Pictures worth a thousand tiles,a geometrical programming language for self-assembly

We present a novel way to design self-assembling systems using a notion of signal (or ray) akin to what is used in analyzing the behaviour of cellular automata. This allows purely geometrical constructions, with a smaller specification and easier analysis. We show how to design a system of signals for a given set of shapes, and how to transform these signals into a set of tiles which self-assemble into the desired shapes.     

Extreme programming from a CMM perspective

Extreme programming has been advocated recently as an appropriate programming method for the high-speed, volatile world of Internet and Web software development. The author reviews XP from the perspective of the capability maturity model for software, gives overviews of both approaches, and critiques XP from a SW-CMM perspective. He concludes that lightweight methodologies such as XP advocate many good engineering practices and that both perspectives have something to offer the other     

Extreme programming. Rapid development for Web-based applications

Agile processes like extreme programming (XP), Scrum, Crystal, and adaptive software development aim to increase a software organization's responsiveness while decreasing development overhead. They focus on delivering executable code and see people as the strongest ingredient of software development. We offer an overview of the philosophy and practice behind XP, which is currently the most popular agile methodology     

S-semantics for logic programming: A retrospective look

The paper provides an overview of the s-semantic approach to the semantics of logic programs which had been developed about twenty years ago. The aim of such an approach was that of providing a suitable base for program analysis by means of a semantics which really captures the operational behavior of logic programs, and thus offers useful notions of observable program equivalences. The semantics is given in terms of extended interpretations, which are more expressive than Herbrand interpretations, extends the standard Herbrand semantics, and can be obtained as a result of both top-down and bottom-up constructions. The approach has been applied to several extensions of positive logic programs and used to develop semantic-based techniques for program analysis, verification and transformation.     

混沌变异进化规划及在数字水印中的应用

针对现有的数字水印算法都是根据人类视觉模型理论来寻找嵌入位置的问题,本文提出一种新的变尺度进化规划算法.该算法根据混沌序列的特性,将混沌引入到进化规划的变异算子中,并利用提出的进化规划算法采寻找数字图像中水印的嵌入部位.理论分析和实验结果表明,该算法具有良好的快速收敛性和鲁棒性,并可以自适应寻找水印的最优嵌入部位,以最大限度地减少因水印的嵌入而对原始图像造成的破坏.     

Choosing a programming language

This paper evaluates the use of a functional language for implementing domain-specific functionality. The factors we consider when choosing a programming language are programmer productivity, maintainability, efficiency, portability, tool support, and software and hardware interfaces. The choice of programming language is a fine balancing act. Modern object-oriented languages such as Java and C# are more orthogonal and hide fewer surprises for the programmer, although the inevitable accumulation of features makes this statement less true with every new version of each language.     

StreamPI: a stream-parallel programming extension for object-oriented programming languages

Because multicore CPUs have become the standard with all major hardware manufacturers, it becomes increasingly important for programming languages to provide programming abstractions that can be mapped effectively onto parallel architectures. Stream processing is a programming paradigm where computations are expressed as independent actors that communicate via FIFO data-channels. The coarse-grained parallelism exposed in stream programs facilitates such an efficient mapping of actors onto the underlying multicore hardware. We propose a stream-parallel programming abstraction that extends object-oriented languages with stream-programming facilities. StreamPI consists of a class hierarchy for actor-specification together with a language-independent runtime system that supports the execution of stream programs on multicore architectures. We show that the language-specific part of StreamPI, i.e., the class hierarchy, can be implemented as a library-level programming language extension. A library-level extension has the advantage that an existing programming language implementation need not be touched. Legacy-code can be mixed with a stream-parallel application, and the use of sequential legacy code with actors is supported. Unlike previous approaches, StreamPI allows dynamic creation and subsequent execution of stream programs. StreamPI actors are typed. Type-safety is achieved through type-checks at stream graph creation time. We have implemented StreamPI??s language-independent runtime system and language interfaces for Ada?2005 and C++ for Intel multicore architectures. We have evaluated StreamPI for up to 16 cores on a two?CPU 8-core Intel Xeon X7560 server, and we provide a performance comparison with StreamIt?(Gordon et al. in International Conference on Architectural Support for Programming Languages and Operating Systems, 2006), which is the de facto standard for stream-parallel programming. Although our approach provides greater programming flexibility than StreamIt, the performance of StreamPI compares favorably to the static compilation model of StreamIt.     

A configurable visual programming environment: a tool fordomain-specific programming

Visual programming is an appealing technique, which many environments support. It can be applied in a system development process that nonsoftware engineers can perform. The key is to use visual domain specific models. Because there are many different domains, it is economical to develop a generic and configurable visual programming environment (VPE) that can be customized for the domains and paradigms. The author discusses a generic VPE's requirements, design, and implementation, and illustrates its use in a system, the Intelligent Process-Control System (IPCS), for the process control domain. This VPE and the IPCS have been developed in a multiyear research effort. Different versions of the VPE are used at many companies, including Boeing, DuPont, and NASA, and the IPCS has been commercialized by the Osaka Gas Information Systems Research Institute (Osaka, Japan)     

PKI: it's not dead, just resting

Like other flexible objects, the public key infrastructure sacrifices some utility in trying to be all things to all people. Mainly, PKI's generic, all-purpose identity certificates fall short of what the marketplace demands, forcing vendors to develop more economically efficient, useful, and imaginative business models. Thus, we must adapt the PKI design to the real world rather than trying to constrain the real world to match the PKI. A variety of alternative approaches, ranging from simple workarounds to designing the application to sidestep PKI's shortcomings entirely, can help solve the problems inherent in the standard X.509 model.

Despite an original design that failed to address the marketplace's needs, the use of innovative public key infrastructure models can make the technology meet today's requirements.     

Computers, programming and people

Now part of consumer society and marketed globally, computers are designed to be sold rather than used. Software marketers, e-businesses, and their technicians consider having an understanding of how the underlying machinery works to be utterly irrelevant. For them, the most important skills are marketing, management, and graphical expertise. The profession should strive to make it easy for people to exploit the computer on their own terms in their own culture. The symbolic programming system should be completely straightforward, but adaptable to different writing systems. Any complexity should be subsumed by the operating system or concealable within the macro-coding system     

Recovery, redemption, and extreme programming

The author retells a downtrodden project's attempt to rejuvenate itself by doing extreme programming, discussing successes, shortcomings, and, ultimately, lessons learned. In particular, the author credits the team's composition for its ultimate success. Although XP wasn't the team's immediate salvation, it made the application sustainable past the project's deadline     

Oto,a generic and extensible tool for marking programming assignments

Marking programming assignments in programming courses involves a lot of work: each program must be tested, the source code must be read and evaluated, etc. With the large classes encountered nowadays, the feedback provided to students through marking is thus rather limited, and often late. Tools providing support for marking programming assignments do exist, ranging from support for administrative aspects through automation of program testing or support for source code evaluation based on metrics. In this paper, we introduce a tool, called Oto, that provides support for submission and marking of assignments. Oto aims at reducing the workload associated with the marking task. Oto also aims at providing timely feedback to the students, including feedback before the final submission. Furthermore, the tool has been designed to be generic and extensible, so that the marking process for a specific assignment can easily be customized and the tool can be extended with various marking components (modules) that allows it to deal with various aspects of marking (testing, style, structure, etc.) and with programs written in various programming languages. Copyright © 2007 John Wiley & Sons, Ltd.     

A partial evaluator,and its use as a programming tool

Programs which perform partial evaluation, beta-expansion, and certain optimizations on programs, are studied with respect to implementation and application. Two implementations are described, one “interpretive” partial evaluator, which operates directly on the program to be partially evaluated, and a “compiling” system, where the program to be partially evaluated is used to generate a specialized program, which in its turn is executed to do the partial evaluation. Three applications with different requirements on these programs are described. Proofs are given for the equivalence of the use of the interpretive system and the compiling system in two of the three cases. The general use of the partial evaluator as a tool for the programmer in conjunction with certain programming techniques is discussed.