lead to the application of possible penalties, it is important to assure that the SBA behaves as predictable.

Tape Mbo’e: A First Experimental Assessment


 
 
 The development of software not only needs to consider the construction process, but also other aspects such as cost, human resources and communication among stakehold- ers. The lack of simplicity into this context becomes explicit when some restrictions, such as service oriented architecture, must be considered as the basic style to build sus- tainable applications into environments were practitioners are not aware of this software technology. In addition to this, most of the available software processes are not directly applicable nor are they reusable, so learning times becomes risk for the development of the project. Therefore, Tape Mbo’e (TME) has been proposed to support the building of such applications, into development environments like developing countries where we can have economic constraints and scarcity of proficient practitioners. The first application of TME has been to develop a service-based application whose goal is to provide the interoperability among legacy systems of different public agencies in Paraguay. Initial results of this experience indicated the feasibility and simplicity of TME when applied in this field. The evaluation process, its results and conclusions are described in this paper.
 
 

Coverage-Based Testing for Service Level Agreements

Service level agreements (SLAs) are typically used to specify rules regarding the consumption of services that are agreed between the providers of the service-based applications (SBAs) and their consumers. An SLA includes a list of terms that contain the guarantees that must be fulfilled during the provisioning and consumption of the services. Since the violation of such guarantees may lead to the application of potential penalties, it is important to assure that the SBA behaves as expected. In this paper, we propose a proactive approach to test SLA-aware SBAs by means of identifying test requirements, which represent situations that are relevant to be tested. To address this issue, we define a four-valued logic that allows evaluating both the individual guarantee terms and their logical relationships. Grounded in this logic, we devise a test criterion based on the modified condition decision coverage (MCDC) in order to obtain a cost-effective set of test requirements from the structure of the SLA. Furthermore by analyzing the syntax and semantics of the agreement, we define specific rules to avoid non-feasible test requirements. The whole approach has been automated and applied over an eHealth case study.

Model driven development of user-centred context aware services

The development of context-aware applications has been an emergent subject of many research works in ubiquitous computing. This work proposes a new approach called context aware model driven development (COMODE) which advocates model driven development for context-aware application development on service platforms. Through concerns separation in individual models and by transformation techniques, context is provided, modelled and adapted independently from business logic and platform details. Three main issues are addressed in this paper and supported by our approach COMODE: Firstly, a proposition of a context meta-model for user-centred ubiquitous applications. The second issue deals with a parameterised transformation technique which allows weaving the context and the business logic at the model level. Finally, we present our COMODE methodology for the development of context-aware services-based applications. An example service-based application is presented and discussed to illustrate our approach.

Dynamic Self-Healing Mechanism for Transactional Business Process

It is clear that transactional behavior consistency is a prerequisite and basis for construction of a reliable services-based business application. However, in previous works, maintaining transactional consistency during exception handling was ignored. Maintaining transactional consistency requires functionality for rolling back some operations and revoking uploaded data. Replacing only the failed service will eventually lead to overall business application failure. In this study, we take fully into account the behavioral consistency of transactional services and propose two effective self-healing mechanisms for service-based applications. If a service enters into potential failure condition, a rescheduling mechanism is triggered to maintain consistent transactional behavior and to ensure reliable execution; if a service fails during execution, the compensation operation is triggered and the system will take action to ensure transactional behavior consistency. Meanwhile, cost-benefit analysis with compensation support is proposed to minimize the dynamic reselection cost. Finally, the experimental analysis shows that the proposed strategies can effectively guarantee the reliability of Web-based applications system.

A taxonomy-centred process for service engineering

Service-oriented software engineering concerns methods to: i engineer services as basic components; ii engineer compositions of services as composites; iii manage services and compositions; iv evaluate the quality of both services and compositions with respect to a SOA maturity model. This work proposes an engineering process based on taxonomy of services. The process consists of four phases: P1 planning, P2 identification, P3 design: describe contract interface, and protocol of services, and P4 construction. The work details these phases by using a running case. This method provides an organisation with a systematic approach to first classify its services and then engineer its computational capabilities as services in order to compose service-based application.