This paper describes Lua, a language for extending applications. Lua combines procedural features with powerful data description facilities, by using a simple, yet powerful, mechanism of tables. This mechanism implements the concepts of records, arrays, and recursive data types (pointers), and adds some object-oriented facilities, such as methods with dynamic dispatching. Lua presents a mechanism of fallbacks that allows programmers to extend the semantics of the language in some unconventional ways. As a noteworthy example, fallbacks allow the user to add different kinds of inheritance to the language. Currently, Lua is being extensively used in production for several tasks, including user configuration, general-purpose data-entry, description of user interfaces, storage of structured graphical metafiles, and generic attribute configuration for finite element meshes.

In this paper we present ALua, an event-driven communication mechanism for developing distributed parallel applications, based on the interpreted language Lua. We propose a dual programming model for parallel applications, where ALua acts as a gluing element, allowing precompiled program parts to run on different machines. We show, through examples, how three types of applications can benefit from the exibility that derives from this model. We then present a study of ALua's performance, by comparing execution times of two parallel applications written in ALua with their counterparts written in PVM

The dramatic growth of the Internet and the World Wide Web creates great demand for tools to support the construction and maintenance of WWW sites. CGILua intends to simplify the task of creating dynamic Web pages, supporting three different paradigms for describing dynamic Web pages: Programming, templates, and database. Besides fully supporting these three paradigms, the user can also freely mix them, allowing the use of CGILua in new interesting ways, even in the description of static pages. CGILua is fully implemented, and is already being used in industrial sites. Keywords: HTML, WWW, CGI, dynamic pages Resumo O enorme crescimento da Internet e do WWW cria uma grande demanda para ferramentas de suporte `a constru¸c~ao e manuten¸c~ao de "sites" WWW. CGILua foi desenvolvido visando simplificar a tarefa de cria¸c~ao de p'aginas Web dinamicas, oferecendo suporte a tres diferentes paradigmas: programa¸c~ao, modelos ("templates") e bancos de dados. Al'em de suportar integralmente os t...

This paper presents ALua, an event-driven communication mechanism based on the interpreted language Lua. This mechanism takes advantage of the interpreted nature of Lua to define messages as chunks of code which are executed by the receiver. The event-driven distributed programming model is discussed and demonstrated with a set of examples. Applicability of ALua in real-sized parallel applications is studied by comparing the implementation of two parallel applications written in ALua with their compiled counterparts. Keywords: distributed systems, parallel applications, interpreted languages, event-driven communication. 1 Introduction The use of prototyping as a technique for program development is becoming more and more widespread. Interpreted languages are considered highly adequate for this type of programming, due to the degree of flexibility and interactivity they offer. Interpreted languages have also been gaining popularity in the extension language paradigm; in this context, ...

Abstract This paper proposes the investigation of the role of interpreted languages as a tool for the development of parallel programs in distributed environments. Besides, it argues that an event-driven approach simplifies many aspects of concurrent programming, since processes are never blocked on communication primitives. These ideas were experimented with through the implementation of several solutions to the classical problem of termination detection. This implementation has used a programming environment based on the extension language Lua.

As the manipulation and use of information forms the base of our economic structure, knowledge workers will become software application integrators. That is, knowledge workers who are experts in their specific domain and its related software, will need to "glue" together databases, analysis, simulation, modelling and visualization tools in order to produce timely information for their organization. In order to perform application integration easily we first need to define a coherent supporting architecture and a programming model. This paper outline this architecture and the programming model and indicates that many of the components to implement this model are available. Unfortunately, the design of many of these components is not consistent, thus, making it difficult for a knowledge worker to integrate applications without a large amount of "inside" technical information. Through the definition of these models we have highlighted the problems that need to be resolved. The a...

Data Views com as notac oes de Objectcharts, Statecharts e redes de Petri. JASMINUM foi motivado pela necessidade de uma notac ao formal que expressasse diretamente alguns aspectos do design de sistema interativos, especialmente a possibilidade de representacao do design do sistema interativo atraves da interface com o usuario. Nosso principal objetivo neste artigo e mostrar como o uso de JASMINUM ajudou a apontar certos erros no design do sistema Waterloo Rita , mostrando com isto que JASMINUM pode ser uma notac ao util para a re-engenharia de sistemas. Abstract. This paper describes experience in using a visual formalism, called JASMINUM, in the design of the user interface of a structured document editor called Waterloo Rita. JASMINUM combines concepts from Abstract Data Views, with notations from Objectcharts, Statecharts, and Petri-nets. JASMINUMwas motivated by the need for a formal notation to express directly some aspects of the design of interactive systems, especi...

This paper describes LuaOrb, a binding between the extension language Lua and CORBA. Like other CORBA bindings, this binding allows a program to manipulate CORBA objects in the same way it manipulates local objects. Unlike conventional bindings, however, LuaOrb is based on the CORBA Dynamic Invocation Interface, mapping its dynamic character to the dynamic type system of Lua. This binding brings together CORBA reuse facilities with the flexibility provided by an interpreted language, fulfilling the "command center" concept proposed by Siegel.