Facilitating modular property-preserving extensions of programming languages

We will explore an approach to modular programming language descriptions and extensions in a denotational style. Based on a language core, language features are added stepwise on the core. Language features can be described separated from each other in a self-contained, orthogonal way. We present an extension semantics framework consisting of mechanisms to adapt semantics of a basic language to new structural requirements in an extended language preserving the behaviour of programs of the basic language. Common templates of extension are provided. These can be collected in extension libraries accessible to and extendible by language designers. Mechanisms to extend these libraries are provided. A notation for describing language features embedding these semantics extensions is presented

Validating Architectural Feature Descriptions using LOTOS

The phases of the ANISE project (Architectural Notions In Service Engineering) are briefly explained with reference to the work reported here. An outline strategy is given for translating ANISE descriptions to LOTOS (Language of Temporal Ordering Specification), thus providing a formal basis. It is shown how modular ANISE descriptions of features can be defined and then merged. Potential feature interactions can be identified statically through structural overlaps. A scenario language is introduced to express validation tests for features in a modular fashion, and a number of examples are given. Scenarios are automatically translated to LOTOS and analysed through LOTOS simulation. This allows features to be validated in isolation, and dynamically in combination with other features. The design of the translation and validation tools is discussed, showing typical results when investigating feature descriptions. The paper concludes with a guide to extending the approach for new features

A framework for deadlock detection in core ABS

We present a framework for statically detecting deadlocks in a concurrent object-oriented language with asynchronous method calls and cooperative scheduling of method activations. Since this language features recursion and dynamic resource creation, deadlock detection is extremely complex and state-of-the-art solutions either give imprecise answers or do not scale. In order to augment precision and scalability we propose a modular framework that allows several techniques to be combined. The basic component of the framework is a front-end inference algorithm that extracts abstract behavioural descriptions of methods, called contracts, which retain resource dependency information. This component is integrated with a number of possible different back-ends that analyse contracts and derive deadlock information. As a proof-of-concept, we discuss two such back-ends: (i) an evaluator that computes a fixpoint semantics and (ii) an evaluator using abstract model checking.Comment: Software and Systems Modeling, Springer Verlag, 201

Modular Structural Operational Semantics

Modular SOS (MSOS) is a variant of conventional Structural Operational Semantics (SOS). Using MSOS, the transition rules for each construct of a programming language can be given incrementally, once and for all, and do not need reformulation when further constructs are added to the language. MSOS thus provides an exceptionally high degree of modularity in language descriptions, removing a shortcoming of the original SOS framework. After sketching the background and reviewing the main features of SOS, the paper explains the crucial differences between SOS and MSOS, and illustrates how MSOS descriptions are written. It also discusses standard notions of semantic equivalence based on MSOS. An appendix shows how the illustrative MSOS rules given in the paper would be formulated in conventional SOS

Composing Programming Languages by Combining Action-Semantics Modules

This article demonstrates a method for composing a programming language by combining action-semantics modules. Each module is defined separately, and then a programming-language module is defined by combining existing modules. This method enables the language designer to gradually develop a language by defining, selecting and combining suitable modules. The resulting modular structure is substantially different from that previously employed in action-semantic descriptions. It also discusses how to resolve the conflicts that may arise when combining modules, and indicates some advantages that action semantics has over other approaches in this respect

McRunjob: A High Energy Physics Workflow Planner for Grid Production Processing

McRunjob is a powerful grid workflow manager used to manage the generation of large numbers of production processing jobs in High Energy Physics. In use at both the DZero and CMS experiments, McRunjob has been used to manage large Monte Carlo production processing since 1999 and is being extended to uses in regular production processing for analysis and reconstruction. Described at CHEP 2001, McRunjob converts core metadata into jobs submittable in a variety of environments. The powerful core metadata description language includes methods for converting the metadata into persistent forms, job descriptions, multi-step workflows, and data provenance information. The language features allow for structure in the metadata by including full expressions, namespaces, functional dependencies, site specific parameters in a grid environment, and ontological definitions. It also has simple control structures for parallelization of large jobs. McRunjob features a modular design which allows for easy expansion to new job description languages or new application level tasks.Comment: CHEP 2003 serial number TUCT00

Specification Techniques for Multi-Modal Dialogues in the U-Wish Project

In this paper we describe the development of a specification\ud technique for specifying interactive web-based services. We\ud wanted to design a language that can be a means of\ud communication between designers and developers of interactive services, that makes it easier to develop web-based services fitted to the users and that shortens the pathway from design to implementation. The language, still under development, is based on process algebra and can be\ud connected to the results of task analysis. We have been\ud working on the automatic generation of executable prototypes\ud out of the specifications. In this way the specification\ud language can establish a connection between users, design\ud and implementation. A first version of this language is\ud available as well as prototype tools for executing the specifications. Ideas will be given as to how to make the connection between specifications and task analysis