On abstraction in the OMG hierarchy: systems, models, and descriptions

The Model-Driven Architecture (MDA) uses a metadata hierarchy with several layers that are placed on top of each other. The traditional view is that the layers provide abstractions related to models in languages defined by meta-models. Over the years, it has been difficult to define a consistent understanding of the layers. In this paper, we propose such a consistent understanding by clarifying the relations between the different elements in the hierarchy. This is done based on the Scandinavian approach to modelling that distinguishes between systems and system descriptions. Systems can be physical, digital, or even mental, while descriptions can be programs, language descriptions, specifications, and diagrams. We relate descriptions and systems by explaining where semantics of objects originate and how they apply in the hierarchy.publishedVersionPaid Open Acces

Structure and Properties of Traces for Functional Programs

The tracer Hat records in a detailed trace the computation of a program written in the lazy functional language Haskell. The trace can then be viewed in various ways to support program comprehension and debugging. The trace was named the augmented redex trail. Its structure was inspired by standard graph rewriting implementations of functional languages. Here we describe a model of the trace that captures its essential properties and allows formal reasoning. The trace is a graph constructed by graph rewriting but goes beyond simple term graphs. Although the trace is a graph whose structure is independent of any rewriting strategy, we define the trace inductively, thus giving us a powerful method for proving its properties

Modelling and analyzing adaptive self-assembling strategies with Maude

Building adaptive systems with predictable emergent behavior is a challenging task and it is becoming a critical need. The research community has accepted the challenge by introducing approaches of various nature: from software architectures, to programming paradigms, to analysis techniques. We recently proposed a conceptual framework for adaptation centered around the role of control data. In this paper we show that it can be naturally realized in a reflective logical language like Maude by using the Reflective Russian Dolls model. Moreover, we exploit this model to specify, validate and analyse a prominent example of adaptive system: robot swarms equipped with self-assembly strategies. The analysis exploits the statistical model checker PVeStA

ModeL4CEP: Graphical domain-specific modeling languages for CEP domains and event patterns

Complex event processing (CEP) is a cutting-edge technology that allows the analysis and correlation of large volumes of data with the aim of detecting complex and meaningful events through the use of event patterns, as well as permitting the inference of valuable knowledge for end users. Despite the great advantages that CEP can bring to expert or intelligent business systems, it poses a substantial challenge to their users, who are business experts but do not have the necessary knowledge and experience using this technology. The main problem these users have to face is precisely hand-writing the code for event pattern definition, which requires them to implement the conditions to be met to detect relevant situations for the domain in question by using a particular event processing language (EPL). In order to respond to this need, in this paper we propose both a graphical domain-specific modeling language (DSML) for facilitating CEP domain definitions by domain experts, and a graphical DSML for event pattern definition by non-technological users. The proposed languages provide high expressiveness and flexibility and are independent of event patterns and actions’ implementation code. This way, domain experts can define the relevant event types and patterns within their business domain, without having to be experts on EPL programming, nor on other complicated computer science technological issues, beyond an understandable and intuitive graphical definition. Furthermore, with these DSMLs, users will also be able to define the actions to be automatically taken once a pattern is detected in the system. Further benefits of these DSMLs are evaluated and discussed in depth in this paper

Web-centred end-user component modelling

This paper formally defines a web component model enabling end-user programmers to build component-based rich internet applications (RIAs) that are tailored to meet their particular needs. It is the product of a series of previously published papers. The formal definition in description logic verifies that the model is consistent and subsumes currently existing models. We demonstrate experimentally that it is more effective than the others. Current tools propose very disparate web component models, which are based on the appropriate invocation of service backends, overlooking user needs in order to exploit these services and resources in a friendly manner. We have proposed a web model based on a detailed study of existing tools, their pros and cons, limitations and key success factors that have enabled other web end-user development (WEUD) solutions to help end-user programmers to build software to support their needs. In this paper we have verified that the proposed model subsumes and is instantiated by the models of the other existing tools that we analysed, coming a step closer to the standardization of end-user centred RIAs and development environments. We have implemented a development tool, called EzWeb, to produce RIAs that implement the proposed model. This tool enables users to develop their application following the model’s component structure based on end-user programming success factors. We report a statistical experiment in which users develop increasingly complex web software using the EzWeb tool generating RIAs that conform to the proposed component model, and other WEUD tools generating RIAs that conform to other models. This experiment confirms the applicability of the proposed model and demonstrates that more enduser programmers (EUPs) (users concerned with programming primarily for personal rather public use) successfully develop web solutions for complex problems using the EzWeb tool that implements the model, which is more efficient than existing tools that implement other models