Generating CAM aspect-oriented architectures using Model-Driven Development

Aspect-Oriented Software Development promotes the separation of those concerns that cut across several components and/or are tangled with the base functionality of a component, through all phases of the software lifecycle. The benefit of identifying these crosscutting concerns (aspects) at the architectural level in particular is to improve the architecture design and its subsequent evolution, before moving onto detailed design and implementation. However, software architects are not usually experts on using specific AO architecture notations. Therefore, the aim of this paper is to provide support to define and specify aspect-oriented (AO) architectures using non-AO ones as the source. We will use the Model-Driven Development approach to transform a component-based architecture model into an AO architecture model. The CAM (component and aspect model) model and the DAOP–ADL language are the proposals used for modelling and specifying AO architectures. We will show how we automated part of the process and the tool support.     

CHARMY: A Framework for Designing and Verifying Architectural Specifications

Introduced in the early stages of software development, the Charmy framework assists the software architect in making and evaluating architectural choices. Rarely, the software architecture of a system can be established once and forever. Most likely poorly defined and understood architectural constraints and requirements force the software architect to accept ambiguities and move forward to the construction of a suboptimal software architecture. Charmy aims to provide an easy and practical tool for supporting the iterative modeling and evaluation of software architectures. From an UML-based architectural design, an executable prototype is automatically created. Charmy simulation and model checking features help in understanding the functioning of the system and discovering potential inconsistencies of the design. When a satisfactory and stable software architecture is reached, Java code conforming to structural software architecture constraints is automatically generated through suitable transformations. The overall approach is tool supported.     

Reconciling software requirements and architectures with intermediate models

Little guidance and few methods are available for the refinement of software requirements into an architecture satisfying those requirements. Part of the challenge stems from the fact that requirements and architectures use different terms and concepts to capture the model elements relevant to each. In this paper we will present CBSP, a lightweight approach intended to provide a systematic way of reconciling requirements and architectures using intermediate models. CBSP leverages a simple set of architectural concepts (components, connectors, overall systems, and their properties) to recast and refine the requirements into an intermediate model facilitating their mapping to architectures. Furthermore, the intermediate CBSP model eases capturing and maintaining arbitrarily complex relationships between requirements and architectural model elements, as well as among CBSP model elements. We have applied CBSP within the context of different requirements and architecture definition techniques. We leverage that experience in this paper to demonstrate the CBSP method and tool support using a large-scale example.     

Architecture compliance checking at run-time

In this paper, we report on our experiences with architecture compliance checking – the process of checking whether the planned or specified software architecture is obeyed by the running system – of an OSGi-based, dynamically evolving application in the office domain. To that end, we first show how to dynamically instrument a running system in the context of OSGi in order to collect run-time traces. Second, we explain how to bridge the abstraction gap between run-time traces and software architectures, through the construction of hierarchical Colored Petri nets (CP-nets). In addition, we demonstrate how to design reusable hierarchical CP-nets. In an industry example, we were able to extract views that helped us to identify a number of architecturally relevant issues (e.g., architectural style violations, behavior violations) that would not have been detected otherwise, and could have caused serious problems like system malfunctioning or unauthorized access to sensitive data. Finally, we package valuable experiences and lessons learned from this endeavor.     

Providing Architectural Languages and Tools Interoperability through Model Transformation Technologies

Many architectural languages have been proposed in the last 15 years, each one with the chief aim of becoming the ideal language for specifying software architectures. What is evident nowadays, instead, is that architectural languages are defined by stakeholder concerns. Capturing all such concerns within a single, narrowly focused notation is impossible. At the same time, it is also impractical to define and use a “universal” notation, such as UML. As a result, many domain-specific notations for architectural modeling have been proposed, each one focusing on a specific application domain, analysis type, or modeling environment. As a drawback, a proliferation of languages exists, each one with its own specific notation, tools, and domain specificity. No effective interoperability is possible to date. Therefore, if a software architect has to model a concern not supported by his own language/tool, he has to manually transform (and, eventually, keep aligned) the available architectural specification into the required language/tool. This paper presents DUALLy, an automated framework that allows architectural languages and tools interoperability. Given a number of architectural languages and tools, they can all interoperate thanks to automated model transformation techniques. DUALLy is implemented as an Eclipse plugin. Putting it in practice, we apply the DUALLy approach to the Darwin/FSP ADL and to a UML2.0 profile for software architectures. By making use of an industrial complex system, we transform a UML software architecture specification in Darwin/FSP, make some verifications by using LTSA, and reflect changes required by the verifications back to the UML specification.     

Performance evaluation of network processor architectures: combining simulation with analytical estimation

The designs of most systems-on-a-chip (SoC) architectures rely on simulation as a means for performance estimation. Such designs usually start with a parameterizable template architecture, and the design space exploration is restricted to identifying the suitable parameters for all the architectural components. However, in the case of heterogeneous SoC architectures such as network processors the design space exploration also involves a combinatorial aspect––which architectural components are to be chosen, how should they be interconnected, task mapping decisions––thereby increasing the design space. Moreover, in the case of network processor architectures there is also an associated uncertainty in terms of the application scenario and the traffic it will be required to process. As a result, simulation is no longer a feasible option for evaluating such architectures in any automated or semi-automated design space exploration process due to the high simulation times involved. To address this problem, in this paper we hypothesize that the design space exploration for network processors should be separated into multiple stages, each having a different level of abstraction. Further, it would be appropriate to use analytical evaluation frameworks during the initial stages and resort to simulation techniques only when a relatively small set of potential architectures is identified. None of the known performance evaluation methods for network processors have been positioned from this perspective.We show that there are already suitable analytical models for network processor performance evaluation which may be used to support our hypothesis. To this end, we choose a reference system-level model of a network processor architecture and compare its performance evaluation results derived using a known analytical model [Thiele et al., Design space exploration of network processor architectures, in: Proc. 1st Workshop on Network Processors, Cambridge, MA, February 2002; Thiele et al., A framework for evaluating design tradeoffs in packet processing architectures, in: Proc. 39th Design Automation Conference (DAC), New Orleans, USA, ACM Press, 2002] with the results derived by detailed simulation. Based on this comparison, we propose a scheme for the design space exploration of network processor architectures where both analytical performance evaluation techniques and simulation techniques have unique roles to play.     

An Empirical Methodology for Exploring Reconfigurable Architectures

Recent research in reduced instruction set computer architectures has emphasized the importance of the empirical approach to designing computer architectures: architectural features are analyzed for utility and cost with respect to the system software that uses them. This approach has resulted in architectural simulators that allow computer designers to vary the features of the architecture being simulated and to analyze how the addition or removal of these features affects the cost and performance of the architecture. In this paper we apply this technique to a new area: reconfigurable architectures. Our approach is to use an empirical methodology that emphasizes the interaction between the target software and the reconfigurability features of parallel architectures. We have developed a set of tools, the reconfigurable architecture workbench, that assists in this methodology by allowing parallel programs to be simulated on a target architecture in order to study the performance implications of various reconfigurability features. The workbench is based on a framework, the PCI model, which describes the range of parallel programs, parallel architectures, and reconfiguration features. We present details of the design and implementation of a prototype workbench, GT-RAW. GT-RAW is being used to study the utility of one dimension of reconfiguration for image processing and image understanding applications. We present an example of the experiments that are being conducted with GT-RAW as a demonstration of our empirical methodology.     

基于进程代数的安全软件体系结构建模

分析了基于进程代数的软件体系结构模型的安全性,将相容性检查和互操作性检查从单个软件体系结构推广到不同风格的体系结构风格,扩展基于进程代数的软件体系结构描述语言,通过顺序进程代数项族和预定义的体系结构类型调用对软件体系结构安全建模。通过一个例子介绍了这种建模方法。     

An object based algebra for specifying a fault tolerant software architecture

In this paper we present an algebra of actors extended with mechanisms to model crash failures and their detection. We show how this extended algebra of actors can be successfully used to specify distributed software architectures. The main components of a software architecture can be specified following an object-oriented style and then they can be composed using asynchronous message passing or more complex interaction patterns. This formal specification can be used to show that several requirements of a software system are satisfied at the architectural level despite failures. We illustrate this process by means of a case study: the specification of a software architecture for intelligent agents which supports a fault tolerant anonymous interaction protocol.     

Mining architectural violations from version history

Software architecture conformance is a key software quality control activity that aims to reveal the progressive gap normally observed between concrete and planned software architectures. However, formally specifying an architecture can be difficult, as it must be done by an expert of the system having a high level understanding of it. In this paper, we present a lightweighted approach for architecture conformance based on a combination of static and historical source code analysis. The proposed approach relies on four heuristics for detecting absences (something expected was not found) and divergences (something prohibited was found) in source code based architectures. We also present an architecture conformance process based on the proposed approach. We followed this process to evaluate the architecture of two industrial-strength information systems, achieving an overall precision of 62.7 % and 53.8 %. We also evaluated our approach in an open-source information retrieval library, achieving an overall precision of 59.2 %. We envision that an heuristic-based approach for architecture conformance can be used to rapidly raise architectural warnings, without deeply involving experts in the process.     

Correct architecture refinement

A method is presented for the stepwise refinement of an abstract architecture into a relatively correct lower-level architecture that is intended to implement it. A refinement step involves the application of a predefined refinement pattern that provides a routine solution to a standard architectural design problem. A pattern contains an abstract architecture schema and a more detailed schema intended to implement it. The two schemas usually contain very different architectural concepts (from different architectural styles). Once a refinement pattern is proven correct, instances of it can be used without proof in developing specific architectures. Individual refinements are compositional, permitting incremental development and local reasoning. A special correctness criterion is defined for the domain of software architecture, as well as an accompanying proof technique. A useful syntactic form of correct composition is defined. The main points are illustrated by means of familiar architectures for a compiler. A prototype implementation of the method has been used successfully in a real application     

基于体系结构模型检查分布式控制系统

分布控制系统是大量硬件设备通过计算机系统得以控制和协调的高度复杂系统,它们也是任务统,需要保障其功能的高度正确性和可靠性.分析复杂控制系统的过程包含了证明或验证设计的系统确实满足某种需求.但由于系统的复杂度,有效分析系统是相当困难的.从系统设计和分析的角度看,基于体系结构方法可以运用层次化构造和抽象的方法来减小模型复杂度.模型检查技术是分析复杂系统构造满足正确和可靠性需求的有效方法.结合软件体系结构描述方法和模型检查技术,提出了基于体系结构的分布式控制系统形式分析方法,通过楼宇综合控制系统实例研究,展示了该方法在提高分布式控制系统设计质量方面的效果.     

SHADD: A scenario-based approach to software architectural defects detection

Although a good architecture is not sufficient to guarantee the success of a software product, undoubtedly it is essential to support the product quality. Evaluating software architecture provides early insight into product capabilities and limitations. The earlier in the life cycle the problems are detected, the cheaper it is to fix them. In this paper, at first, a review on well-known scenario-based methods to evaluate software architectures is presented, and their advantages and limitations are discussed. Then, a method named SHADD with different characteristics is introduced to detect architectural defects. Using a scenario-based approach, the proposed method finds out the critical aspects and potential problems threatening the system from the stakeholder’s point of view. Scenarios are then used as a basis for the process of architectural defects detection. SHADD and its elements are specified in a systematic form and an illustration of its application on the architecture of a real system is also presented. The results show that SHADD can be used to detect those architectural defects which may be uncovered during the application of conventional evaluation methods.     

Semi-automated architectural abstraction specifications for supporting software evolution

In this paper we present an approach for supporting the semi-automated architectural abstraction of architectural models throughout the software life-cycle. It addresses the problem that the design and implementation of a software system often drift apart as software systems evolve, leading to architectural knowledge evaporation. Our approach provides concepts and tool support for the semi-automatic abstraction of architecture component and connector views from implemented systems and keeping the abstracted architecture models up-to-date during software evolution. In particular, we propose architecture abstraction concepts that are supported through a domain-specific language (DSL). Our main focus is on providing architectural abstraction specifications in the DSL that only need to be changed, if the architecture changes, but can tolerate non-architectural changes in the underlying source code. Once the software architect has defined an architectural abstraction in the DSL, we can automatically generate architectural component views from the source code using model-driven development (MDD) techniques and check whether architectural design constraints are fulfilled by these models. Our approach supports the automatic generation of traceability links between source code elements and architectural abstractions using MDD techniques to enable software architects to easily link between components and the source code elements that realize them. It enables software architects to compare different versions of the generated architectural component view with each other. We evaluate our research results by studying the evolution of architectural abstractions in different consecutive versions of five open source systems and by analyzing the performance of our approach in these cases.     

Preserving architectural decisions through architectural patterns

Architectural decisions have emerged as a means to maintain the quality of the architecture during its evolution. One of the most important decisions made by architects are those about the design approach such as the use of patterns or styles in the architecture. The structural nature of this type of decisions give them the potential to be controlled systematically. In the literature, there are some works on the automation of architectural decision violation checking. In this paper we show that these works do not allow to detect all possible architectural decision violations. To solve this problem we propose an approach which: (i) describes architectural patterns that hold the architectural decision definition, (ii) integrates architectural decisions into an architectural model and, (iii) automates the architectural decision conformance checking. The approach is implemented using Eclipse modeling framework and its accompanying technologies. Starting from well-known architectural patterns, we show that we can formalize all those related to the structural aspect. Through two evaluations, we show that our approach can be adapted to different architecture paradigms and allows to detect more violations comparing to the existing approaches.