Ermeson C. Andrade

A Methodology for Mapping SysML Activity Diagram to Time Petri Net for Requirement Validation of Embedded Real-Time Systems with Energy Constraints

In this paper we use the Activity diagram of the System Modeling Language (SysML) in combination with the new UML profile for Modeling and Analysis of Real-Time and Embedded systems (MARTE) in order to validate functional, timing and low power requirements in early phases of the embedded system development life-cycle. However, SysML lacks a formal semantics and hence it is not possible to apply, directly, mathematical techniques on SysML models for system validation. Thus, a novel approach for automatic translation of SysML Activity diagram into Time Petri Net with Energy constraints (ETPN) is proposed. In order to depict the practical usability of the proposed method, a case study is presented, namely, pulse-oximeter. Besides, the estimates obtained (execution time and energy consumption) from the model are 95% close to the respective measures obtained from the real hardware platform.

Candy: Component-based Availability Modeling Framework for Cloud Service Management Using SysML

High-availability assurance of cloud service is a critical and challenging issue for cloud service providers. To quantify the availability of cloud services from both architectural and operational points of views, availability modeling and evaluation are essential. This paper presents a component-based availability modeling framework, named Candy, which constructs a comprehensive availability model semi-automatically from system specifications described by Systems Modeling Language (SysML). SysML diagrams are translated into components of availability model and the components are assembled together to form the entire availability model in Stochastic Reward Nets (SRNs). In order to incorporate the maintenance operations of cloud services in availability models, Candy defines the translation rules from Activity diagram to SRN and synchronizes the related SRNs according to SysML allocation notations. The feasibility of the proposed modeling and availability evaluation process is studied by an illustrative example of a web application service hosted on a cloud infrastructure having multiple failure isolation zones and automatic scale-up function.

Energy consumption and execution time estimation of embedded system applications

Embedded systems often have conflicting constraints such as energy and time which considerably harden the design of those systems. In this context, this work proposes a mechanism for supporting design decisions on energy consumption and performance of embedded system applications. In order to depict the practical usability of the proposed methodology, a real case study as well as customized examples are presented. The estimates obtained through the conceived model are 93% close to the respective measures obtained from the real hardware platform.

Performance Modeling for Evaluation and Planning of Electronic Funds Transfer Systems with Bursty Arrival Traffic

As business enterprisers are increasingly becoming dependent on using online transactions, the demand for high-end and efficient transaction monitor systems becomes a serious issue. Hence, the performance evaluation of Electronic Funds Transfer (EFT) systems has an enormous importance for companies that implement this service, since the computing resources must be used efficiently in order to ensure high availability, reliability, scalability and security. This paper presents a stochastic model for performance evaluation and planning EFT systems computational resources in the course of demonstrating that the effect of the traffic variations mechanism in computational resources is magnified when the interarrivals are highly bursty and correlated. At the end, a real case study is presented in order to describe the adequacy of presented approach and results.

Availability Modeling and Analysis for Data Backup and Restore Operations

Data backup operation is an essential part of common IT system administration to protect against data loss caused by any storage failures, human errors, or disasters. Lost data can be recovered from the backed up data if it exists. Since the backup and restore operations accrue downtime overhead or performance degradation, they have to be designed to ensure the data reliability while minimizing the performance and availability overhead. In this paper, we study the impacts of different backup policies on availability measures such as storage availability, system availability, and user-perceived availability. Backup and restore operations are designed using SysML Activity diagrams that are automatically translated into Stochastic Reward Net (SRN) to compute the availability measures. Our numerical results show the effectiveness of the combination of full backup and partial backup in terms of user-perceived data availability and data loss rate. Furthermore, the sensitivity ranking can help improve the availability measures.

A coloured petri net based approach for estimating execution time and energy consumption in embedded systems

This paper presents a Coloured Petri net based approach for estimating execution time and energy consumption in embedded systems. The aim of this work is to provide, in the design phase, a mechanism that helps the designer informing the energy consumption and the performance of the code in analysis. Experimental results have demonstrated an accuracy of 96% using the proposed formal method in comparison with the values obtained with the hardware platform.

Mapping UML Interaction Overview Diagram to Time Petri Net for Analysis and Verification of Embedded Real-Time Systems with Energy Constraints

With the heterogeneity and complexity growth of embedded real-time systems (ERTS) is required an interdisciplinary approaches in the development processes embracing software engineering, mechanics, electric and electronics areas. Accordingly, a modeling language, called Unified Modeling Language (UML), has been specified by OMG (Object Management Group). However, when dealing with ERTS is indispensable the description of quantitative system aspects such as time and energy consumption. For that, a new UML Profile for Modeling and Analysis of Real-Time and Embedded systems (MARTE) has been also specified by OMG. Nevertheless, these UML models themselves are not directly analyzable. This paper presents the mapping process of interaction overview diagram (IO) into a time Petri net with energy constraints (ETPN) so as to analyze and verify the functional, timing and energy requirements in early phases of the life-cycle development.

A formal model for performance and energy evaluation of embedded systems

Embedded systems designers need to verify their design choices to find the proper platform and software that satisfy a given set of requirements. In this context, it is essential to adopt formal-based techniques to evaluate the impact of design choices on system requirements. To be useful, such techniques must produce accurate results with minimal computation time. This paper proposes an approach based on Coloured Petri Nets for evaluating embedded systems performance and energy consumption. In particular, this work presents a method for specifying and evaluating the workload and the platform components, such as processors and shared or private memories. The method is applied to model single processor and multiprocessor platforms. Experimental results demonstrate an average accuracy of 96% in comparison with the respective measures assessed from the real hardware platform.

Software fault mitigation and availability assurance techniques

Companies are expected to keep their systems up and running and make data continuously available. Several recent studies have established that most system outages are due to software faults. In this paper, we discuss availability aspects of large software-based systems. We begin by classifying software faults into Bohrbugs and Mandelbugs, and identify aging-related bugs as a subtype of the latter. We then examine mitigation methods for Mandelbugs in general and aging-related bugs in particular. Finally, we discuss techniques for the quantitative availability assurance for such systems.

Combining Performance and Availability Analysis in Practice

Abstract Composite performance and availability analysis of computer systems has gained considerable attention in recent years. Pure performance analysis of a system tends to be optimistic since it ignores the failure–repair behavior of the system. On the other hand, pure availability analysis tends to be too conservative since the behavior of the system is captured by only two states (functioning or failed). To analyze the degradation of a systems performance in consideration with availability metrics, combined measures of performance and availability are essential. This chapter introduces the basics of analytic models for the combined performance and availability analysis of computer systems together with some practical examples.