Abstract-Architecting software systems according to the serviceoriented paradigm, and designing runtime self-adaptable systems are two relevant research areas in today's software engineering. In this paper we address issues that lie at the intersection of these two important fields. First, we present a characterization of the problem space of self-adaptation for service-oriented systems, thus providing a frame of reference where our and other approaches can be classified. Then, we present MOSES, a methodology and a software tool implementing it to support QoS-driven adaptation of a service-oriented system. It works in a specific region of the identified problem space, corresponding to the scenario where a service-oriented system architected as a composite service needs to sustain a traffic of requests generated by several users. MOSES integrates within a unified framework different adaptation mechanisms. In this way it achieves a greater flexibility in facing various operating environments and the possibly conflicting QoS requirements of several concurrent users. Experimental results obtained with a prototype implementation of MOSES show the effectiveness of the proposed approach.Index Terms-Service-oriented architecture, runtime adaptation, quality of service.

SummaryContainerization is a lightweight virtualization technology enabling the deployment and execution of distributed applications on cloud, edge/fog, and Internet‐of‐Things platforms. Container technologies are evolving at the speed of light, and there are many open research challenges. In this paper, an extensive literature review is presented that identifies the challenges related to the adoption of container technologies in High Performance Computing, Big Data analytics, and geo‐distributed (Edge, Fog, Internet‐of‐Things) applications. From our study, it emerges that performance, orchestration, and cyber‐security are the main issues. For each challenge, the state‐of‐the‐art solutions are then analyzed. Performance is related to the assessment of the performance footprint of containers and comparison with the footprint of virtual machines and bare metal deployments, the monitoring, the performance prediction, the I/O throughput improvement. Orchestration is related to the selection, the deployment, and the dynamic control of the configuration of multi‐container packaged applications on distributed platforms. The focus of this work is on run‐time adaptation. Cyber‐security is about container isolation, confidentiality of containerized data, and network security. From the analysis of 97 papers, it came out that the state‐of‐the‐art is more mature in the area of performance evaluation and run‐time adaptation rather than in security solutions. However, the main unsolved challenges are I/O throughput optimization, performance prediction, multilayer monitoring, isolation, and data confidentiality (at rest and in transit).

Abstract-One of the major current trends in serviceoriented systems is the emphasis given to the need of introducing runtime adaptation features, so that the system can meet its QoS requirements in a volatile operating environment. In this paper we present the design and implementation of a service broker that supports the QoS-driven runtime adaptation of SOA applications offered as composite services to users. We describe the functionalities provided by the broker components and present their design and implementation according to two different versions we have developed and that are both based on open source products. The components of the first version have been developed in Java as Web services, while the second version takes advantage of OpenESB. Since the broker needs to sustain a traffic of requests generated by several concurrent users, we also present the replicated architectures of the two broker versions. We discuss the design tradeoffs and the lesson we have learned in developing the broker.