Aplicando Padrões de Gerência de Configuração de Software em Projetos Geograficamente Distribuídos1
Software Configuration Management (SCM) plays an important role in software development projects ... more Software Configuration Management (SCM) plays an important role in software development projects by controlling the consistency of artifacts during the whole project life cycle. In this article we discuss how a well-known SCM pattern language was applied in a medium size outsourced project. For each applied pattern we explain the motivations, the context, the forces considered and the positive and negative consequences. We present the ideas by looking to the SCM system as continuous evolving system as the patterns are applied. Special nuances, common to the complex world of outsourcing, are also emphasized.
Mandos: A User Interaction Method in Embedded Applications for Mobile Telephony
With the intense use of applicative in mobile device, the question "usability" begins to invigora... more With the intense use of applicative in mobile device, the question "usability" begins to invigorate strongly as a study object, it is being considered a determinant factor of the success of this segment of the mobile computation. This article proposes an improvement way in the usability of the embedded applicative in mobile devices, considering a new method of user interaction. The Mandos interaction method is based on task idea, which consists in a possible operation that could be executed in an applicative by the user and probabilities between task changes. The cited probabilities will be used for construction of the user interface to interact dynamically with the user. To validate the considered method was developed a framework, called Mandos, which propitiates functionalities to the applicative developer that uses Java technology. A case study will be presented where some prototypes of embedded applicative mobile was developed, using Mandos framework for the interaction method evaluation. The evaluation was established in order to identify any relation of usability gain or loss of applicative, having like approvers the own users of the embedded applicative in mobile telephones.
In recent days, the amount of functions has increased significantly in embedded products so that ... more In recent days, the amount of functions has increased significantly in embedded products so that systems development methodologies play an important role to ensure the product's quality, cost, and time. Furthermore, this complexity coupled with constantly evolving specifications, has led to propose a semiformal development methodology to support the building of embedded real-time systems. A platform-based design approach has been used to balance costs and time-to-market in relation to performance and functionality constraints. We performed three expressive case studies and we concluded that the proposed methodology significantly reduces design time and improves software modularity and reliability.
The complexity of software in embedded systems has increased significantly over the last years so... more The complexity of software in embedded systems has increased significantly over the last years so that software verification now plays an important role in ensuring the overall product quality. In this context, SAT-based bounded model checking has been successfully applied to discover subtle errors, but for larger applications, it often suffers from the state space explosion problem. This paper describes a new approach called continuous verification to detect design errors as quickly as possible by looking at the Software Configuration Management (SCM) system and by combining dynamic and static verification to reduce the state space to be explored. We also give a set of encodings that provide accurate support for program verification and use different background theories in order to improve scalability and precision in a completely automatic way. A case study from the telecommunications domain shows that the proposed approach improves the error-detection capability and reduces the overall verification time by up to 50%.
The transition from single-core to multi-core processors has made multi-threaded software an impo... more The transition from single-core to multi-core processors has made multi-threaded software an important subject in computer aided verification. Here, we describe and evaluate an extension of the ESBMC model checker to support the verification of multi-threaded software with shared variables and locks using bounded model checking (BMC) based on Satisfiability Modulo Theories (SMT). We describe three approaches to model check multi-threaded software and our modelling of the synchronization primitives of the Pthread library. In the lazy approach, we generate all possible interleavings and call the BMC procedure on each of them individually, until we either find a bug, or have systematically explored all interleavings. In the schedule recording approach, we encode all possible interleavings into one single formula and then exploit the high speed of the SMT solvers. In the underapproximation-widening approach, we reduce the state space by abstracting the number of state variables and interleavings from the proofs of unsatisfiability generated by the SMT solvers. In all three approaches, we use partial-order reduction (POR) techniques to reduce the number of interleavings explored. Experiments show that our approaches can analyze larger problems and substantially reduce the verification time compared to state-of-the-art techniques that combine classic POR methods with symbolic algorithms and others that implement the Counter-Example Guided Abstraction Refinement technique.
In this paper, we introduce the ezRealtime project, which relies on the Time Petri Net (TPN) form... more In this paper, we introduce the ezRealtime project, which relies on the Time Petri Net (TPN) formalism and defines a Domain-Specific Modeling (DSM) tool to provide an easyto-use environment for specifying Embedded Hard Real-Time (EHRT) systems and for synthesizing timely and predictable scheduled C code. Therefore, this paper presents a generative programming method in order to boost code quality and improve substantially developer productivity by making use of automated software synthesis. The ezRealtime tool reads and automatically translates the system's specification to a time Petri net model through composition of building blocks with the purpose of providing a complete model of all tasks in the system. Hence, this model is used to find a feasible schedule by applying a depth-first search algorithm. Finally, the scheduled code is generated by traversing the feasible schedule, and replacing transition's instances by the respective code segments. We also present the application of the proposed method in an expressive case study.
The transition from single-core to multi-core processors has made multi-threaded software an impo... more The transition from single-core to multi-core processors has made multi-threaded software an important subject over the last years in computer-aided verification. Model checkers have been successfully applied to discover subtle errors, but they suffer from combinatorial state space explosion when verifying multi-threaded software. In our previous work, we have extended the encodings from SMT-based bounded model checking (BMC) to provide more accurate support for program verification and to use different background theories and solvers in order to improve scalability and precision in a completely automatic way. We now focus on extending this work to support an SMT-based BMC formulation of multithreaded software which allows the state space to be reduced by abstracting the number of state variables and interleavings from the proof of unsatisfiability generated by the SMT solvers. The core idea of our approach aims to extract the proof objects produced by the SMT solvers in order to control the number of interleavings and to remove logic that is not relevant to a given property. This work aims to develop a new algorithmic method and corresponding tools based on SMT to verify embedded software in multi-core systems.
In recent years, discrete control systems play an important role in the development and advanceme... more In recent years, discrete control systems play an important role in the development and advancement of modern civilization and technology. Practically every aspect of our life is affected by some type of control systems. This kind of system maybe classified as an embedded real-time system and requires rigorous methodologies to develop the software that is under stringent hardware constraints. Therefore, the proposed development methodology adapts agile principles and patterns in order to build embedded control systems focusing on the issues related to the system's constraints and safety. Strong unit testing is the foundation of the proposed methodology for ensuring timeliness and correctness. Moreover, platform-based design approach is used to balance costs and time-to-market in view of performance and functionality constraints. We conclude that the proposed methodology reduces significantly the design time and cost as well as leads to better software modularity and reliability.
The complexity of software in embedded systems has increased significantly over the last years so... more The complexity of software in embedded systems has increased significantly over the last years so that software verification now plays an important role in ensuring the overall product quality. In this context, SAT-based bounded model checking has been successfully applied to discover subtle errors, but for larger applications, it often suffers from the state space explosion problem. This paper describes a new approach called continuous verification to detect design errors as quickly as possible by looking at the Software Configuration Management (SCM) system and by combining dynamic and static verification to reduce the state space to be explored. We also give a set of encodings that provide accurate support for program verification and use different background theories in order to improve scalability and precision in a completely automatic way. A case study from the telecommunications domain shows that the proposed approach improves the error-detection capability and reduces the overall verification time by up to 50%.
Propositional bounded model checking has been applied successfully to verify embedded software bu... more Propositional bounded model checking has been applied successfully to verify embedded software but is limited by the increasing propositional formula size and the loss of structure during the translation. These limitations can be reduced by encoding word-level information in theories richer than propositional logic and using SMT solvers for the generated verification conditions. Here, we investigate the application of different SMT solvers to the verification of embedded software written in ANSI-C. We have extended the encodings from previous SMT-based bounded model checkers to provide more accurate support for finite variables, bit-vector operations, arrays, structures, unions and pointers. We have integrated the CVC3, Boolector, and Z3 solvers with the CBMC front-end and evaluated them using both standard software model checking benchmarks and typical embedded applications from telecommunications, control systems and medical devices. The experiments show that our approach can analyze larger problems and substantially reduce the verification time.
Model-Driven Engineering (MDE) has been advocated as an effective way to deal with today's softwa... more Model-Driven Engineering (MDE) has been advocated as an effective way to deal with today's software complexity. MDE can be seen as an integrative approach combining existing techniques such as Domain-Specific Modeling Languages (DSML) and Transformation Engines. This paper presents the ezRealtime, an MDE-based tool that relies on the Time Petri Net (TPN) formalism and defines a DSML to provide an easy-to-use environment for specifying Embedded Hard Real-Time (EHRT) systems and for synthesizing timely and predictable scheduled C code. The ezRealtime adopts the universal XML-based transfer syntax for Petri nets, named as PNML. The main idea of this work is to propose a generative programming method and tool to boost code quality and improve developer productivity with automated software synthesis. The ezRealtime tool reads and automatically translates the specification to a time Petri net model through composition of building blocks with the purpose of providing a complete model of all tasks in the system. Therefore, this model is used to find a feasible schedule by applying a depth-first search algorithm. Finally, the scheduled code is generated by traversing the feasible schedule, and replacing transition's instances by the respective code segments. We also present the application of the proposed method in a case study.
A discrete control system, with stringent hardware constraints, is effectively an embedded real-t... more A discrete control system, with stringent hardware constraints, is effectively an embedded real-time system and hence requires a rigorous methodology to develop the software involved. The development methodology proposed in this paper adapts agile principles and patterns to support the building of embedded control systems, focusing on the issues relating to a system's constraints and safety. Strong unit testing, to ensure correctness, including the satisfaction of timing constraints, is the foundation of the proposed methodology. A platform-based design approach is used to balance costs and time-to-market in relation to performance and functionality constraints. It is concluded that the proposed methodology significantly reduces design time and costs, as well as leading to better software modularity and reliability.
Propositional bounded model checking has been applied successfully to verify embedded software bu... more Propositional bounded model checking has been applied successfully to verify embedded software but is limited by the increasing propositional formula size and the loss of structure during the translation. These limitations can be reduced by encoding word-level information in theories richer than propositional logic and using SMT solvers for the generated verification conditions. Here, we investigate the application of different SMT solvers to the verification of embedded software written in ANSI-C. We have extended the encodings from previous SMT-based bounded model checkers to provide more accurate support for finite variables, bit-vector operations, arrays, structures, unions and pointers. We have integrated the CVC3, Boolector, and Z3 solvers with the CBMC front-end and evaluated them using both standard software model checking benchmarks and typical embedded applications from telecommunications, control systems and medical devices. The experiments show that our approach can analyze larger problems and substantially reduce the verification time.
A car racing based strategy for the Dynamic Voltage and Frequency Scaling technique
This work proposes the application of a car racing analogy to develop real-time applications with... more This work proposes the application of a car racing analogy to develop real-time applications with low energy consumption using the Dynamic Voltage and Frequency Scaling technique. Although several previous works had dealt with the DVFS technique, our proposed method offers two main improvements. First, it can be applied to multiple preemptable real-time tasks. Second, in our method, energy consumption optimization may be carried out even when the worst case execution path is followed. The proposed method takes into account the limited set of available frequencies, and consider both the timing and energy overheads for changing the frequency/voltage. Our simulation results indicate clearly the practical usability, efficiency, and the advantages of the proposed method.
We describe and evaluate three approaches to model check multi-threaded software with shared vari... more We describe and evaluate three approaches to model check multi-threaded software with shared variables and locks using bounded model checking based on Satisfiability Modulo Theories (SMT) and our modelling of the synchronization primitives of the Pthread library. In the lazy approach, we generate all possible interleavings and call the SMT solver on each of them individually, until we either find a bug, or have systematically explored all interleavings. In the schedule recording approach, we encode all possible interleavings into one single formula and then exploit the high speed of the SMT solvers. In the underapproximation and widening approach, we reduce the state space by abstracting the number of interleavings from the proofs of unsatisfiability generated by the SMT solvers. In all three approaches, we bound the number of context switches allowed among threads in order to reduce the number of interleavings explored. We implemented these approaches in ESBMC, our SMT-based bounded model checker for ANSI-C programs. Our experiments show that ESBMC can analyze larger problems and substantially reduce the verification time compared to stateof-the-art techniques that use iterative context-bounding algorithms or counter-example guided abstraction refinement.
In recent days, the complexity of software has increased significantly in embedded products in su... more In recent days, the complexity of software has increased significantly in embedded products in such a way that the verification of Embedded Software (ESW) now plays an important role to ensure the product's quality. Embedded systems engineers usually face the problems of verifying properties that have to meet the application's deadline, access the memory region, handle concurrency, and control the hardware registers. This work proposes a semiformal verification approach that combines dynamic and static verification to stress and cover exhaustively the state space of the system. We perform a case study on embedded software used in the medical devices domain. We conclude that the proposed approach improves the coverage and reduces substantially the verification time.
Embedded systems are everywhere, from home appliances to critical systems such as medical devices... more Embedded systems are everywhere, from home appliances to critical systems such as medical devices. They usually have associated timing constraints that need to be verified for the implementation. Here, we use an untimed bounded model checker to verify timing properties of embedded C programs. We propose an approach to specify discrete time timing constraints using code annotations. The annotated code is then automatically translated to code that manipulates auxiliary timer variables and is thus suitable as input to conventional, untimed software model checker such as ESBMC. Thus, we can check timing constraints in the same way and at the same time as untimed system requirements, and even allow for interaction between them. We applied the proposed method in a case study, and verified timing constraints of a pulse oximeter, a noninvasive medical device that measures the oxygen saturation of arterial blood.
In this paper, we introduce the ezRealtime project, which relies on the Time Petri Net (TPN) form... more In this paper, we introduce the ezRealtime project, which relies on the Time Petri Net (TPN) formalism and defines a Domain-Specific Modeling (DSM) tool to provide an easy- to-use environment for specifying Embedded Hard Real-Time (EHRT) systems and for synthesizing timely and predictable scheduled C code. Therefore, this paper presents a generative programming method in order to boost code quality and improve substantially developer productivity by making use of automated software synthesis. The ezRealtime tool reads and automatically translates the system's specification to a time Petri net model through composition of building blocks with the purpose of providing a complete model of all tasks in the system. Hence, this model is used to find a feasible schedule by applying a depth-first search algorithm. Finally, the scheduled code is generated by traversing the feasible schedule, and replacing transition's instances by the respective code segments. We also present the application of the proposed method in an expressive case study.
This paper describes a pattern language for managing multi-site software projects which aims at m... more This paper describes a pattern language for managing multi-site software projects which aims at minimizing the main problems present on the multi-site software development context. The practices and patterns of the proposed language were first identified from the literature and adapted according to the authors' experience after running some multi-site software projects. This exercise has led to the identification of two new patterns: "Stories Rework Subsystem", and "Plan Bugs On a Sustainable Pace", as well as to an alternative application of the existing "Inversion of Control" pattern to the organizational context.
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