As the design of software architectures emerges as a discipline within software engineering, it will become increasingly important to support architectural description and analysis with tools and environments. In this paper we describe a system for developing architectural design environments that exploit architectural styles to guide software architects in producing specific systems. The primary contributions of this research are: (a) a generic object model for representing architectural designs; (b) the characterization of architectural styles as specializations of this object model; and (c) a toolkit for creating an open architectural design environment from a description of a specific architectural style. We use our experience in implementing these concepts to illustrate how style-oriented architectural design raises new challenges for software support environments.

this paper I briefly outline and compare three approaches to providing such a basis. 2. Basic Properties

The Chimera Methodology is a new software engineering paradigm which addresses the problem of developing dynamically reconfigurable and reusable real-time software. The foundation of the Chimera methodology is the port-based object model of a reusable software component. The model is obtained by applying the port-automaton formal computational model to object-based design. Global state variable table real-time communication is used to integrate port-based objects, which eliminates the need for writing and debugging glue code. The Chimera real-time operating system provides tools to support the software models defined by the Chimera methodology, so that real-time software can be executed predictably using common real-time scheduling algorithms. A hypermedia user interface has been designed to allow users to easily assemble the real-time software components that are designed based on the Chimera methodology. Use of the methodology can result in a significant decrease the development time and cost of real-time applications.

We describe two integrated languages and associated tools for capturing and analyzing two different views of the architecture of an embedded system. One language is tailored to address guidance, navigation and control issues, while the other is tailored to address real-time, fault-tolerance, secure partitioning and multi-processor system issues. Both languages have tools that perform analyses appropriate for the issues each addresses, and tools to automatically configure the application software from a sufficiently detailed specification. The integrated languages and tools are intended to support an architecture reuse development process, in which the development of a new product in a family of similar products starts from a generic or reusable architecture specification for that product family.

Software system builders are increasingly recognizing the importance of exploiting design knowledge in the engineering of new systems. One way to do this is to define an architectural style for a collection of related systems. The style determines a coherent vocabulary of system design elements and rules for their composition. By structuring the design space for a family of related systems a style can, in principle, drastically simplify the process of building a system, reduce costs of implementation through reusable infrastructure, and improve system integrity through style-specific analyses and checks. In this article we describe one way to realize these benefits. Specifically, we describe Aesop, an environment for architectural design that supports the definition and use of architectural styles. Aesop adopts an object-oriented approach to the representation of both styles and designs. It also provides a repository of reusable architectural design fragments. In this way it...

The solution to the complex nature of developing software is software engineering. Software engineering provides techniques for structured design, formal- and informal analysis, and software metrics. The part of software engineering concerned with highlevel design and analysis is called software architectures. The objective of architectural analysis is to verify quality requirements on software. It can be applied on any level in the design but it focuses on the structure of the software. While the architecture provides a high-level abstraction of the software, divergences between the designed system and the requirements can be detected early in the design phase. However, the structure of the software alone does not always provide enough information in order to analyze all requirements put upon a software system. Additional information about the software construction is provided by different architectural views. The number of views, and their contents varies depending on the system domain and the required quality properties to analyze.

6 2 Introduction 7 3 Distributed Architecture Description Language 11 3.1 Overview : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 11 3.2 Backus-Naur Form (BNF) Semantics : : : : : : : : : : : : : : 12 3.3 Conversations : : : : : : : : : : : : : : : : : : : : : : : : : : : 13 3.3.1 Conversation Identifier : : : : : : : : : : : : : : : : : : 13 3.4 Connections : : : : : : : : : : : : : : : : : : : : : : : : : : : : 14 3.4.1 Connection Identifier : : : : : : : : : : : : : : : : : : : 15 3.4.2 Connectivity : : : : : : : : : : : : : : : : : : : : : : : : 15 3.4.3 Order : : : : : : : : : : : : : : : : : : : : : : : : : : : 15 3.4.4 Delivery : : : : : : : : : : : : : : : : : : : : : : : : : : 15 3.5 Dagent : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 16 3.5.1 Dagent Identifier : : : : : : : : : : : : : : : : : : : : : 16 3.5.2 Dagent Connections : : : : : : : : : : : : : : : : : : : 16 3.6 Alphabet : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 17 3....

This paper presents the first step towards a formalism for the modelling and analysis of dynamic reconfiguration of dependable real-time systems. The first version of our formalism (CCSdp) is focused on dynamic process reconfiguration. That is, process creation, deletion and replacement at runtime. We illustrate the process through which CCSdp is being developed using a series of trials in modelling a highly simplified sensor array, in order to determine the simplest construct necessary for modelling process reconfiguration. We define the syntax and operational semantics of CCSdp, and identify a bisimulation for further investigation.

A specification/generation software tool for building hard real-time distributed systems was redeveloped to generate Ada 95 rather that Ada 83 and targeted to the GNAT Ada 95 compiler under Sun Solaris. The resulting simulator was tested with missile flight simulation code. Language issues discovered and paradigms used are discussed with recommendations in the paper. Performance data is provided.

Abstract—Component-based software engineering is generally recognized as one of the best methods to develop, deploy, and manage increasingly complex software systems. To enable the dynamic composition of software modules, it is often required to expose their functionality dependencies. This results the a well-known requires-provides specifications ’ model. In this paper, we introduce a framework that enables individual software components to specify their requires-provides interfaces in a policy dependent way. Our framework specifies policies as combinations of Constraint Logic Programming (CLP) based rules. Moreover, our policies are flexible and expressive, allowing the enforcement of multiple aspects for the requested composition including security and quality of service. We apply our framework to specify Quality of Protection (QoP) and Quality of Service (QoS) policies. We demonstrate the applicability of our policy language using as an example a teleconferencing application with diverse requirements for the specification of security and resource policies. Keywords-Policy-based software composition; Policies for software interfaces; Policies for aspect-oriented software I.