A Comparison between EJB and COM+ Business Components, Case Study: Response Time and Scalability

Most distributed system architectures are designed as a three-tier systems consisting of a thin-client, middleware and a database. The overall performance of such systems depends on the performance of each tier individually and the overhead incurred by the collaboration between these three tiers. Nowadays, the two most popular middleware systems are: Microsoft’s .NET platform and Sun’s Java 2 Enterprise Edition (J2EE) platform. In J2EE, the middle tier infrastructure is called Enterprise JavaBeans (EJB) and in the .NET framework, it is called Component-Oriented Middle-Tier (COM+). Usually, the middle tier provides the business logic (any code that is not specifically related to storing and retrieving data, or formatting data for display to the user) and the performance of this tier is crucial to the overall performance of the distributed system

Measurements based performance analysis of Web services

Web services are increasingly used to enable interoperability and flexible integration of software systems. In this thesis we focus on measurement-based performance analysis of an e-commerce application which uses Web services components to execute business operations. In our experiments we use a session-oriented workload generated by a tool developed accordingly to TPC-W specification. The empirical results are obtained for two different user profiles, Browsing and Ordering, under different workload intensities. In addition to variation in workloads we also study the applications performance when Web services are implemented using .NET and J2EE. Unlike the previous work which was focused on the overall server response time and throughput, we present Web interaction, software architecture, and hardware resource level analysis of the system performance. In particular, we propose a method for extracting component level response times from the application server logs and study the impact of Web services and other components on the server performance. The results show that the response times of Web services components increase significantly under higher workload intensities when compared to other components. (Abstract shortened by UMI.)

Automated extraction of palladio component models from running enterprise Java applications

Nowadays, software systems have to fulfill increasingly strin-gent requirements for performance and scalability. To ensure that a system meets its performance requirements during op-eration, the ability to predict its performance under different configurations and workloads is essential. Most performance analysis tools currently used in industry focus on monitoring the current system state. They provide low-level monitoring data without any performance prediction capabilities. For performance prediction, performance models are normally required. However, building predictive performance models manually requires a lot of time and effort. In this paper, we present a method for automated extraction of perfor-mance models of Java EE applications, based on monitor-ing data collected during operation. We extract instances of the Palladio Component Model (PCM)- a performance meta-model targeted at component-based systems. We eval-uate the model extraction method in the context of a case study with a real-world enterprise application. Even though the extraction requires some manual intervention, the case study demonstrates that the existing gap between low-level monitoring data and high-level performance models can be closed. 1

Model-Driven System Capacity Planning under Workload Burstiness

In this paper, we define and study a new class of capacity planning models called MAP queueing networks. MAP queueing networks provide the first analytical methodology to describe and predict accurately the performance of complex systems operating under bursty workloads, such as multi-tier architectures or storage arrays. Burstiness is a feature that significantly degrades system performance and that cannot be captured explicitly by existing capacity planning models. MAP queueing networks address this limitation by describing computer systems as closed networks of servers whose service times are Markovian Arrival Processes (MAPs), a class of Markov-modulated point processes that can model general distributions and burstiness. In this paper, we show that MAP queueing networks provide reliable performance predictions even if the service processes are bursty. We propose a methodology to solve MAP queueing networks by two state space transformations, which we call Linear Reduction (LR) and Quadratic Reduction (QR). These transformations dramatically decrease the number of states in the underlying Markov chain of the queueing network model. From these reduced state spaces, we obtain two classes of bounds on arbitrary performance indexes, e.g., throughput, response time, utilizations. Numerical experiments show that LR an QR bounds achieve good accuracy. We also illustrate the high effectiveness of the LR and QR bounds in the performance analysis of a real multi-tier architecture subject to TPC-W workloads that are characterized as bursty. These results promote MAP queueing networks as a new robust class of capacity planning models

CoMoM: Efficient Class-Oriented Evaluation of Multiclass Performance Models

We introduce the Class-oriented Method of Moments (CoMoM), a new exact algorithm to compute performance indexes in closed multiclass queueing networks. Closed models are important for performance evaluation of multi-tier applications, but when the number of service classes is large they become too expensive to solve with exact methods such as Mean Value Analysis (MVA). CoMoM addresses this limitation by a new recursion that scales efficiently with the number of classes. Compared to the MVA algorithm, which recursively computes mean queue-lengths, CoMoM carries on in the recursion also information on higher-order moments of queue-lengths. We show that this additional information greatly reduces the number of operations needed to solve the model and makes CoMoM the best-available algorithm for networks with several classes. We conclude the paper by generalizing CoMoM to the efficient computation of marginal queue-length probabilities, which finds application in the evaluation of state-dependent attributes such as energy consumption or quality-of-service metrics

SLA-based trust model for secure cloud computing

Cloud computing has changed the strategy used for providing distributed services to many business and government agents. Cloud computing delivers scalable and on-demand services to most users in different domains. However, this new technology has also created many challenges for service providers and customers, especially for those users who already own complicated legacy systems. This thesis discusses the challenges of, and proposes solutions to, the issues of dynamic pricing, management of service level agreements (SLA), performance measurement methods and trust management for cloud computing.In cloud computing, a dynamic pricing scheme is very important to allow cloud providers to estimate the price of cloud services. Moreover, the dynamic pricing scheme can be used by cloud providers to optimize the total cost of cloud data centres and correlate the price of the service with the revenue model of service. In the context of cloud computing, dynamic pricing methods from the perspective of cloud providers and cloud customers are missing from the existing literature. A dynamic pricing scheme for cloud computing must take into account all the requirements of building and operating cloud data centres. Furthermore, a cloud pricing scheme must consider issues of service level agreements with cloud customers.I propose a dynamic pricing methodology which provides adequate estimating methods for decision makers who want to calculate the benefits and assess the risks of using cloud technology. I analyse the results and evaluate the solutions produced by the proposed scheme. I conclude that my proposed scheme of dynamic pricing can be used to increase the total revenue of cloud service providers and help cloud customers to select cloud service providers with a good quality level of service.Regarding the concept of SLA, I provide an SLA definition in the context of cloud computing to achieve the aim of presenting a clearly structured SLA for cloud users and improving the means of establishing a trustworthy relationship between service provider and customer. In order to provide a reliable methodology for measuring the performance of cloud platforms, I develop performance metrics to measure and compare the scalability of the virtualization resources of cloud data centres. First, I discuss the need for a reliable method of comparing the performance of various cloud services currently being offered. Then, I develop a different type of metrics and propose a suitable methodology to measure the scalability using these metrics. I focus on virtualization resources such as CPU, storage disk, and network infrastructure.To solve the problem of evaluating the trustworthiness of cloud services, this thesis develops a model for each of the dimensions for Infrastructure as a Service (IaaS) using fuzzy-set theory. I use the Takagi-Sugeno fuzzy-inference approach to develop an overall measure of trust value for the cloud providers. It is not easy to evaluate the cloud metrics for all types of cloud services. So, in this thesis, I use Infrastructure as a Service (IaaS) as a main example when I collect the data and apply the fuzzy model to evaluate trust in terms of cloud computing. Tests and results are presented to evaluate the effectiveness and robustness of the proposed model

Relato de experiência com testes de performance em aplicações de entrega contínua

A verificação e a validação de sistemas de software são fundamentais para a diminuição de seus custos de manutenção. Dentro da área de testes de software existem inúmeras técnicas com os mais diferentes objetivos e abordagens. Dentre elas, uma das mais importantes é o teste de desempenho, também chamado de teste de performance. Principalmente para sistemas de médio e grande porte, com larga escalabilidade e entrega contínua, testes de desempenho são de extrema importância para garantir o nível de satisfabilidade de um sistema sob alta carga de dados e cenários que podem ocorrer na vida real e que se tornam inviáveis de reproduzir com testes manuais e unitários. Devido à complexidade no início das atividade de um profissional de engenharia de performance, o crescimento constante na área e a alta rotatividade de funcionários em empresas de grande porte, é necessário um modelo de teste de performance para profissionais da TI com pouca experiência em análise de desempenho. O objetivo do trabalho propõe a definição de um modelo abstrato, independente de tecnologia para esses profissionais. O modelo proposto é baseado em outros modelos encontrados na literatura desde abordagens sistemáticas e teóricas até modelos mais práticos e técnicos mas acrescido de informações de profissionais atuando há anos na indústria como engenheiros de performance e as principais informações dos modelos na literatura. Para estudo de caso o modelo foi aplicado em um sistema de análise de crédito de uma empresa globalmente distribuída e de larga escala há 15 anos no mercado. Com a previsão de aumento do volume e uma nova configuração dos servidores físicos uma série de testes de desempenho é definida para avaliar o comportamento e disponibilidade do sistema.The verification and validation of software systems are fundamental for their decrease in maintenance costs. On software testing area there are countless techniques with the most different objectives and approaches. Among them, one of the most important is the performance testing. Mainly for medium and large systems, with large scalability and continuous delivery, performance testing is highly important to ensure the satisfactory level of a system under high load of data and scenarios that might occur in real life but are infeasible to reproduce with manual or unit tests. Due to the complexity of a performance engineering first activities, the constant growth on the area and high turnover of employees from large size companies, it is necessary a model of performance testing for IT professionals with less experience on the area. The goal of this work proposes the definition of an abstract and technology independent model for those professionals. The proposed model is based on other models found in the literature since systematic and theorical approaches to practical and technical models but added with information from professionals acting for years on industry as performance engineers and with the main information from the models on literature. For a case study the model was applied on a credit analysis system from a large scale and globally distributed company acting for 15 years in the market. With a perspective of a volume increasing and a new physical servers configuration a series of performance testing is defined to evaluate the system behavior and availability

A Framework for Secure Management of Web Services (SMaWS) in Enterprise Application Integration

This dissertation addresses challenges currently faced by enterprises that have embraced the new technology called Web Service in order to reduce the cost of enterprise application integration (EAI) as well as improve operational efficiency of their mission-critical business processes. The nature of Web Service introduces new challenges such as dependency among applications, and a failure in one application can lead to a failure in other dependent applications. Such challenges have led to a growing need for enterprises to confront Web Service monitoring and management issues as a priority. As a solution, this dissertation proposes a SMaWS (Secure Management of Web Services) infrastructure for secure monitoring and management of Web Services. Its goals are to provide deeper visibility into Web Service runtime activities as compared to currently Web Service management tools; access to information about the Quality of Service (QoS) of these Web Services; and a unified monitoring environment for Web Services deployed across enterprise business units. This enables an earlier detection of poor performance problem in each interdependent Web Service, which would lead to a faster diagnose and fixing of possible performance issue, and thus maximize availability. This dissertation describes the requirements analysis for monitoring and management of Web Services across an enterprise environment. It describes the architecture and design of the SMaWS infrastructure proposed for secure monitoring and management of Web Service. The proposed SMaWS framework enables the instrumentation of existing and newly developed Web Service applications, and extracts Web Service performance statistics. It determines Web Service identity, reliability, availability, security, usage, and license used by Web Service consumers to access a given service. This dissertation describes the SMaWS Repository and Security concepts that are proposed to address the challenges faced by most distributed architectures to enable the client applications determine the location of the server (“bootstrapping problem”), and at the same time ensuring both the integrity and confidentiality of parties involved. Finally, this dissertation presents a prototype implementation of SMaWS Manager Application and Sample SMaWS Web Service applications. The experimental results obtained, in terms of overhead induced by the SMaWS framework on the monitored Web Service applications, demonstrate the feasibility of the SMaWS infrastructure

Automated Experiments for Deriving Performance-relevant Properties of Software Execution Environments

The execution environment can play a crucial role when analyzing the performance of a software system. However, detecting execution environment properties and integrating such properties into performance analyses is a manual, error-prone task. In this thesis, a novel approach for detecting performance-relevant properties of the software execution environment is presented. These properties are automatically detected using predefined experiments and integrated into performance prediction tools

QoS control of E-business systems through performance modelling and estimation

E-business systems provide the infrastructure whereby parties interact electronically via business transactions. At peak loads, these systems are susceptible to large volumes of transactions and concurrent users and yet they are expected to maintain adequate performance levels. Over provisioning is an expensive solution. A good alternative is the adaptation of the system, managing and controlling its resources. We address these concerns by presenting a model that allows fast evaluation of performance metrics in terms of measurable or controllable parameters. The model can be used in order to (a) predict the performance of a system under given or assumed loading conditions and (b) to choose the optimal configuration set-up for certain controllable parameters with respect to specified performance measures. Firstly, we analyze the characteristics of E-business systems. This analysis leads to the analytical model, which is sufficiently general to capture the behaviour of a large class of commonly encountered architectures. We propose an approximate solution which is numerically efficient and fast. By mean of simulation, we prove that its accuracy is acceptable over a wide range of system configurations and different load levels. We further evaluate the approximate solution by comparing it to a real-life E-business system. A J2EE application of non-trivial size and complexity is deployed on a 2-tier system composed of the JBoss application server and a database server. We implement an infrastructure fully integrated on the application server, capable of monitoring the E-business system and controlling its configuration parameters. Finally, we use this infrastructure to quantify both the static parameters of the model and the observed performance. The latter are then compared with the metrics predicted by the model, showing that the approximate solution is almost exact in predicting performance and that it assesses the optimal system configuration very accurately.EThOS - Electronic Theses Online ServiceGBUnited Kingdo