Nelson Lago

Monitoring service choreographies from multiple sources

Modern software applications are more and more conceived as distributed service compositions deployed over Grid and Cloud technologies. Choreographies provide abstract specifications of such compositions, by modeling message-based multi-party interactions without assuming any central coordination. To enable the management and dynamic adaptation of choreographies, it is essential to keep track of events and exchanged messages and to monitor the status of the underlying platform, and combine these different levels of information into complex events meaningful at the application level. Towards this goal, we propose a Multi-source Monitoring Framework that we are developing within the EU Project CHOReOS, which can correlate the messages passed at business-service level with observations relative to the infrastructure resources. We present the monitor architecture and illustrate it on a use-case excerpted from the CHOReOS project.

A middleware for reflective web service choreographies on the cloud

Web service composition is a commonly used solution to build distributed systems on the cloud. Choreographies are one specific kind of service composition in which the responsibilities for the execution of the system are shared by its service components without a central point of coordination. Due to the distributed nature of these systems, a manual approach to resource usage monitoring and allocation to maintain the expected Quality of Service (QoS) is not only inefficient but also does not scale. In this paper, we present an open source choreography enactment middleware that is capable of automatically deploying and executing a composition. Additionally, it also monitors the composition execution to perform automatic resource provisioning and dynamic service reconfiguration based on pre-defined Service Level Agreement (SLA) constraints. To achieve that, it keeps a meta-level representation of the compositions, which contains their specifications, deployment statuses, and QoS attributes. Application developers can write specific rules that take into account these meta-data to reason about the performance of the composition and change its behavior. Our middleware was evaluated on Amazon EC2 and our results demonstrate that, with little effort from the choreography developer or deployer, the middleware is able to maintain the established SLA using both horizontal and vertical scaling when faced with varying levels of load. Additionally, it also reduces operational costs by using as little computational resources as possible.

Free and Open Source Software Development and Research: Opportunities for Software Engineering

Free/Libre/Open Source Software (FLOSS) communities have produced a large amount of valuable software that is directly or indirectly used daily by any person with access to a computer. The field of Software Engineering studies processes, mechanisms, tools, and frameworks for the development of software artifacts. Historically, however, most of Software Engineering research and education does not benefit from the large and rich source of data and experimental testbeds offered by FLOSS projects and their hundreds of millions of lines of working code. In this paper, we discuss how Software Engineering research and education can greatly benefit from the wealth of information available in the FLOSS ecosystem. We then evaluate how FLOSS has been used, up to now, by papers published in the Brazilian Symposium on Software Engineering. Finally, we present an agenda for the future, proposing concrete ways to exploit the synergies between research and education in Software Engineering and FLOSS projects.

Towards an Enactment Engine for Dynamically Reconfigurable and Scalable Choreographies

Service compositions have recently been in the spotlight. Although they are not something new, as the complexity of service based systems grows, we observe an ever increasing interest in these approaches. Choreographies are one specific kind of service composition in which the responsibilities for the execution of the system are shared by its service components without any central point of coordination. Choreography clients expect a minimum level of Quality of Services (QoS), however, due to the distributed nature of these systems, a manual approach to resource usage monitoring and allocation is not only inefficient but also does not scale. In this paper we present an open source choreography enactment engine that is capable of automatically deploying and executing a given composition. Additionally, it also monitors a composition execution to perform automatic resource provisioning and dynamic service reconfiguration based on pre-defined Service Level Agreements (SLA) constraints. We evaluated our system on Amazon EC2 and preliminary results demonstrate that it is able maintain the QoS of a composition, even when faced with varying levels of load, while at the same time reducing costs by using as little computational resources as possible.

Ranking Source Code Static Analysis Warnings for Continuous Monitoring of FLOSS Repositories

Performing source code static analysis during the software development cycle is a difficult task. There are different static analyzers available, and each of them usually works better in a small subset of problems, making it hard to choose a single tool. Combining the analysis of different tools solves this problem, but brings about other problems, namely the generated false positives and a large amount of unsorted alarms. This paper presents kiskadee, a system to support the usage of static analysis during software development by providing carefully ranked static analysis reports. First, it runs multiple static analyzers on the source code. Then, using a classification model, the potential bugs detected by the static analyzers are ranked based on their importance, with critical flaws ranked first, and potential false positives ranked last. Our experimental results show that, on average, when inspecting warnings ranked by kiskadee, one hits 5.2 times less false positives before each bug than when using a randomly sorted warning list.

InterSCSimulator: Large-Scale Traffic Simulation in Smart Cities Using Erlang

Large cities around the world face numerous challenges to guarantee the quality of life of its citizens. A promising approach to cope with these problems is the concept of Smart Cities, of which the main idea is the use of Information and Communication Technologies to improve city services. Being able to simulate the execution of Smart Cities scenarios would be extremely beneficial for the advancement of the field. Such a simulator, like many others, would need to represent a large number of various agents (e.g. cars, hospitals, and gas pipelines). One possible approach for doing this in a computer system is to use the actor model as a programming paradigm so that each agent corresponds to an actor. The Erlang programming language is based on the actor model and is the most commonly used implementation of it. In this paper, we present the first version of InterSCSimulator, an open-source, extensible, large-scale Traffic Simulator for Smart Cities developed in Erlang, capable of simulating millions of agents using a real map of a large city. Future versions will be extended to address other Smart City domains.

InterSCity: A Scalable Microservice-based Open Source Platform for Smart Cities.

Smart City technologies emerge as a potential solution to tackle common problems in large urban centers by using city resources efficiently and providing quality services for citizens. Despite the various advances in middleware technologies to support future smart cities, there are no universally accepted platforms yet. Most of the existing solutions do not provide the required flexibility to be shared across cities. Moreover, the extensive use and development of non-open-source software leads to interoperability issues and limits the collaboration among R&D groups. In this paper, we explore the use of a microservices architecture to address key practical challenges in smart city platforms. We present InterSCity, a microservice-based open source smart city platform that aims at supporting collaborative, novel smart city research, development, and deployment initiatives. We discuss how the microservice approach enables a flexible, extensible, and loosely coupled architecture and present experimental results demonstrating the scalability of the proposed platform.

A Network of FLOSS Competence Centres

The goal of a Network of Competence Centers is to provide to FLOSS users, developers, and consumers, high-quality resources and expertise on the various topics related to FLOSS. This may be achieved via education, training, consulting, hosting, and certification not only in terms of tools and platforms but also methodologies, studies, and best practices. Based on the experience of QualiPSo Competence Centres, we observe how such a Network is working as a mechanism for sharing success stories, failures, questions, recommendations, best practices, and any kind of information that could help the establishment of a solid international collaborative environment for supporting quality in FLOSS. New Competence Centres are invited to the QualiPSo Network after their proposals are evaluated by the QualiPSo Competence Centres Board to ensure that the prospective Competence Centre is compliant with the QualiPSo Network Agreement, sharing a common vision and ethics. Each Competence Centre acts in its geographical region to increase the awareness of FLOSS and to better prepare the IT workforce for developing and using FLOSS based solutions. As of 2009, the process for Competence Centre creation is sustainable and reusable; guidelines for establishing proposals and opening new Competence Centres have been created, and promotion of Qualipso Competence Centres is done world wide from India to USA thanks to key initiatives such as the Open World Forum and the FLOSS Competence Centre Summit. This lecture will expose how these Competence Centres relate to each other, which governance model is used and, based on existing experiences, will describe how they currently operate in Europe and Brazil and what is planned in Italy, Belgium, Japan, and China for 2010.