Towards Management of Complex Service Compositions

Many companies offer physical products combined with on-line services. For example, product configuration, ordering, order tracking, and payments can be done on-line. The service part of the total offering (the composition) is typically composed of services offered by providers where performance of both the composition (provided by the company) and the input services (obtained from providers) is governed by service level agreements (SLAs). The goal of our approach is to diagnose the performance of an on-line service composition in terms of the performance of on-line input services, with respect to the performance indicators mentioned in the SLAs, and to do this in real-time. Classical SLA monitoring techniques are batch-oriented and are not usable in the highly dynamic environment of Web service provision, where provider relations may change even during service delivery. Our techniques use real-time analysis of log files to trace and diagnose performance on-the-fly. Current Web service monitoring techniques do not relate a composite service to its components, as needed to provide diagnostic information. Furthermore, current approaches do not take into account that the dependency of a composition on its components varies for different attributes (such as cost and response time). In this paper we propose to extend our previous research in this area by lifting a number of simplifying assumptions to make the approach applicable in real-life, and by extending our study to frequently used SLAs in practice

Monitoring Dependencies for SLAs: The MoDe4SLA Approach

In service oriented computing different techniques for monitoring Service Level Agreements (SLAs) are available. Many of these monitoring approaches focus on bilateral agreements between partners. However, when monitoring composite services it is not only important to figure out whether SLAs are violated, but we also need to analyze why these violations have occurred. When offering a composite service a company depends on its content providers to meet the service level they agreed upon. Due to these dependencies a company should not only monitor the SLA of the composite service, but also the SLAs of the services it depends on. By analyzing and monitoring the composite service in this way, causes for SLA violations can be easier found. In this paper we demonstrate how to analyze SLAs during development phase and how to monitor these dependencies using event logs during runtime. We call our approach MoDe4SLA (Monitoring Dependencies for SLAs)

Constraint-Flow Nets: A Model for Building Constraints from Resource Dependencies

The major research in the resource management literature focuses primarily on two complementary sub-problems: (1) specification languages for formulating resource requests and (2) constraint problems modelling allocation and scheduling. Both directions assume the knowledge of the underlying platform architecture and the dependencies it induces on the usage of the various resources. In this paper, we bridge this gap by introducing constraint-flow nets (cfNets). A cfNet is defined by a set of resources and dependencies between them, each dependency having an associated constraint schema. The model is inspired by Petri nets, with resources corresponding to places and dependencies—to transitions. Given an architecture of dependent resources, an initial resource request is propagated through the dependencies. The generated constraints are then conjuncted into the global allocation constraint. We study the notion of conflicts in cfNets and prove that for conflict-free cfNets the global allocation constraint can be constructed unambiguously. Furthermore, we provide an SMT-based algorithm for conflict detection and discuss the use of priorities to dynamically resolve conflicts at run-time. Finally, we illustrate the use of cfNets on a case study inspired by the Kalray MPPA architecture

Model of Adaptive System for Continuous Monitoring and Performance Prediction of Distributed Applications

Stalno praćenje rada softvera je neophodno da bi se utvrdilo da li softver poštuje zadate nivoe kvaliteta. Na osnovu sakupljenih podataka, moguće je da se predvidi i dalje ponašanje aplikacije i da se izvrši izbor daljih akcija da bi se održao zahtevani nivo. Tema ove disertacije je razvoj sistema za kontinualno praćenje performansi softvera, kao i razvoj modela za predviđanje performansi softvera. Za implementaciju sistema potrebljena je JEE tehnologija, ali je sistem razvijen tako da može da se primeni i za praćenje softvera razvijenog za druge platforme. Sistem je modelovan tako minimalno utiče na performanse sistema softvera koji se prati. Linearna regresija je upotrebljena za modelovanje zavisnosti performansi od okruženja u kom se softver izvršava. Sistem je upotrebljen za praćenje izabrane JEE aplikacije.Continuous monitoring of software is necessary to determine whether the software performs within required service perfomance levels. Based on collected data, it is possible to predict the future performance of applications and to plan further actions in order to maintain the required service levels. The theme of this dissertation is the development of systems for continuous performance monitoring software, as well as the development of models for predicting the performance of software. To implement the system was used JEE technologies, but the system was developed so that it can be used for tracking software developed for other platforms. The system is modeled as a minimum impact on system performance software that is monitored. Linear regression was used for modeling the dependence of the performance environment in which the software is running. The system was used to monitor selected JEE applications

Automated IT Service Fault Diagnosis Based on Event Correlation Techniques

In the previous years a paradigm shift in the area of IT service management could be witnessed. IT management does not only deal with the network, end systems, or applications anymore, but is more and more concerned with IT services. This is caused by the need of organizations to monitor the efficiency of internal IT departments and to have the possibility to subscribe IT services from external providers. This trend has raised new challenges in the area of IT service management, especially with respect to service level agreements laying down the quality of service to be guaranteed by a service provider. Fault management is also facing new challenges which are related to ensuring the compliance to these service level agreements. For example, a high utilization of network links in the infrastructure can imply a delay increase in the delivery of services with respect to agreed time constraints. Such relationships have to be detected and treated in a service-oriented fault diagnosis which therefore does not deal with faults in a narrow sense, but with service quality degradations. This thesis aims at providing a concept for service fault diagnosis which is an important part of IT service fault management. At first, a motivation of the need of further examinations regarding this issue is given which is based on the analysis of services offered by a large IT service provider. A generalization of the scenario forms the basis for the specification of requirements which are used for a review of related research work and commercial products. Even though some solutions for particular challenges have already been provided, a general approach for service fault diagnosis is still missing. For addressing this issue, a framework is presented in the main part of this thesis using an event correlation component as its central part. Event correlation techniques which have been successfully applied to fault management in the area of network and systems management are adapted and extended accordingly. Guidelines for the application of the framework to a given scenario are provided afterwards. For showing their feasibility in a real world scenario, they are used for both example services referenced earlier

Konzeption einer Service-MIB

In den letzten Jahren ließ sich ein starker Trend hin zum dienstorientierten Management verzeichnen. Betreiber von IT-Diensten gehen verstärkt dazu über, den Betrieb ihrer Infrastrukturen an technischen und organisatorischen Dienstmanagementkonzepten auszurichten und versuchen dadurch, den durch gesteigerte Kundenbedürfnisse und komplexere Diensterbringungsszenarien induzierten Rahmenbedingen zu begegnen. Mit der Einführung neuer Dienstmanagementsysteme wächst allerdings gleichzeitig der Bedarf nach Interoperabilität: Hierbei stellt insbesondere das Vorhandensein einer standardisierten Managementinformationsbasis (MIB) die entscheidende Prämisse für einen anwendungsübergreifenden Austausch bzw. eine Wiederbenutzung von Managementinformationen dar. Um eine Integration des Dienstmanagements zu unterstützen, wird deshalb in dieser Arbeit eine dienstorientierte Informationsbasis (Service-MIB) konzipiert. Die Grundlage dafür bildet eine vierstufige Methodik: Zunächst wird innerhalb der Analysephase der Bedarf an dienstorientierter Managementinformation anhand mehrerer Gesichtspunkte ermittelt und somit der Frage nachgegangen, welche Informationen zur Erfüllung von Dienstmanagementaufgaben effektiv benötigt werden. Daran anschließend widmet sich die Spezifikationsphase der Modellierung und adäquaten Beschreibung von Dienstmanagementinformationen. Hierbei werden die vorab ermittelten Entitäten, Attribute und Beziehungen in objektorientierte Modelle überführt und mit Hilfe einer, in dieser Phase entwickelten, deklarativen Spezifikationssprache \emph{(SISL)} formalisiert. Ein entscheidendes Kriterium für eine Service-MIB stellt ferner ihre Aktualität dar, d.h. in ihr enthaltene Informationen müssen den aktuellen Zustand des Dienstes reflektieren. Dies wird innerhalb der Überwachungsphase durch Einführung einer geeigneten Dienstüberwachung adressiert: Basierend auf SISL-Spezifikationen werden komponentenorientierte Managementinformation mit Hilfe eines Überwachungswerkzeugs (SMONA) aggregiert und zu Dienstmanagementinformationen verdichtet. Abschließend beschäftigt sich die Nutzungsphase mit Möglichkeiten zur Einbettung in bestehende Managementarchitekturen