Semantics for a real-time object-oriented programming language

Concurrency has been with us almost from the beginning of computing. Managing and programming for concurrency is a difficult problem and various solutions have been suggested over the years. Debates on message passing vs. remote procedure call, synchronous vs. asynchronous message passing, bounded vs. unbounded buffers, active vs. passive objects etc. still continue. No solution is entirely satisfactory. Concurrent programming usually depends heavily on the nature of the problem at hand and the architecture of the target machine.

Abstract. This paper presents a completeness result, with respect to a possible world semantics, for a combination of a first-order temporal logic and neighbourhood logic. This logic was considered by Qiu and Zhou (1998, Proceedings of the PROCOMET ‘98 , pp 444–461) to define semantics of a real-time OCCAM-like programming language.

We present a type system for E code, which is an assembly language that manages the release, interaction, and termination of real-time tasks. E code specifies a deadline for each task, and the type system ensures that the deadlines are path-insensitive. We show that typed E programs allow, for given worst-case execution times of tasks, a simple schedulability analysis. Moreover, the real-time programming language Giotto can be compiled into typed E~code. This shows that typed E~code identifies an easily schedulable yet expressive class of real-time programs. We have extended the Giotto compiler to generate typed E code, and enabled the run-time system for E code to perform a type and schedulability check before executing the code.

Multi-core processors are increasingly popular because they yield higher performance, but they also present new challenges for hard real-time systems in that they make it much more difficult to estimate a task's worst-case execution time (WCET). Partitioned cache architecture is being used to ease the problem by providing an isolated execution environment for each thread. Although simple to implement and use, this method may be sub-optimal with respect to both energy consumption and performance since it prevents taking advantage of information shared across threads for both instructions and data. This work presents a new cache architecture termed SPACE (Semi-Partitioned CachE) that makes it possible to leverage information sharing, yielding in turn a tighter WCET. The SPACE architecture together with our new WCET algorithm can be used to maintain the predictability of the execution time of the parallel threads while reducing the overall energy consumption of the system. The new proposed cache architecture was implemented using Verilog and deployed on a Xilinx MicroBlaze multi-core design for testing, validation and measurements. The application level experiments were conducted using the Chronos tool for estimation and the Wattch/SimpleScalar simulator for execution. Using three real-time programs–a radar tracker, a DES encryption algorithm, and an FM radio–we showed that SPACE together with the enhanced WCET algorithm reduce the average system WCET of these applications by 31 percent and reduce the actual energy consumption by 18 percent in comparison with other cache architectures.

Mainstream object-oriented languages often fail to provide complete powerful features altogether, such as, multiple inheritance, dynamic overloading and copy semantics of inheritance. In this paper we present a core object-oriented imperative language that integrates all these features in a formal framework. We define a static type system and a translation of the language into the meta-language λ_object, , in order to account for semantic issues and prove type safety of our proposal.

Concurrent C (ConcC) [1] is a relatively new language that extends the C programming language [2] by incorporating multitasking facilities. These facilities are mainly based on the bidirectional rendez-vous concept, and they offer flexible and efficient mechanisms for the specification of concurrency, communication and synchronization often required in real-time systems. However, as for most real-time and concurrent programming languages such as Ada [3], the description of multitasking facilities in ConcC is lacking a rigorous and formal semantical definition. Most existing introductory materials to ConcC by its authors are informally described, and cannot be easily understood. In this paper, we explain the semantics of multitasking facilities in ConcC using the Petri net model. As is well known, the Petri net model is a formal graphical model that can describe concurrent behaviours of systems in a natural and intuitive manner, and yet it is based on strong mathematical and semantical foundations. Timed, inhibitor arc and predicate Petri nets are extensions that are used to enhance the expressive power of the basic Petri net to model and explain all ConcC multitasking features.

The objective of the research presented is the development of an approach for developing real time programs by successive refinement of abstract specifications. It is based on the approach by C. Morgan (1994), which assures the correctness of non real time sequential programs on the basis of the 'method of construction'. The consideration of time, however, makes the refinement a more complex task, primarily because the execution time of any program depends not only on the program itself but also on factors outside it, namely, on compiler strategies, architecture of the underlying machine, its run time environment and so on. Furthermore, real time programs may have explicitly specified timing constraints such as the arrival time of the request for program execution, the computation time and the deadline or the request period depending on whether the program is to be executed periodically or not. Production or communication time of data may also play a crucial role in real time programs. The paper introduces a framework for refinement in real time programs and a number of refinement rules. It demonstrates the approach using a case study.

Part 1 Computers in control systems: historical development digital computer interfacing structure of a digital control loop interface units data representation and aliasing. Part 2 The z-transformation: definition of the z-transform z-transform properties inverse z-transform pulse of z-transfer functions of systems discrete approximations numerical integration pole-zero mapping modified z-transform multi-rate sampling systems analysis of multi-rate systems fast-slow multi-rate systems closed-loop multi-rate systems. Part 3 Analysis of sampled-data control systems z-transformation of systems stability in discrete systems time domain analysis root locus analysis frequency domain analysis. Part 4 Digital compensator design: continuous domain design digital design digital root locas design state feedback design digital PID control disign deadbeat response design optimal control design controller design in the presence of noise. Part 5 Real-time computer control systems: hardware requirements the digital computer and peripheral equipment the real-time clock interface units software aspects controller implementation programming languages system design co-ordination sampling rate selection and quantization errors computer/device communications interrupt handling multi-tasking and background/foreground. Part 6 Advances in computer control: artificial intelligence expert systems examples of expert systems knowledge based systems in control engineering conventional controller design methods manual control methods fuzzy sets and rule-based control basic fuzzy operations fuzzy relations fuzzy control algorithms parallel processing techniques parallel computers algorithms for parallel (MIMD) computers programming parallel computers performance of parallel computers parallel processing in control engineering matrix algebra numerical integration fault tolerance. Appendices: Table of laplace and z-transforms continuous second-order systems response specifications frequency response characteristics the transputer and occam occam overview transputer systems and occam configuration vibration control of a flexible cantilever system simulation modelling and state estimation controller design user interface solutions.

The total functional real-time data-flow programming language Sig features a core layer with elegant denotational semantics, in terms of Mealy stream transducers and coiterative causal stream functions, that is convenient for domain experts in the primary application domains, such as scientific modeling and digital music and event arts. The core suffices for the implementation of many basic signal processing components. For the expression of more sophisticated computations, a second layer of Sig provides additional features, namely higher-order functional programming and multi-rate synchronicity, reducible by transformational semantics to the core layer. Here we describe the design of the upper layer of Sig and demonstrate its usage with the Shepard Tone, a well-known sound synthesis problem and model of psycho-acoustically paradoxical perception of relative musical pitch.

In recent years, distributed intelligent microelectromechanical systems (DiMEMSs) have appeared as a new form of distributed embedded systems. DiMEMSs contain thousands or millions of removable autonomous devices, which will collaborate with each other to achieve the final target of the whole system. Programming such systems is becoming an extremely difficult problem. The difficulty is due not only to their inherent nature of distributed collaboration, mobility, large scale, and limited resources of their devices (e.g., in terms of energy, memory, communication, and computation) but also to the requirements of real-time control and tolerance for uncertainties such as inaccurate actuation and unreliable communications. As a result, existing programming languages for traditional distributed and embedded systems are not suitable for DiMEMSs. In this article, we first introduce the origin and characteristics of DiMEMSs and then survey typical implementations of DiMEMSs and related research hotspots. Finally, we propose a real-time programming framework that can be used to design new real-time programming languages for DiMEMSs. The framework is composed of three layers: a real-time programming model layer, a compilation layer, and a runtime system layer. The design challenges and requirements of these layers are investigated. The framework is then discussed in further detail and suggestions for future research are given.

A Realtime Programming Language and its Application for Measuring Processes

Computer programming language is the foundation of developing computer application technologies and software. C language and object-oriented programming language belong to commonly-utilized advanced computer languages, and they have certain relevance in logic. Meanwhile, they have their own advantages. In other words, C language and object-oriented programming language possess both relevance and differences in the aspects of selection and application. The work discussed the compiling essentials of C language and object-oriented programming language. Besides, the differences and applicability of those two languages in the aspect of programming were further analyzed.

Abstract. At a fundamental level, functional and object-oriented programming languages are all ‘higher-order’, in the sense that they support computing with values that are themselves pieces of program code encapsulated with a local environment. In functional languages these ‘active’ values are functions, while in object-oriented languages they are objects. Both styles of higher-order language claim to provide good support for writing adaptable programs, but functional and object-oriented languages achieve this adaptability in different ways: functional programs rely on parameterisation at the value, type and module level, while object-oriented languages rely primarily on subtyping and implementation inheritance. Here we compare these two approaches, mainly in terms of the features and properties of their type systems, and consider the benefits and disadvantages of unifying (or merging) the two paradigms by adding object-oriented features to ML as a base language. We argue that while some of the simpler aspects of object-oriented languages are compatible with ML, adding a full- edged class-based object system to ML leads to an excessively complex type system and relatively little expressive gain, especially if we aim to preserve that mostly functional style of programming that is a major advantage of ML.

In this paper we present NLOMJ—a natural language object model in Java with English as the experiment language. It describes the grammar elements of any permissible expression in a natural language and their complicated relations with each other with the concept “Object” in OOP. Directly mapped to the syntax and semantics of the natural language, it can be used in information retrieval as a linguistic method. Around the UML diagram of the NLOMJ the important classes (Sentence, Clause and Phrase) and their sub classes are introduced and their syntactic and semantic meanings are explained.Key wordsnatural language processing (NLP)object oriented programming (OOP)natural language object model in Java (NLOMJ)

Chapter 5 discusses some fundamentals of object-oriented programming languages (Section 5.1) and distributed programming languages (Section 5.4). It also specifically summarizes the major features of two object-oriented programming languages: c++ (Section 5.2) and SMALLTALK (Section 5.3), and one distributed programming language, namely, OCCAM and its predecessor CSP (Section 5.5). Although there are other object-oriented languages (e.g., ACTOR 1 and EFFEL 2 and distributed programming languages (see Section 5.4), these three languages are chosen to illustrate some basic ideas behind object-oriented programming and distributed programming. It is assumed that the reader is familiar with c.