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

Hierarchical models for service-oriented systems

We present our approach to the denotation and representation of hierarchical graphs: a suitable algebra of hierarchical graphs and two domains of interpretations. Each domain of interpretation focuses on a particular perspective of the graph hierarchy: the top view (nested boxes) is based on a notion of embedded graphs while the side view (tree hierarchy) is based on gs-graphs. Our algebra can be understood as a high-level language for describing such graphical models, which are well suited for defining graphical representations of service-oriented systems where nesting (e.g. sessions, transactions, locations) and linking (e.g. shared channels, resources, names) are key aspects

Design, construction, and application of a generic visual language generation environment

2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A Framework for Specifying and Monitoring User Tasks

Knowledge about user task execution can help systems better reason about when to interrupt users. To enable recognition and forecasting of task execution, we develop a novel framework for specifying and monitoring user task sequences. For task specification, our framework provides an XML-based language with tags inspired by regular expressions. For task monitoring, our framework provides an event handler that manages events from any instrumented application and a monitor that observes a user's transitions within and among specified tasks. The monitor supports multiple active tasks and multiple instances of the same task. The use of our framework will enable systems to consider a user's position within a task model when reasoning about when to interrupt

A Component-Based Approach for Specifying Reusable Visual Languages

International audienceModel-Driven Engineering (MDE) encourages the use of graphical modeling tools, which facilitate the development process from modeling to coding. Such tools can be designed using the MDE approach into metamodeling environments called metaCASE tools. It turned out that current metaCASE tools still require, in most cases, manual programming to build full tool support for the modeling language, especially for users' native methodologies and representational elements and suffer from gaps in terms of reusability. In this context, we propose MID, a set of metamodels supporting the specification of modeling editors by means of reusable components and explain how representational metamodeling is carried out with it

An Algebra of Hierarchical Graphs and its Application to Structural Encoding

We define an algebraic theory of hierarchical graphs, whose axioms characterise graph isomorphism: two terms are equated exactly when they represent the same graph. Our algebra can be understood as a high-level language for describing graphs with a node-sharing, embedding structure, and it is then well suited for defining graphical representations of software models where nesting and linking are key aspects. In particular, we propose the use of our graph formalism as a convenient way to describe configurations in process calculi equipped with inherently hierarchical features such as sessions, locations, transactions, membranes or ambients. The graph syntax can be seen as an intermediate representation language, that facilitates the encodings of algebraic specifications, since it provides primitives for nesting, name restriction and parallel composition. In addition, proving soundness and correctness of an encoding (i.e. proving that structurally equivalent processes are mapped to isomorphic graphs) becomes easier as it can be done by induction over the graph syntax