[서평]「Component Software」 - Beyond Object-Oriented Programming -

In the last decade, a large number of different software component models have been developed, with different aims and using different principles and technologies. This has resulted in a number of models which have many similarities, but also principal differences, and in many cases unclear concepts. Component-based development has not succeeded in providing standard principles, as has, for example, object-oriented development. In order to increase the understanding of the concepts and to differentiate component models more easily, this paper identifies, discusses, and characterizes fundamental principles of component models and provides a Component Model Classification Framework based on these principles. Further, the paper classifies a large number of component models using this framework.

A Classification Framework for Software Component Models

I provide an overview of the Fault Tree Analysis method.I review different extensions of fault trees.A number of model-based dependability analysis approaches are reviewed.I outline the future outlook for model-based dependability analysis. Fault Tree Analysis (FTA) is a well-established and well-understood technique, widely used for dependability evaluation of a wide range of systems. Although many extensions of fault trees have been proposed, they suffer from a variety of shortcomings. In particular, even where software tool support exists, these analyses require a lot of manual effort. Over the past two decades, research has focused on simplifying dependability analysis by looking at how we can synthesise dependability information from system models automatically. This has led to the field of model-based dependability analysis (MBDA). Different tools and techniques have been developed as part of MBDA to automate the generation of dependability analysis artefacts such as fault trees. Firstly, this paper reviews the standard fault tree with its limitations. Secondly, different extensions of standard fault trees are reviewed. Thirdly, this paper reviews a number of prominent MBDA techniques where fault trees are used as a means for system dependability analysis and provides an insight into their working mechanism, applicability, strengths and challenges. Finally, the future outlook for MBDA is outlined, which includes the prospect of developing expert and intelligent systems for dependability analysis of complex open systems under the conditions of uncertainty.

https://hull-repository.worktribe.com/preview/582881/2018-02-04%2015186%20Kabir.pdf

An overview of fault tree analysis and its application in model based dependability analysis

It’s a fact of life that organizations love to reorganize. Reorganizations have a profound effect on the way product lines are governed. We introduce the concept of the Responsibility, Authority, and Accountability (RAA) network. An RAA network assists in the governance process of product lines for internal information systems, even in the face of massive reorganization. Armour (“Reorg Cycle” [1]) describes the pressures of reorganization to balance the “dimensions of organization” (e.g., geography, customers, product technology); we apply polarity management to balance the dimensions. Armour describes the difficulty of applying hierarchical organization charts—“single dimension management structures”—to the above “multidimensional environments”; we apply lean RAA networks to span organization charts and provide the multidimensional view needed for product lines. Armour observes that network organization approaches “do not have a good track record”; our experience is that lean, resilient RAA networks document the product line’s governance architecture. These governance architecture patterns are applied repeatedly to the strata of products in the product line. We present the governance architect’s RAA to define, monitor, and sustain governance health using these tools: polarity maps, polarity networks, RAA maps, and RAA networks.

Software Product Lines

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 variables of finite bit width, 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 software applications from telecommunications, control systems, and medical devices. The experiments show that our approach can analyze larger problems and substantially reduce the verification time.

/pdf/smt-based-bounded-model-checking-for-embedded-ansi-c-4g7djuda50.pdf

SMT-Based Bounded Model Checking for Embedded ANSI-C Software

https://www.es.mdh.se/pdf_publications/930.pdf

The SAVE approach to component-based development of vehicular systems

The embedded systems domain represents a class of systems that have high requirements on cost efficiency as well as run-time properties such as timeliness and dependability. The research on component-based systems has produced component technologies for guaranteeing real-time properties. However, the issue of saving resources by allocating several components to real-time tasks has gained little focus. Trade-offs when allocating components to tasks are, e.g., CPU-overhead, footprint and integrity. In this paper we present a general approach for allocating components to real-time tasks, while utilizing existing real-time analysis to ensure a feasible allocation. We demonstrate that CPU-overhead and memory consumption can be reduced by as much as 48% and 32% respectively for industrially representative systems.

/pdf/optimizing-resource-usage-in-component-based-real-time-54c309plc7.pdf

Optimizing resource usage in component-based real-time systems

We present a contract-based technique to achieve reuse of known worst-case execution times (WCET) in conjunction with reuse of software components. For resource constrained systems, or systems where high degree of predictability is needed, classical techniques for WCET- estimation will result in unacceptable overestimation of the execution-time of reusable software components with rich behavior. Our technique allows different WCETs to be associated with subsets of the component behavior. The appropriate WCET for any usage context of the component is selected be means of component contracts over the input domain. In a case-study we illustrate our technique and demonstrate its potential in achieving tight WCET- estimates for reusable components with rich behavior.

/pdf/contract-based-reusableworst-case-execution-time-estimate-2haffglzee.pdf

Contract-Based ReusableWorst-Case Execution Time Estimate

We compare existing component technologies for embedded systems with respect to industrial requirements. The requirements are collected from the vehicular industry, but our findings are applicable to similar industries developing resource constrained safety critical embedded distributed real-time computer systems. One of our conclusions is that none of the studied technologies is a perfect match for the industrial requirements. Furthermore, no single technology stands out as being a significantly better choice than the others; each technology has its own pros and cons. The results of our evaluation can be used to guide modifications or extensions to existing technologies, making them better suited for industrial deployment. Companies that want to make use of component-based software engineering as available today can use this evaluation to select a suitable technology.

/pdf/evaluation-of-component-technologies-with-respect-to-565yscj8wu.pdf

Evaluation of component technologies with respect to industrial requirements

Safety critical embedded real-time systems represent a class of systems that has attracted relatively little attention in research addressing component based software engineering. Hence, the most widely spread component technologies are not used for resource constrained safety critical real-time systems. They are simply to resource demanding, to complex and to unpredictable. In this paper we show how to use component based software engineering for low footprint systems with very high demands on safe and reliable behaviour. The key concept is to provide expressive design time models and yet resource effective run-time models by statically resolve resource usage and timing by powerful compile time techniques. This results in a component technology for resource effective and temporally verified mapping of a component model to a commercial real-time operating system.

Johan Fredriksson

Papers

The SAVE approach to component-based development of vehicular systems

Optimizing resource usage in component-based real-time systems

Contract-Based ReusableWorst-Case Execution Time Estimate

Evaluation of component technologies with respect to industrial requirements

Introducing a component technology for safety critical embedded real-time systems