Tomi Männistö

Towards a general ontology of configuration

This article presents a generalized ontology of product configuration as a step towards a general ontology of configuration, which is needed to reuse and share configuration knowledge. The ontology presented consists of a set of concepts for representing the knowledge on a configuration and the restrictions on possible configurations. The ontology is based on a synthesis of the main approaches to configuration. Earlier approaches are extended with new concepts arising from our practical experience on configurable products. The concepts include components, attributes, resources, ports, contexts, functions, constraints, and relations between these. The main contributions of this work are in the detailed conceptualization of knowledge on product structures and in extending the resource concept with contexts for limiting the availability and use of resources. In addition, constraint sets representing different views on the product are introduced. The ontology is compared with the previous work on configuration. It covers all the principal approaches, that is, connection-based, structure-based, resource-based, and function-based approaches to configuration. The dependencies between the concepts arising from different conceptualizations are briefly analyzed. Several ways in which the ontology could be extended are pointed out.

Kumbang: A domain ontology for modelling variability in software product families

Variability is the ability of a system to be efficiently extended, changed, customised or configured for use in a particular context. There is an ever-growing demand for variability of software. Software product families are an important means for implementing software variability. We present a domain ontology called Kumbang for modelling the variability in software product families. Kumbang synthesises previous approaches to modelling variability in software product families. In addition, it incorporates modelling constructs developed in the product configuration domain for modelling the variability in non-software products. The modelling concepts include components and features with compositional structure and attributes, the interfaces of components and connections between them, and constraints. The semantics of Kumbang is rigorously described using natural language and a UML profile. We provide preliminary proof of concept for Kumbang: the domain ontology has been provided with a formal semantics by implementing a translation into a general-purpose knowledge representation language with formal semantics and inference support. A prototype tool for resolving variability has been implemented.

Modelling generic product structures in STEP

Industrial companies need powerful data modelling mechanisms, e.g. classification, for the description of their products. The companies that adapt their products to the needs of individual customers in a routine manner have perhaps the most urgent needs. They must efficiently describe large numbers of product variants. STEP Application Protocol 214 (AP 214) for the automotive industry also addresses the modelling of product variants, i.e. generic product structure modelling. In addition to AP 214, the same mechanisms are needed in other standardization efforts as well, e.g. STEPlib of AP 221 and PLIB. STEP, however, does not include a mechanism for using classification and inheritance for modelling products of an individual company. These facilities are included in EXPRESS, but EXPRESS can only be used for describing the data schema to be standardized. The fundamental structure of STEP, therefore, prohibits a company from modelling its products in an object-oriented manner. This is an issue that may seriously affect the future of STEP as a general product-modelling methodology. The problems and possibilities of extending STEP in this direction within its current structure are discussed and a new mechanism is outlined as an alternative solution.

State-of-the-practice in product configuration — a survey of 10 cases in the Finnish industry

The design and production of goods that satisfy the special needs of individual customers are of central interest to the European industry. A major trend is to improve customer specific adaptation with configurable products. We are interested in the methods, practices and tools that support product configuration tasks. The research described in this paper is meant to guide our future work. We have 1) established a framework for understanding the problem area of product configuration in a fairly wide sense by identifying a number of factors and 2) carried out ten actual case studies using the proposed framework.

A unified conceptual foundation for feature modelling

Feature modelling has become perhaps the most popular method for representing variabilities and commonalities in software product families. A large number of feature modelling methods and supporting tools have been reported. The conceptual foundation of feature models remains vague, a fact that severely undermines the usability of feature models. Therefore, we introduce Forfamel, a rigorous conceptual foundation for feature modelling. Forfamel synthesises existing feature modelling methods in the sense that it covers most concepts and constructs found in existing feature modelling methods. In addition, Forfamel includes a few additional constructs that may prove to be useful. We show the novel contribution of Forfamel by reflecting it against previous feature modelling methods and arguing for its underlying design decisions.

Nivel: a metamodelling language with a formal semantics

Much work has been done to clarify the notion of metamodelling and new ideas, such as strict metamodelling, distinction between ontological and linguistic instantiation, unified modelling elements and deep instantiation, have been introduced. However, many of these ideas have not yet been fully developed and integrated into modelling languages with (concrete) syntax, rigorous semantics and tool support. Consequently, applying these ideas in practice and reasoning about their meaning is difficult, if not impossible. In this paper, we strive to add semantic rigour and conceptual clarity to metamodelling through the introduction of Nivel, a novel metamodelling language capable of expressing models spanning an arbitrary number of levels. Nivel is based on a core set of conceptual modelling concepts: class, generalisation, instantiation, attribute, value and association. Nivel adheres to a form of strict metamodelling and supports deep instantiation of classes, associations and attributes. A formal semantics is given for Nivel by translation to weight constraint rule language (WCRL), which enables decidable, automated reasoning about Nivel. The modelling facilities of Nivel and the utility of the formalisation are demonstrated in a case study on feature modelling.

Multiple abstraction levels in modelling product structures

Abstract The need for product customisation is driving industrial companies towards a very large product variety, which affects many functions of a company, including the after-sales. Systematic maintenance records of very different product individuals cannot be kept without an abstract view to the population of delivered products. However, the older the product individual, the less systematically recorded information there usually is about it. We defined a novel mechanism based on generic models of product individuals organised into a specialisation hierarchy to support multiple abstraction levels. For creating such hierarchies, we defined a set of transformation operations on models.

A Koala-Based Approach for Modelling and Deploying Configurable Software Product Families

An approach for modelling configurable software product families (CSPFs) and for automated configuring of product individuals using the models is presented. It is based on a similar approach for configuring physical products. The conceptual foundation and syntax of the Koalish modelling language used for this purpose are defined. The language extends Koala, a component model and architecture description language, with explicit variation modelling mechanisms. Koalish is further provided a formal semantics by defining a translation from it to Weight Constraint Rule Language (WCRL), a form of logic programs. This allows using an existing inference tool for WCRL, smodels, to implement the reasoning needed in the configurator. The configurator is able to construct all valid product individuals, with respect to a Koalish model of a CSPF, that satisfy a given set of requirements. The implemented functionality of the configurator has been tested using small-scale toy examples, for which it performs adequately.

Evolution and change in data management — issues and directions

One of the fundamental aspects of information and database systems is that they change. Moreover, in so doing they evolve, although the manner and quality of this evolution is highly dependent on the mechanisms in place to handle it. While changes in data are handled well, changes in other aspects, such as structure, rules, constraints, the model, etc., are handled to varying levels of sophistication and completeness. In order to study this in more detail a workshop on Evolution and Change in Data Management was held in Paris in November 1999. It brought together researchers from a wide range of disciplines with a common interest in handling the fundamental characteristics and the conceptual modelling of change in information and database systems. This short report of the workshop concentrates on some of the general lessons that emerged during the four days.

Variability in software architecture: current practice and challenges

Variability in software-intensive systems is usually understood as the ability of a software artifact to be changed in order to fit different contexts, environments, or purposes. Software architecture on the other hand determines the structure of a software system, and is described in an architecture description. This description includes the major stakeholders of a software system and their concerns. Variability is reflected in and facilitated through the software architecture. The First International Workshop on Variability in Software Architecture (VARSA) was held jointly with WICSA 2011 in Boulder, Colorado. The goal of the workshop was to explore and advance the state-of-the art in variability in software architecture. It featured four research paper presentations, two invited talks, and three working groups that discussed specific topics. This report summarizes the themes of the workshop, presents the results of the working group discussions, and suggests topics for further research.