Context and motivation: Service-Based Systems are highly dynamic software systems composed of several web services. In contrast to other types of systems, Service-Based Systems rely on service providers to ensure that their web services comply with the agreed Quality of Service. Delivering an adequate Quality of Service is a critical and significant challenge that requires monitoring along the different activities in the Service-Based System's lifecycle.; Question/problem: Current monitoring systems are designed to support specific activities (e.g. service selection, adaptation, etc.), but do not fulfil the requirements of all the activities in the Service-Based System's lifecycle.; Principal ideas/results: In this paper, we present SALMon, a QoS monitoring framework able to support the whole Service-Based System's lifecycle. SALMon is highly versatile, since it combines different strategies for its configuration (model-based and invocation-based) and for the way it gets the Quality of Service (passive monitoring and online testing). Furthermore, its architecture supports easy extensibility with new quality attributes, independence of the technology of the monitored services and interoperability with other tools. We conducted a performance evaluation over real web services using suitable estimators for response time and evaluated both its overhead and capacity.; Contribution: SALMon provides infrastructure that can be used in very different scenarios, as exemplified in this paper, both in terms of the lifecycle's phase addressed and the type of system (pure Service-Oriented Architecture, cloud-based systems, etc.). This diversity of situations addressed makes SALMon a significant contribution both for practitioners that may be interested in integrating a working technology in their software solutions, and for researchers who can conduct their investigation on top of a reliable infrastructure.
La Computació Orientada a Serveis (SOC) ha esdevingut en els darrers anys un paradigma exitós en el camp de l'Enginyeria del Software. Els sistemes construïts sota aquest paradigma, coneguts com Sistemes Basats en Serveis (SBS), estan composats de diversos serveis, que són, usualment, programari de tercers executats per proveïdors de serveis externs.Els SBS depenen dels proveïdors dels serveis per garantir que els serveis compleixen amb la Qualitat del Servei (QoS) acordada.En contrast amb altres sistemes, el comportament dinàmic dels SBS requereix d'informació actualitzada del QoS per a la correcta administració de les diferents etapes del cicle de vida dels SBS: des de la seva construcció inicial fins a la seva clausura.Proveir d'aquesta informació de QoS ha resultat en diferents solucions tecnològiques construïdes al voltant d'un monitor. Malgrat això, diversos reptes de recerca en el camp encara romanen obertes, des d'aspectes teòrics de l'assegurança de qualitat, a reptes arquitectònics en la monitorització descentralitzada.Basat en els reptes de recerca actuals per a la monitorització de serveis, els forats de recerca en els que pretenem contribuir són dobles:- Investigar en la definició i estructura dels diferents factors de qualitat dels serveis, i proveir un marc de treball d'entesa comuna per a la definició de què monitoritzar.- Investigar en les diferents característiques requerides per donar suport a les activitats de tot el cicle de vida dels SBS (i.e. commonitoritzar), i desenvolupar una plataforma de monitorització que acompleixi aquestes característiques.Com a resultats de la tesis, proveïm:Què monitoritzar- Una distribució dels models de qualitat al llarg de la dimensió temporal i la identificació de les seves interrelacions.- Un anàlisi de la mida i definició de la cobertura dels models de qualitat proposats.- Una cobertura quantificada dels diferents factors de qualitat ISO/IEC 25010 donat en les diferents propostes.- La identificació dels factors de qualitat més utilitzats, i la definició dels termes més consolidats.Com monitoritzar- L'elicitació dels requeriments per a les diferents activitats en el cicle de vida dels SBS.- La definició del conjunt de característiques que donen suport als requeriments elicitats.- Una platforma modular orientada a serveis, anomenat SALMon, que implementa les característiques definides. SALMon ha estatvalidat incloent la plataforma en diversos marcs de treball donant suport a les diferents activitats
Service Oriented Computing (SOC) has been established in the last recent years as a successful paradigm in Software Engineering. The systems built under this paradigm, known as Service Based System (SBS), are composed of several services, which are usually third-party software run by external service providers. SBS rely on these service providers to ensure that their services comply with the agreed Quality of Service (QoS). In contrast to
other systems, the dynamic behaviour of SBS requires up-to-date QoS information for its proper management in the different stages of its lifecycle, from their initial construction until their decommission.
Providing such QoS information has resulted in different technological solutions built around a monitor. Nonetheless, several research challenges in the field remain still open, ranging from theoretical aspects of quality assurance to architectonical challenges in decentralized monitoring.
Based on the current research challenges for service monitoring, the research gaps in which we aim to contribute are twofold:
- To investigate on the definition and structure of the different quality factors of services, and provide a framework of common understanding for the definition of what to monitor.
- To investigate on the different features required to support the activities of the whole SBS lifecycle (i.e. how to monitor), and develop a monitoring framework that accomplishes such features.
As a result of this thesis, we provide:
What to monitor
- A distribution of the quality models along the time dimension and the identification of their relationships.
- An analysis of the size and definition coverage of the proposed quality models.
- A quantified coverage of the different ISO/IEC 25010 quality factors given by the proposals.
- The identification of the most used quality factors, and provided the most consolidated definitions for them.
How to monitor
- The elicitation of the requirements of the different activities in the SBS lifecycle.
- The definition of the set of features that supports the elicited requirements.
- A modular service-oriented monitoring framework, named SALMon, implementing the defined features. SALMon has been validated by including it in several frameworks supporting the different activities of the SBS lifecycle. Finally, we have conducted a performance evaluation of SALMon over real web services.
La Computació Orientada a Serveis (SOC) ha esdevingut en els darrers anys un paradigma exitós en el camp de l'Enginyeria del Software. Els sistemes construïts sota aquest paradigma, coneguts com Sistemes Basats en Serveis (SBS), estan composats de diversos serveis, que són, usualment, programari de tercers executats per proveïdors de serveis externs. Els SBS depenen dels proveïdors dels serveis per garantir que els serveis compleixen amb la Qualitat del Servei (QoS) acordada. En contrast amb altres sistemes, el comportament dinàmic dels SBS requereix d'informació actualitzada del QoS per a la correcta administració de les diferents etapes del cicle de vida dels SBS: des de la seva construcció inicial fins a la seva clausura. Proveir d'aquesta informació de QoS ha resultat en diferents solucions tecnològiques construïdes al voltant d'un monitor. Malgrat això, diversos reptes de recerca en el camp encara romanen obertes, des d'aspectes teòrics de l'assegurança de qualitat, a reptes arquitectònics en la monitorització descentralitzada. Basat en els reptes de recerca actuals per a la monitorització de serveis, els forats de recerca en els que pretenem contribuir són dobles: - Investigar en la definició i estructura dels diferents factors de qualitat dels serveis, i proveir un marc de treball d'entesa comuna per a la definició de què monitoritzar. - Investigar en les diferents característiques requerides per donar suport a les activitats de tot el cicle de vida dels SBS (i.e. com monitoritzar), i desenvolupar una plataforma de monitorització que acompleixi aquestes característiques. Com a resultats de la tesis, proveïm: Què monitoritzar - Una distribució dels models de qualitat al llarg de la dimensió temporal i la identificació de les seves interrelacions. - Un anàlisi de la mida i definició de la cobertura dels models de qualitat proposats. - Una cobertura quantificada dels diferents factors de qualitat ISO/IEC 25010 donat en les diferents propostes. - La identificació dels factors de qualitat més utilitzats, i la definició dels termes més consolidats. Com monitoritzar - L'elicitació dels requeriments per a les diferents activitats en el cicle de vida dels SBS. - La definició del conjunt de característiques que donen suport als requeriments elicitats. - Una platforma modular orientada a serveis, anomenat SALMon, que implementa les característiques definides. SALMon ha estatvalidat incloent la plataforma en diversos marcs de treball donant suport a les diferents activitats
Services as part of our daily life represent an important means to deliver value to their consumers and have a great economic impact for organizations. The service consumption and their exponential proliferation show the importance and acceptance by their customers. In this sense, it is possible to predict that the infrastructure of future cities will be supported by different kind of services, such as smart city services, open data services, as well as common services (e.g., e-mail services), etc. Nowadays a large percentage of services are provided on the web and are commonly called web services (WSs). This kind of services has become one of the most used technologies in software systems. Among the challenges when integrating web services in a given system, requirements-driven selection occupies a prominent place. A comprehensive selection process needs to check compliance of Non-Functional Requirements (NFRs) which can be assessed by analyzing the Quality of Service (QoS). In this paper, we describe a framework called WeSSQoS that aims at ranking available WSs based on the comparison of their QoS and the stated NFRs. The framework is designed as an open Service Oriented Architecture (SOA) that hosts a configurable portfolio of normalization procedures and ranking algorithms which can be selected by users when starting a selection process. The QoS data from WSs can be obtained either from a static, WSDL-like description or dynamically through monitoring techniques. WeSSQoS is designed to work over multiple WS repositories and QoS sources. The impact of having a portfolio of different normalization and ranking algorithms is illustrated with an example.
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.
Cabrera, O.; Franch, X.; Marco, J. International Conference on Research Challenges in Information Science p. 1-12 DOI: 10.1109/RCIS.2014.6861079 Presentation's date: 2014-05-28 Presentation of work at congresses
Nowadays services as those provided by smart cities, health smart services, as well as common services (e.g., telephonic services, e-mail services), have a great economic impact for organisations and represent an important mean to deliver value to their consumers. The malfunctions of both the services themselves as well as the entities responsible for their execution and consumption might cause economic losses, consumers' dissatisfaction and even shorten the service life cycle, among other risks. To avoid malfunctions beyond maintaining quality levels desired, it is important to take into account the widest possible context information that cause either positive or negative effects around services and entities involved in their provisioning and consumption. In this paper, we propose an upper ontology for service provisioning and consumption from a service-centric perspective. Specifically, we focus on software services, although we could argue for more generic applications. The contribution is the analysis, evaluation and reuse of existing proposals on context models to identify the strengths and weaknesses of its current status as well as to identify contexts not yet considered, and consolidate an integrated view of these proposals. The ultimate intention is to provide a well-defined and consolidated infrastructure of context information as a common body of knowledge, that could be instantiated on variety of use cases, for example, to be instantiated by monitors as context information useful to be monitored, or to be used as context information that allows knowing which contexts affect a service when a user consumes it, among others.
Oriol, M.; Franco, O.; Franch, X.; Marco, J. International Conference on Research Challenges in Information Science p. 6861064-1-6861064-6 DOI: 10.1109/RCIS.2014.6861064 Presentation's date: 2014-05 Presentation of work at congresses
The quality of Open Source Software products is directly related to its community's health. To date, health analysis is made accessing available data repositories or using software management tools that are often too static or ad hoc. To address this issue, we propose to adopt principles and methods from the Service Oriented Computing field. Particularly, we propose to adapt the concepts of quality service and service level agreement, and propose to reuse the existing body of knowledge and techniques from SOC monitoring. To demonstrate the feasibility of the approach, we use a service monitoring framework called SALMonOSS as a proof of concept to realize the implementation of the proposal.
Müller, C.; Oriol, M.; Franch, X.; Marco, J.; Resinas, M.; Ruiz-Cortés, A.; Rodriguez, M. IEEE transactions on services computing Vol. 7, num. 2, p. 168-183 DOI: 10.1109/TSC.2013.45 Date of publication: 2014-04-01 Journal article
Service Level Agreements (SLAs) establish the Quality of Service (QoS) agreed between service-based systems consumers and providers. Since the violation of such SLAs may involve penalties, quality assurance techniques have been developed to supervise the SLAs fulfillment at runtime. However, existing proposals present some drawbacks: 1) the SLAs they support are not expressive enough to model real-world scenarios, 2) they couple the monitoring configuration to a given SLA specification, 3) the explanations of the violations are difficult to understand and even potentially inaccurate, 4) some proposals either do not provide an architecture, or present low cohesion within their elements. In this paper, we propose a comprehensive solution, from a conceptual reference model to its design and implementation, that overcomes these drawbacks. The resulting platform, SALMonADA, receives the SLA agreed between the parties as input and reports timely and comprehensive explanations of SLA violations. SALMonADA performs an automated monitoring configuration and it analyses highly expressive SLAs by means of a constraint satisfaction problems based technique. We have evaluated the impact of SALMonADA over the resulting service consumption time performance. The results are satisfactory enough to consider SALMonADA for SLA supervision because of its low intrusiveness.
Cloud Computing enables the construction and the provisioning of virtualized service-based applications in a simple and cost effective outsourcing to dynamic service environments. Cloud Federations envisage a distributed, heterogeneous environment consisting of various cloud infrastructures by aggregating different IaaS provider capabilities coming from both the commercial and the academic area. In this paper, we introduce a federated cloud management solution that operates the federation through utilizing cloud-brokers for various IaaS providers. In order to enable an enhanced provider selection and inter-cloud service executions, an integrated monitoring approach is proposed which is capable of measuring the availability and reliability of the provisioned services in different providers. To this end, a minimal metric monitoring service has been designed and used together with a service monitoring solution to measure cloud performance. The transparent and cost effective operation on commercial clouds and the capability to simultaneously monitor both private and public clouds were the major design goals of this integrated cloud monitoring approach. Finally, the evaluation of our proposed solution is presented on different private IaaS systems participating in federations.
Aquesta tesis proposa una definició formal per la relació d¿especialització en el marc de treball i* que permet la seva utilització d¿una manera ben definida. La proposta que es presenta està basada en treballs existents en diferents àrees interessades en la representació del coneixement: representació de coneixement de l¿àrea de la Intel¿ligència Artificial, i modelització conceptual i programació orientada a objectes de l¿àrea de Desenvolupament de Software. També s'han tingut en compte els resultats d'una enquesta realitzada a la comunitat d'i*, que ha proporcionat la percepció sobre el que els modeladors esperen de l'especialització. Com a conseqüència d'aquest doble anàlisi, s'han identificat 3 operacions d'especialització: extensió, refinament i redefinició. Per cada una d'aquestes, s'ha:¿ motivat la seva necessitat i proporcionat la motivació per a la seva utilització,¿ identificat els diferents casos que s¿hi poden donar, ¿ definit els elements involucrats en cada cas i les condicions de correctesa que s'han de complir,¿ demostrat per inducció el compliment de les condicions identificades per preservar la satisfacció, i finalment¿ proporcionat alguns exemples il¿lustratius en el context de l'exemple sobre agencies de viatge i viatgers.La relació d'especialització s'ha ofert en el marc de treball i* fent servir el constructor is-a definit sobre actors (un subactor is-a superactor) des de la seva primera proposta. Encara que el significat general del constructor és molt intuïtiu, els seus efectes a nivell d'elements intencionals i dependències no està sempre clar, dificultant seriosament la seva correcta utilització. Per poder raonar sobre correctesa i satisfacció, s¿han definit prèviament les condicions que s¿han de preservar quan una operació d¿especialització s¿utilitza. A més, es proporciona una metodologia amb uns passos ben definits que contextualitzen els aspectes formals d¿aquesta tesis en el procés de desenvolupament dels models.Com a conclusió, aquesta tesis possibilita la utilització de la relació d¿especialització en els models i* d¿una manera precisa i sense ambigüitats.
This thesis provides a formal proposal for the specialization relationship in the i* framework that allows its use in a well-defined manner. I root my proposal over existing works in different areas that are interested in representing knowledge: knowledge representation from Artificial Intelligence and conceptual modeling and object-oriented programming languages from Software Development. Also, I use the results of a survey conducted in the i* community that provides some insights about what i* modelers expect from specialization. As a consequence of this twofold analysis, I identify three specialization operations: extension, refinement and redefinition. For each of them, I:
- motivate its need and provide some rationale;
- distinguish the several cases that can occur in each operation;
- define the elements involved in each of these cases and the correctness conditions that must be fulfilled;
- demonstrate by induction the fulfilment of the conditions identified for preserving satisfaction;
- provide some illustrative examples in the context of an exemplar about travel agencies and travelers.
The specialization relationship is offered by the i* framework through the is-a construct defined over actors (a subactor is-a superactor) since it was first released. Although the overall meaning of this construct is highly intuitive, its effects at the level of intentional elements and dependencies are not always clear, hampering seriously its appropriate use.
In order to be able to reason about correctness and satisfaction, I define previously the conditions that must be preserved when a specialization takes place. In addition, I provide a methodology with well-defined steps that contextualize the formal aspects of this thesis in a development process.
As a conclusion, this thesis is making possible the use of the specialization relationship in i* in a precise, non-ambiguous manner.
Similarity metrics are widely used in computer graphics. In this paper, we will concentrate on a new, algorithmic complexity-based metric called Normalized Compression Distance. It is a universal distance used to compare strings. This measure has also been used in computer graphics for image registration or viewpoint selection. However, there is no previous study on how the measure should be used: which compressor and image format are the most suitable. This paper presents a practical study of the Normalized Compression Distance (NCD) applied to color images. The questions we try to answer are: Is NCD a suitable metric for image comparison? How robust is it to rotation, translation, and scaling? Which are the most adequate image formats and compression algorithms? The results of our study show that NCD can be used to address some of the selected image comparison problems, but care must be taken on the compressor and image format selected.
The specialization relationship is offered by the i* modeling language through the is-a construct defined over actors (a subactor is-a superactor). Although the overall meaning of this construct is highly intuitive, its semantics when it comes to the fine-grained level of strategic rationale (SR) diagrams is not defined, hampering seriously its appropriate use. In this paper
we provide a formal definition of the specialization relationship at the level of
i* SR diagrams. We root our proposal over existing work in conceptual modeling in general, and object-orientation in particular. Also, we use the results of a survey conducted in the i* community that provides some hints about what i* modelers expect from specialization. As a consequence of this twofold analysis, we identify, define and specify two specialization operations,
extension and refinement, that can be applied over SR diagrams. Correctness conditions for them are also clearly stated. The result of our work is a formal proposal of specialization for i* that allows its use in a well-defined manner
Müller, C.; Oriol, M.; Rodriguez, M.; Franch, X.; Marco, J.; Resinas, M.; Ruiz, A. Jornadas de Ciencia e Ingeniería de Servicios p. 157-160 Presentation's date: 2012-09-19 Presentation of work at congresses
Several research frameworks in both academy and industry aim at monitoring conditions stated in Service Level Agreements (SLAs). However, up to our knowledge, none of them present reasoning capabilities over the SLA
with a clear explanation of the concrete statements that violate the agreement.
In this paper we present SALMonADA, a platform to monitor SLAs specified with WS–Agreement, that provides agreement violations explanations by pointing both: violated terms of the WS–Agreement document, and violating measures of a monitoring management document.
The specialization relationship is offered by the i* modeling language through the is-a construct defined over actors (a subactor is-a superactor). Although the overall meaning of this construct is highly intuitive, its semantics of strategic rationale (SR) diagrams is not defined. In this report we provide a formal definition of the specialization relationship at the level of i* SR diagrams. We root our proposal over existing work in conceptual modeling in general, and object-orientation in particular. Also, we use the results of a survey conducted in the i* community that provides some hints about what i* modelers expect from specialization. As a consequence of this twofold analysis, we identify, define and specify two specialization operations, extension and refinement, that can be applied over SR diagrams. Correctness conditions for them are also clearly stated. The result of our work is a formal proposal of specialization for i* that allows its use in a well-defined manner.
Oriol, M.; Qureshi, N.; Franch, X.; Perini, A.; Marco, J. International Working Conference on Requirements Engineering: Foundation for Software Quality p. 280-287 DOI: 10.1007/978-3-642-28714-5_25 Presentation's date: 2012-03 Presentation of work at congresses
Context and motivation: Adaptive Service Based Applications (SBAs) need to cope with continuously changing environments. Monitoring becomes a key requirement for engineering Adaptive SBAs. Question/problem:
Ongoing research on Requirements Engineering (RE) for Adaptive SBAs strives to answer challenging questions such as how to monitor changes affecting user’s requirements? and how the monitored information helps in adapting to the candidate solutions? Principal ideas/results: Existing approaches and techniques to specify requirements monitoring for Adaptive SBAs are either formal or specialized to a particular domain. A convenient and easy approach to specify requirements monitoring for Adaptive SBAs is still missing. In this paper, we focus on this issue. Contribution: We describe a systematic approach for deriving requirements monitoring specifications for the running Adaptive SBA. We use a running example from a travel domain case study to elaborate our approach.
Kertesz, A.; Kecskemeti, G.; Marosi, A.; Oriol, M.; Franch, X.; Marco, J. Euromicro International Conference on Parallel, Distributed, and Network-Based Processing p. 567-574 DOI: 10.1109/PDP.2012.25 Presentation's date: 2012 Presentation of work at congresses
Müller, C.; Oriol, M.; Rodriguez, M.; Franch, X.; Marco, J.; Resinas, M.; Ruiz, A. International Workshop on Principles of Engineering Service-Oriented Systems p. 43-49 DOI: 10.1109/PESOS.2012.6225938 Presentation's date: 2012 Presentation of work at congresses
Quality assurance techniques have been developed to supervise the service quality (QoS) agreed between service-based systems (SBSs) consumers and providers. Such QoS is usually included in service level agreements (SLAs) and thus, SLA monitoring platforms have been developed supporting violation detection. However, just a few of them provide explanation of the violations caused by observed QoS at monitoring time, but not in an user-friendly format. Therefore, we propose a general monitoring and analysis conceptual reference model and we instantiated it with SALMonADA, a SBS that notifies the clients with violations and their causes in their own easy-to-understand specification terms. In addition, our platform performs an early analysis notification that avoids delays in the client notification time when a violation takes place. Moreover, we have implemented a web application as a SALMonADA client, to prove how it monitors, analyses and reports to their clients the service level fulfillment of real services subject to a SLA specified with WS-Agreement.
Web Services (WS) have become one the most used technologies nowadays in software systems. Among the challenges when integrating WS in a given system, requirements-driven selection occupies a prominent place. A comprehensive selection process needs to check compliance of Non-Functional Requirements (NFR), which can be assessed by analysing WS Quality of Service (QoS). In this paper, we describe the
WeSSQoS system that aims at ranking available WS based on the comparison of their QoS and the stated NFRs. WeSSQoS is
designed as an open service-oriented architecture that hosts a configurable portfolio of normalization and ranking
algorithms that can be selected by the engineer when starting a selection process. WS’ QoS can be obtained either from a
static, WSDL-like description, or computed dynamically through monitoring techniques. WeSSQoS is designed to work over multiple WS repositories and QoS sources. The impact of
having a portfolio of different normalization and ranking algorithms is illustrated with an example.
Image registration is an important task in medicine, especially when images have been acquired by different scanner/sensor types, since they provide information on different body structures (bones, muscles, vessels...). Several techniques have been proposed in the past, and among those, Normalized Mutual Information has been proven as successful in many cases. Normalized Compression Distance has been proposed as a simple yet effective technique for image registration. It is especially suitable for the case of CT-MRI registration. However, other image modalities such as PET pose some problems and do not achieve accurate registration. In this paper we analyse and propose a valid approach for image registration using compression that works properly for different combinations of CT, MRI and PET images.
Sammodi, O.; Metzger, A.; Franch, X.; Oriol, M.; Marco, J.; Pohl, K. International Computer Software and Applications Conference p. 582-587 DOI: 10.1109/COMPSAC.2011.81 Presentation's date: 2011-07-21 Presentation of work at congresses
Franch, X.; Grünbacher, P.; Oriol, M.; Burgstaller, B.; Dhungana, D.; Lopez, L.; Marco, J.; Pimentel, J. International Computer Software and Applications Conference p. 458-463 DOI: 10.1109/COMPSACW.2011.83 Presentation's date: 2011-07 Presentation of work at congresses
Service-based systems need to provide flexibility to adapt both to evolving requirements from multiple, often conflicting, ephemeral and unknown stakeholders, as well as to changes in the runtime behavior of their component services.
Goal-oriented models allow representing the requirements of the system whilst keeping information about alternatives. We present the MAESoS approach which uses i* diagrams to identify quality of service requirements over services. The alternatives are extracted and kept in a variability model. A monitoring infrastructure identifies changes in runtime behavior that can propagate up to the level of stakeholder goals and trigger
the required adaptations. We illustrate the approach with a scenario of use.
Volume models often show high complexity. Local details and overall shape may sometimes be difficult to perceive. Unsharp masking techniques improve the perception of those small features by increasing the local contrast. In this paper we present a simple and fast method for feature enhancement based on 3D mipmaps. In contrast to other
approaches, in addition to increasing luminance on the feature details, we also darken the valleys of the volume thus increasing local contrast and making neighboring details more visible. Our approach is fast and simple, with small memory requirements thanks to the use of 3D mipmaps. We also propose a color selection strategy, based on harmonic colors, that further enhances the salient features without abrupt or uncomfortable color changes.
The clear definition of a metamodel can be considered helpful for any conceptual modeling approach, and the i* framework is not an exception. Agreeing on a metamodel for i* can be considered even more convenient than ever when we are aware of the different dialects and variations that the commu-nity proposed, and keep proposing, over the seminal i* definition. In this paper we present the revised version of the i* metamodel proposed by the GESSI re-search group at 2005 and we report some current contexts of use: 1) definition of a data interchange format; 2) definition of the inheritance construct; 3) defi-nition of a modularity construct; and 4) definition of a metrics framework.
S-Cube, the Software Services and Systems Network (www.s-cube-network.eu) will establish a unified, multidisciplinary, vibrant research community which will enable Europe to lead the software-services revolution.\n\nBy integrating diverse research communities, S-Cube intends to achieve world-wide scientific excellence in a field that is critical for European competitiveness. S-Cube will accomplish its aims by meeting the following objectives:\n- Re-aligning, re-shaping and integrating research agendas of key European players from diverse research areas and by synthesizing and integrating diversified knowledge, thereby establishing a long-lasting foundation for steering research and for achieving innovation at the highest level.\n- Inaugurating a Europe-wide common program of education and training for researchers and industry thereby creating a common culture that will have a profound impact on the future of the field.\n- Establishing a pro-active mobility plan to enable cross-fertilisation and thereby fostering the integration of research communities and the establishment of a common software services research culture.\n- Establishing trust relationships with industry via European Technology Platforms (specifically NESSI) to achieve a catalytic effect in shaping European research, strengthening industrial competitiveness and addressing main societal challenges.\n\nS-Cube will produce an integrated research community of international reputation and acclaim that will help define the future shape of the field of software services. S-Cube will provide service engineering methodologies which facilitate the development, deployment and adjustment of sophisticated hybrid service-based systems. S-Cube will further introduce an advanced training program for researchers and practitioners. Finally, S-Cube intends to bring strategic added value to European industry by using industry best-practice models and by implementing research results into pilot business cases
Cabrera, O.; Oriol, M.; Lopez, L.; Franch, X.; Marco, J.; Fragoso, O.; Santaolaya, R. Jornadas Científico-Técnicas en Servicios Web y SOA Presentation's date: 2009-09-30 Presentation of work at congresses
Los Servicios Web (WS) se han convertido en una tecnología altamente utilizada en el desarrollo de sistemas software. Una de sus
problemáticas más importantes es la selección de los WS más apropiados para
satisfacer los requisitos de dichos sistemas. Si consideramos los requisitos no
funcionales (NFR), la calidad de servicio de los WS contiene la información necesaria para analizar dicha satisfacción. En este artículo se describe el sistema WeSSQoS para la ordenación de WS según su grado de satisfacción de los NFR, calculable a partir de la calidad de servicio de dichos WS, que puede declararse en el WSDL mismo o bien calcularse dinámicamente mediante
monitorización. Esta información acerca de la calidad puede provenir de diversas fuentes (diferentes repositorios WSDL, diferentes monitores, etc.). La arquitectura de WeSSQoS permite la coexistencia de diversos algoritmos de ordenación de los WS, si bien en este artículo nos centramos en uno de ellos que usa la distancia euclidiana como criterio de ordenación.
In this paper, we present HiME, a tool for editing i* models. The distinguishing characteristic of HiME is its ability to deal with inheritance. It includes specific operations for declaring an actor as heir of another and then stating the relationships between the intentional elements of both actors.
Adaptability is a key feature of Service-Oriented-Architecture (SOA) Systems. These systems must evolve themselves in order to ensure their initial requirement as well as to satisfy arising new ones. In SOA Systems there are a lot of dependencies between services, but each service is an independent element of the system. In this situation it is necessary not only ensuring that the system fulfils its requirements but also that every system satisfies its own requirements, and dynamically adapting the system when some of them cannot be ensured. In this paper we propose a SOA system, named Service Level Agreement Monitor (SALMon), for monitoring and adapting SOA Systems at run time. SALMon is based on monitoring the services for detecting Service Level Agreement (SLA) violations. The SALMon architecture is composed of three types of components: Monitors, which are composed of measure instruments themselves; the Analyzer, which checks the SLA rules; and the Decision Maker that performs corrective actions to satisfy SLA rules again. These three types of components are mostly technology-independent and the act as service inside of a SOA system making our architecture very scalable and comfortable for its purpose.
The is-a relationship among actors has been introduced since the very
beginning in the i* framework. However, the effect of this construct
at the level of intentional elements and dependencies is not always completely determined.
In this paper, we explore the semantics of inheritance in i* with focus on SR models. Aligning with its usual meaning in object-orientation, we distinguish 3 main notions to be defined: extension, refinement,
and redefinition. For each of them, we have studied its effects on the different types of intentional elements and their links, and also dependencies, making explicit what can be and cannot be done. We have also analysed the proposal with an example that makes
intensive use of inheritance, a multi-stakeholder distributed system in which different types of related stakeholders co-exist.
Clotet, R.; Dhungana, D.; Franch, X.; Grünbacher, P.; Lopez, L.; Marco, J.; Seyff, N. International Workshop on Variability Modelling of Software-intensive Systems p. 43-52 Presentation's date: 2008-01-16 Presentation of work at congresses
Variability modelling and service-orientation are important
approaches for achieving both the flexibility and
adaptability required by stakeholders of software systems.
In this paper we present an approach that integrates domain
models captured in the i* modelling framework with
variability models to support runtime monitoring and
adaptation of service-oriented systems. We believe that
approaches integrating goal-oriented modelling and
variability management are needed to build, operate, and
evolve such systems. We illustrate our approach using
two scenarios and present a tentative tool architecture
based on an existing product line engineering tool suite.
Clotet, R.; Franch, X.; Lopez, L.; Marco, J.; Seyff, N.; Grünbacher, P. International Workshop on Agent-Oriented Information Systems p. 651-666 Presentation's date: 2007-06-11 Presentation of work at congresses
The is-a relationship among actors has been introduced since the very beginning of i*. However, the effect of this construct at the level of intentional elements and dependencies is not always clear. In this paper, we explore the semantics of inheritance in i*. Aligning with its usual meaning in object-orientation, we distinguish 3 main notions to be defined: extension, refinement, and redefinition. For each of them, we study its effects on the different types of intentional elements and their links, and also dependencies, making explicit what can be and cannot be done. We illustrate the proposal with an example
that makes intensive use of inheritance, a multi-stakeholder distributed system in which different types of related stakeholders co-exist.
Clotet, R.; Franch, X.; Grünbacher, P.; Lopez, L.; Marco, J.; Quintus, M.; Seyff, N. International Conference on Research Challenges in Information Science p. 413-424 Presentation's date: 2007-04-26 Presentation of work at congresses
Multi-Stakeholder Distributed Systems (MSDS) are distributed systems in which subsets of the nodes are designed, owned, or operated by distinct stakeholders. New computing paradigms such as service-oriented computing mean that challenges posed by MSDS will be more dominant in the future. These challenges have particular implications for requirements engineering (RE). For example, in MSDS decisions about the system architecture are increasingly shifted from system design to system operation. In this paper we discuss the characteristics of
MSDS and present a framework for structuring the MSDS research issues. Using an example we illustrate that existing RE approaches for goal modelling, variability modelling, and negotiation techniques can be used successfully if used in an integrated manner to address the identified challenges.
Grünbacher, P.; Dhungana, D.; Seyff, N.; Quintus, M.; Lopez, L.; Franch, X.; Clotet, R.; Marco, J. International Workshop on Software and Service Variability Management Workshop - Concepts, Models, and Tools (SSVM) p. 99-104 Presentation's date: 2007-04-19 Presentation of work at congresses