A formal support to business and architectural design for service-oriented systems

Architectural Design Rewriting (ADR) is an approach for the design of software architectures developed within Sensoria by reconciling graph transformation and process calculi techniques. The key feature that makes ADR a suitable and expressive framework is the algebraic handling of structured graphs, which improves the support for specification, analysis and verification of service-oriented architectures and applications. We show how ADR is used as a formal ground for high-level modelling languages and approaches developed within Sensoria

Constraint Design Rewriting

We propose an algebraic approach to the design and transformation of constraint networks, inspired by Architectural Design Rewriting. The approach can be understood as (i) an extension of ADR with constraints, and (ii) an application of ADR to the design of reconfigurable constraint networks. The main idea is to consider classes of constraint networks as algebras whose operators are used to denote constraint networks with terms. Constraint network transformations such as constraint propagations are specified with rewrite rules exploiting the network’s structure provided by terms

Ten virtues of structured graphs

This paper extends the invited talk by the first author about the virtues of structured graphs. The motivation behind the talk and this paper relies on our experience on the development of ADR, a formal approach for the design of styleconformant, reconfigurable software systems. ADR is based on hierarchical graphs with interfaces and it has been conceived in the attempt of reconciling software architectures and process calculi by means of graphical methods. We have tried to write an ADR agnostic paper where we raise some drawbacks of flat, unstructured graphs for the design and analysis of software systems and we argue that hierarchical, structured graphs can alleviate such drawbacks

Exploiting the Hierarchical Structure of Rule-Based Specifications for Decision Planning

Rule-based specifications have been very successful as a declarative approach in many domains, due to the handy yet solid foundations offered by rule-based machineries like term and graph rewriting. Realistic problems, however, call for suitable techniques to guarantee scalability. For instance, many domains exhibit a hierarchical structure that can be exploited conveniently. This is particularly evident for composition associations of models. We propose an explicit representation of such structured models and a methodology that exploits it for the description and analysis of model- and rule-based systems. The approach is presented in the framework of rewriting logic and its efficient implementation in the rewrite engine Maude and is illustrated with a case study.

Architectural abstraction as transformation of poset labelled graphs

The design of large, complex computer based systems, based on their architecture, will benefit from a formal system that is intuitive, scalable and accessible to practitioners. The work herein is based in graphs which are an efficient and intuitive way of encoding structure, the essence of architecture. A model of system architectures and architectural abstraction is proposed, using poset labelled graphs and their transformations. The poset labelled graph formalism closely models several important aspects of architectures, namely topology, type and levels of abstraction. The technical merits of the formalism are discussed in terms of the ability to express and use domain knowledge to ensure sensible refinements. An abstraction / refinement calculus is introduced and illustrated with a detailed usage scenario. The paper concludes with an evaluation of the formalism in terms of its rigour, expressiveness, simplicity and practicality. © J.UCS

Towards Consistency Management for a Business-Driven Development of SOA

The usage of the Service Oriented Architecture (SOA) along with the Business Process Management has emerged as a valuable solution for the complex (business process driven) system engineering. With a Model Driven Engineering where the business process models drive the supporting service component architectures, less effort is gone into the Business/IT alignment during the initial development activities, and the IT developers can rapidly proceed with the SOA implementation. However, the difference between the design principles of the emerging domainspecific languages imposes serious challenges in the following re-design phases. Moreover, enabling evolutions on the business process models while keeping them synchronized with the underlying software architecture models is of high relevance to the key elements of any Business Driven Development (BDD). Given a business process update, this paper introduces an incremental model transformation approach that propagates this update to the related service component configurations. It, therefore, supports the change propagation among heterogenous domainspecific languages, e.g., the BPMN and the SCA. As a major contribution, our approach makes model transformation more tractable to reconfigure system architecture without disrupting its structural consistency. We propose a synchronizer that provides the BPMN-to-SCA model synchronization with the help of the conditional graph rewriting

Full Semantics Preservation in Model Transformation – A Comparison of Proof Techniques

Model transformation is a prime technique in modern, model-driven software design. One of the most challenging issues is to show that the semantics of the models is not affected by the transformation. So far, there is hardly any research into this issue, in particular in those cases where the source and target languages are different.\ud \ud In this paper, we are using two different state-of-the-art proof techniques (explicit bisimulation construction versus borrowed contexts) to show bisimilarity preservation of a given model transformation between two simple (self-defined) languages, both of which are equipped with a graph transformation-based operational semantics. The contrast between these proof techniques is interesting because they are based on different model transformation strategies: triple graph grammars versus in situ transformation. We proceed to compare the proofs and discuss scalability to a more realistic setting.\u

Generic approach for graph-based description of dynamically reconfigurable architectures

Architectural adaptation is studied for handling adaptation in autonomic distributed systems. It is achieved by implementing a model-based approach for managing reconfiguration of dynamic architectures. Describing such architectures includes defining rules for describing both architectural styles and theirs reconfiguration mechanisms. Within this research context, the work presented in this paper is conducted using formal specification based on graphs and graph rewriting appropriately for tackling architectural adaptation problems. A graph-based general approach for describing architectures and handling their dynamic reconfiguration is introduced. Our approach is illustrated in the context of a distributed hierarchical application. The formal models that allow the generation of a graph grammar for dynamic architecture description and the automatic definition of transformation rules for achieving intern self-protecting during the adaptation are elaborated

Constraint design rewriting

Constraint networks are hyper-graphs whose nodes and hyper-edges represent variables and relations between them, respectively. The problem to assign values to variables by satisfying all constraints is NP-complete. We propose an algebraic approach to the design and transformation of constraint networks, inspired by Architectural Design Rewriting (ADR). The main idea is to exploit ADR to equip constraint networks with some hierarchical structure and represent them as terms of a suitable algebra, when possible. Constraint network transformations such as constraint propagations are then specified with efficient rewrite rules exploiting the network's structure provided by terms. The approach can be understood as (i) an extension of ADR with constraints, and (ii) an application of ADR to the design of reconfigurable constraint networks

A survey of self-management in dynamic software architecture specifications

As dynamic software architecture use becomes more widespread, a variety of formal specification languages have been developed to gain a better understanding of the foundations of this type of software evolutionary change. In this paper we survey 14 formal specification approaches based on graphs, process algebras, logic, and other formalisms. Our survey will evaluate the ability of each approach to specify self-managing systems as well as the ability to address issues regarding expressiveness and scalability. Based on the results of our survey we will provide recommendations on future directions for improving the specification of dynamic software architectures, specifically self-managed architectures