Generation of Network Service Descriptors from Network Service Requirements

Network Function Virtualization (NFV) is a new paradigm in Network Service (NS) provisioning. European Telecommunications Standards Institute (ETSI) proposed and standardized an architectural framework for NFV. By leveraging virtualization and Software-Defined Networking (SDN) technologies, NFV decouples network functionality from hardware infrastructure. This enables the automated provisioning of NSs and reduces the capital and operational costs for service operators. NFV Management and Orchestration (NFV-MANO) is a functional block in the NFV framework, and it is responsible for the deployment and life-cycle management of NSs. With NFV, the telecommunication industry is moving towards zero-touch, i.e. automation of all the processes. In order to orchestrate and manage an NS, NFV-MANO requires the NS’s deployment template. This template is referred to as NS Descriptor (NSD) and contains all the details for deployment and orchestration of the NS. De-signing such a descriptor requires the design of the NS, which is actually out of the NFV scope. Traditionally, service operators’ experts design NSs and NSDs. However, this design activity is time-consuming and error-prone; moreover, it is not fitting the Telecom’s vision of zero-touch. In this thesis, we will propose an approach to automate the process of NS and NSD design. The approach starts from a set of requirements provided as Network Service Requirements (NSReq). The NSReq describes the required network service at a high level of abstraction and focuses on the functional, architectural, and non-functional characteristics. With the help of an ontology representing the knowledge from Telecom standards and previous successful experiences, we decompose the NSReq. We select the set of Virtual Network Functions (VNF) from a catalog to design the NS. Considering all the levels of decomposition and the VNF’s dependencies captured from the ontology, we design all the possible for-warding graphs that can form an NS. We design each forwarding graph through different steps at different abstraction levels, i.e. functional, architectural, and VNF levels. According to each forwarding graph, we design an NSD along with the traffic flows in the NS. We re-fine each NSD by dimensioning its VNFs using the non-functional requirements in the NSReq. Accordingly, we refine the deployment flavor of each NSD. We have developed a prototype tool as a proof of concept for our proposed approach which we will discuss later in this thesis

Reasoning with qualitative preferences for optimization of component-based system development

A component-based system is a set of entities that work together in well-defined ways to satisfy a given requirement specified by the stakeholders for the system. This requirement can be modeled as a set of combinations of traits, which represent acceptable alternatives for providing the required functionality. A system satisfies its requirement if and only if it provides one of the required sets of traits in its entirety. Beyond the requirement, system stakeholders may also have preferences with respect to optional functionality that could be provided by a system, tradeoffs between non-functional properties, or other system design options. This work focuses on integrating support for both qualitative preference reasoning and formal verification into the component-based system design process in order to choose a set of components for the system that, when composed, will (1) satisfy the stakeholders\u27 requirement for the system and (2) provide a set of traits that is optimal with respect to the given preferences. Our primary research objective is to develop a generic, modular, end-to-end framework for developing component-based systems of any type which are correct according to the system requirement and most preferred with respect to the stakeholders\u27 preferences. Applications of the framework to problems in Web service composition, goal-oriented requirements engineering, and other areas will be discussed, along with future work toward integrating multi-stakeholder preference reasoning and partial satisfaction of traits into the framework

A Framework for Requirements Decomposition, SLA Management and Dynamic System Reconfiguration

To meet user requirements, systems can be built from Commercial-Off-The-Shelf (COTS) components, potentially from different vendors. However, the gap between the requirements referring to the overall system and the components to build the system from can be large. To close the gap, it is required to decompose the requirements to a level where they can be mapped to components. When the designed system is deployed and ready for operations, its services are sold and pro-vided to customers. One important goal for service providers is to optimize system resource utilization while ensuring the quality of service expressed in the Service Level Agreements (SLAs). For this purpose, the system can be reconfigured dynamically according to the cur-rent workload to satisfy the SLAs while using only necessary resources. To manage the re-configuration of the system at runtime, a set of previously defined patterns called elasticity rules can be used. In elasticity rules, the actions that need to be taken to reconfigure the sys-tem are specified. An elasticity rule is generally invoked by a trigger, which is generated in reaction to a monitoring event. In this thesis, we propose a model-driven management framework which aims at user re-quirements satisfaction, SLA compliance management and enabling dynamic reconfiguration by reusing the design information at runtime. An approach has been developed to derive automatically a valid configuration starting from low level requirements called service configurations. However, the service configurations are far from requirements a user would express. To generate a system configuration from user requirements and alleviate the work of designer, we generate service configurations by de-composing functional user requirements to the level where components can be selected and put together to satisfy the user requirements. We integrated our service configurations gen-erator with the previous configuration generator. In our framework, we reuse the information acquired from system configuration and dimen-sioning to generate elasticity rules offline. We propose a model driven approach to check the compliance of SLAs and generate triggers for invoking applicable elasticity rules when system reconfiguration is required. For handling multiple triggers generated at the same time, we propose a solution to automatically correlate the actions of invoked elasticity rules, when re-quired. The framework consists of a number of metamodels and a set of model transfor-mations. We use the Unified Modeling Language (UML) and its profiling mechanism to de-scribe all the artifacts in the proposed framework. We implement the profiles using Eclipse Modeling Framework (EMF) and Papyrus. To implement the processes, we use the Atlas Transformation Language (ATL). We also use the APIs of the Object Constraint Language (OCL) in the Eclipse environment to develop a tool for checking constraints and generating triggers

Dynamic Connector Synthesis: Principles, Methods, Tools and Assessment

CONNECT adopts a revolutionary approach to the seamless networking of digital systems, that is, onthe- fly synthesis of the connectors via which networked systems communicate. Within CONNECT, the role of the WP3 work package is to devise automated and efficient approaches to the synthesis of such emergent connectors, provided the behavioral specification of the components to be connected. Thanks to WP3 scientific and technology development, emergent connectors can be synthesized on the fly as networked systems get discovered, implementing the necessary mediation between networked systems' protocols, from application down to middleware layers. This document being the final report about WP3 achievements, it outlines both: (i) specific contributions over the reporting period, and (ii) overall contributions in the area of automated, on-the-fly protocol mediation, from theory to supporting tool

Synthèse d'orchestrateur pour la composition de services

La composition de comportement est un aspect important dans beaucoup de domaines, surtout dans la programmation orientée service (Service Oriented Computing) et dans les systèmes Multi-agents. L'objectif est d'orchestrer le comportement des différents modules, modelisés par des système de transitions étiquetés (abelled transition systems - LTS), pour satisfaire une specification but, de même modelisé comme LTS. Un problème majeur qu'on trouve dans la plupart des approches, est le nombre élevé d'états. L'objectif de cette thèse est de développer des méthodes efficaces pour résoudre le problème de composition de comportement.D'abord on analyse le cas où toutes les actions sont observables. Nous developpons ensuite une caractérisation de l'existence d'une solution en terme d'une relation entre les différentes composantes d'une part et la specification but d'autre part. En utilisant cette caractérisation , nous développons un algorithme qui trouve à la volée une solution au problème si cette dernière existe. Nous démontrons que l'algorithme est correct et sa complexité est polynomiale par rapport à la taille des composants. Nous prouvons également que l'algorithme est robuste par rapport à l'échec d'un des composants. Ensuite, nous proposons une méthode d'abstraction qui réduit considérablement le nombre d'états. Cette abstraction est utilisée comme outil heuristique qui accélère la recherche. Finalement, nous développons une caractérisation de l'existence d'une solution dans le cas d'observation partielle. Cette caractérisation est elaborée en introduisant le concept de contrabilité. Nous démontrons qu'une solution existe si et seulement si les composantes sont controlables par rapport au but. Nous developpons un algorithme pour trouver la relation de controlabilité à la volée. La complexité de l'algorithme est EXPTIME en terme de la taille des composants.The behavior composition problem is an important aspect in many fields, especially in Service Oriented Computing and in Multi-agent systems. The basic objective is to orchestrate the behavior of the different available components, modeled as labeled transition systems (LTS), in order to satisfy a given goal specification, also modeled as an LTS . A major concern has been the large state space of typical situations which made existing approaches very compute intensive. The aim of this thesis is to develop efficient methods to solve the behavior composition problem. First we study the case when all actions are observable. We develop a characterization of the existence of a solution in term of existence of a relation between the different available components, considered as a single system, on one hand and the goal specification on the other. Using that characterization we develop an on-the-fly algorithm that finds a solution to the problem when one exists. The algorithm is shown to be correct and has polynomial complexity with the respect to the size of the components. We also show that the algorithm is robust with respect to component failure. Then we propose an abstraction method that reduces drastically the number of states. We show that the non-existence of a solution in the abstracted systems implies the non-existence of solution in the original system. Also the result of the abstraction is used as an input to the above algorithm for use as a heuristic to speed up the search. Finally, we develop a characterization of the behavior composition problem in the case of partial observation by using the concept of controllability. We show that a solution to the composition problem with partial observation exists if and only if the components are controllable with respect to the goal specification. We also develop an on-the-fly algorithm to compute the controllability of the system. The complexity of the algorithm is EXPTIME in the size of the components

Finalised dependability framework and evaluation results

The ambitious aim of CONNECT is to achieve universal interoperability between heterogeneous Networked Systems by means of on-the-fly synthesis of the CONNECTors through which they communicate. The goal of WP5 within CONNECT is to ensure that the non-functional properties required at each side of the connection going to be established are fulfilled, including dependability, performance, security and trust, or, in one overarching term, CONNECTability. To model such properties, we have introduced the CPMM meta-model which establishes the relevant concepts and their relations, and also includes a Complex Event language to express the behaviour associated with the specified properties. Along the four years of project duration, we have developed approaches for assuring CONNECTability both at synthesis time and at run-time. Within CONNECT architecture, these approaches are supported via the following enablers: the Dependability and Performance analysis Enabler, which is implemented in a modular architecture supporting stochastic verification and state-based analysis. Dependability and performance analysis also relies on approaches for incremental verification to adjust CONNECTor parameters at run-time; the Security Enabler, which implements a Security-by-Contract-with-Trust framework to guarantee the expected security policies and enforce them accordingly to the level of trust; the Trust Manager that implements a model-based approach to mediate between different trust models and ensure interoperable trust management. The enablers have been integrated within the CONNECT architecture, and in particular can interact with the CONNECT event-based monitoring enabler (GLIMPSE Enabler released within WP4) for run-time analysis and verification. To support a Model-driven approach in the interaction with the monitor, we have developed a CPMM editor and a translator from CPMM to the GLIMPSE native language (Drools). In this document that is the final deliverable from WP5 we first present the latest advances in the fourth year concerning CPMM, Dependability&Performance Analysis, Incremental Verification and Security. Then, we make an overall summary of main achievements for the whole project lifecycle. In appendix we also include some relevant articles specifically focussing on CONNECTability that have been prepared in the last period

Goal-oriented business process engineering

Service-orientierte Architekturen haben sich als Architekturstil für die Entwicklung von Geschäftsanwendungen etabliert. Dementsprechend spielen Geschäftsprozessmodelle eine zentrale Rolle sowohl für die Beschreibung fachlicher Anforderungen als auch für die Spezifikation der erforderlichen Service-Kompositionen. Die modellierten Geschäftsprozesse dienen in der Regel keinem Selbstzweck, sondern der Erreichung eines strategischen Geschäftsziels. Um die Angemessenheit der Geschäftsprozessmodelle, zum Beispiel hinsichtlich ihrer Vollständigkeit und Relevanz, zu bewerten, müssen ihre Beziehungen und Abhängigkeiten zu den Unternehmensziele berücksichtigt werden.In bestehenden Arbeiten gibt es keine integrierte und durchgängige Spezifikationsmethode, die die zielorientierte Spezifikation, die systematische Ableitung von Geschäftsprozessmodellen und die Sicherstellung der Qualität ausreichend berücksichtigt. In dieser Arbeit wird ein Ansatz zur zielorientierten Spezifikation von Geschäftsprozessen vorgestellt, der Modellierungstechniken und Qualitätsanalysefunktionen beinhaltet. Basierend auf einer vorhandenen Ziebeschreibungssprache wird ein erweiterter Modellierungsansatz vorgestellt, der die Beschreibung von Abhängigkeiten zwischen Geschäftszielen und relevanten Elementen im Geschäftskontext sowie die Identifikation von komponierbaren Aktionen unterstützt. In einem systematischen Ableitungsverfahren wird beschrieben, wie diese Informationen bei der Komposition eines Geschäftsprozesses berücksichtigt werden können. Die Qualität der Spezifikation wird durch verschiedene Analyseverfahren sichergestellt.Service-oriented architectures have emerged as an architectural style for the design of business applications. Accordingly, business process models play a central role in the description of business requirements as well as in the specification of required service compositions.The modeling of business processes is not pursued for its own sake, but contributes to the achievement of strategic concerns represented by business goals. In order to evaluate the suitability of business process models, e.g. with respect to completeness and relevance, their relations to business goals need to be considered. This comprises the initial specification of business goals and business processes as well as the preservation of consistency between evolving models.In previous work, several goal-oriented requirements engineering approaches and business process modeling techniques have been proposed. Nonetheless, there is no integrated specification method that supports the goal-oriented specification, the systematic derivation of business process models and the assurance of quality in a sufficient manner.In this thesis, we present an approach for goal-oriented business process engineering that provides modeling techniques and analysis capabilities to assure the overall specification quality. Based on an existing goal-modeling notation, we introduce an extended modeling approach that supports the expression of goal dependencies, relevant business context elements and the identification of composable actions. Further, we describe a systematic derivation method to ensure the consideration of this information in the business process composition. To ensure a valid and consistent specification, a quality analysis and assurance framework is introduced.Tag der Verteidigung: 04.05.2015Paderborn, Univ., Diss., 201