General Component Model Research Articles

Development of a novel component-based open CNC software system

Component-based software development (CBSD) is widely utilized to develop open CNC applications. It aims to build an open CNC application by composing a set of components, each implementing specific CNC sub-domain logic. Components conform to a certain component model to keep conformant interactive behaviors. Due to there is no standard granularity to decompose CNC domain and no general component model, as well as seldom consider extra-functional properties, components are heterogeneous. Moreover, they have a direct dependency rather than depending on abstractions. In a nutshell, there are many open-source CNC applications built by heterogeneous and tightly coupled components. They can implement CNC functionality but are good at functional extension and reconfiguration. In this paper, we apply CBSD and dependency inversion principle to develop a novel open CNC application which allows customizing CNC functionality. Specifically, a new granularity to decompose CNC domain is proposed. A special sub-domain is designed to encapsulate the execution logic of other sub-domains at an abstract level and instantiate concrete implementation details at runtime according to configuration. The functional properties of sub-domains are exposed via abstractions. Therefore, as long as re-writing the execution logic and configuring corresponding implementation details, CNC functionality can be extended or reconfigured. A prototype and several components have been developed to test the performance of the application.

Comparison of Methods for Factor Invariance Testing of a 1-Factor Model With Small Samples and Skewed Latent Traits.

A primary underlying assumption for researchers using a psychological scale is that scores are comparable across individuals from different subgroups within the population. In the absence of invariance, the validity of these scores for inferences about individuals may be questionable. Factor invariance testing refers to the methodological approach to assessing whether specific factor model parameters are indeed equivalent across groups. Though much research has investigated the performance of several techniques for assessing invariance, very little work has examined how methods perform under small sample size, and non-normally distributed latent trait conditions. Therefore, the purpose of this simulation study was to compare invariance assessment Type I error and power rates between (a) the normal based maximum likelihood estimator, (b) a skewed-t distribution maximum likelihood estimator, (c) Bayesian estimation, and (d) the generalized structured component analysis model. The study focused on a 1-factor model. Results of the study demonstrated that the maximum likelihood estimator was robust to violations of normality of the latent trait, and that the Bayesian and generalized component models may be useful in particular situations. Implications of these findings for research and practice are discussed.

On the Observable Behaviour of Composite Components

The crucial strength of the component paradigm lies in the possibility to encapsulate behaviours. In this work, we focus on the observable behaviour of composite components which encapsulate the behaviour of (possibly large) assemblies of connected subcomponents. We first present our general component model which is equipped with a precise formal semantics allowing us to distinguish systematically different kinds of behaviours for ports, for components, and for component assemblies; technically we use UML2 notation for describing component structures and I/O-transition systems for behaviours. Then we investigate an efficient method for the computation of the observable behaviour of composite components which can circumvent the possibly infeasible intermediate computation of the usually complex behaviour of underlying assemblies if there are behaviourally neutral subcomponents. Finally, we utilise the fact that components are connected via ports such that checks for behavioural neutrality of components can be reduced to checks for behavioural neutrality of connected ports in the case of weakly deterministic port behaviours.

The Algebra of Connectors—Structuring Interaction in BIP

We provide an algebraic formalization of connectors in the BIP component framework. A connector relates a set of typed ports. Types are used to describe different modes of synchronization: rendezvous and broadcast, in particular. Connectors on a set of ports P are modeled as terms of the algebra AC(P), generated from P by using a binary fusion operator and a unary typing operator. Typing associates with terms (ports or connectors) synchronization types --- trigger or synchron --- that determine modes of synchronization. Broadcast interactions are initiated by triggers. Rendezvous is a maximal interaction of a connector including only synchrons. The semantics of AC(P) associates with a connector the set of its interactions. It induces on connectors an equivalence relation which is not a congruence as it is not stable for fusion. We provide a number of properties of AC(P) used to symbolically simplify and handle connectors. We provide examples illustrating applications of AC(P), including a general component model encompassing synchrony, methods for incremental model decomposition, and efficient implementation by using symbolic techniques.

Verified systems by composition from verified components

This paper presents an approach to integration of model checking into component-based development of software systems. This approach assists in development of highly reliable component-based software systems and reduces the complexity of verifying these systems by utilizing their compositional structures. Temporal properties of a software component are specified, verified, and packaged with the component. Selection of a component for reuse considers not only its functionality but also its temporal properties. When a component is composed from other components, a property of the component is verified on an abstraction of the component. The abstraction is constructed from environment assumptions of the component and verified properties of its sub-components. A general component model that enables component verification is defined. Component verification is discussed in the context of the instantiation of the general component model on an Asynchronous Interleaving Message-passing computation model. This approach has been applied to improve reliability of instances of TinyOS, a component-based run-time system for networked sensors. A case study on TinyOS is included, which illustrates the applicability of this approach, the detection of a bug, and the reduction in model checking complexity.

Towards a General Component Model for Web-Based Applications

The cost effective development of web applications is perhaps one of the most challenging areas of software engineering today. Not only are the problems to be solved, and the solution technologies to be used, in web application development among the most rapidly changing in the software industry, but the business pressures of cost, quality and time-to-market are among the most extreme. Web application development therefore has potentially the most to gain from software reuse approaches that can offer a greater return on development time than traditional approaches. However, simply combining ideas from these reuse paradigms and traditional web development technologies in ad-hoc ways will not result in sustainable improvements. In this paper we describe a systematic way of combining the benefits of component-based development and model driven architectures, two important reuse approaches, to support the cost effective development and maintenance of web applications. After first defining a suitably abstract component-model, the paper explains how component architectures can be systematically and rigorously modeled using UML. It then describes a powerful technique, known as stratification, for separating the various cross cutting aspects of a web application such that a suitable platform specific architecture can be traceably generated. Finally, the paper introduces a technique for increasing the trustworthiness of components by giving them the capability to check their deployment environment at run-time.

6.5.1 Using COTS tools in the development of a Model Based Avionics Architecture Tool

AbstractInformation and discussion of the development of an Avionics Architecture Tool that is model‐based using commercial off the shelf (COTS) products will be provided. Statemate Magnum from I‐Logix Inc. was used in this work. A number of areas of interest will be discussed, including the user and institutional needs affecting tool design, development, and deliverables, how plug‐and‐play general component models is used for avionics architecture rapid prototyping, the basic architecture of a general component model, and preliminary results of utilising the tool to develop a “straw man” avionics architecture.

Single-phase power distribution system power flow and fault analysis

Alternative methods for power flow and fault analysis of single-phase distribution systems are presented. The algorithms for both power flow and fault analysis utilize a generalized approach to network modeling. The generalized admittance matrix, formed using elements of linear graph theory, is an accurate network model for all possible single-phase network configurations. Unlike the standard nodal admittance matrix formulation algorithms, the generalized approach uses generalized component models for the transmission line and transformer. The standard assumption of a common node voltage reference point is not required to construct the generalized admittance matrix. Therefore, truly accurate simulation results can be obtained for networks that cannot be modeled using traditional techniques. >