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AsyncSLA: Towards a Service Level Agreement for Asynchronous Services
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In the Internet-of-Things (IoT) vision, everyday objects evolve into cyber-physical systems. The massive use and deployment of these systems has given place to the Industry 4.0 or Industrial IoT (IIoT). Due to its scalability requirements, IIoT architectures are typically distributed and asynchronous. In this scenario, one of the most widely used paradigms is publish/subscribe , where messages are sent and received based on a set of categories or topics . However, these architectures face interoperability challenges. Consistency in message categories and structure is the key to avoid potential losses of information. Ensuring this consistency requires complex data processing logic both on the publisher and the subscriber sides. In this paper, we present our proposal relying on AsyncAPI to automate the design and implementation of these asynchronous architectures using model-driven techniques for the generation of (part of) message-driven infrastructures. Our proposal offers two different ways of designing the architectures: either graphically, by modeling and annotating the messages that are sent among the different IoT devices, or textually, by implementing an editor compliant with the AsyncAPI specification. We have evaluated our proposal by conducting a set of experiments with 25 subjects with different expertise and background. The experiments show that one-third of the subjects were able to design and implement a working architecture in less than an hour without previous knowledge of our proposal, and an additional one-third estimated that they would only need less than two hours in total.
With the advancement of mobile networks, the demand for increased throughput is continuously rising. Throughput is the amount of error‐free bits transmitted in a given period of time. Heterogeneous networks (HetNet) are widely accepted to enhance the throughput as they do have low pathloss among the others. HetNet deploys another cell under the coverage area of the macro cell. The HetNet offloads the macro cell that avoids congestion and enhances the coverage of the network. In HetNet, however, intercell interference is a major challenge that adversely degrades the throughput. In this paper, coordinated multipoint transmission (CoMP) along with a coordinated beamforming (CBF) is integrated to mitigate the intercell interference (ICI). In general, the results have shown that the proposed technique has resulted into significant interference reduction and hence improved throughput and spectral efficiency.
Abstract Internet of Things (IoT) is a new paradigm that has changed the traditional way of living into a high tech life style. Smart city, smart homes, pollution control, energy saving, smart transportation, smart industries are such transformations due to IoT. A lot of crucial research studies and investigations have been done in order to enhance the technology through IoT. However, there are still a lot of challenges and issues that need to be addressed to achieve the full potential of IoT. These challenges and issues must be considered from various aspects of IoT such as applications, challenges, enabling technologies, social and environmental impacts etc. The main goal of this review article is to provide a detailed discussion from both technological and social perspective. The article discusses different challenges and key issues of IoT, architecture and important application domains. Also, the article bring into light the existing literature and illustrated their contribution in different aspects of IoT. Moreover, the importance of big data and its analysis with respect to IoT has been discussed. This article would help the readers and researcher to understand the IoT and its applicability to the real world.
The OpenAPI Specification (OAS) is the de facto standard to describe RESTful APIs from a functional perspective. OAS has been a success due to its simple model and the wide ecosystem of tools supporting the SLA-Driven API development lifecycle. Unfortunately, the current OAS scope ignores crucial information for an API such as its Service Level Agreement (SLA). Therefore, in terms of description and management of non-functional information, the disadvantages of not having a standard include the vendor lock-in and prevent the ecosystem to grow and handle extra functional aspects.
Unmanned aerial vehicle is one of the main announced use cases of 5G/IMT2020, which is expected to have various applications in many fields. These devices have limited capabilities in terms of energy and processing. Due to the complex structure of unmanned aerial vehicle networks and the high mobility constraints, design of efficient routing protocol, for supporting such network, is a challenge. Thus, efficient routing of data among unmanned aerial vehicles between source and destination is an important issue in designing unmanned aerial vehicle networks. Proactive routing protocols are one of the main categories of routing protocols developed for mobile ad hoc networks and vehicular ad hoc networks. Optimized link state routing protocol is one of the most common proactive routing protocols that has been modified to support unmanned aerial vehicle networks, considering high mobility feature of the network. In this work, we propose a latency and energy-efficient proactive routing protocol for dense unmanned aerial vehicle networks, with high-density devices, based on optimized link state routing protocol algorithm, referred to as multi-objective optimized link state routing protocol. The proposed routing protocol is topology aware and can be used for low-latency and high-mobility applications. The proposed multi-objective optimized link state routing protocol routing algorithm considers all modified versions of optimized link state routing protocol and introduces a novel method for selecting multipoint relay nodes that considers the traffic load on the communication channel and the load on each unmanned aerial vehicle node. Moreover, the proposed algorithm considers the communication link stability and the energy constraints. The system is simulated over a reliable environment for various scenarios, and it is compared to the original optimized link state routing protocol and its modified versions. Simulation results indicate that the proposed protocol achieves higher efficiency in terms of latency, energy, and reliability.
In the Internet of Things (IoT), billions of physical devices, distributed over a large geographic area, provide a near real-time state of the world. These devices’ capabilities can be abstracted as IoT services and delivered to users in a demand-driven way. In such a dynamic large-scale environment, a service provider who supports a service level agreement (SLA) can have a comprehensive competitive edge in terms of service quality management, service customization, optimized resource allocation, and trustworthiness. However, there is no consistent way of drafting an SLA with respect to describing heterogeneous IoT services, which obstructs automatic service selection, SLA negotiation, and SLA monitoring. In this paper, we propose an ontology, WIoT-SLA, to achieve semantic interoperability. We combine IoT service properties with two prominent web service SLA specifications: WS-Agreement and WSLA, to take advantage of their complementary features. This ontology is used to formalize the SLAs and SLA negotiation offers, which further facilitates the service selection and automatic SLA negotiation. It can also be used by a monitoring engine to detect SLA violations by providing the semantics of service level objectives (SLOs) and quality metrics. To evaluate our work, a prototype is implemented to demonstrate its feasibility and efficiency.
Service-oriented computing is the prominent paradigm for viewing business processes as composed of functions provided by modular and standardized services. Web services are the building blocks for the application of service-oriented computing on the Web and provide the necessary support for the consolidation of multiple services into a single composite service corresponding to the overall process. In such a context, service providers are strategically interested in both describing the quality of service (QoS) characteristics of offered services, to better qualify their offer and gain a significant advantage in the global marketplace, and predicting the level of QoS that can be offered to service consumers when building composite web services that make use of services managed by various service providers. This paper illustrates a model-driven method to automatically describe and predict the QoS of composite web services specified by use of business process execution language (BPEL). The paper specifically addresses the reliability characteristic of the QoS. The proposed method is founded on Q-WSDL, a lightweight WSDL extension for the description of the QoS characteristics of a web service, and exploits Q-WSDL to annotate reliability data onto a BPEL-based UML model of the composite service. The UML model is then used to predict and describe the reliability of the composite web service. The proposed method is illustrated by use of an example application that deals with a composite web service for the migration of PSTN telephone numbers.
Articulating proper services search queries has been a challenging task for clients when searching for relevant Web services. Service discovery search results will not be improved unless we determine ways for correctly understanding client discovery goals. In this paper, we introduce a solution to this problem and perform a key study for understanding service discovery goals. We introduce the concept of quality of Web service (QWS) for our quality-driven ranking mechanism. Based on our study, we determine that service discovery goals can be defined as exploratory or informational. We further use these findings to demonstrate how the knowledge of service discovery goals are beneficial in improving the way clients perform service search queries. Results from our experiments are intriguing and show that the performance of informational service queries in terms of precision improves the querying process by 36.26% and 40.39% when compared to Google's PageRank and Yahoo, respectively. We further use our findings to provide insights on improving the service retrieval process.
We describe a novel framework for specifying and monitoring Service Level Agreements (SLA) for Web Services. SLA monitoring and enforcement become increasingly important in a Web Service environment where enterprise applications and services rely on services that may be subscribed dynamically and on-demand. For economic and practical reasons, we want an automated provisioning process for both the service itself as well as the SLA managment system that measures and monitors the QoS parameters, checks the agreed-upon service levels, and reports violations to the authorized parties involved in the SLA management process. Our approach to these issues is presented in this paper. The Web Service Level Agreement (WSLA) framework is targeted at defining and monitoring SLAs for Web Services. Although WSLA has been designed for a Web Services environment, it is applicable as well to any inter-domain management scenario, such as business process and service management, or the management of networks, systems and applications in general. The WSLA framework consists of a flexible and extensible language based on XML Schema and a runtime architecture comprising several SLA monitoring services, which may be outsourced to third parties to ensure a maximum of objectivity. WSLA enables service customers and providers to unambiguously define a wide variety of SLAs, specify the SLA parameters and the way they are measured, and relate them to managed resource instrumentations. Upon receipt of an SLA specification, the WSLA monitoring services are automatically configured to enforce the SLA. An implementation of the WSLA framework, termed SLA Compliance Monitor, is publicly available as part of the IBM Web Services Toolkit.
Application or web services are increasingly being used across organisational boundaries. Moreover, new services are being introduced at the network and storage level. Languages to specify interfaces for such services have been researched and transferred into industrial practice. We investigate end-to-end quality of service (QoS) and highlight that QoS provision has multiple facets and requires complex agreements between network services, storage services and middleware services. We introduce SLAng, a language for defining Service Level Agreements (SLAs) that accommodates these needs. We illustrate how SLAng is used to specify QoS in a case study that uses a web services specification to support the processing of images across multiple domains and we evaluate our language based on it.
Internet of Things and cloud services are one of main enablers in fourth industrial revolution. Real-time industrial systems have high availability requirements of 99.9% to 99.999% whereas architectures built on regional cloud services and IoT do not provide similar guarantees or Service Level Agreement. These differences of QoS and SLA availability between Operational Technology and Information Technology has become a main challenge in adoption of Industrial Internet of Things (IIoT) for real-time applications.This work presents an approach to find end-to-end QoS and availability for an IIoT architecture. Device-to-cloud, cloud-to-cloud and inside-cloud experiments have been performed over eight weeks where each experiment have more then four million QoS measurements. Our availability analysis shows that a remote IoT connected to a less busy cloud region gives higher availability as compared to an IoT device inside a busy cloud region. IIoT and regional cloud services provide good QoS with 99% to 99.9% availability for 1sec soft real-time requirements. In 100ms applications, more efforts are required to achieve higher then 95% availability and design industrial SLA. IIoT applications with 10sec latency like machine learning models can get 99.9% availability with cloud. Availability loss due to communication is almost 1% for 100ms applications. These results also provide requirements and future work of industrial edge computing for IIoT on real-time cloud.
Cyber Physical System (CPS) has provided an outstanding foundation to build advanced industrial systems and applications by integrating innovative functionalities through Internet of Things (IoT) and Web of Things (WoB) to enable connection of the operations of the physical reality with computing and communication infrastructures. A wide range of industrial CPS-based applications have been developed and deployed in Industry 4.0. In order to understand the development of CPS in Industry 4.0, this paper reviews the current research of CPS, key enabling technologies, major CPS applications in industries, and identifies research trends and challenges. A main contribution of this review paper is that it summarizes the current state-of-the-art CPS in Industry 4.0 from Web of Science (WoS) database (including 595 articles) and proposes a potential framework of CPS systematically.
As billions of devices connect to the Internet, a new Web of Things is emerging, with virtual representations of physical or abstract realities increasingly accessible via Web technologies. Achieving a new phase of exponential growth, comparable to the earliest days of the Web, will require open markets, open standards, and the vision to imagine the potential for this expanding WoT.
Context: Quality of Service (QoS) is a major issue in various web service related activities. Quality models have been proposed as the engineering artefact to provide a common framework of understanding for QoS, by defining the quality factors that apply to web service usage. Objective: The goal of this study is to evaluate the current state of the art of the proposed quality models for web services, specifically: (1) which are these proposals and how are they related; (2) what are their structural characteristics; (3) what quality factors are the most and least addressed; and (4) what are their most consolidated definitions. Method: We have conducted a systematic mapping by defining a robust protocol that combines automatic and manual searches from different sources. We used a rigorous method to elicitate the keywords from the research questions and a selection criteria to retrieve the final papers to evaluate. We have adopted the ISO/IEC 25010 standard to articulate our analysis. Results: We have evaluated 47 different quality models from 65 papers that fulfilled the selection criteria. By analyzing in depth these quality models, we have: (1) distributed the proposals along the time dimension and identified their relationships; (2) analyzed their size (visualizing the number of nodes and levels) and definition coverage (as indicator of quality of the proposals); (3) quantified the coverage of the different ISO/IEC 25010 quality factors by the proposals; (4) identified the quality factors that appeared in at least 30% of the surveyed proposals and provided the most consolidated definitions for them. Conclusions: We believe that this panoramic view on the anatomy of the quality models for web services may be a good reference for prospective researchers and practitioners in the field and especially may help avoiding the definition of new proposals that do not align with current research.
Knowledge about properties of network traf- fic can be beneficial when studying network protocols. It enables realistic models of network traffic to be created and evaluations of current protocols to take place. This study examines trends in round-trip times (RTTs) at a university Web server. Round-trip time is a particularly important characteristic of transport layer Internet traffic to measure because it impacts the throughput of TCP. In addition to examining trends of RTTs, this paper examines the relationship between RTT and the time between the SYNACK and ACK packets. The relationship between this heuristic for estimating RTT and actual measured RTTs is relevant for protocols such as TCP Vegas that need to estimate RTT early in a connection.
This paper describes SLA*, a domain-independent syntax for machine-readable Service Level Agreements (SLAs) and SLA templates. Historically, SLA* was developed as a generalisation and refinement of the web-service specific XML standards: WS-Agreement, WSLA, and WSDL. Instead of web-services, however, SLA* deals with services in general, and instead of XML, it is language independent. SLA* provides a specification of SLA(T) content at a fine-grained level of detail, which is both richly expressive and inherently extensible: supporting controlled customisation to arbitrary domain-specific requirements. The model was developed as part of the FP7 ICT Integrated Project SLA@SOI, and has been applied to a range of industrial use-cases, including; ERP hosting, Enterprise IT, live-media streaming and health-care provision. At the time of writing, the abstract syntax has been realised in concrete form as a Java API, XML-Schema, and BNF Grammar.
Current Web services standards lack the means for expressing a service's nonfunctional attributes - namely, its quality of service. QoS can be objective (encompassing reliability, availability, and request-to-response time) or subjective (focusing on user experience). QoS attributes are key to dynamically selecting the services that best meet user needs. This article addresses dynamic service selection via an agent framework coupled with a QoS ontology. With this approach, participants can collaborate to determine each other's service quality and trustworthiness.
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