Web and Semantic Web Query Languages

A number of techniques have been developed to facilitate powerful data retrieval on the Web and Semantic Web. Three categories of Web query languages can be distinguished, according to the format of the data they can retrieve: XML, RDF and Topic Maps. This article introduces the spectrum of languages falling into these categories and summarises their salient aspects. The languages are introduced using common sample data and query types. Key aspects of the query languages considered are stressed in a conclusion

Reusable semantics for implementation of Python optimizing compilers

Le langage de programmation Python est aujourd'hui parmi les plus populaires au monde grâce à son accessibilité ainsi que l'existence d'un grand nombre de librairies standards. Paradoxalement, Python est également reconnu pour ses performances médiocres lors de l'exécution de nombreuses tâches. Ainsi, l'écriture d’implémentations efficaces du langage est nécessaire. Elle est toutefois freinée par la sémantique complexe de Python, ainsi que par l’absence de sémantique formelle officielle. Pour régler ce problème, nous présentons une sémantique formelle pour Python axée sur l’implémentation de compilateurs optimisants. Cette sémantique est écrite de manière à pouvoir être intégrée et analysée aisément par des compilateurs déjà existants. Nous introduisons également semPy, un évaluateur partiel de notre sémantique formelle. Celui-ci permet d'identifier et de retirer automatiquement certaines opérations redondantes dans la sémantique de Python. Ce faisant, semPy génère une sémantique naturellement plus performante lorsqu'exécutée. Nous terminons en présentant Zipi, un compilateur optimisant pour le langage Python développé avec l'assistance de semPy. Sur certaines tâches, Zipi offre des performances compétitionnant avec celle de PyPy, un compilateur Python reconnu pour ses bonnes performances. Ces résultats ouvrent la porte à des optimisations basées sur une évaluation partielle générant une implémentation spécialisée pour les cas d'usage fréquent du langage.Python is among the most popular programming language in the world due to its accessibility and extensive standard library. Paradoxically, Python is also known for its poor performance on many tasks. Hence, more efficient implementations of the language are required. The development of such optimized implementations is nevertheless hampered by the complex semantics of Python and the lack of an official formal semantics. We address this issue by presenting a formal semantics for Python focussed on the development of optimizing compilers. This semantics is written as to be easily reusable by existing compilers. We also introduce semPy, a partial evaluator of our formal semantics. This tool allows to automatically target and remove redundant operations from the semantics of Python. As such, semPy generates a semantics which naturally executes more efficiently. Finally, we present Zipi, a Python optimizing compiler developped with the aid of semPy. On some tasks, Zipi displays performance competing with those of PyPy, a Python compiler known for its good performance. These results open the door to optimizations based on a partial evaluation technique which generates specialized implementations for frequent use cases

Survey over Existing Query and Transformation Languages

A widely acknowledged obstacle for realizing the vision of the Semantic Web is the inability of many current Semantic Web approaches to cope with data available in such diverging representation formalisms as XML, RDF, or Topic Maps. A common query language is the first step to allow transparent access to data in any of these formats. To further the understanding of the requirements and approaches proposed for query languages in the conventional as well as the Semantic Web, this report surveys a large number of query languages for accessing XML, RDF, or Topic Maps. This is the first systematic survey to consider query languages from all these areas. From the detailed survey of these query languages, a common classification scheme is derived that is useful for understanding and differentiating languages within and among all three areas

A Process Model for the Integrated Reasoning about Quantitative IT Infrastructure Attributes

IT infrastructures can be quantitatively described by attributes, like performance or energy efficiency. Ever-changing user demands and economic attempts require varying short-term and long-term decisions regarding the alignment of an IT infrastructure and particularly its attributes to this dynamic surrounding. Potentially conflicting attribute goals and the central role of IT infrastructures presuppose decision making based upon reasoning, the process of forming inferences from facts or premises. The focus on specific IT infrastructure parts or a fixed (small) attribute set disqualify existing reasoning approaches for this intent, as they neither cover the (complex) interplay of all IT infrastructure components simultaneously, nor do they address inter- and intra-attribute correlations sufficiently. This thesis presents a process model for the integrated reasoning about quantitative IT infrastructure attributes. The process model’s main idea is to formalize the compilation of an individual reasoning function, a mathematical mapping of parametric influencing factors and modifications on an attribute vector. Compilation bases upon model integration to benefit from the multitude of existing specialized, elaborated, and well-established attribute models. The achieved reasoning function consumes an individual tuple of IT infrastructure components, attributes, and external influencing factors to expose a broad applicability. The process model formalizes a reasoning intent in three phases. First, reasoning goals and parameters are collected in a reasoning suite, and formalized in a reasoning function skeleton. Second, the skeleton is iteratively refined, guided by the reasoning suite. Third, the achieved reasoning function is employed for What-if analyses, optimization, or descriptive statistics to conduct the concrete reasoning. The process model provides five template classes that collectively formalize all phases in order to foster reproducibility and to reduce error-proneness. Process model validation is threefold. A controlled experiment reasons about a Raspberry Pi cluster’s performance and energy efficiency to illustrate feasibility. Besides, a requirements analysis on a world-class supercomputer and on the European-wide execution of hydro meteorology simulations as well as a related work examination disclose the process model’s level of innovation. Potential future work employs prepared automation capabilities, integrates human factors, and uses reasoning results for the automatic generation of modification recommendations.IT-Infrastrukturen können mit Attributen, wie Leistung und Energieeffizienz, quantitativ beschrieben werden. Nutzungsbedarfsänderungen und ökonomische Bestrebungen erfordern Kurz- und Langfristentscheidungen zur Anpassung einer IT-Infrastruktur und insbesondere ihre Attribute an dieses dynamische Umfeld. Potentielle Attribut-Zielkonflikte sowie die zentrale Rolle von IT-Infrastrukturen erfordern eine Entscheidungsfindung mittels Reasoning, einem Prozess, der Rückschlüsse (rein) aus Fakten und Prämissen zieht. Die Fokussierung auf spezifische Teile einer IT-Infrastruktur sowie die Beschränkung auf (sehr) wenige Attribute disqualifizieren bestehende Reasoning-Ansätze für dieses Vorhaben, da sie weder das komplexe Zusammenspiel von IT-Infrastruktur-Komponenten, noch Abhängigkeiten zwischen und innerhalb einzelner Attribute ausreichend berücksichtigen können. Diese Arbeit präsentiert ein Prozessmodell für das integrierte Reasoning über quantitative IT-Infrastruktur-Attribute. Die grundlegende Idee des Prozessmodells ist die Herleitung einer individuellen Reasoning-Funktion, einer mathematischen Abbildung von Einfluss- und Modifikationsparametern auf einen Attributvektor. Die Herleitung basiert auf der Integration bestehender (Attribut-)Modelle, um von deren Spezialisierung, Reife und Verbreitung profitieren zu können. Die erzielte Reasoning-Funktion verarbeitet ein individuelles Tupel aus IT-Infrastruktur-Komponenten, Attributen und externen Einflussfaktoren, um eine breite Anwendbarkeit zu gewährleisten. Das Prozessmodell formalisiert ein Reasoning-Vorhaben in drei Phasen. Zunächst werden die Reasoning-Ziele und -Parameter in einer Reasoning-Suite gesammelt und in einem Reasoning-Funktions-Gerüst formalisiert. Anschließend wird das Gerüst entsprechend den Vorgaben der Reasoning-Suite iterativ verfeinert. Abschließend wird die hergeleitete Reasoning-Funktion verwendet, um mittels “What-if”–Analysen, Optimierungsverfahren oder deskriptiver Statistik das Reasoning durchzuführen. Das Prozessmodell enthält fünf Template-Klassen, die den Prozess formalisieren, um Reproduzierbarkeit zu gewährleisten und Fehleranfälligkeit zu reduzieren. Das Prozessmodell wird auf drei Arten validiert. Ein kontrolliertes Experiment zeigt die Durchführbarkeit des Prozessmodells anhand des Reasonings zur Leistung und Energieeffizienz eines Raspberry Pi Clusters. Eine Anforderungsanalyse an einem Superrechner und an der europaweiten Ausführung von Hydro-Meteorologie-Modellen erläutert gemeinsam mit der Betrachtung verwandter Arbeiten den Innovationsgrad des Prozessmodells. Potentielle Erweiterungen nutzen die vorbereiteten Automatisierungsansätze, integrieren menschliche Faktoren, und generieren Modifikationsempfehlungen basierend auf Reasoning-Ergebnissen

Simpl: valdkonnaspetsiifiliste keelte loomise tööriist ettevõttetarkvara arendamiseks

Domain specific languages (DSLs) are languages designed with the specific purpose of developing or configuring part of a software system using concepts that are close to those of the system's application domain. Documented benefits of DSLs include increased development productivity, flexibility and maintainability, as well as separation of business and technical aspects allowing in some cases non-technical stakeholders to closely partake in the software development process. DSLs however comes at a potentially non-negligible cost, that of creating and maintaining DSL implementations. These costs can be reduced by means of specialized tools that support the creation of parsers, analyzers, code generators, pretty-printers, and other functions associated with a DSL. This thesis deals with the problem of enabling cost-effective DSL-based development in the context of Enterprise Information Systems (EIS). EISs are generally built using application frameworks and middleware. Accordingly, it must be possible to package the DSL implementation as a module that can be called from either the build system or from the enterprise system itself. Additionally, the DSL tool should be accessible to enterprise system developers with little or no expertise in development of programming languages and supporting tools, such as Integrated Development Environments. The central contribution of the thesis is Simpl, a DSL toolkit designed to meet the needs of enterprise software development. Simpl builds up on top of existing tools and programming languages, and introduces the following features: a grammar description language that supports the generation of both the parser and the data types for representing abstract syntax trees; support for lexer states that add context-sensitivity to lexer in a controlled manner; a pretty-printing library; an IDE framework; and an integration layer that combines all components into a single whole and minimizes the need for boilerplate code.Valdkonnaspetsiifilised programmeerimiskeeled (domain specific language, DSL) on keeled, mis on välja töötatud kasutamiseks mingis konkreetses rakendusvaldkonnas. Spetsialiseerumine võimaldab DSLis kasutada konstruktsioone, mis sobivad hästi antud valdkonna mõistete esitamiseks. DSLide kasutamine annab võrreldes üldotstarbeliste keeltega mitmeid eeliseid nagu näiteks kõrgem tarkvaraarenduse efektiivsus ning paindlikum ja hästi hooldatav lõpptulemus. Samuti saavad DSLide abil tarkvaraarenduses osaleda ka isikud, kelle tehnilised oskused ei ole piisavad üldotstarbelistes keeltes programmeerimiseks, näiteks süsteemianalüütikud, lõppkasutajad jne. Teisest küljest kaasnevad DSLide kasutamisega ka kulutused DSLide välja töötamiseks ning haldamiseks. DSL-põhist tarkvaraarendust saab muuta efektiivsemaks, kasutades DSLide realiseerimiseks spetsiaalseid tööriistu. Käesoleva väitekirja fookuses on kuluefektiivne DSLide kasutamisel põhinev ettevõttetarkvara arendus. Ettevõtteinfosüsteemid realiseeritakse tüüpiliselt raamistike ja valmiskomponentide abil. Seega peab olema võimalik pakendada DSLi realisatsioon moodulina, mida on võimalik välja kutsuda kas ehitussüsteemist või EISist endast. DSLi realiseerimise tööriist peab sobima kasutamiseks ka tarkvaraarendajatele, kellel ei ole kogemusi programmeerimiskeelte ja neid toetavate vahendite arendamiseks. Töö olulisemad väited on järgmised. Esiteks, ettevõttetarkvara arendamisel on oma spetsiifika, mis seab nõudeid DSLidele ning nende realiseerimiseks kasutatavatele tööriistadele. Teiseks, enamik populaarseid tööriistu, eriti integreeritud tööriistu, mis katavad ära kogu DSLi realiseerimiseks vajaliku tegevuste spektri, ei rahulda vähemalt osaliselt neid nõudeid. Kolmandaks, me demonstreerime, et on võimalik töötada välja DSL tööriist, mis on sobiv ettevõtteinfosüsteemide arendamiseks ning mis pakub olemasolevate tööriistadega võrreldavat kasutusmugavust.valdkonnaspetsiifilised keeledettevõttedhaldusinfosüsteemiddomain specific languagesenterprisesmanagement information system

Investigation of hadron matter using lattice QCD and implementation of lattice QCD applications on heterogeneous multicore acceleration processors

Observables relevant for the understanding of the structure of baryons were determined by means of Monte Carlo simulations of Lattice Quantum Chromodynamics (QCD) using 2+1 dynamical quark flavours. Especial emphasis was placed on how these observables change when flavour symmetry is broken in comparison to choosing equal masses for the two light and the strange quark. The first two moments of unpolarised, longitudinally, and transversely polarised parton distribution functions were calculated for the nucleon and hyperons. The latter are baryons which comprise a strange quark. Lattice QCD simulations tend to be extremely expensive, reaching the need for petaflop computing and beyond, a regime of computing power we just reach today. Heterogeneous multicore computing is getting increasingly important in high performance scientific computing. The strategy of deploying multiple types of processing elements within a single workflow, and allowing each to perform the tasks to which it is best suited is likely to be part of the roadmap to exascale. In this work new design concepts were developed for an active library (QDP++) harnessing the compute power of a heterogeneous multicore processor (IBM PowerXCell 8i processor). Not only a proof-of-concept is given furthermore it was possible to run a QDP++ based physics application (Chroma) achieving a reasonable performance on the IBM BladeCenter QS22