Felipe Pinto

Selecting Architecture Configurations in Self- Adaptive Systems Using QoS Criteria

The process for choosing the best architectural elements to build systems has become increasingly complex. It becomes more critical if it is necessary to consider many combinations of components in the context of an architectural configuration. This paper proposes an approach for the dynamic selection of architectural configurations based on quality of system criteria of the system, which can be used during a dynamic adaptation, the MoSAC. This module uses the MAUT theory (Multi-Attribute Utility Theory) for decision making from a finite set of possibilities, which involve multiple criteria to be analyzed. We also present a case study that is an application in the context of Iterative Digital TV to evaluate the time spent on the module to return a valid configuration to be used in a middleware with self-adaptive features, the middleware FRAME.

Definition of a Component Selection Process Based on QoS Criteria and Its Application to Self-adaptive Software Systems

Nowadays, self-adaptive systems use the concept of feedback loops. This approach is based on the selection of components that conform to the expected requirements. The selection became increasingly complex in such systems due to the variety of criteria. This paper proposes a process for dynamic selection of components using multi-attribute utility theory based on Quality of Service (QoS) criteria. Furthermore, it defines a model that can be used to represent the current needs of an application, and that is used by the proposed selection process for evaluating the candidate components. As a proof of concept, its presented the AnaMoC module that performs the selection of components based on the proposed process.

Estabelecimento de critérios para adaptaçao dinâmica de QoS em sistemas multimídia distribuídos com base em testes experimentais realizados no framework cosmos

Applications in distributed multimedia systems need to manage the levels of quality of services in environments that have wide variations of operation properties. So, most of the recent researches are directed towards the establishment of criteria that lead higher quality of services levels. For this, they consider the availability of resources in the current execution context. In this direction, this work has been focused on criteria definitions that can subside decision-making processes which are related to dynamic evaluation and selection of properties and components. The intention is to keep the system operating in a consistent way by considering the established levels of quality. For this, the work considers the several experimental tests that have been conducted in a Cosmos framework based environment, where were analyzed different requirements such as loading and platform requirements.

Conditional execution: a pattern for the implementation of fine-grained variabilities in software product lines

This paper presents the Conditional Execution design pattern that aims to help the implementation of fine-grained variabilities in the context of software product lines of information systems. The pattern has been used successfully in three product lines of web information systems developed by Informatics Superintendence (SINFO) at Federal University of Rio Grande do Norte.

Modularization of variabilities from software product lines of web information systems (in Portuguese)

This paper presents an industrial experience of design pattern application for the modularization of variabilities from software product lines of web information systems. These web systems were developed at the Superintendência de Informática (SINFO) from Federal University of Rio Grande do Norte (UFRN). The work describes details about the adoption and composition of traditional design patterns to the modularization of variabilities (optional, alternative and or-feature) that are usually used in web information systems. Furthermore, it also reports some usage scenarios of the conditional execution annotative technique in the implementation of fine-grained variabilities, which are not adequately implemented using traditional design patterns.

A Model for the Transmission of Multimedia Data Flow Based on the Use of Shared Memory Mechanism

The communication between multimedia components located on the same physical machine, but in different address space, uses mechanisms designed for distributed environments. The present paper proposes an inter-component communication model in this context through the use of a shared memory mechanism. This model is based on the shared memory primitives offered by different operating systems. The model can be used in different middleware platforms. To evaluate the model, an application written in Java was developed, that, through functions written in C language, has access to the primitives of manipulation of the shared address space.

Automating the performance deviation analysis for multiple system releases: An evolutionary study

This paper presents a scenario-based approach for the evaluation of the quality attribute of performance, measured in terms of execution time (response time). The approach is implemented by a framework that uses dynamic analysis and repository mining techniques to provide an automated way for revealing potential sources of performance degradation of scenarios between releases of a software system. The approach defines four phases: (i) preparation - choosing the scenarios and preparing the target releases; (ii) dynamic analysis - determining the performance of scenarios and methods by calculating their execution time; (iii) degradation analysis - processing and comparing the results of the dynamic analysis for different releases; and (iv) repository mining - identifying development issues and commits associated with performance deviation. The paper also describes an evolutionary study of applying the approach to multiple releases of the Netty, Wicket and Jetty frameworks. The study analyzed seven releases of each system and addressed a total of 57 scenarios. Overall, we have found 14 scenarios with significant performance deviation for Netty, 13 for Wicket, and 9 for Jetty, almost all of which could be attributed to a source code change. We also discuss feedback obtained from eight developers of Netty, Wicket and Jetty as result of a questionnaire.

A Metadata-based Framework for Quality Attribute Degradation Analysis in Web Systems

This paper presents a metadata-based framework for software architecture evaluation of quality attributes. It implements a scenario-based approach that uses dynamic analysis and code repository mining to provide an automated way to reveal degradations of scenarios on releases of web-based systems. The evaluation process has three phases: (i) dynamic analysis that collects information of scenarios in terms of measurable quality attributes; (ii) degradation analysis that processes and compares the results of the dynamic analysis in term of quality attributes for two or more existing releases of a web-based system to identify degraded scenarios considering the desired quality attributes; (iii) repository mining that looks for development issues and commits associated to code assets of the degraded scenarios. The paper also presents and discusses the obtained results of the framework instantiation for the library module of a large-scale web system.

An Automated Architectural Evaluation Approach Based on Metadata and Code Analysis

Traditional methods of scenario-based software architecture evaluation rely on manual review and advanced skills from architects and developers. They are used when the system architecture has been specified, but before its implementation has begun. When the system implementation evolves, code analysis can enable the automation of this process and the reuse of architectural information. We propose an approach that introduces metadata about use case scenarios and quality attributes in the source code of the system in order to support automated architectural evaluation through of static and dynamic code analysis and produce reports about scenarios, quality attributes, code assets, and potential tradeoff points among quality attributes. Our work also describes the implementation of a code analysis tool that provides support to the approach. In addition, the paper also presents the preliminary results of its application for the architectural analysis of an enterprise web system and an e-commerce web system.

Automated architectural evaluation of web information systems

Traditional scenario-based architectural analysis methods rely on manual review-based evaluation that requires advanced skills from architects and developers. They are usually applied when the architecture is under development, but before its implementation has begun. The system implementation is one additional and fundamental element that should be used and considered during the software architecture evaluation. In this paper, we propose an approach to add information, which ideally should come from traditional evaluation methods, about scenarios and quality attributes to the source code of web-based systems using metadata. The main aim is to enable the automatic architecture analysis by producing a report with information about scenarios, quality attributes and source code assets, such as: (i) the potential tradeoff points among quality attributes, (ii) the execution time for scenarios and if it has failed or not. Up to now, the approach has been applied mainly to web-based systems, but it can be adapted to other software domains. The paper also presents the tool used to perform static and dynamic analysis, and the results of its application to an e-commerce web system and an enterprise information web system.