Modern embedded computing systems tend to be heterogeneous in the sense of being composed of subsystems with very different characteristics, which communicate and interact in a variety of ways---synchronous or asynchronous, buffered or unbuffered, etc. Obviously, when designing such systems, a modeling language needs to reflect this heterogeneity. Today's modeling environments usually offer a variant of what we call amorphous heterogeneity to address this problem. This paper argues that modeling systems in this manner leads to unexpected and hard-to-analyze interactions between the communication mechanisms and proposes a more structured approach to heterogeneity, called hierarchical heterogeneity to solve this problem. It proposes a model structure and semantic framework that support this form of heterogeneity, and discusses the issues arising from heterogeneous component interaction and the desire for component reuse. It introduces the notion of domain polymorphism as a way to address these issues.

Triggers, which make databases active, are specified as event-action pairs. We have developed a model for specifying composite events, which are events that are composed from simple events or from other composite events. Composite events are specified as event expressions. The occurrence of a composite event is detected by the finite automaton implementing the corresponding event expression. Composite events are built using event specification operators which are classified into two categories: basic and additional. The addtional operators, with few exceptions, can be expressed in terms of the basic operators. We have built a prototype system, COMPOSE, for specifying and detecting composite events". Our implementation techniques can handle automata with "masks" and automata with parameters. A real-time "stock" feed is used to experiment with the specification of stock market related events. In this paper, we describe how composite events are specified, illustrate composite event specif...

The catch/throw mechanism is a programming construct for non-local exit. In the practical programming, this mechanism plays an important role when programmers handle exceptional situations. In this paper we give a constructive formalization which captures the mechanism in the proofs-as-programs notion. We introduce a modified version of LJ equipped with inference rules corresponding to the operations of catch and throw. Then we show that we can actually extract programs which make use of the catch/throw mechanism from proofs under a certain realizability interpretation. Although the catch/throw mechanism provides only a restricted access to the current continuation, the formulation remains constructive in contrast to the works due to Griffin and Murthy on more powerful facilities such as call/cc (call-with-current-continuation) of Scheme.

Knowledge-based programming tutors are supposed to analyze the students' programs using knowledge of the concepts of programming language, skills to build programs, misconceptions of novice programmers, and information about the programs to be analyzed. The last one provides the programming tutor with the intentions of programmers, and this allows the tutor to do an intention-based diagnosis(Johnson86). This is given to the system in the form of a problem description by human instructors. However, it is very hard for instructors to write a problem description. For instructors, the simplest way to describe a problem may be to write a model program of that problem. This paper describes the system named GOES, a GOal Extraction System, which extracts the purposes (Goals) of a model program automatically.

It is usually claimed that lexical analysis routines are still coded by hand, despite the widespread availability of scanner generators, for efficiency reasons. While efficiency is a consideration, there exist freely available scanner generators such as GLA [7] that can generate scanners that are faster than most hand-coded ones. However, most generated scanners are tailored for a particular environment, and retargetting these scanners to other environments, if possible, is usually complex enough to make a hand-coded scanner more appealing. In this paper we describe RE2C, a scanner generator that not only generates scanners which are faster (and usually smaller) than those produced by any other scanner generator known to the authors, including GLA, but also adapt easily to any environment. Categories and Subject Descriptors: D.3.2 [Programming Languages]: Language Classifications -- specialized application languages; D.3.4 [Programming Languages]: Processors General Terms: Al...

This document represents a preliminary draft of the CERT C Programming Language Secure Coding Standard. This project was initiated following the 2006 Berlin meeting of WG14 to produce a secure coding standard based on the C99 standard. Although this is an incomplete work, we would greatly appreciate your comments and feedback at this time to further the development and refinement of the material. Please provide comments that are commensurate with the existing detail in the document. For example, if a rule or recommendation is simply a stub you may wish to comment if you think having a rule or recommendation in that area is unwarranted. This work is sponsored by the U.S. Department of Defense.