Mrv Michel Chaudron

In practice: UML software architecture and design description

The Unified Modeling Language has attracted many organizations and practitioners. UML is now the de facto modeling language for software development. Several features account for its popularity: its a standardized notation, rich in expressivity; UML 2.0 provides 13 diagram types that enable modeling several different views and abstraction levels. Furthermore, UML supports domain-specific extensions using stereotypes and tagged values. Finally, several case tools integrate UML modeling with other tasks such as generating code and reverse-engineering models from code. Our study focused on UML use and model quality in actual projects rather than on its adequacy as a notation or language.

Predicting real-time properties of component assemblies: a scenario-simulation approach

This work addresses the problem of predicting timing properties of multitasking component assemblies during the design phase. For real-time applications, it is of vital importance to guarantee that the timing requirements of an assembly are met. We propose a simulation-based approach for predicting the real-time behaviour of an assembly based on models of its constituent components. Our approach extends the scenario-based method in [J. Muskens et al. (2004)] by offering a system model that is tailored to the domain of real-time applications. Contributions of This work include the possibility to handle the following features: mutual exclusion, combinations of aperiodic and periodic tasks and synchronization constraints. The analytical approach we used in previous work cannot handle these features. Therefore, we introduce the simulation-based approach. Our simulator provides data about dynamic resource consumption and real-time properties like response time, blocking time and number of missed deadlines per task. We have validated our approach using a video-decoder application.

Visual Exploration of Combined Architectural and Metric Information

We present MetricView, a software visualization and exploration tool that combines traditional UML diagram visualization with metric visualization in an effective way. MetricView is very easy and natural to use for software architects and developers yet offers a powerful set of mechanisms that allow fine customization of the visualizations for getting specific insights. We discuss several visual and architectural design choices which turned out to be important in the construction of MetricView, and illustrate our approach with several results using real-life datasets

Exploring performance trade-offs of a JPEG decoder using the deepcompass framework

Designing embedded systems for multiprocessor platforms requires early prediction and balancing of multiple system quality attributes. We present a design space exploration framework for component-based software systems that allows an architect to get insight into a space of possible design alternatives with further evaluation and comparison of these alternatives. The framework provides (a) tool-guided design of multiple alternatives of software and hardware architectures, (b) early design-time predictions of performance properties and identification of bottlenecks for each architectural alternative, and (c) evaluation of each alternative with respect to multi-objective trade-offs. The performance prediction technique employs modeling of individual components and composition of the models into a system model representing the system behaviour and resource usage. We illustrate the framework by a case study of a JPEG decoder application. For this system, we consider architectural alternatives, show their specification, and explore their trade-offs with respect to task latencies, resource utilization and system cost.

A component framework for consumer electronics middleware

Developers of Consumer Electronics (CE) devices face the problem of the ever increasing amount of software that needs to be developed. At the same time the time to market of their products needs to decrease. In other domains Component Based software development aids in solving the resulting problems. However, existing component frameworks fail to meet some of the requirements specific for the CE domain. In order to improve this situation a component-based framework has been developed. In this chapter we describe this framework and motivate the architectural choices. These choices are influenced by the requirements on the framework. Some of these requirements are specific for the CE domain, others are more general.

Prediction of Run-Time Resource Consumption in Multi-task Component-Based Software Systems

Embedded systems must be cost-effective. This imposesstrict requirements on the resource consumption of their applications. It is therefore desirable to be able to determine the resource consumption of applications as early as possible in its development. Only then, a designer is able to guarantee that an application will fit on a target device.

Compositional Performance Analysis of Component-Based Systems on Heterogeneous Multiprocessor Platforms

This paper presents a compositional performance analysis technique, enabling predictable deployment of software components on heterogeneous multiprocessor architectures. This analysis technique introduces (a) composable software and hardware component models representing abstract specification of the component behaviour and corresponding resources, (b) operational semantics enabling composition of the models into an executable system model, and (c) simulation-based analysis of the obtained executable model resulting in predicted performance attributes. Example attributes are response time, throughput, utilization of processors, memory and communication lines. Special attention is paid to modeling of both passive and active components exploiting synchronous method invocation and asynchronous message passing interaction. We made an experimental validation of the above framework for two case studies: an MPEG-4 decoder and a car navigation system. It was found that the prediction error on task latencies and processor usage was within 10%

Four Automated Approaches to Analyze the Quality of UML Sequence Diagrams

UML sequence diagrams describe the interaction between objects of a system. In this paper, we present four approaches to analyze the quality of sequence diagrams. First, we propose formal model checking techniques and visualization to analyze the possible interaction traces and to identify ambiguities in a sequence diagram. Second, we identified patterns of common interactive behavior and we present an approach to identify these patterns. This approach is useful to identify implicit patterns and make them explicit. Third, we propose a series of checks to identify syntactic defects in sequence diagrams. The fourth approach consists of metrics describing properties such as coverage. The proposed approaches complement each other rather than being competing alternatives. We implemented these approaches in our SquAT tool and conducted a multi case study on three industrial and five research models to validate them. These models showed a large number of defects which were acknowledged by their designers.

Adaptive runtime fault management for service instances in component-based software applications

The Trust4All project aims to define an open, component-based framework for the middleware layer in high-volume embedded appliances that enables robust and reliable operation, upgrading and extension. To improve the availability of each individual application in a Trust4All system, a runtime configurable fault management mechanism (FMM) is proposed, which detects deviations from given service specifications by intercepting interface calls. When repair is necessary, FMM picks a repair action that incurs the best tradeoff between the success rate and the cost of repair. Considering that it is rather difficult to obtain sufficient information about third party components during their early stage of usage, FMM is designed to be able to accumulate knowledge and adapts its capability accordingly.

PARS: A Process Algebra with Resources and Schedulers

In this paper, we introduce a dense time process algebraic formalism with support for specification of (shared) resource requirements and resource schedulers. The goal of this approach is to facilitate and formalize introduction of scheduling concepts into process algebraic specification using separate specifications for resource requiring processes, schedulers and systems composing the two. The benefits of this research are twofold. Firstly, it allows for formal investigation of scheduling strategies. Secondly, it provides the basis for an extension of schedulability analysis techniques to the formal verification process, facilitating the modelling of real-time systems in a process algebraic manner using the rich background of research in scheduling theory.