Cesar A. L. Oliveira

Modeling and analyzing resource-constrained business processes

In this paper we review several approaches for the performance evaluation of business workflows and propose an approach based on Generalized Stochastic Petri Nets, which presents desirable characteristics, such as analytic solutions. We present a case study demonstrating the application of our proposal and compare the results with that obtained by a colored Petri net model.

Quantitative Analysis of Resource-Constrained Business Processes

To address the need for evaluation techniques for complex business processes, also known as workflows, this paper proposes an approach based on generalized stochastic Petri nets (GSPNs). We review ten related approaches published in the last fifteen years and compare them to our approach using a wide range of criteria. On the basis of this evaluation, we observe that the newly proposed approach provides results that are at least as good as those from the most accepted alternatives and holds a number of additional advantages, such as modeling simplicity, improved precision, and model reuse for qualitative analyses. The overall approach is formally defined in this paper, along with the definition of several performance metrics. Part of these metrics can be computed analytically, while the remainder can be obtained by simulating the GSPN. Furthermore, a tool has been developed to translate automatically business process execution language processes into GSPNs. Finally, we present a case study in which we applied the proposed approach, colored Petri net tools, and an industrial tool to obtain performance insights into a realistic workflow. The results were highly similar, demonstrating the feasibility and the accuracy of our approach.

Performance evaluation of service-oriented architecture through stochastic Petri nets

The Service-Oriented Architecture (SOA) has become an unifying technical architecture that can be embodied with Web Service technologies, in which the Web Service is thought as a fundamental building block. This paper proposes a simulation modeling approach based on stochastic Petri nets to estimate the performance of SOA applications. Using the proposed model it is possible to predict resource consumption and service levels degradation in scenarios with different compositions and workloads. A case study was conducted to validate the approach and to compare the results against an existing analytical modeling approach.

Using process mining in software development process management: A case study

In this paper we describe the application of process mining techniques to analyze a software development process. Software engineering practitioners often conduct quality auditing of the development process to assure conformance with organizational standards. Despite some works have explored process mining techniques for the conformance analysis of general business processes, it is not of our knowledge any study that applies process mining to conformance checking of software development processes. Under a practical perspective, this paper explores a real database with event logs generated in the past five years of execution of a software development process. The database was gently provided by a Brazilian software house with annual revenue of more than US

A quality-driven approach for resources planning in Service-Oriented Architectures

500 million and includes more than 2,000 cases (process instances). The results show that process mining can be effectively employed as a supporting tool for the management of software development processes and for the improvement of the maturity level of software engineering organizations.

Optimizing generated aspect-oriented assertion checking code for JML using program transformations: An empirical study

Performance estimation of in-development SOA-based systems.Availability estimation of in-development SOA-based systems.SLA planning for in-development SOA-based systems.Bottleneck discovering and reshaping in SOA processes.Methodology for the incremental improvement of SOA infrastructures. Service-Oriented Architecture (SOA) is a paradigm for software development based on the concept of service. In SOA, the Quality of Services (QoS) impacts on the status of a business and on the relationship between service customers and providers. As customers expect to receive services with quality no less than they have paid for, it is usual to stress a SOA application in order to measure its QoS levels, which can be expensive and time consuming. This paper shows that the behavior of a SOA system can be modeled by Petri Nets and, from the model, QoS levels (performance and availability) can be estimated. In this way, the analysis can be conducted without necessarily implementing the real system, which tends to be valuable in the design phase of SOA. Additionally, we present a methodology to implement the model findings, which allows to verify its accuracy in practice. As a final contribution we associate our modeling approach to the Service Level Agreements (SLA) composition, which allows to discover and prevent bottlenecks delaying the system and to anticipate potential SLA violations. Two examples illustrate our results.

Computing Strategic Trade-Offs in Web Service Deployment and Selection

The AspectJ JML compiler (ajmlc) explores aspect-oriented programming (AOP) mechanisms to implement JML specifications, such as pre- and postconditions, and enforce them during runtime. This compiler was created to improve source-code modularity. Some experiments were conducted to evaluate the performance of the code generated through ajmlc. Results demonstrated that the strategy of adopting AOP to implement JML specifications is very promising. However, there is still a need for optimization of the generated codes bytecode size and running time. This paper presents a catalog of transformations which represent the optimizations implemented in the new optimized version of the ajmlc compiler. We employ such transformations to reduce the bytecode size and running time of the code generated through the ajmlc compiler. Aiming at demonstrating the impact of such transformation on the code quality, we conduct an empirical study using four applications in optimized and non-optimized versions generated by ajmlc. We show that our AOP transformations provide a significant improvement, regarding bytecode size and running time.

A stochastic model for performance evaluation and bottleneck discovering on SOA-based systems

The subject of business-IT alignment has increasingly attracted the attention of executives in the past decade. The purpose is to leverage the potential of IT to improve business performance. This goal can be achieved by developing mechanisms to enhance the communication between business and IT. In the same track, its essential to apply methods to assure that IT investments are driven by the strategic goals and priorities of the company. Service-Oriented Architecture (SOA)is widely recognized as a technology that promotes IT alignment and business agility. However, strategic goals of firms have been frequently neglected when dealing with technical subjects such as web service selection and deployment. In this work, we propose a multiple criteria decision method based on the Analytic Hierarchy Process (AHP) that is able to accommodate in a single framework both the technical and the strategic requirements of web service deployment and selection. Our framework help IT managers to find the configuration that best translates the preferences of the customer and the priorities of the company. A numeric case study compares our approach to other traditional uses of AHP.

Declarative Versus Imperative Business Process Languages

The Service-Oriented Architecture (SOA) has become a unifying technical architecture that may be embodied through Web Service technologies. Predicting the variable behavior of SOA systems can mean a way to improve the quality of the business transactions. This paper proposes a simulation modeling approach based on stochastic Petri nets to estimate the performance of SOA-applications. Using the proposed model is possible to predict resource consumption and service levels degradation in scenarios with different compositions and workloads, even before developing the application. A case study was conducted in order to validate our approach, comparing its accuracy with the results from an analytical model existent in the literature.

Planning service agreements in soa-based systems through stochastic models

It has been argued that traditional workflows lack of flexibility to cope with complex and changing environments found in several business domains. The declarative approach surged with the aim of enabling more flexible business process management systems. Processes are designed in terms of activities and rules that constrain their execution. As such, declarative models are less rigid and prescriptive than workflows, since this approach focus on modeling what must be done but not how. Despite these arguments, there is no quantitative evidence that the benefits provided by current declarative approaches outperform the features of traditional workflows. In this work, we present the results of a controlled experiment conducted to empirically compare Workflow and Declarative approaches to business process modeling. Our findings suggest that there is no signficative difference from adopting one approach or the other.