We have designed, implemented, and proved the correctness of a compiler generator that accepts action semantic descriptions of imperative programming languages. The generated compilers emit absolute code for an abstract RISC machine language that currently is assembled into code for the SPARC and the HP Precision Architecture. Our machine language needs no run-time type-checking and is thus more realistic than those considered in previous compiler proofs. We use solely algebraic specifications; proofs are given in the initial model. 1 Introduction The previous approaches to proving correctness of compilers for non-trivial languages all use target code with run-time type-checking. The following semantic rule is typical for these target languages: (FIRST : C; hv 1 ; v 2 i : S) ! (C; v 1 : S) The rule describes the semantics of an instruction that extracts the first component of the top-element of the stack, provided that the top-element is a pair. If not, then it is implicit that the...

We describe the automatic generation of a provably correct compiler for a non-trivial subset of Ada. The compiler is generated from an action semantic description; it emits absolute code for an abstract RISC machine language that currently is assembled into code for the SPARC and the HP Precision Architecture. The generated code is an order of magnitude better than what is produced by compilers generated by the classical systems of Mosses, Paulson, and Wand. The use of action semantics makes the processable language specification easy to read and pleasant to work with. In Proc. ICCL'92, Fourth IEEE International Conference on Computer Languages, pages 117--126. 1 Introduction The purpose of a language designer's workbench, envisioned by Pleban, is to drastically improve the language design process. The major components in such a workbench are: ffl A specification language whose specifications are easily maintainable, and accessible without knowledge of the underlying theory; and f...

The web is being used for applications that contain significant business logic complexity and have considerable user interface requirements. The ad hoc enhancements that have made web application software possible (such as CGI and JavaScript) have created an application support infrastructure that makes application software upgrades and maintenance very complicated. Furthermore, the web has particularly poor support for complex user interfaces. The fundamental request-reply nature of HTTP means that it is difficult to avoid artificial segmentation of an application's execution and user interface. Event-driven user interfaces are commonly used in traditional non-distributed applications. Unfortunately, the limitations of the existing web infrastructure mean that purely event-based user interaction is unsuitable within web applications. Nevertheless, we believe that integrating event-based user interaction in certain parts of a large web application will have positive effects if a suitable architecture is used. In this paper, we explore an architecture that accommodates a partial integration of an event-driven user interface and hides some of the ad hoc web infrastructure. We also suggest ways in which eventbased interaction can be incorporated within a web application framework such as J2EE.

This paper outlines the main benefits of using Internet technologies for the remote monitoring of railway equipment. We present two prototypes of a remote monitoring tool for railway equipment. The first has a 2tier architecture and is based on Java technology and Java RMI as a communication protocol. The second has a 3tier architecture and is based on XML/XSL technology and HTTP as a communication protocol. We compare both systems and we give some conclusions from the actual work. This paper is intended for people concerned with industrial applications on the Internet and especially for those developing remote monitoring tools for embedded systems.