Dynamic Maintenance of Service Orchestrations

International audienceService-oriented architectures evolved rapidly as the solution to the latest requirements for loosely-coupled distributed computing. Into this broad context several approaches emerged towards the discovery and the systematic composition/orchestration of services. One of the next challenges in this field is the maintenance of service-oriented architectures towards accomplishing the ultimate goal of constructing eternal service-oriented systems out of loosely- coupled basic engineering elements. The particular problem we deal with in this paper is the dynamic maintenance of service orchestrations in the presence of unavailable services. Specifically, we focus on the dynamic substitution of stateful services that become unavailable during the execution of service orchestrations. As an answer to this problem, we propose the SIROCO middleware platform which is further detailed along with an experimental evaluation of our first prototype. Our findings show that SIROCO provides the necessary means for achieving dynamic maintenance with a reasonable expense on the execution of service orchestrations

A reference architecture for multi-level SLA management

There is a global trend towards service-orientation, both for organizing business interactions but also in modern IT architectures. At the business-level, service industries are becoming the dominating sector in which solutions are flexibly composed out of networked services. At the IT level, the paradigms of Service-Oriented Architecture and Cloud Computing realize service-orientation for both software and infrastructure services. Again, flexible composition across different layers is a major advantage of this paradigm. Service Level Agreements (SLA) are a common approach for specifying the exact conditions under which services are to be delivered and, thus, are a prerequisite for supporting the flexible trading of services. However, typical SLAs are just specified at a single layer and do not allow service providers to manage their service stack accordingly. They have no insight on how SLAs at one layer translate to metrics or parameters at the various lower layers of the service stack. In this paper, we present a reference architecture for a multi-level SLA management framework. We discuss the fundamental concepts and detail the main architectural components and interfaces. Furthermore, we show how the framework can be flexibly used for different industrial scenarios

Dependable distributed OSGi environment

As the concept of Service Oriented Computing matures the need for well defined architectures and protocols to address this trend is essential if IT is going to properly embrace SOC. The SOC paradigm has several requirements to work properly such as service composition and cooperation in a loosely coupled fashion, ability to adapt autonomously to environmental and business changes and address concerns such as modularity, dynamicity and proper integration between services. The popularization of the OSGi platform its another effort towards the SOC paradigm by issuing key aspects such as modularity and dynamicity in its service oriented design. However there is much room for improvement namely on the creation of architectures and mechanisms to improve the dependability of the overall solution by strengthening key properties such as the availability, reliability, integrity, safety and maintainability of the platform. In this work we propose a middleware layer that offers the strong modular and dynamic properties required in an SOC environment by relying on OSGi while addressing dependability concerns. The starting point to achieve this is by instrumenting an OSGi implementation and providing means to monitor and manage it accordingly to business and environmental requirements. By relying on group communication facilities and some properties from the OSGi specification we are able to migrate OSGi environments between nodes thus minimizing service delivery disruption in the presence of faults and addressing, at the same time SLA properties by migrating (or shutting down) services that are consuming more resources than agreed/expected.(undefined

Microservice Transition and its Granularity Problem: A Systematic Mapping Study

Microservices have gained wide recognition and acceptance in software industries as an emerging architectural style for autonomic, scalable, and more reliable computing. The transition to microservices has been highly motivated by the need for better alignment of technical design decisions with improving value potentials of architectures. Despite microservices' popularity, research still lacks disciplined understanding of transition and consensus on the principles and activities underlying "micro-ing" architectures. In this paper, we report on a systematic mapping study that consolidates various views, approaches and activities that commonly assist in the transition to microservices. The study aims to provide a better understanding of the transition; it also contributes a working definition of the transition and technical activities underlying it. We term the transition and technical activities leading to microservice architectures as microservitization. We then shed light on a fundamental problem of microservitization: microservice granularity and reasoning about its adaptation as first-class entities. This study reviews state-of-the-art and -practice related to reasoning about microservice granularity; it reviews modelling approaches, aspects considered, guidelines and processes used to reason about microservice granularity. This study identifies opportunities for future research and development related to reasoning about microservice granularity.Comment: 36 pages including references, 6 figures, and 3 table

Exploring Maintainability Assurance Research for Service- and Microservice-Based Systems: Directions and Differences

To ensure sustainable software maintenance and evolution, a diverse set of activities and concepts like metrics, change impact analysis, or antipattern detection can be used. Special maintainability assurance techniques have been proposed for service- and microservice-based systems, but it is difficult to get a comprehensive overview of this publication landscape. We therefore conducted a systematic literature review (SLR) to collect and categorize maintainability assurance approaches for service-oriented architecture (SOA) and microservices. Our search strategy led to the selection of 223 primary studies from 2007 to 2018 which we categorized with a threefold taxonomy: a) architectural (SOA, microservices, both), b) methodical (method or contribution of the study), and c) thematic (maintainability assurance subfield). We discuss the distribution among these categories and present different research directions as well as exemplary studies per thematic category. The primary finding of our SLR is that, while very few approaches have been suggested for microservices so far (24 of 223, ?11%), we identified several thematic categories where existing SOA techniques could be adapted for the maintainability assurance of microservices

Quality-aware model-driven service engineering

Service engineering and service-oriented architecture as an integration and platform technology is a recent approach to software systems integration. Quality aspects ranging from interoperability to maintainability to performance are of central importance for the integration of heterogeneous, distributed service-based systems. Architecture models can substantially influence quality attributes of the implemented software systems. Besides the benefits of explicit architectures on maintainability and reuse, architectural constraints such as styles, reference architectures and architectural patterns can influence observable software properties such as performance. Empirical performance evaluation is a process of measuring and evaluating the performance of implemented software. We present an approach for addressing the quality of services and service-based systems at the model-level in the context of model-driven service engineering. The focus on architecture-level models is a consequence of the black-box character of services

Management and Service-aware Networking Architectures (MANA) for Future Internet Position Paper: System Functions, Capabilities and Requirements

Future Internet (FI) research and development threads have recently been gaining momentum all over the world and as such the international race to create a new generation Internet is in full swing: GENI, Asia Future Internet, Future Internet Forum Korea, European Union Future Internet Assembly (FIA). This is a position paper identifying the research orientation with a time horizon of 10 years, together with the key challenges for the capabilities in the Management and Service-aware Networking Architectures (MANA) part of the Future Internet (FI) allowing for parallel and federated Internet(s)