129 research outputs found
An approach for automated service selection and ranking using services choreography
In todayâs highly competitive market, it is critical to provide customers services with a high level of
configuration to answer their business needs. Knowing in advance the performance associated with a
specific choreography of services (e.g., by taking into account the expected results of each component
service) represents an important asset that allows businesses to provide a global service tailored to
customersâ specific requests. This research work aims at advancing the state-of-the-art in this area by
proposing an approach for service selection and ranking using services choreography, predicting the
behavior of the services considering customersâ requirements and preferences, business process constraints
and characteristics of the execution environment
A framework for SLA-centric service-based Utility Computing
Nicht angegebenService oriented Utility Computing paves the way towards realization of service markets, which promise metered services through negotiable Service Level Agreements (SLA). A market does not necessarily imply a simple buyer-seller relationship, rather it is the culmination point of a complex chain of stake-holders with a hierarchical integration of value along each link in the chain.
In service value chains, services
corresponding to different partners are aggregated in a producer-consumer manner resulting in hierarchical
structures of added value. SLAs are contracts between service providers and service consumers, which ensure the expected Quality of Service (QoS) to different stakeholders at various levels in this hierarchy. \emph{This thesis addresses the challenge of realizing SLA-centric infrastructure to enable service markets for Utility Computing.}
Service Level Agreements play a pivotal role throughout the life cycle of service aggregation. The activities of service selection and service negotiation followed by the hierarchical aggregation and validation of services in service value chain, require SLA as an enabling technology. \emph{This research aims at a SLA-centric framework where the requirement-driven selection of services, flexible SLA negotiation, hierarchical SLA aggregation and validation, and related issues such as privacy, trust and security have been formalized and the prototypes of the service selection model and the validation model have been implemented. } The formal model for User-driven service selection utilizes Branch and Bound and Heuristic algorithms for its implementation. The formal model is then extended for SLA negotiation of configurable services of varying granularity in order to tweak the interests of the service consumers and service providers. %and then formalizing the requirements of an enabling infrastructure for aggregation and validation of SLAs existing at multiple levels and spanning % along the corresponding service value chains.
The possibility of service aggregation opens new business opportunities in the evolving landscape of IT-based Service Economy. A SLA as a unit of business relationships helps establish innovative topologies for business networks. One example is the composition of computational services to construct services of bigger granularity thus giving room to business models based on service aggregation, Composite Service Provision and Reselling. This research introduces and formalizes the notions of SLA Choreography and hierarchical SLA aggregation in connection with the underlying service choreography to realize SLA-centric service value chains and business networks. The SLA Choreography and aggregation poses new challenges regarding its description, management, maintenance, validation, trust, privacy and security. The aggregation and validation models for SLA Choreography introduce concepts such as: SLA Views to protect the privacy of stakeholders; a hybrid trust model to foster business among unknown partners; and a PKI security mechanism coupled with rule based validation system to enable distributed queries across heterogeneous boundaries. A distributed rule based hierarchical SLA validation system is designed to demonstrate the practical significance of these notions
Elastic Business Process Management: State of the Art and Open Challenges for BPM in the Cloud
With the advent of cloud computing, organizations are nowadays able to react
rapidly to changing demands for computational resources. Not only individual
applications can be hosted on virtual cloud infrastructures, but also complete
business processes. This allows the realization of so-called elastic processes,
i.e., processes which are carried out using elastic cloud resources. Despite
the manifold benefits of elastic processes, there is still a lack of solutions
supporting them.
In this paper, we identify the state of the art of elastic Business Process
Management with a focus on infrastructural challenges. We conceptualize an
architecture for an elastic Business Process Management System and discuss
existing work on scheduling, resource allocation, monitoring, decentralized
coordination, and state management for elastic processes. Furthermore, we
present two representative elastic Business Process Management Systems which
are intended to counter these challenges. Based on our findings, we identify
open issues and outline possible research directions for the realization of
elastic processes and elastic Business Process Management.Comment: Please cite as: S. Schulte, C. Janiesch, S. Venugopal, I. Weber, and
P. Hoenisch (2015). Elastic Business Process Management: State of the Art and
Open Challenges for BPM in the Cloud. Future Generation Computer Systems,
Volume NN, Number N, NN-NN., http://dx.doi.org/10.1016/j.future.2014.09.00
FLACOSâ08 Workshop proceedings
The 2nd Workshop on Formal Languages and Analysis of Contract-Oriented Software (FLACOSâ08) is held in Malta. The aim of the workshop is to bring together researchers and practitioners working on language-based solutions to contract-oriented software development. The workshop is partially funded by the Nordunet3 project âCOSoDISâ (Contract-Oriented Software Development for Internet Services) and it attracted 25 participants. The program consists of 4 regular papers and 10 invited participant presentations
A Calculus for Orchestration of Web Services
Service-oriented computing, an emerging paradigm for distributed computing based on the use of services, is calling for the development of tools and techniques to build safe and trustworthy systems, and to analyse their behaviour. Therefore, many researchers have proposed to use process calculi, a cornerstone of current foundational research on specification and analysis of concurrent, reactive, and distributed systems. In this paper, we follow this approach and introduce CWS, a process calculus expressly designed for specifying and combining service-oriented applications, while modelling their dynamic behaviour. We show that CWS can model all the phases of the life cycle of service-oriented applications, such as publication, discovery, negotiation, orchestration, deployment, reconfiguration and execution. We illustrate the specification style that CWS supports by means of a large case study from the automotive domain and a number of more specific examples drawn from it
Insider Threats in Emerging Mobility-as-a-Service Scenarios
Mobility as a Service (MaaS) applies the everything-as- \ a-service paradigm of Cloud Computing to transportation: a MaaS \ provider offers to its users the dynamic composition of solutions of \ different travel agencies into a single, consistent interface. \ Traditionally, transits and data on mobility belong to a scattered \ plethora of operators. Thus, we argue that the economic model of \ MaaS is that of federations of providers, each trading its resources to \ coordinate multi-modal solutions for mobility. Such flexibility comes \ with many security and privacy concerns, of which insider threat is \ one of the most prominent. In this paper, we follow a tiered structure \ â from individual operators to markets of federated MaaS providers \ â to classify the potential threats of each tier and propose the \ appropriate countermeasures, in an effort to mitigate the problems
KPI-related monitoring, analysis, and adaptation of business processes
In today's companies, business processes are increasingly supported by IT systems. They can be implemented as service orchestrations, for example in WS-BPEL, running on Business Process Management (BPM) systems. A service orchestration implements a business process by orchestrating a set of services. These services can be arbitrary IT functionality, human tasks, or again service orchestrations. Often, these business processes are implemented as part of business-to-business collaborations spanning several participating organizations. Service choreographies focus on modeling how processes of different participants interact in such collaborations.
An important aspect in BPM is performance management. Performance is measured in terms of Key Performance Indicators (KPIs), which reflect the achievement towards business goals. KPIs are based on domain-specific metrics typically reflecting the time, cost, and quality dimensions. Dealing with KPIs involves several phases, namely monitoring, analysis, and adaptation. In a first step, KPIs have to be monitored in order to evaluate the current process performance. In case monitoring shows negative results, there is a need for analyzing and understanding the reasons why KPI targets are not reached. Finally, after identifying the influential factors of KPIs, the processes have to be adapted in order to improve the performance. %The goal thereby is to enable these phases in an automated manner.
This thesis presents an approach how KPIs can be monitored, analyzed, and used for adaptation of processes. The concrete contributions of this thesis are: (i) an approach for monitoring of processes and their KPIs in service choreographies; (ii) a KPI dependency analysis approach based on classification learning which enables explaining how KPIs depend on a set of influential factors; (iii) a runtime adaptation approach which combines monitoring and KPI analysis in order to enable proactive adaptation of processes for improving the KPI performance; (iv) a prototypical implementation and experiment-based evaluation.Die AusfĂŒhrung von GeschĂ€ftsprozessen wird heute zunehmend durch IT-Systeme unterstĂŒtzt und auf Basis einer serviceorientierten Architektur umgesetzt. Die Prozesse werden dabei hĂ€ufig als Service Orchestrierungen implementiert, z.B. in WS-BPEL. Eine Service Orchestrierung interagiert mit Services, die automatisiert oder durch Menschen ausgefĂŒhrt werden, und wird durch eine ProzessausfĂŒhrungsumgebung ausgefĂŒhrt. DarĂŒber hinaus werden GeschĂ€ftsprozesse oft nicht in Isolation ausgefĂŒhrt sondern interagieren mit weiteren GeschĂ€ftsprozessen, z.B. als Teil von Business-to-Business Beziehungen. Die Interaktionen der Prozesse werden dabei in Service Choreographien modelliert.
Ein wichtiger Aspekt des GeschĂ€ftsprozessmanagements ist die Optimierung der Prozesse in Bezug auf ihre Performance, die mit Hilfe von Key Performance Indicators (KPIs) gemessen wird. KPIs basieren auf Prozessmetriken, die typischerweise die Dimensionen Zeit, Kosten und QualitĂ€t abbilden, und evaluieren diese in Bezug auf die Erreichung von Unternehmenszielen. Die Optimierung der Prozesse in Bezug auf ihre KPIs umfasst mehrere Phasen. Im ersten Schritt mĂŒssen KPIs durch Monitoring der Prozesse zur Laufzeit erhoben werden. Falls die KPI Werte nicht zufriedenstellend sind, werden im nĂ€chsten Schritt die Faktoren analysiert, die die KPI Werte beeinflussen. SchlieĂlich werden auf Basis dieser Analyse die Prozesse angepasst um die KPIs zu verbessern.
In dieser Arbeit wird ein integrierter Ansatz fĂŒr das Monitoring, die Analyse und automatisierte Adaption von Prozessen mit dem Ziel der Optimierung hinsichtlich der KPIs vorgestellt. Die BeitrĂ€ge der Arbeit sind wie folgt: (i) ein Ansatz zum Monitoring von KPIs ĂŒber einzelne Prozesse hinweg in Service Choreographien, (ii) ein Ansatz zur Analyse von beeinflussenden Faktoren von KPIs auf Basis von EntscheidungsbĂ€umen, (iii) ein Ansatz zur automatisierten, proaktiven Adaption von Prozessen zur Laufzeit auf Basis des Monitorings und der KPI Analyse, (iv) eine prototypische Implementierung und experimentelle Evaluierung
The CHORCH Approach: How to Model B2Bi Choreographies for Orchestration Execution
The establishment and implementation of cross-organizational business processes is an implication of today's market pressure for efficiency gains.
In this context, Business-To-Business integration (B2Bi) focuses on the information integration aspects of business processes.
A core task of B2Bi is providing adequate models that capture the message exchanges between integration partners.
Following the terminology used in the SOA domain, such models will be called choreographies in the context of this work.
Despite the enormous economic importance of B2Bi, existing choreography languages fall short of fulfilling all relevant
requirements of B2Bi scenarios.
Dedicated B2Bi choreography standards allow for inconsistent outcomes of basic interactions and
do not provide unambiguous semantics for advanced interaction models.
In contrast to this, more formal or technical choreography languages may provide unambiguous modeling semantics,
but do not offer B2Bi domain concepts or an adequate level of abstraction.
Defining valid and complete B2Bi choreography models becomes a challenging task in the face of these shortcomings.
At the same time, invalid or underspecified choreography definitions are particularly costly considering the organizational
setting of B2Bi scenarios.
Models are not only needed to bridge the typical gap between business and IT,
but also as negotiation means among the business users of the integration partners on the one hand
and among the IT experts of the integration partners on the other.
Misunderstandings between any two negotiation partners potentially affect the agreements between all other negotiation partners.
The CHORCH approach offers tailored support for B2Bi by combining the strengths of both dedicated B2Bi standards and formal rigor.
As choreography specification format, the ebXML Business Process Specification Schema (ebBP) standard is used.
ebBP provides dedicated B2Bi domain concepts such as so-called BusinessTransactions (BTs) that abstractly specify the exchange of a request business document
and an optional response business document.
In addition, ebBP provides a format for specifying the sequence of BT executions for capturing complex interaction scenarios.
CHORCH improves the offering of ebBP in several ways.
Firstly, the execution model of BTs which allows for inconsistent outcomes among the integration partners
is redefined such that only consistent outcomes are possible.
Secondly, two binary choreography styles are defined as B2Bi implementation contract format in order to streamline implementation projects.
Both choreography styles are formalized and provided with a formal execution semantics for ensuring unambiguity.
In addition, validity criteria are defined that ensure implementability using BPEL-based orchestrations.
Thirdly, the analysis of the synchronization dependencies of complex B2Bi scenarios is supported
by means of a multi-party choreography style combined with an analysis framework.
This choreography style also is formalized and standard state machine semantics are reused in order to ensure unambiguity.
Moreover, validity criteria are defined that allow for analyzing corresponding models for typical multi-party choreography issues.
Altogether, CHORCH provides choreography styles that are B2Bi adequate, simple, unambiguous, and implementable.
The choreography styles are B2Bi adequate in providing B2Bi domain concepts, in abstracting from low-level implementation details
and in covering the majority of real-world B2Bi scenarios.
Simplicity is fostered by using state machines as underlying specification paradigm.
This allows for thinking in the states of a B2Bi scenario and for simple control flow structures.
Unambiguity is provided by formal execution semantics whereas implementability (for the binary choreography styles) is ensured by providing
mapping rules to BPEL-based implementations.
The validation of CHORCH's choreography styles is performed in a twofold way.
Firstly, the implementation of the binary choreography styles based on Web Services and BPEL technology is demonstrated
which proves implementability using relatively low-cost technologies.
Moreover, the analysis algorithms for the multi-party choreography styles are validated using a Java-based prototype.
Secondly, an abstract visualization of the choreography styles based on BPMN is provided that abstracts from
the technicalities of the ebBP standard.
This proves the amenability of CHORCH to development methods that start out with visual models.
CHORCH defines how to use BPMN choreographies for the purpose of B2Bi choreography modeling
and translates the formal rules for choreography validity into simple composition rules that
demonstrate valid ways of connecting the respective modeling constructs.
In summary, CHORCH allows integration partners to start out with a high-level visual model of their interactions in BPMN
that identifies the types and sequences of the BusinessTransactions to be used.
For multi-party choreographies, a framework for analyzing synchronization dependencies then is available.
For binary choreographies, an ebBP refinement can be derived that fills in the technical parameters that are needed for deriving the implementation.
Finally, Web Services and BPEL based implementations can be generated.
Thus, CHORCH allows for stepwise closing the semantic gap between the information perspective of business process models
and the corresponding implementations.
It is noteworthy that CHORCH uses international standards throughout all relevant layers, i.e., BPMN, ebBP, Web Services and BPEL,
which helps in bridging the heterogeneous IT landscapes of B2Bi partners.
In addition, the adoption of core CHORCH deliverables as international standards of the RosettaNet community
give testament to the practical relevance and promise dissemination throughout the B2Bi community.BetriebsĂŒbergreifende GeschĂ€ftsprozessintegration ist eine logische Konsequenz allgegenwĂ€rtigen Wettbewerbsdrucks.
In diesem Kontext fokussiert Business-To-Business integration (B2Bi) auf die
Informationsaustausche zwischen Unternehmen.
Eine B2Bi-Kernanforderung ist die Bereitstellung adÀquater Modelle zur Spezifikation der Nachrichtenaustausche zwischen Integrationspartnern.
Diese werden im Rahmen dieser Arbeit in Anlehnung an Service-orientierte Architekturen (SOA)-Terminologie Choreographien genannt.
Bestehende Choreographiesprachen decken die Anforderungen an B2Bi-Choreographien nicht vollstÀndig ab.
Dedizierte B2Bi-Choreographiestandards definieren inkonsistente Austauschprozeduren fĂŒr grundlegende Interaktionen
und nur unvollstĂ€ndige Semantiken fĂŒr fortgeschrittene Interaktionen.
Formale oder Technik-getriebene Choreographiesprachen bieten die benötigte PrÀzision,
lassen aber DomÀnenkonzepte vermissen oder operieren auf einer niedrigen Abstraktionsebene.
Angesichts solcher MÀngel wird die Spezifikation valider und vollstÀndiger B2Bi-Choreographien zu einer echten Herausforderung.
Gleichzeitig sind mangelhafte Choreographiemodelle gerade im B2Bi-Bereich besonders problematisch,
da diese nicht nur zwischen Fach- und IT-Abteilung, sondern auch ĂŒber Unternehmensgrenzen hinweg eingesetzt werden.
Der CHORCH-Ansatz schafft an dieser Stelle mittels maĂgeschneiderter Choreographien Abhilfe,
welche die Vorteile von B2Bi-Choreographien und von formalen AnsÀtzen kombinieren.
Als Ausgangspunkt wird das ebXML Business Process Specification Schema (ebBP) verwendet,
das als B2Bi-Choreographiestandard DomÀnenkonzepte wie zum Beispiel
sogenannte BusinessTransactions (BTs) bietet.
Eine BT ist der Basisbaustein von B2Bi-Choreographien und spezifiziert
den Austausch eines GeschÀftsdokuments sowie eines optionalen Antwortdokuments.
DarĂŒber hinaus bietet ebBP ein Format zur Spezifikation von BT-Kompositionen zur UnterstĂŒtzung komplexer Interaktionen.
CHORCH erweitert ebBP wie folgt.
Erstens, das AusfĂŒhrungsmodell fĂŒr BTs wird neu definiert, um inkonsistente ErgebniszustĂ€nde zu eliminieren.
Zweitens, fĂŒr Entwicklungsprojekte werden zwei binĂ€re Choreographieklassen definiert, die als B2Bi-Implementierungskontrakt dienen sollen.
Die Formalisierung beider Klassen sowie formale operationale Semantiken gewÀhrleisten Eindeutigkeit,
wĂ€hrend ValiditĂ€tskriterien die AusfĂŒhrbarkeit entsprechender Modelle mittels BPEL-basierter Orchestrationen garantieren.
Drittens, zur Analyse der Synchronisationsbeziehungen komplexer B2Bi-Szenarien wird eine Multi-Party-Choreographieklasse nebst Analyseframework definiert.
Wiederum wird fĂŒr diese Klasse eine Formalisierung definiert, die mittels Standard-Zustandsautomatensemantik Eindeutigkeit gewĂ€hrleistet.
Ferner garantieren ValiditÀtskriterien die Anwendbarkeit der definierten Analysealgorithmen.
Insgesamt bieten die Choreographieklassen des CHORCH-Ansatzes ein B2Bi-adÀquates, einfaches, eindeutiges und implementierbares
Modell der Nachrichtenaustausche zwischen B2Bi-Partnern.
B2Bi-AdÀquatheit wird durch Verwendung von B2Bi-DomÀnenkonzepten, Abstraktion von rein technischen Kommunikationsdetails
und Abdeckung der meisten praktisch relevanten B2Bi-Szenarien gewÀhrleistet.
Einfachheit ist ein Ausfluss der Verwendung eines Zustandsmaschinen-basierten Modellierungsparadigmas,
das die Definition des Interaktionsfortschritts in Form von ZustÀnden sowie einfache Kontrollflussstrukturen ermöglicht.
Eindeutigkeit wird durch die Verwendung formaler Semantiken garantiert, wĂ€hrend Implementierbarkeit (fĂŒr die beiden binĂ€ren Choreographieklassen)
durch Angabe von Mapping-Regeln auf BPEL-Orchestrationen sichergestellt wird.
Die Validierung der CHORCH-Choreographieklassen erfolgt in zweierlei Hinsicht.
Erstens, die Implementierbarkeit der binÀren Choreographieklassen mit Hilfe von Web Services und BPEL wird durch die Definition entsprechender
Mappingregeln belegt. Weiterhin wird das Analyseframework der Multi-Party-Choreographieklasse als Java-Prototyp implementiert.
Zweitens, fĂŒr alle Choreographieklassen wird eine abstrakte Visualisierung auf BPMN-Basis definiert, die von diversen technischen Parametern
des ebBP-Formats abstrahiert.
Damit wird die Integrierbarkeit der CHORCH-Choreographieklassen in EntwicklungsansÀtze,
die ein visuelles Modell als Ausgangspunkt vorsehen, belegt.
CHORCH definiert, wie sogenannte BPMN-Choreographien zum Zweck der B2Bi-Choreographiemodellierung zu verwenden sind
und ĂŒbersetzt die ValiditĂ€tskriterien der CHORCH-Choreographieklassen in einfache Modell-Kompositionsregeln.
In seiner Gesamtheit bietet CHORCH somit einen Ansatz, mit Hilfe dessen B2Bi-Partner zunÀchst
die Typen und zulÀssigen Reihenfolgen ihrer GeschÀftsdokumentaustausche auf Basis eines abstrakten visuellen BPMN-Modells identifizieren können.
Im Fall von Multi-Party-Choreographien steht dann ein Framework zur Analyse der Synchronisationsbeziehungen zwischen den Integrationspartnern zur VerfĂŒgung.
Im Fall von binÀren Choreographien können ebBP-Verfeinerungen abgeleitet werden, welche die Modelle um technische Parameter anreichern, die zur Ableitung
einer Implementierung benötigt werden. Diese ebBP-Modelle sind in Web Services- und BPEL-basierte Implementierungen ĂŒbersetzbar.
Damit erlaubt CHORCH die schrittweise ĂberbrĂŒckung der semantischen LĂŒcke zwischen der Informationsaustauschperspektive von
GeschÀftsprozessmodellen und den zugehörigen Implementierungen.
Ein beachtenswerter Aspekt des CHORCH-Ansatzes ist die Verwendung einschlÀgiger internationaler Standards auf allen Abstraktionsebenen,
im Einzelnen BPMN, ebBP, Web Services und BPEL. Die Verwendung von Standards trÀgt dem heterogenen Umfeld von B2Bi-Szenarien Rechnung.
ZusÀtzlich wurden Kernergebnisse des CHORCH-Ansatzes als internationale Standards der RosettaNet-B2Bi-Community veröffentlicht.
Dies belegt die praktische Relevanz des Ansatzes und fördert die Verbreitung innerhalb der B2Bi-Community
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