Advance Reservations for Distributed Real-Time Workflows with Probabilistic Service Guarantees

This paper addresses the problem of optimum allocation of distributed real-time workflows with probabilistic service guarantees over a Grid of physical resources made available by a provider. The discussion focuses on how such a problem may be mathematically formalised, both in terms of constraints and objective function to be optimized, which also accounts for possible business rules for regulating the deployment of the workflows. The presented formal problem constitutes a probabilistic admission control test that may be run by a provider in order to decide whether or not it is worth to admit new workflows into the system, and to decide what the optimum allocation of the workflow to the available resources is. Various options are presented which may be plugged into the formal problem description, depending on the specific needs of individual workflows

Optimum Allocation of Distributed Service Workflows with Probabilistic Real-Time Guarantees

This paper addresses the problem of optimum allocation of distributed real-time workflows with probabilistic service guarantees over a set of physical resources. The discussion focuses on how such a problem may be mathematically formalized, in terms of both constraints and objective function to be optimized, which also accounts for possible business rules for regulating the deployment of the workflows. The presented formal problem constitutes a probabilistic admission control test that may be run by a provider in order to decide whether or not it is worth to admit new workflows into the system and to decide what the optimum allocation of the workflow to the available resources is. Various options are presented, which may be plugged into the formal problem description, depending on the specific needs of individual workflows. The presented problem has been implemented using GAMS and has been tested under various solvers. An illustrative numerical example and an analysis of the results of the implemented model under realistic settings are presented

Elastic admission control for federated cloud services

This paper presents a technique for admission control of a set of horizontally scalable services, and their optimal placement, into a federated Cloud environment. In the proposed model, the focus is on hosting elastic services whose resource requirements may dynamically grow and shrink, depending on the dynamically varying number of users and patterns of requests. The request may also be partially accommodated in federated external providers, if needed or more convenient. In finding the optimum allocation, the presented mechanism uses a probabilistic optimization model, which takes into account eco-efficiency and cost, as well as affinity and anti-affinity rules possibly in place for the components that comprise the services. In addition to modelling and solving the exact optimization problem, we also introduce a heuristic solver that exhibits a reduced complexity and solving time. We show evaluation results for the proposed technique under various scenarios

Software modernization and cloudification using the ARTIST migration methodology and framework

International audienceCloud computing has leveraged new software development and provisioning approaches by changing the way computing, storage and networking resources are purchased and consumed. The variety of cloud offerings on both technical and business level has considerably advanced the development process and established new business models and value chains for applications and services. However, the modernization and cloudification of legacy software so as to be offered as a service still encounters many challenges. In this work, we present a complete methodology and a methodology instantiation framework for the effective migration of legacy software to modern cloud environments

Resilience Analysis of Service Oriented Collaboration Process Management systems

Collaborative business process management allows for the automated coordination of processes involving human and computer actors. In modern economies it is increasingly needed for this coordination to be not only within organizations but also to cross organizational boundaries. The dependence on the performance of other organizations should however be limited, and the control over the own processes is required from a competitiveness perspective. The main objective of this work is to propose an evaluation model for measuring a resilience of a Service Oriented Architecture (SOA) collaborative process management system. In this paper, we have proposed resilience analysis perspectives of SOA collaborative process systems, i.e. overall system perspective, individual process model perspective, individual process instance perspective, service perspective, and resource perspective. A collaborative incident and maintenance notification process system is reviewed for illustrating our resilience analysis. This research contributes to extend SOA collaborative business process management systems with resilience support, not only looking at quantification and identification of resilience factors, but also considering ways of improving the resilience of SOA collaborative process systems through measures at design and run-time

Optimum allocation of real-time workflows with probabilistic service level guarantees

This thesis addresses the problem of optimum allocation of distributed real-time workflows with probabilistic service guarantees over a set of physical resources. The discussion focuses on how such a problem may be mathematically formalized, in terms of both constraints and objective function to be optimized, which also accounts for possible business rules for regulating the deployment of the workflows.The presented formal problem constitutes a probabilistic admission control test that may be run by a provider in order to decide whether or not it is worth to admit new workflows into the system and in case of acceptance to decide what the optimum allocation of the workflows to the available resources is.Various options are presented, which may be plugged into the formal problem description, depending on the specific needs of individual workflows. The presented problem has been implemented using GAMS (General Algebraic Modeling System) and has been tested under various solvers. An illustrative numerical example and an analysis of the results of the implemented GAMS models under realistic settings are presented that validate the correctness and the usefulness of the presented stochastic admission control and optimum allocation model.Η διατριβή αντιμετωπίζει το πρόβλημα της βέλτιστης κατανομής ροών εργασίας πραγματικού χρόνου σε ένα σύνολο από φυσικούς πόρους, υπό πιθανοτικές εγγυήσεις. Η μελέτη εστιάζει στην μαθηματική μοντελοποίηση του εν λόγω προβλήματος αναφορικά με τους περιορισμούς και την αντικειμενική συνάρτηση προς βελτιστοποίηση, η οποία εμπεριέχει επιχειρηματικούς κανόνες σχετικά με την τοποθέτηση των ροών εργασίας.Η επίσημη μορφή του προβλήματος που παρουσιάζεται αποτελεί έναν πιθανοτικό έλεγχο εισδοχής (admission control), τον οποίο μπορεί να πραγματοποιήσει ο πάροχος των πόρων προκειμένου να αποφασίσει το αν αξίζει ή όχι να αποδεχτεί τις νέες εφαρμογές στο υποκείμενο σύστημα που διαθέτει, και επιπλέον στην περίπτωση που αυτές γίνονται δέκτες, να κατανείμει τις εργασίες από τις όποιες αποτελούνται οι εφαρμογές κατά βέλτιστο τρόπο στους υποκείμενους φυσικούς πόρους. Επιπλέον, παρουσιάζονται διαφοροποιήσεις του επίσημου προβλήματος, ανάλογα με τις συγκεκριμένες ανάγκες των ροών εργασίας.Το γενικό πρόβλημα που παρουσιάζεται μοντελοποιήθηκε κάνοντας χρήση του συστήματος GAMS (General Algebraic Modeling System) και συνδυάστηκε με διάφορες μεθόδους επίλυσης. Επίσης, παρέχεται ένα επεξηγηματικό αριθμητικό παράδειγμα καθώς και εκτενής ανάλυση των αποτελεσμάτων των μοντέλων βελτιστοποίησης κάτω από ρεαλιστικές συνθήκες, τα οποία επικυρώνουν την ορθότητα και την χρησιμότητα του προτεινόμενου στοχαστικού μοντέλου ελέγχου εισδοχής και βέλτιστης κατανομής

Optimum allocation of real-time workflows with probabilistic service level guarantees

This thesis addresses the problem of optimum allocation of distributed real-time workflows with probabilistic service guarantees over a set of physical resources. The discussion focuses on how such a problem may be mathematically formalized, in terms of both constraints and objective function to be optimized, which also accounts for possible business rules for regulating the deployment of the workflows.The presented formal problem constitutes a probabilistic admission control test that may be run by a provider in order to decide whether or not it is worth to admit new workflows into the system and in case of acceptance to decide what the optimum allocation of the workflows to the available resources is.Various options are presented, which may be plugged into the formal problem description, depending on the specific needs of individual workflows. The presented problem has been implemented using GAMS (General Algebraic Modeling System) and has been tested under various solvers. An illustrative numerical example and an analysis of the results of the implemented GAMS models under realistic settings are presented that validate the correctness and the usefulness of the presented stochastic admission control and optimum allocation model.Η διατριβή αντιμετωπίζει το πρόβλημα της βέλτιστης κατανομής ροών εργασίας πραγματικού χρόνου σε ένα σύνολο από φυσικούς πόρους, υπό πιθανοτικές εγγυήσεις. Η μελέτη εστιάζει στην μαθηματική μοντελοποίηση του εν λόγω προβλήματος αναφορικά με τους περιορισμούς και την αντικειμενική συνάρτηση προς βελτιστοποίηση, η οποία εμπεριέχει επιχειρηματικούς κανόνες σχετικά με την τοποθέτηση των ροών εργασίας.Η επίσημη μορφή του προβλήματος που παρουσιάζεται αποτελεί έναν πιθανοτικό έλεγχο εισδοχής (admission control), τον οποίο μπορεί να πραγματοποιήσει ο πάροχος των πόρων προκειμένου να αποφασίσει το αν αξίζει ή όχι να αποδεχτεί τις νέες εφαρμογές στο υποκείμενο σύστημα που διαθέτει, και επιπλέον στην περίπτωση που αυτές γίνονται δέκτες, να κατανείμει τις εργασίες από τις όποιες αποτελούνται οι εφαρμογές κατά βέλτιστο τρόπο στους υποκείμενους φυσικούς πόρους. Επιπλέον, παρουσιάζονται διαφοροποιήσεις του επίσημου προβλήματος, ανάλογα με τις συγκεκριμένες ανάγκες των ροών εργασίας.Το γενικό πρόβλημα που παρουσιάζεται μοντελοποιήθηκε κάνοντας χρήση του συστήματος GAMS (General Algebraic Modeling System) και συνδυάστηκε με διάφορες μεθόδους επίλυσης. Επίσης, παρέχεται ένα επεξηγηματικό αριθμητικό παράδειγμα καθώς και εκτενής ανάλυση των αποτελεσμάτων των μοντέλων βελτιστοποίησης κάτω από ρεαλιστικές συνθήκες, τα οποία επικυρώνουν την ορθότητα και την χρησιμότητα του προτεινόμενου στοχαστικού μοντέλου ελέγχου εισδοχής και βέλτιστης κατανομής

D5.1.1 Models of Real-time Applications on Service Oriented Infrastructures

The IRMOS project is developing tools and techniques for modelling, simulating, analysing, and planning real-time applications on service oriented infrastructures. These tools and techniques support the processes involved in designing, developing, deploying and executing applications where guaranteed QoS is needed. The report considers the value-chain for real-time applications hosted by third-party service providers. In the context of this value chain, we analyse who might benefit from the use of models, how and why these models might be used, and when during the application lifecycle modelling is most useful. Techniques are presented for building models of real-time applications including the use of stochastic process algebras, finite state automata, workflow models (e.g. BPEL, BPMN and YAWL) and specification languages (e.g. UML MARTE). The report discusses how these models need to be supported by estimation of application resource consumption, e.g. through benchmarking and fitting, and how mapping techniques allow models to be built for different actors in the value chain, e.g. for application providers and infrastructure providers. Tool support is also discussed e.g. PRISM for probabilistic model checking and Visual Service Composition Studio for service-oriented modelling. A detailed and specific real-time application scenario is included and modelled to allow the various techniques presented in this document to be demonstrated and quantitatively evaluated. The scenario also reveals the level of detail needed in order for meaningful modelling to be achieved in practice. The modelling scenario has been carefully engineered to be as representative as possible of the broad range of application characteristics encountered in the three reference IRMOS applications (film postproduction, eLearning, virtual and augmented reality). The modelling techniques discussed and then demonstrated in this report include identifying what resources are necessary to support an application, when those resources will be required during the application workflow, what performance is needed from them (i.e. QoS) and what will happen to the application if the required performance is not delivered. All of these are essential when developing and then agreeing service level agreements between the various entities in a service oriented infrastructure