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doi: 10.1145/1922649.1922655pmid: N/A
Object-oriented programming represents an original implementation issue due to its philosophy of making the program behavior depend on the dynamic type of objects. This is expressed by the late binding mechanism, aka message sending. The underlying principle is that the address of the actually called procedure is not statically determined at compile-time, but depends on the dynamic type of a distinguished parameter known as the receiver. A similar issue arises with attributes, because their position in the object layout may also depend on the object's dynamic type. Furthermore, subtyping introduces another original feature (i.e., runtime subtype checks). All three mechanisms need specific implementations and data structures. In static typing, late binding is generally implemented with so-called virtual function tables. These tables reduce method calls to pointers to functions via a small fixed number of extra indirections. It follows that object-oriented programming yields some overhead, as compared to the usual procedural languages. The different techniques and their resulting overhead depend on several parameters. First, inheritance and subtyping may be single or multiple, and even a mixing is possible, as in Java and NET which present single inheritance for classes and multiple subtyping for interfaces. Multiple inheritance is a well-known complication. Second, the production of executable programs may involve various schemes, from global compilation, which implies the closed-world assumption (CWA), as the whole program is known at compile time, to separate compilation and dynamic loading, where each program unit is compiled and loaded independently of any usage, hence under the open-world assumption (OWA). Global compilation is well-known to facilitate optimization. This article reviews the various implementation techniques available in static typing and in the three cases of single inheritance, multiple inheritance, and multiple subtyping. This language-independent survey focuses on separate compilation and dynamic loading, as they represent the most commonly used and the most demanding framework. However, many works have been undertaken in the global compilation framework, mostly for dynamically typed languages, but also applied to the EIFFEL language. Hence, we also examine global techniques and how they can improve implementation efficiency. Finally, mixed frameworks that combine open and closed world assumptions are considered. For instance, just-in-time (JIT) compilers work under provisional CWA, at the expense of possible recompilations. In contrast, we present an experimental compiler-linker, where separate compilation implies the OWA, whereas the whole program is finally linked under the CWA.
Karimi, Sarvnaz; Scholer, Falk; Turpin, Andrew
doi: 10.1145/1922649.1922654pmid: N/A
Machine transliteration is the process of automatically transforming the script of a word from a source language to a target language, while preserving pronunciation. The development of algorithms specifically for machine transliteration began over a decade ago based on the phonetics of source and target languages, followed by approaches using statistical and language-specific methods. In this survey, we review the key methodologies introduced in the transliteration literature. The approaches are categorized based on the resources and algorithms used, and the effectiveness is compared.
Ko, Amy J.; Abraham, Robin; Beckwith, Laura; Blackwell, Alan; Burnett, Margaret; Erwig, Martin; Scaffidi, Chris; Lawrance, Joseph; Lieberman, Henry; Myers, Brad; Rosson, Mary Beth; Rothermel, Gregg; Shaw, Mary; Wiedenbeck, Susan
doi: 10.1145/1922649.1922658pmid: N/A
Most programs today are written not by professional software developers, but by people with expertise in other domains working towards goals for which they need computational support. For example, a teacher might write a grading spreadsheet to save time grading, or an interaction designer might use an interface builder to test some user interface design ideas. Although these end-user programmers may not have the same goals as professional developers, they do face many of the same software engineering challenges, including understanding their requirements, as well as making decisions about design, reuse, integration, testing, and debugging. This article summarizes and classifies research on these activities, defining the area of End-User Software Engineering (EUSE) and related terminology. The article then discusses empirical research about end-user software engineering activities and the technologies designed to support them. The article also addresses several crosscutting issues in the design of EUSE tools, including the roles of risk, reward, and domain complexity, and self-efficacy in the design of EUSE tools and the potential of educating users about software engineering principles.
doi: 10.1145/1922649.1922660pmid: N/A
Disk drives have experienced dramatic development to meet performance requirements since the IBM 1301 disk drive was announced in 1961. However, the performance gap between memory and disk drives has widened to 6 orders of magnitude and continues to widen by about 50 per year. Furthermore, energy efficiency has become one of the most important challenges in designing disk drive storage systems. The architectural design of disk drives has reached a turning point which should allow their performance to advance further, while still maintaining high reliability and energy efficiency. This article explains how disk drives have evolved over five decades to meet challenging customer demands. First of all, it briefly introduces the development of disk drives, and deconstructs disk performance and power consumption. Secondly, it describes the design constraints and challenges that traditional disk drives are facing. Thirdly, it presents some innovative disk drive architectures discussed in the community. Fourthly, it introduces some new storage media types and the impacts they have on the architecture of the traditional disk drives. Finally, it discusses two important evolutions of disk drives: hybrid disk and solid state disk. The article highlights the challenges and opportunities facing these storage devices, and explores how we can expect them to affect storage systems.
doi: 10.1145/1922649.1922653pmid: N/A
Human activity recognition is an important area of computer vision research. Its applications include surveillance systems, patient monitoring systems, and a variety of systems that involve interactions between persons and electronic devices such as human-computer interfaces. Most of these applications require an automated recognition of high-level activities, composed of multiple simple (or atomic) actions of persons. This article provides a detailed overview of various state-of-the-art research papers on human activity recognition. We discuss both the methodologies developed for simple human actions and those for high-level activities. An approach-based taxonomy is chosen that compares the advantages and limitations of each approach. Recognition methodologies for an analysis of the simple actions of a single person are first presented in the article. Space-time volume approaches and sequential approaches that represent and recognize activities directly from input images are discussed. Next, hierarchical recognition methodologies for high-level activities are presented and compared. Statistical approaches, syntactic approaches, and description-based approaches for hierarchical recognition are discussed in the article. In addition, we further discuss the papers on the recognition of human-object interactions and group activities. Public datasets designed for the evaluation of the recognition methodologies are illustrated in our article as well, comparing the methodologies' performances. This review will provide the impetus for future research in more productive areas.
Ko, Andrew J.; Abraham, Robin; Beckwith, Laura; Blackwell, Alan; Burnett, Margaret; Erwig, Martin; Scaffidi, Chris; Lawrance, Joseph; Lieberman, Henry; Myers, Brad; Rosson, Mary Beth; Rothermel, Gregg; Shaw, Mary; Wiedenbeck, Susan
doi: 10.1145/1922649.1922658pmid: N/A
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