11 research outputs found
How to Measure Scalability of Distributed Stream Processing Engines?
Scalability is promoted as a key quality feature of modern big data stream processing engines. However, even though research made huge efforts to provide precise definitions and corresponding metrics for the term scalability, experimental scalability evaluations or benchmarks of stream processing engines apply different and inconsistent metrics. With this paper, we aim to establish general metrics for scalability of stream processing engines. Derived from common definitions of scalability in cloud computing, we propose two metrics: a load capacity function and a resource demand function. Both metrics relate provisioned resources and load intensities, while requiring specific service level objectives to be fulfilled. We show how these metrics can be employed for scalability benchmarking and discuss their advantages in comparison to other metrics, used for stream processing engines and other software systems
Prospects for Scalability: Relationships and Uncertainty in Responsive Regulation
Ian Ayresâs and John Braithwaiteâs book Responsive Regulation: Transcending the Regulatory Debate (1992) gave us many significant insights. The book has transcended its own time. At the same time, on the 20th anniversary of its publication, two things about Responsive Regulation are striking. The first is the direct, personal relationship on which the regulatory interaction is premised. The second is the boundedness and manageability of the regulatory project. At least in prudential regulation of global financial institutions in the wake of the recent financial crisis (though surely elsewhere too), neither of these features can be taken for granted. This brief essay seeks to open a preliminary conversation about Responsive Regulation in terms of its scalability. It considers whether as a practical matter, Responsive Regulation can be scaled up to more diffuse, multiparty, logistically complex contexts, such as financial regulation. As a matter of representation, it asks whether by projecting outward from its focal object, the responsive relationship, Responsive Regulation distorts our image of regulation in other contexts (or even in Responsive Regulationâs own home environment). The essay closes by arguing that in order to incorporate Responsive Regulationâs considerable discursive and relational benefits into regulatory environments such as global financial regulation, it needs to be buttressed by additional regulatory technologies
Efficient Processing of Geospatial mHealth Data Using a Scalable Crowdsensing Platform
Smart sensors and smartphones are becoming increasingly prevalent. Both can be used to gather environmental data (e.g., noise). Importantly, these devices can be connected to each other as well as to the Internet to collect large amounts of sensor data, which leads to many new opportunities. In particular, mobile crowdsensing techniques can be used to capture phenomena of common interest. Especially valuable insights can be gained if the collected data are additionally related to the time and place of the measurements. However, many technical solutions still use monolithic backends that are not capable of processing crowdsensing data in a flexible, efficient, and scalable manner. In this work, an architectural design was conceived with the goal to manage geospatial data in challenging crowdsensing healthcare scenarios. It will be shown how the proposed approach can be used to provide users with an interactive map of environmental noise, allowing tinnitus patients and other health-conscious people to avoid locations with harmful sound levels. Technically, the shown approach combines cloud-native applications with Big Data and stream processing concepts. In general, the presented architectural design shall serve as a foundation to implement practical and scalable crowdsensing platforms for various healthcare scenarios beyond the addressed use case
Elastic Highly Available Cloud Computing
High availability and elasticity are two the cloud computing services technical features. Elasticity is a key feature of cloud computing where provisioning of resources is closely tied to the runtime demand. High availability assure that cloud applications are resilient to failures. Existing cloud solutions focus on providing both features at the level of the virtual resource through virtual machines by managing their restart, addition, and removal as needed. These existing solutions map applications to a specific design, which is not suitable for many applications especially virtualized telecommunication applications that are required to meet carrier grade standards. Carrier grade applications typically rely on the underlying platform to manage their availability by monitoring heartbeats, executing recoveries, and attempting repairs to bring the system back to normal. Migrating such applications to the cloud can be particularly challenging, especially if the elasticity policies target the application only, without considering the underlying platform contributing to its high availability (HA). In this thesis, a Network Function Virtualization (NFV) framework is introduced; the challenges and requirements of its use in mobile networks are discussed. In particular, an architecture for NFV framework entities in the virtual environment is proposed. In order to reduce signaling traffic congestion and achieve better performance, a criterion to bundle multiple functions of virtualized evolved packet-core in a single physical device or a group of adjacent devices is proposed. The analysis shows that the proposed grouping can reduce the network control traffic by 70 percent. Moreover, a comprehensive framework for the elasticity of highly available applications that considers the elastic deployment of the platform and the HA placement of the applicationâs components is proposed. The approach is applied to an internet protocol multimedia subsystem (IMS) application and demonstrate how, within a matter of seconds, the IMS application can be scaled up while maintaining its HA status
Quantifying cloud performance and dependability:Taxonomy, metric design, and emerging challenges
In only a decade, cloud computing has emerged from a pursuit for a service-driven information and communication technology (ICT), becoming a significant fraction of the ICT market. Responding to the growth of the market, many alternative cloud services and their underlying systems are currently vying for the attention of cloud users and providers. To make informed choices between competing cloud service providers, permit the cost-benefit analysis of cloud-based systems, and enable system DevOps to evaluate and tune the performance of these complex ecosystems, appropriate performance metrics, benchmarks, tools, and methodologies are necessary. This requires re-examining old system properties and considering new system properties, possibly leading to the re-design of classic benchmarking metrics such as expressing performance as throughput and latency (response time). In this work, we address these requirements by focusing on four system properties: (i) elasticity of the cloud service, to accommodate large variations in the amount of service requested, (ii) performance isolation between the tenants of shared cloud systems and resulting performance variability, (iii) availability of cloud services and systems, and (iv) the operational risk of running a production system in a cloud environment. Focusing on key metrics for each of these properties, we review the state-of-the-art, then select or propose new metrics together with measurement approaches. We see the presented metrics as a foundation toward upcoming, future industry-standard cloud benchmarks
The Advanced Framework for Evaluating Remote Agents (AFERA): A Framework for Digital Forensic Practitioners
Digital forensics experts need a dependable method for evaluating evidence-gathering tools. Limited research and resources challenge this process and the lack of multi-endpoint data validation hinders reliability in distributed digital forensics. A framework was designed to evaluate distributed agent-based forensic tools while enabling practitioners to self-evaluate and demonstrate evidence reliability as required by the courts. Grounded in Design Science, the framework features guidelines, data, criteria, and checklists. Expert review enhances its quality and practicality
A framework for the characterization and analysis of software systems scalability
The term scalability appears frequently in computing literature, but it is a term that is poorly defined and
poorly understood. It is an important attribute of computer systems that is frequently asserted but rarely
validated in any meaningful, systematic way. The lack of a consistent, uniform and systematic treatment
of scalability makes it difficult to identify and avoid scalability problems, clearly and objectively describe
the scalability of software systems, evaluate claims of scalability, and compare claims from different
sources.
This thesis provides a definition of scalability and describes a systematic framework for the characterization
and analysis of software systems scalability. The framework is comprised of a goal-oriented
approach for describing, modeling and reasoning about scalability requirements, and an analysis technique
that captures the dependency relationships that underlie typical notions of scalability. The framework
is validated against a real-world data analysis system and is used to recast a number of examples
taken from the computing literature and from industry in order to demonstrate its use across different
application domains and system designs
Intensional Cyberforensics
This work focuses on the application of intensional logic to cyberforensic
analysis and its benefits and difficulties are compared with the
finite-state-automata approach. This work extends the use of the intensional
programming paradigm to the modeling and implementation of a cyberforensics
investigation process with backtracing of event reconstruction, in which
evidence is modeled by multidimensional hierarchical contexts, and proofs or
disproofs of claims are undertaken in an eductive manner of evaluation. This
approach is a practical, context-aware improvement over the finite state
automata (FSA) approach we have seen in previous work. As a base implementation
language model, we use in this approach a new dialect of the Lucid programming
language, called Forensic Lucid, and we focus on defining hierarchical contexts
based on intensional logic for the distributed evaluation of cyberforensic
expressions. We also augment the work with credibility factors surrounding
digital evidence and witness accounts, which have not been previously modeled.
The Forensic Lucid programming language, used for this intensional
cyberforensic analysis, formally presented through its syntax and operational
semantics. In large part, the language is based on its predecessor and
codecessor Lucid dialects, such as GIPL, Indexical Lucid, Lucx, Objective
Lucid, and JOOIP bound by the underlying intensional programming paradigm.Comment: 412 pages, 94 figures, 18 tables, 19 algorithms and listings; PhD
thesis; v2 corrects some typos and refs; also available on Spectrum at
http://spectrum.library.concordia.ca/977460
Quality Goal Oriented Architectural Design and Traceability for Evolvable Software Systems
Softwaresysteme werden heute z.B. aufgrund sich Àndernder GeschÀftsprozesse
oder Technologien mit hÀufigen VerÀnderungen konfrontiert. Die Software und
speziell ihre Architektur muss diese Ănderungen zur dauerhaften Nutzbarkeit
ermöglichen.WĂ€hrend der Software-Evolution können Ănderungen zu einer
Verschlechterung der Architektur fĂŒhren, der Architekturerosion. Dies
erschwert oder verhindert weitere Ănderungen wegen Inkonsistenz oder
fehlendem Programmverstehen. Zur Erosionsvermeidung mĂŒssen QualitĂ€tsziele
wie Weiterentwickelbarkeit, Performanz oder Usability sowie die
Nachvollziehbarkeit von Architekturentwurfsentscheidungen berĂŒcksichtigt
werden. Dies wird jedoch oft vernachlÀssigt.Existierende Entwurfsmethoden
unterstĂŒtzen den Ăbergang von QualitĂ€tzielen zu geeigneten
Architekturlösungen nur unzureichend aufgrund einer LĂŒcke zwischen Methoden
des Requirements Engineering und des Architekturentwurfs. Insbesondere gilt
dies fĂŒr Weiterentwickelbarkeit und die Nachvollziehbarkeit von
Entwurfsentscheidungen durch explizite ModellabhÀngigkeiten.Diese Arbeit
prÀsentiert ein neues Konzept, genannt Goal Solution Scheme, das
QualitĂ€tsziele ĂŒber Architekturprinzipien auf Lösungsinstrumente durch
explizite AbhÀngigkeiten abbildet. Es hilft somit, Architekturlösungen
entsprechend ihrem Einfluss auf QualitÀtsziele auszuwÀhlen. Das Schema wird
speziell hinsichtlich Weiterentwickelbarkeit diskutiert und ist in ein
zielorientiertes Vorgehen eingebettet, das etablierte Methoden und Konzepte
des Requirements Engineering und Architekturentwurfs verbessert und
integriert. Dies wird ergÀnzt durch ein Traceability-Konzept, welches einen
regelbasierten Ansatz mit Techniken des Information Retrieval verbindet.
Dies ermöglicht eine (halb-) automatische Erstellung von Traceability Links
mit spezifischen Linktypen und Attributen fĂŒr eine reichhaltige Semantik
sowie mit hoher Genauigkeit und Trefferquote.Die Realisierbarkeit des
Ansatzes wird an einer Fallstudie einer Software fĂŒr mobile Serviceroboter
gezeigt. Das Werkzeug EMFTrace wurde als eine erweiterbare Plattform
basierend auf Eclipse-Technologie implementiert, um die Anwendbarkeit der
Konzepte zu zeigen. Es integriert Entwurfsmodelle von externen CASE-Tools
mittels XML-Technologie in einem gemeinsamen Modell-Repository, wendet
Regeln zur Linkerstellung an und bietet Validierungsfunktionen fĂŒr Regeln
und Links.Today software systems are frequently faced with demands for changes, for
example, due to changing business processes or technologies. The software
and especially its architecture has to cope with those frequent changes to
permanently remain usable.During software evolution changes can lead to a
deterioration of the structure of software architectures called
architectural erosion, which hampers or even inhibits further changes
because of inconsistencies or lacking program comprehension. To support
changes and avoid erosion, especially quality goals, such as evolvability,
performance, or usability, and the traceability of design decisions have to
be considered during architectural design. This however often is
neglected.Existing design methods do not sufficiently support the
transition from the quality goals to appropriate architectural solutions
because there is still a gap between requirements engineering and
architectural design methods. Particularly support is lacking for the goal
evolvability and for the traceability of design decisions by explicit model
dependencies.This thesis presents a new concept called Goal Solution
Scheme, which provides a mapping from goals via architectural principles to
solution instruments by explicit dependencies. Thus it helps to select
appropriate architectural solutions according to their influence on quality
goals. The scheme is discussed especially regarding evolvability, and it is
embedded in a goal-oriented architectural design method, which enhances and
integrates established methods and concepts from requirements engineering
as well as architectural design. This is supplemented by a traceability
concept, which combines a rule-based approach with information retrieval
techniques for a (semi-) automated establishment of links with specific
link types and attributes for rich semantics and a high precision and
recall.The feasibility of the design approach has been evaluated in a case
study of a software platform for mobile robots. A prototype tool suite
called EMFTrace was implemented as an extensible platform based on Eclipse
technology to show the practicability of the thesis' concept. It integrates
design models from external CASE tools in a joint model repository by means
of XML technology, applies rules for link establishment, and provides
validation capabilities for rules and links