Architectural Modeling and Analysis for Safety Engineering

Architectural design modeling has emerged as a discipline in a complex system development. To implement early safety analysis, techniques for architectural design have been extended to concern the safety property. Various safety standard profiles, quantitative and qualitative analysis methods are proposed for assessment. However, few of them focuses on the feedback of the safety properties or analysis results on the adjustment to improve original architecture. In this paper, we present an approach to combine safety analysis with architecture modeling. First, we extend the meta-model of our architecture description language - Breeze/ADL with safety elements for design. Second, safety specifications are generated from Breeze/ADL, and then to be converted into Open FTA for FTA (Fault Tree Analysis). Our Breeze/ADL also supports rule definitions to adjust the architecture, to cope with safety problems. Moreover, model checking will be applied to verify the correctness of the adjustment. Finally, the tool Breeze/SA demonstrates the feasibility of our approach.

: Architecture Description Languages provide significant opportunity for the incorporation of formal methods and engineering models into the analysis of software and system architectures. A standard is being developed for embedded real-time safety critical systems which will support the use of various formal approaches to analyze the impact of the composition of systems from hardware and software and which will allow the generation of system glue code with the performance qualities predicted. The standard the Avionics Architecture Description Language (AADL), is based on the MetaH language developed under DARPA and US Army funding and on the model driven architectural based approach demonstrated with this technology over the last 12 years. The AADL standard will include a UML profile useful for avionics, space, automotive, robotics and other real-time concurrent processing domains including safety critical applications.

Software product line (SPL) engineering has emerged to become a mature domain for maximizing reuse within the context of a family of related software products. Within the process of SPL, the variability and commonality among the different products within the scope of a family is captured and modeled into a system's `feature model'. Currently, there are no architecture description languages (ADLs) that support the relationship between the feature model domain and the system architecture domain, leaving a gap which significantly increases the complexity of analyzing the system's architecture and insuring that it complies with its set feature model and variability requirements. In this paper we present ADLARS, an architecture description language that supports the relationship between the system's feature model and the architectural structures in an attempt to alleviate the aforementioned problem. The link between the two spaces also allows the automatic generation of product architectures from the family reference architecture

Software architecture is high-level software design, dealing with the structure and organization of software systems. A software architecture is defined in terms of computational components and interactions among those components. Architecture description languages (ADLs) represent architecture-level software designs. Different ADLs often have different intents; e.g., Rapide supports architecture simulation and Acme is intended to be both an ADL and an ADL interchange format. Experimental applications of two ADLs were conducted to determine the effectiveness of ADLs for architecture-level analysis of simulation systems; one of them is reported. Acme was used to model the architecture of ModSAF and to analyze its run-time performance. The model was used to analyze execution time at the component and federate levels and to estimate the maximum number of internal and external simulation entities that could be supported by the ModSAF architecture. The experiment showed that ADLs could model important features of simulation system architectures.

In recent years, the MicroServices architectural style has significantly grown in popularity due to its application to large-scale software systems with positive results. In the domain of Software Architecture, textual Architecture Description Languages (ADLs) can be used to describe the architecture of a software intensive system at an abstract level. μσADL is such an ADL, co-created by the author, designed in order to provide to software architects and various stakeholders a practical way for describing software systems that follow the microservices architectural style. In this paper, an example is presented, where a system based upon this style is described using μσADL. The constructs provided by the language concerning the description and dynamic reconfiguration of a microservice architecture are presented.

There are many challenges which face designers of complex system architectures, particularly safety–critical or real-time systems. The introduction of Architecture Description Languages (ADLs) has helped to meet these challenges by consolidating information about a system and providing a platform for modelling and analysis capabilities. However, managing this wealth of information can still be problematic, and evaluation of potential design decisions is still often performed manually. Automatic architectural optimisation can be used to assist this decision process, enabling designers to rapidly explore many different options and evaluate them according to specific criteria. In this paper, we present a multi-objective optimisation approach based on EAST-ADL, an ADL in the automotive domain, with the goal of combining the advantages of ADLs and architectural optimisation. The approach is designed to be extensible and leverages the capabilities of EAST-ADL to provide support for evaluation according to different factors, including dependability, timing/performance, and cost. The technique is applied to an illustrative example system featuring both hardware and software perspectives, demonstrating the potential benefits of this concept to the design of embedded system architectures.

This paper presents a framework for generating assembler and disassembler from ADL (architecture description language), which enables processor architecture designers to explore a large design space by quickly modifying the architecture description written in high abstraction level ADL. We present our ADL: GADL(GNU tool chain based ADL) and propose the binary utilities generation algorithms for GADL. Some issues are discussed and resolved which have not been covered by related research. We have implemented the binary utilities generator with the proposed algorithms and used it to generate the binary utilities for a DSP we are designing, which shows the efficiency of the algorithms.

Software architecture research focuses on models of software architectures as specified in architecture description languages (ADLs). As research progresses in specific areas of software architectures, more and more architectural information is created. Ideally, this information can be stored in the model. An extensible modeling language is crucial to experimenting with and building tools for novel modeling constructs that arise from evolving research. Traditional ADLs typically support a small set of modeling constructs very well, but adapt to others poorly. XML provides an ideal platform upon which to develop an extensible modeling language for software architectures. Previous XML-based ADLs successfully leveraged XML's large base of off-the-shelf tool support, but did not take advantage of its extensibility. To give software architecture researchers more freedom to explore new possibilities and modeling techniques, while maximizing reuse of tools and modeling constructs, we have developed xADL 2.0, a highly extensible XML-based ADL. xADL 2.0 supports run-time and design time modeling, architecture configuration management and model-based system instantiation. Additionally, xADL 2.0 has a set of extensible infrastructure tools that support the creation, manipulation, and sharing of xADL 2.0 documents.

Software applications are continuing to grow at a rapid pace and became more and more complex. Thus, the use of software architectures in the development process is the ideal solution to deal with this issue. In this context, many Architecture Description Languages (ADLs) have been introduced to define the software architecture and its elements. Most of these ADLs do not address the dynamic behavior of the software architecture. This dynamic behavior is most commonly known as architectural reconfiguration. In our work, we use the Architecture Analysis and Design Language (AADL) due to its capacity to represent the architectural reconfiguration. However, AADL suffers from the absence of a concrete model to define its formal semantics. This paper presents a formal approach based on Bigraphical Reactive Systems (BRS) to model the dynamic architectural reconfiguration of embedded real-time systems expressed in AADL.

Research and experimentation in software architectures over the past decade (1992-2002) have yielded a plethora of software architecture description languages (ADLs). Continuing innovation indicates that it is reasonable to expect more new ADLs, or at least ADL features. This research process is impeded by the difficulty and cost associated with developing new notations. An architect in need of a unique set of modeling features must either develop a new architecture description language from scratch or undertake the daunting task of modifying an existing language. In either case, it is unavoidable that a significant effort will be expended in building or adapting tools to support the language. To remedy this situation, we have developed an infrastructure for the rapid development of new architecture description languages. Key aspects of the infrastructure are its XML-based modular extension mechanism, its base set of reusable and customizable architectural modeling constructs, and its equally important set of flexible support tools. The paper introduces the infrastructure and demonstrates its value in the context of several real-world applications.

The analysis of software architecture plays an important role in understanding the system structures and facilitate proper implementation of user requirements. Despite its importance in the software engineering practice, the lack of formal description and verification support in this domain hinders the development of quality architectural models. To tackle this problem, in this work, we develop an approach for modeling and verifying software architectures specified using Monterey Phoenix (MP) architecture description language. MP is capable of modeling system and environment behaviors based on event traces, as well as supporting different architecture composition operations and views. First, we formalize the syntax and operational semantics for MP; therefore, formal verification of MP models is feasible. Second, we extend MP to support shared variables and stochastic characteristics, which not only increases the expressiveness of MP, but also widens the properties MP can check, such as quantitative requirements. Third, a dedicated model checker for MP has been implemented, so that automatic verification of MP models is supported. Finally, several experiments are conducted to evaluate the applicability and efficiency of our approach.

Component-based development leverages software reusability and reduces development costs. Enterprise JavaBeans (EJB) is a component model developed to reduce the complexity of software development and to facilitate reuse of components. However, EJB does not support component assembly by a plug-and-play technique due to the hard-wired composition at the code level. To cope with this problem, an architecture for EJB component assembly is defined at the abstract level and the inconsistency between the system architecture and its implementation must be eliminated at the implementation level. We propose a component-based application development tool named the COBALT assembler that supports the design and implementation of EJB component assembly by a plug-and-play technique based on the architecture style. The system architecture is first defined by the Architecture Description Language (ADL). The wrapper code and glue code are then generated for the assembly. After the consistency between the architecture and its implementation is checked, the assembled EJB components are deployed in an application server as a new composite component. We use the COBALT assembler for a shopping mall system and demonstrate that it can promote component reuse and leverage the system maintainability.

In this article we contribute to the issue of the recent research work, in which software architecture is oriented more toward the OMG group. Thus, we try to map any ADL (Architecture Description Language) into MDA (Model Driven Architecture) platform. Our strategy is based on constructing a meta ontology that next can be used as a facade meta-model for semantic mapping of ADLs into MDA platforms. We show how this strategy can be used by mapping COSA architectural description concepts into CORBA. The goal of our work is to increase the high level of systems' concepts abstracting for wrapping and integrating heterogeneous software concepts into MDA platforms via a top-level ontology.

Self-adaptive systems evolve during system's execution against changes in operating environment. Such evolution and reconfiguration can be specified at architecture level using a syntactical expressive language such as Architecture Description Languages (ADLs). Variability modeling is an excellent instrument to model variations of software artifacts and their behavior within a self-adaptive system. However, existing ADLs that support dynamic reconfiguration do not explicitly model variation points on which the reconfiguration is based. This constitutes a barrier for a flexible management of reconfiguration at architecture level as well as traceability issues between a dynamic description given at architectural level and its counterpart at other abstraction levels. In this paper, we propose a variant-rich service-oriented ADL that enables system to reconfigure itself at runtime in response to a context change. To this end, our modular ADL, called Dynamic Service-Oriented Product Lines Architecture Description Language (DSOPL-ADL), specifies dynamic reconfigurations at architecture level besides specifying structural, variability and context information. Among several specified variable configurations at architecture level, one concrete configuration is generated at runtime triggered by a context value. Furthermore, an implementation code can be automatically generated from the architectural description.

The benefits offered by software architectures include providing an improved understanding of high-level relationships amongst systems components and facilitating in making principled decisions between alternatives. A vast majority of architectural decisions are focused on realising functional requirements and often ignore the nonfunctional requirements (quality attributes) altogether or include them as an afterthought. This has a negative impact on the overall acceptance of the software system by its intended users. Moreover, these architectures are specified using diagrammatic notations such as boxes and lines as connectors between them. As a result, such semiformal representations lack precision in their definitions and may lead to misinterpretations of the architecture resulting in errors being introduced at later stages of development. Although several Architectural Description Languages (ADLs) exist for the formalisation of systems architectures, few are designed for formalising nonfunctional requirements. Since ADLs concentrate on component-level representations and not on the system as a whole, their support of non-functional requirements is limited. Additionally, as each ADL normally supports one quality attribute, multiple ADLs are required to cater for various quality attributes. This articles aims to address the challenges of inadequacies of specifying quality attributes in software systems in a manner that is both formal and applicable to a wider range of quality attributes. To achieve this goal, this paper present a process model that assists in formalising the non-functional requirements of a service-based software system and eliminates the need for multiple ADLs. It demonstrates the practicability of the proposed model by applying it to one quality attribute, namely “availability”, using the general purpose Z specification language.