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

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

SLAs in Virtualized Cloud Computing Infrastructures with QoS Assurance

Cloud Computing is gaining momentum as one of the technologies that promises to subvert our own idea of computing. With an increasing usage of cloud applications and their consequent dependency from connectivity, the nowadays Personal Computer is becoming merely a mobile device acting as a front-end to on-line applications and services. This huge paradigm shift in computing is witnessed for example by big market players who announced the imminent launch of innovative products and Operating Systems (like Chrome notebooks and the accompanying Chrome OS2. by Google), which are capable of projecting the user into the network in a few seconds by booting and starting immediately a web browser and (mostly) nothing else. In such a challenging scenario, more and more of the applications that we traditionally used locally on our PC are being hosted on cloud infrastructures and operated remotely through the Internet. This includes not only batch tasks, but also interactive applications which need to operate inherently with good levels of responsiveness. In this paper, the challenging problem is discussed of how to ensure predictable levels of Quality of Service (QoS) to cloud applications across the multiple layers of a typical cloud infrastructure, and how a reasonable Service Level Agreement (SLA) management and enforcement policy might look like. The scope of this paper represents a hands-on experience that was gained by the authors realising the IRMOS real-time cloud-computing infrastructure in the context of the IRMOS European Project

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

177 σ.Η παρούσα 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 οποίες 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.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.Κλεοπάτρα Γ. Κωνσταντέλ

Probabilistic Admission Control for Elastic Cloud Computing

Abstract—This paper tackles the problem of optimum allocation of elastic services on virtualized physical resources by incorporating a probabilistic approach in terms of availability guarantees, which allows for reducing the physical computational resources that are required for elasticity reasons. The resulting probabilistic optimization problem also allows for proper trade-offs among business level objectives. Its output is the set of the admitted services, as well as the allocated computing capacity for each service component that comprise the services on the selected physical hosts. The problem was modeled on the General Algebraic Modeling System (GAMS) and solved under realistic provider’s settings that demonstrate the efficiency of the proposed method. Keywords-admission control; elasticity; cloud computing; optimum allocation. I

Admission Control for Elastic Cloud Services

Abstract—This paper presents an admission control test for deciding whether or not it is worth to admit a set of services into a Cloud, and in case of acceptance, obtain the optimum allocation for each of the components that comprise the services. In the proposed model, the focus is on hosting elastic services the resource requirements of which may dynamically grow and shrink, depending on the dynamically varying number of users and patterns of requests. In finding the optimum allocation, the presented admission control test uses an optimization model, which incorporates business rules in terms of trust, eco-efficiency and cost, and also takes into account affinity rules the components that comprise the service may have. The problem is modeled on the General Algebraic Modeling System (GAMS) and solved under realistic provider’s settings that demonstrate the efficiency of the proposed method. Index Terms—admission control; elasticity; cloud computing; optimum allocation; I