Jakob Henriksson

On Language-Independent Model Modularisation

As model-driven software development covers additional parts of the development process, the complexity of software models increases as well. At the same time, however, many modelling languages do not provide adequate support for modularising models. For this reason, there has been an increasing interest in the topic of model modularisation, often under the heading of aspect-oriented modelling (AOM). The approaches range from techniques that closely mimic concepts from aspect-oriented programming (AOP), such as AspectJ, to very powerful composition techniques for specific types of models--for example, state machines. We believe that AOM is more than just copying the concepts of AOP at the modelling level and should rightly include a large number of other model-composition techniques. However, developing model composition techniques and tooling is costly. To minimise the effort required, this paper presents a generic technique for model composition. The technique is based on invasive software composition and our Reuseware tooling and can be used with arbitrary modelling languages. The basic technique itself is language independent, but it can be adapted to construct language- and purpose-specific composition techniques for specific modelling languages and situations. Hence, it can be used both as a tool for developing specific model-modularisation techniques and as an instrument of research for studying basic properties and concepts of model modularisation. The paper gives a detailed description of our approach and evaluates it using a number of examples.

Extending grammars and metamodels for reuse: the Reuseware approach

The trend toward domain-specific languages leads to an ever-growing plethora of highly specialized languages. Developers of such languages focus on their specific domains rather than on technical challenges of language design. Generic features of languages are rarely included in special-purpose languages. One very important feature is the ability to formulate partial programs in separate encapsulated entities, which can be composed into complete programs in a well-defined manner. This paper presents a language-independent approach for adding useful constructs for defining components. We discuss the underlying concepts and describe a composition environment and tool supporting these ideas ‐ the Reuseware Composition Framework. To evaluate our approach we enrich the (Semantic) Web query language Xcerpt with an additional useful reuse concept—modules.

Combining safe rules and ontologies by interfacing of reasoners

The paper presents a framework for hybrid combination of rule languages with constraint languages including but not restricted to Description-Logic-based ontology languages. It shows how reasoning in a combined language can be done by interfacing reasoners of the component languages. A prototype system based on the presented principle integrates Datalog with OWL by interfacing XSB Prolog [2] with a DIG-compliant [1] DL reasoner (e.g. Racer[17] ).

Hybrid reasoning with rules and constraints under well-founded semantics

The paper presents an architecture and implementation techniques for hybrid integration of normal clauses under well-founded semantics with ontologies specified in Description Logics. The described prototype uses XSB Prolog both for rule reasoning and for controlling communication with the ontology reasoner RacerPro. The query answering techniques for hybrid rules implemented in this prototype are sound wrt. the declarative semantics, extending the well-founded semantics of normal programs and are faithful wrt. FOL.

Reuseware – Adding Modularity to Your Language of Choice.

There is disclosed a device for dewatering sludge, sewage and other materials containing water and solid particles. The device comprises at least two rotatable and two superimposed power driven filter bands which are successively guided to and about the perforated cylindrical walls of the drums in pressure engagement therewith so as to drive the drums in opposite direction and causing release of water from sludge fed between the two filter bands. After leaving the last drum the bands are guided by rolls along a meandering path along which the sludge is repeatedly stretched and pressed to cause further release of water from the sludge and to discharge the now dewaterized sludge at the end of the path.

A Good Role Model for Ontologies: Collaborations

Although ontologies are gaining more and more acceptance, they are often not engineered in a componentbased manner due to, among various reasons, a lack of appropriate constructs in current ontology languages. This hampers reuse and makes creating new ontologies from existing building blocks difficult. We propose to apply the notion of roles and role modeling to ontologies and present an extension of the Web Ontology Language OWL for this purpose. Ontological role models allow for clearly separating different concerns of a domain and constitute an intuitive reuse unit.

Ontology Design and Reuse with Conceptual Roles

Ontologies are already used in the life sciences and the Semantic Web, but are expected to be deployed in many other areas in the near future--for example, in software development. As the use of ontologies becomes commonplace, they will be constructed more frequently and also become more complex. To cope with this issue, modularization paradigms and reuse techniques must be defined for ontologies and supported by ontology languages. In this paper, we propose the use of roles from conceptual modeling for this purpose, and show how they can be used to define ontological reuse units and enable modularization. We present role-based ontologies as an extension of standard ontologies and define their semantics through a reduction to standard Description Logics, such that existing reasoners can be used.

A generic module system for web rule languages: divide and rule

An essential feature in practically usable programming languages is the ability to encapsulate functionality in reusable modules. Modules make large scale projects tractable by humans. For Web and Semantic Web programming, many rule-based languages, e.g. XSLT, CSS, Xcerpt, SWRL, SPARQL, and RIF Core, have evolved or are currently evolving. Rules are easy to comprehend and specify, even for non-technical users, e.g. business managers, hence easing the contributions to the Web. Unfortunately, those contributions are arguably doomed to exist in isolation as most rule languages are conceived without modularity, hence without an easy mechanism for integration and reuse. In this paper a generic module system applicable to many rule languages is presented. We demonstrate and apply our generic module system to a Datalog-like rule language, close in spirit to RIF Core. The language is gently introduced along the EU-Rent use case. Using the Reuseware Composition Framework, the module system for a concrete language can be achieved almost for free, if it adheres to the formal notions introduced in this paper.

Static Type-Checking of Datalog with Ontologies

We show how coupling of the emerging rule level of the Semantic Web to the existing ontology level can be achieved by static typing of web rules of a given application with classes of the ontology describing the application domain. This paper describes the principles and the implementation of a system that checks correctness of a given set of Datalog rules encoded in XML (according to the RuleML standard) wrt a type specification, where the Datalog predicates are typed with classes described by an OWL ontology. The type checker is based on a well-known verification technique for logic programs and employs the RACER reasoner for checking the verification conditions.

A Generic Module System forWeb Rule Languages:Divide and Rule

An essential feature in practically usable programming languages is the ability to encapsulate functionality in reusable modules. Modules make large scale projects tractable by humans. For Web and Semantic Web programming, many rule-based languages, e.g. XSLT, CSS, Xcerpt, SWRL, SPARQL, and RIF Core, have evolved or are currently evolving. Rules are easy to comprehend and specify, even for non-technical users, e.g. business managers, hence easing the contributions to the Web. Unfortunately, those contributions are arguably doomed to exist in isolation as most rule languages are conceived without modularity, hence without an easy mechanism for integration and reuse. In this paper a generic module system applicable to many rule languages is presented. We demonstrate and apply our generic module system to a Datalog-like rule language, close in spirit to RIF Core. The language is gently introduced along the EU-Rent use case. Using the Reuseware Composition Framework, the module system for a concrete language can be achieved almost for free, if it adheres to the formal notions introduced in this paper.