Wolfgang Emmerich

Bio: Wolfgang Emmerich is an academic researcher from University College London. The author has contributed to research in topics: Middleware & Middleware (distributed applications). The author has an hindex of 42, co-authored 206 publications receiving 7591 citations. Previous affiliations of Wolfgang Emmerich include Uppsala University & Northampton Community College.

The reservoir model and architecture for open federated cloud computing

Abstract: The emerging cloud-computing paradigm is rapidly gaining momentum as an alternative to traditional IT (information technology). However, contemporary cloud-computing offerings are primarily targeted for Web 2.0-style applications. Only recently have they begun to address the requirements of enterprise solutions, such as support for infrastructure service-level agreements. To address the challenges and deficiencies in the current state of the art, we propose a modular, extensible cloud architecture with intrinsic support for business service management and the federation of clouds. The goal is to facilitate an open, service-based online economy in which resources and services are transparently provisioned and managed across clouds on an ondemand basis at competitive costs with high-quality service. The Reservoir project is motivated by the vision of implementing an architecture that would enable providers of cloud infrastructure to dynamically partner with each other to create a seemingly infinite pool of IT resources while fully preserving their individual autonomy in making technological and business management decisions. To this end, Reservoir could leverage and extend the advantages of virtualization and embed autonomous management in the infrastructure. At the same time, the Reservoir approach aims to achieve a very ambitious goal: creating a foundation for next-generation enterprise-grade cloud computing.

CARISMA: context-aware reflective middleware system for mobile applications

Abstract: Mobile devices, such as mobile phones and personal digital assistants, have gained wide-spread popularity. These devices will increasingly be networked, thus enabling the construction of distributed applications that have to adapt to changes in context, such as variations in network bandwidth, battery power, connectivity, reachability of services and hosts, etc. In this paper, we describe CARISMA, a mobile computing middleware which exploits the principle of reflection to enhance the construction of adaptive and context-aware mobile applications. The middleware provides software engineers with primitives to describe how context changes should be handled using policies. These policies may conflict. We classify the different types of conflicts that may arise in mobile computing and argue that conflicts cannot be resolved statically at the time applications are designed, but, rather, need to be resolved at execution time. We demonstrate a method by which policy conflicts can be handled; this method uses a microeconomic approach that relies on a particular type of sealed-bid auction. We describe how this method is implemented in the CARISMA middleware architecture and sketch a distributed context-aware application for mobile devices to illustrate how the method works in practice. We show, by way of a systematic performance evaluation, that conflict resolution does not imply undue overheads, before comparing our research to related work and concluding the paper.

xlinkit: a consistency checking and smart link generation service

Abstract: xlinkit is a lightweight application service that provides rule-based link generation and checks the consistency of distributed Web content. It leverages standard Internet technologies, notably XML, XPath, and XLink. xlinkit can be used as part of a consistency management scheme or in applications that require smart link generation, including portal construction and management of large document repositories. In this article we show how consistency constraints can be expressed and checked. We describe a novel semantics for first-order logic that produces links instead of truth values and give an account of our content management strategy. We present the architecture of our service and the results of two substantial case studies that use xlinkit for checking course syllabus information and for validating UML models supplied by industrial partners.

SLAng: a language for defining service level agreements

Abstract: 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.

Software engineering and middleware: a roadmap

Abstract: The construction of a large class of distributed systems can be simplified by leveraging middleware, which is layered between network operating systems and application components. Middleware resolves heterogeneity, and facilitates communication and coordination of distributed components. Existing middleware products enable software engineers to build systems that are distributed across a local-area network. State-of-the-art middleware research aims to push this boundary towards Internet-scale distribution, adaptive and reconfigurable middleware and middleware for dependable and wireless systems. The challenge for software engineering research is to devise notations, techniques, methods and tools for distributed system construction that systematically build and exploit the capabilities that middleware deliver. 1 I N T R O D U C T I O N Various commercial trends have lead to an increasing demand for distributed systems. Firstly, the number of mergers between companies is continuing to increase. The different divisions of a newly merged company have to deliver unified services to their customers and this usually demands an integration of their IT systems. The time available for delivery of such an integration is often so short that building a new system is not an option and therefore existing system components have to be integrated into a distributed system that appears as an integrating computing facility. Secondly, the time available for providing new services are decreasing. Often this can only be achieved if components are procured off-the-shelf and then integrated into a system rather than built from scratch. Components to be integrated may have incompatible requirements for their hardware and operating system platforms; they have to be deployed on different hosts, forcing the resulting system to be distributed. Finally, the Internet provides new opportunities to offer products and services to a vast number of potential customers. In this setting, it is difficult to estimate the scalability requirements. Permission to make digital or hard copies of all or part of this work lbr personal or classroom use is granted without fee provided that copies are not made or distributed tbr profit or commercial advantage and that copies bear this notice and the lull citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a tee. Future of Sofware Engineering Limerick Ireland Copyright ACM 2000 1-58113-253-0/00/6...$5.00 An e-commerce site that was designed to cope with a given number of transactions per day may suddenly find itself exposed to demand that is by orders of magnitude larger. The required scalability cannot usually be achieved by centralized or client-server architectures but demands a distributed system. Distributed systems can integrate legacy components, thus preserving investment, they can decrease the time to market, they can be scalable and tolerant against failures. The caveat, however, is that the construction of a truly distributed systems is considerably more difficult than building a centralized or client/server system. This is because there are multiple points of failure in a distributed system, system components need to communicate with each other through a network, which complicates communication and opens the door for security attacks. Middleware has been devised in order to conceal these difficulties from application engineers as much as possible; As they solve a real problem and simplify distributed system construction, middleware products are rapidly being adopted in industry [6]. In order to build distributed systems that meet the requirements, software engineers have to know what middleware is available, which one is best suited to the problems at hand, and how middleware can be used in the architecture, design and implementation of distributed systems. The principal contribution of this paper is an assessment of both, the state-of-the-practice that current middleware products offer and the state-of-the-art in middleware research. Software engineers increasingly use middleware to build distributed systems. Any research into distributed software engineering that ignores this trend will only have limited impact. We, therefore, analyze the influence that the increasing use of middleware should have on the software engineering research agenda. We argue that requirements engineering techniques are needed that focus on non-functional requirements, as these influence the selection and use of middleware. We identify that software architecture research should produce methods that guide engineers towards selecting the right middleware and employing it so that it meets a set of non-functional requirements. We then highlight that the use of middleware is not transparent for system design and that design methods are needed that address this issue.

Internet of Things: A Survey on Enabling Technologies, Protocols, and Applications

Abstract: This paper provides an overview of the Internet of Things (IoT) with emphasis on enabling technologies, protocols, and application issues. The IoT is enabled by the latest developments in RFID, smart sensors, communication technologies, and Internet protocols. The basic premise is to have smart sensors collaborate directly without human involvement to deliver a new class of applications. The current revolution in Internet, mobile, and machine-to-machine (M2M) technologies can be seen as the first phase of the IoT. In the coming years, the IoT is expected to bridge diverse technologies to enable new applications by connecting physical objects together in support of intelligent decision making. This paper starts by providing a horizontal overview of the IoT. Then, we give an overview of some technical details that pertain to the IoT enabling technologies, protocols, and applications. Compared to other survey papers in the field, our objective is to provide a more thorough summary of the most relevant protocols and application issues to enable researchers and application developers to get up to speed quickly on how the different protocols fit together to deliver desired functionalities without having to go through RFCs and the standards specifications. We also provide an overview of some of the key IoT challenges presented in the recent literature and provide a summary of related research work. Moreover, we explore the relation between the IoT and other emerging technologies including big data analytics and cloud and fog computing. We also present the need for better horizontal integration among IoT services. Finally, we present detailed service use-cases to illustrate how the different protocols presented in the paper fit together to deliver desired IoT services.

Context Aware Computing for The Internet of Things: A Survey

Abstract: As we are moving towards the Internet of Things (IoT), the number of sensors deployed around the world is growing at a rapid pace. Market research has shown a significant growth of sensor deployments over the past decade and has predicted a significant increment of the growth rate in the future. These sensors continuously generate enormous amounts of data. However, in order to add value to raw sensor data we need to understand it. Collection, modelling, reasoning, and distribution of context in relation to sensor data plays critical role in this challenge. Context-aware computing has proven to be successful in understanding sensor data. In this paper, we survey context awareness from an IoT perspective. We present the necessary background by introducing the IoT paradigm and context-aware fundamentals at the beginning. Then we provide an in-depth analysis of context life cycle. We evaluate a subset of projects (50) which represent the majority of research and commercial solutions proposed in the field of context-aware computing conducted over the last decade (2001-2011) based on our own taxonomy. Finally, based on our evaluation, we highlight the lessons to be learnt from the past and some possible directions for future research. The survey addresses a broad range of techniques, methods, models, functionalities, systems, applications, and middleware solutions related to context awareness and IoT. Our goal is not only to analyse, compare and consolidate past research work but also to appreciate their findings and discuss their applicability towards the IoT.

A break in the clouds: towards a cloud definition

Abstract: This paper discusses the concept of Cloud Computing to achieve a complete definition of what a Cloud is, using the main characteristics typically associated with this paradigm in the literature. More than 20 definitions have been studied allowing for the extraction of a consensus definition as well as a minimum definition containing the essential characteristics. This paper pays much attention to the Grid paradigm, as it is often confused with Cloud technologies. We also describe the relationships and distinctions between the Grid and Cloud approaches.