Resumo em Inglês:

When compiling a high level language like Java, Lisp or Smalltalk, the implementation of primitive data types is a large part of the task. The powerful data types make most of the virtual machine, and code generation for them must be rewritten if any of the specifications of the data types change. Moreover, most of the differences between different implementations of the same data types are in the format of their representations. By describing format and semantics separately we can create more modular and reusable specifications, and therefore more modular and reusable interfaces with the back-end of the compiler. This paper presents a model for specifying data type implementations in a compiler, and a prototype system that was built following that model. This system automatically generates a compiler component from the specifications of a data type, assuring consistency between implementation and specification. The system also provides a visual interface to inspect and specify data type formats.

Resumo em Inglês:

In this article we present a survey on the area of Requirements Engineering anchored on the analysis of a real life case study, the London Ambulance Service [56]. We aim at bringing to context new methods, techniques and tools that should be of help to both reaserchers and practitioners. The case study in question is of special interest in that it is available to the public and deals with a very large system, of which the software system is only a part of. The survey is divided into four topics of interest: viewpoints, social aspects, evolution and non-functional requirements. This division resulted from the work method adopted by the authors. Our main goal is to bridge recent findings in Requirements Engineering research to a real world problem. In this light, we believe this article to be an important educational device.

Resumo em Inglês:

We describe here a collection of heuristics for producing "nice"- drawings of directed graphs, and a simple dual-mode software tool for testing and evaluating them. In playing mode, the heuristics are applied in random sequence over a set of drawings, in the manner of an asynchronous team (A-team). As new drawings are added to the set, others are deleted based on a multi-valued aesthetic evaluation function. By inspecting the "pedigree" of the best solutions found in playing mode, the user can obtain insights into the best order in which the heuristics should be applied. Then the user can test these insights in the working mode, where the heuristics are applied in a fixed sequence.Some of the heuristics that we describe here are similar to the steps of Sugiyama's D-ABDUCTOR graph-drawing package; and indeed we can obtain results similar to those of D-ABDUCTOR, by applying our heuristics in the proper sequence.

Resumo em Inglês:

With the popularity of personal computers and powerful workstations, today’s users are no longer satisfied with the traditional data processing. They demand eagerly to putting up graphics on existing applications, putting a lot of pressure in system re-engineering. The Client/Server architecture is a less risky and less costly approach in adding a Graphical User Interface for users. The developer has to determine data and program logic distribution among client, middleware server, and the top-tier server. Middleware is a kind of software that links programs running on different platforms, transmitting messages and data. It plays an important role in 3-tier architecture. There are two types of middlewares: the first connects client programs to server programs, and the second provides data access connections to heterogeneous data sources. The developer also needs to separate on-line transaction processing, project-oriented data processing, and history data from each other. In view of no existing standard method in developing a middleware server, this paper outlines a methodology to design a 3-tier Client/Server database system. It identifies the role of middleware as temporary storage for better performance and as database gateway for Database Management Systems connectivity. Case studies are used to illustrate the steps.