Towards dynamic term size computation via program transformation

Knowing the size of the terms to which program variables are bound at run-time in logic programs is required in a class of applications related to program optimization such as, for example, recursion elimination and granularity analysis. Such size is difficult to even approximate at compile time and is thus generally computed at run-time by using (possibly predefined) predicates which traverse the terms involved. We propose a technique based on program transformation which has the potential of performing this computation much more efficiently. The technique is based on finding program procedures which are called before those in which knowledge regarding term sizes is needed and which traverse the terms whose size is to be determined, and transforming such procedures so that they compute term sizes "on the fly". We present a systematic way of determining whether a given program can be transformed in order to compute a given term size at a given program point without additional term traversal. Also, if several such transformations are possible our approach allows finding minimal transformations under certain criteria. We also discuss the advantages and present some applications of our technique.

Towards data-aware resource analysis for service orchestrations

Compile-time program analysis techniques can be applied to Web service orchestrations to prove or check various properties. In particular, service orchestrations can be subjected to resource analysis, in which safe approximations of upper and lower resource usage bounds are deduced. A uniform analysis can be simultaneously performed for different generalized resources that can be directiy correlated with cost- and performance-related quality attributes, such as invocations of partners, network traffic, number of activities, iterations, and data accesses. The resulting safe upper and lower bounds do not depend on probabilistic assumptions, and are expressed as functions of size or length of data components from an initiating message, using a finegrained structured data model that corresponds to the XML-style of information structuring. The analysis is performed by transforming a BPEL-like representation of an orchestration into an equivalent program in another programming language for which the appropriate analysis tools already exist.

Combining static analysis and profiling for estimating execution times in logic programs

Effective static analyses have been proposed which allow inferring functions which bound the number of resolutions or reductions. These have the advantage of being independent from the platform on which the programs are executed and such bounds have been shown useful in a number of applications, such as granularity control in parallel execution. On the other hand, in certain distributed computation scenarios where different platforms come into play, with each platform having different capabilities, it is more interesting to express costs in metrics that include the characteristics of the platform. In particular, it is specially interesting to be able to infer upper and lower bounds on actual execution time. With this objective in mind, we propose a method which allows inferring upper and lower bounds on the execution times of procedures of a program in a given execution platform. The approach combines compile-time cost bounds analysis with a one-time profiling of the platform in order to determine the values of certain constants for that platform. These constants calibrate a cost model which from then on is able to compute statically time bound functions for procedures and to predict with a significant degree of accuracy the execution times of such procedures in the given platform. The approach has been implemented and integrated in the CiaoPP system.

Using global analysis, partial specifications, and an extensible assertion language for program validation and debugging

We present a framework for the application of abstract interpretation as an aid during program development, rather than in the more traditional application of program optimization. Program validation and detection of errors is first performed statically by comparing (partial) specifications written in terms of assertions against information obtained from static analysis of the program. The results of this process are expressed in the user assertion language. Assertions (or parts of assertions) which cannot be verified statically are translated into run-time tests. The framework allows the use of assertions to be optional. It also allows using very general properties in assertions, beyond the predefined set understandable by the static analyzer and including properties defined by means of user programs. We also report briefly on an implementation of the framework. The resulting tool generates and checks assertions for Prolog, CLP(R), and CHIP/CLP(fd) programs, and integrates compile-time and run-time checking in a uniform way. The tool allows using properties such as types, modes, non-failure, determinacy, and computational cost, and can treat modules separately, performing incremental analysis. In practice, this modularity allows detecting statically bugs in user programs even if they do not contain any assertions.

A proposal for an interchange abstract syntax for (parallel) Prolog

We propose an abstract syntax for Prolog that will help the manipulation of programs at compile-time, as well as the exchange of sources and information among the tools designed for this manipulation. This includes analysers, partial evaluators, and program transformation tools. We have chosen to concentrate on the information exchange format, rather than on the syntax of programs, for which we assume a simplified format. Our purpose is to provide a low-level meeting point for the tools which will allow them to read the same programs and understand the information about them. This report describes our first design in an informal way. We expect this design to evolve and concretize, along with the future development of the tools, during the project.

Optimization of logic programs with dynamic scheduling

Dynamic scheduling increases the expressive power of logic programming languages, but also introduces some overhead. In this paper we present two classes of program transformations designed to reduce this additional overhead, while preserving the operational semantics of the original programs, modulo ordering of literals woken at the same time. The first class of transformations simplifies the delay conditions while the second class moves delayed literals later in the rule body. Application of the program transformations can be automated using information provided by compile-time analysis. We provide experimental results obtained from an implementation of the proposed techniques using the CIAO prototype compiler. Our results show that the techniques can lead to substantial performance improvement.

A technique for dynamic term size computation via program transformation

Knowing the size of the terms to which program variables are bound at run-time in logic programs is required in a class of applications related to program optimization such as, for example, granularity analysis and selection among different algorithms or control rules whose performance may be dependent on such size. Such size is difficult to even approximate at compile time and is thus generally computed at run-time by using (possibly predefined) predicates which traverse the terms involved. We propose a technique based on program transformation which has the potential of performing this computation much more efficiently. The technique is based on finding program procedures which are called before those in which knowledge regarding term sizes is needed and which traverse the terms whose size is to be determined, and transforming such procedures so that they compute term sizes "on the fly". We present a systematic way of determining whether a given program can be transformed in order to compute a given term size at a given program point without additional term traversal. Also, if several such transformations are possible our approach allows finding minimal transformations under certain criteria. We also discuss the advantages and applications of our technique and present some performance results.

Towards extracting non-strict independent and-parallelism using sharing and freeness information

Logic programming systems which exploit and-parallelism among non-deterministic goals rely on notions of independence among those goals in order to ensure certain efficiency properties. "Non-strict" independence (NSI) is a more relaxed notion than the traditional notion of "strict" independence (SI) which still ensures the relevant efficiency properties and can allow considerable more parallelism than SI. However, all compilation technology developed to date has been based on SI, presumably because of the intrinsic complexity of exploiting NSI. This is related to the fact that NSI cannot be determined "a priori" as SI. This paper fills this gap by developing a technique for compile-time detection and annotation of NSI. It also proposes algorithms for combined compile- time/run-time detection, presenting novel run-time checks for this type of parallelism. Also, a transformation procedure to eliminate shared variables among parallel goals is presented, attempting to perform as much work as possible at compiletime. The approach is based on the knowledge of certain properties about run-time instantiations of program variables —sharing and freeness— for which compile-time technology is available, with new approaches being currently proposed.

Dynamic term size computation in logic programs via program transformation

Knowing the size of the terms to which program variables are bound at run-time in logic programs is required in a class of applications related to program optimization such as, for example, recursion elimination and granularity analysis. Such size is difficult to even approximate at compile time and is thus generally computed at run-time by using (possibly predefined) predicates which traverse the terms involved. We propose a technique based on program transformation which has the potential of performing this computation much more efficiently. The technique is based on finding program procedures which are called before those in which knowledge regarding term sizes is needed and which traverse the terms whose size is to be determined, and transforming such procedures so that they compute term sizes "on the fly". We present a systematic way of determining whether a given program can be transformed in order to compute a given term size at a given program point without additional term traversal. Also, if several such transformations are possible our approach allows finding minimal transformations under certain criteria. We also discuss the advantages and present some applications of our technique.

Integrating software testing and run-time checking in an assertion verification framework.

We have designed and implemented a framework that unifies unit testing and run-time verification (as well as static verification and static debugging). A key contribution of our approach is that a unified assertion language is used for all of these tasks. We first propose methods for compiling runtime checks for (parts of) assertions which cannot be verified at compile-time via program transformation. This transformation allows checking preconditions and postconditions, including conditional postconditions, properties at arbitrary program points, and certain computational properties. The implemented transformation includes several optimizations to reduce run-time overhead. We also propose a minimal addition to the assertion language which allows defining unit tests to be run in order to detect possible violations of the (partial) specifications expressed by the assertions. This language can express for example the input data for performing the unit tests or the number of times that the unit tests should be repeated. We have implemented the framework within the Ciao/CiaoPP system and effectively applied it to the verification of ISO-prolog compliance and to the detection of different types of bugs in the Ciao system source code. Several experimental results are presented that illustrate different trade-offs among program size, running time, or levels of verbosity of the messages shown to the user.

Three decades of Space Activities at the Instituto Universitario de Microgravedad "Ignacio Da Riva" / Universidad Politécnica de Madrid (IDR/UPM) en History of Rocketry and Astronautics

Strictly speaking, space related activities at the Escuela Técnica Superior de Ingenieros Aeronáuticos (ETSIA) begun in 1973, when Prof. Ignacio Da Riva got a contract from the European Space Agency (ESA) to compile a handbook on spacecraft thermal control. By the same time, ESA issued an announcement of opportunities offering to the European scientific community the possibility of perform microgravity relevant experiments on board space platform like the European orbital laboratory Spacelab. Prof. Da Riva proposed one of the few selected experiments dealing with fluid physics under microgravity conditions, later flown on Spacelab-1 mission in 1983. These two events were the starting point where Prof. Da Riva, full professor of Aerodynamics at ETSIA, nucleated a small group of young professors and students located at the Laboratorio de Aerodinámica y Mecánica de Fluidos (LAMF) of ETSIA. Such group was leaded by Prof. Da Riva since its creation till 1991, when Prof. Da Riva died, and it was the seed of the more recently created research institute for aerospace science and technology named "Ignacio Da Riva" (IDR) in his honour. In this communication space related activities performed either at LAMF or IDR during the last three decades are briefly described.

Towards a systematic benchmarking of ontology-based query rewriting systems

Query rewriting is one of the fundamental steps in ontologybased data access (OBDA) approaches. It takes as inputs an ontology and a query written according to that ontology, and produces as an output a set of queries that should be evaluated to account for the inferences that should be considered for that query and ontology. Different query rewriting systems give support to different ontology languages with varying expressiveness, and the rewritten queries obtained as an output do also vary in expressiveness. This heterogeneity has traditionally made it difficult to compare different approaches, and the area lacks in general commonly agreed benchmarks that could be used not only for such comparisons but also for improving OBDA support. In this paper we compile data, dimensions and measurements that have been used to evaluate some of the most recent systems, we analyse and characterise these assets, and provide a unified set of them that could be used as a starting point towards a more systematic benchmarking process for such systems. Finally, we apply this initial benchmark with some of the most relevant OBDA approaches in the state of the art.

Explotación de servicios de la Infraestructura de Datos Espaciales de España (IDEE) en dispositivos móviles

En los últimos años el número de dispositivos móviles y smartphones ha aumentado drásticamente, así como el número de aplicaciones destinadas a estos. Los desarrolladores siempre se han visto frenados en la creación de estas aplicaciones debido a la complejidad que supone la diversidad de sistemas operativos (Android, iOS, Windows Phone, etc), que utilizan lenguajes de programación diferentes, haciendo que, para poder desarrollar una aplicación que funcione en estas plataformas, en verdad haya que implementar una aplicación independiente para cada una de las plataformas. Para solucionar este problema han surgido frameworks, como Appcelerator Titanium, que permiten escribir una sola vez la aplicación y compilarla para las diferentes plataformas móviles objetivo. Sin embargo, estos frameworks están aún en estado muy temprano de desarrollo, por lo que no resuelven toda la problemática ni dan una respuesta completa a los desarrolladores. El objetivo de este Trabajo de Fin de Grado ha sido contribuir a la evolución de estos frameworks mediante la creación de un módulo para Appcelerator Titanium que permita construir de manera ágil aplicaciones multiplataforma que hagan uso de visualizadores de información geográfica. Para ello se propone el desarrollo de un módulo de mapa con soporte para capas WMS, rutas y polígonos en WKT, KML y GeoJSON. Se facilitará además que estas aplicaciones puedan acceder a capacidades del hardware como la brújula y el GPS para realizar un seguimiento de la localización, a la vez que se hace uso de la aceleración por el hardware subyacente para mejorar la velocidad y fluidez de la información visualizada en el mapa. A partir de este módulo se ha creado una aplicación que hace uso de todas sus características y posteriormente se ha migrado a la plataforma Wirecloud4Tablet como componente nativo que puede integrarse con otros componentes web (widgets) mediante técnicas de mashup. Gracias a esto se ha podido fusionar por un lado todas las ventajas que ofrece Wirecloud para el rápido desarrollo de aplicaciones sin necesidad de tener conocimientos de programación, junto con las ventajas que ofrecen las aplicaciones nativas en cuanto a rendimiento y características extras. Usando los resultados de este proyecto, se pueden crear de manera ágil aplicaciones composicionales nativas multiplataforma que hagan uso de visualización de información geográfica; es decir, se pueden crear aplicaciones en pocos minutos y sin conocimientos de programación que pueden ejecutar diferentes componentes (como el mapa) de manera nativa en múltiples plataformas. Se facilita también la integración de componentes nativos (como es el mapa desarrollado) con otros componentes web (widgets) en un mashup que puede visualizarse en dispositivos móviles mediante la plataforma Wirecloud. ---ABSTRACT---In recent years the number of mobile devices and smartphones has increased dramatically as well as the number of applications targeted at them. Developers always have been slowed in the creation of these applications due to the complexity caused by the diversity of operating systems (Android, iOS, Windows Phone, etc), each of them using different programming languages, so that, in order to develop an application that works on these platforms, the developer really has to implement a different application for each platform. To solve this problem frameworks such as Appcelerator Titanium have emerged, allowing developers to write the application once and to compile it for different target mobile platforms. However, these frameworks are still in very early stage of development, so they do not solve all the difficulties nor give a complete solution to the developers. The objective of this final year dissertation is to contribute to the evolution of these frameworks by creating a module for Appcelerator Titanium that permits to nimbly build multi-platform applications that make use of geographical information visualization. To this end, the development of a map module with support for WMS layers, paths, and polygons in WKT, KML, and GeoJSON is proposed. This module will also facilitate these applications to access hardware capabilities such as GPS and compass to track the location, while it makes use of the underlying hardware acceleration to improve the speed and fluidity of the information displayed on the map. Based on this module, it has been created an application that makes use of all its features and subsequently it has been migrated to the platform Wirecloud4Tablet as a native component that can be integrated with other web components (widgets) using mashup techniques. As a result, it has been fused on one side all the advantages Wirecloud provides for fast application development without the need of programming skills, along with the advantages of native apps, such as performance and extra features. Using the results of this project, compositional platform native applications that make use of geographical information visualization can be created in an agile way; ie, in a few minutes and without having programming skills, a developer could create applications that can run different components (like the map) natively on multiple platforms. It also facilitates the integration of native components (like the map) with other web components (widgets) in a mashup that can be displayed on mobile devices through the Wirecloud platform.

Towards a Systematic benchmarking of ontology-based query rewriting systems

Query rewriting is one of the fundamental steps in ontologybased data access (OBDA) approaches. It takes as inputs an ontology and a query written according to that ontology, and produces as an output a set of queries that should be evaluated to account for the inferences that should be considered for that query and ontology. Different query rewriting systems give support to different ontology languages with varying expressiveness, and the rewritten queries obtained as an output do also vary in expressiveness. This heterogeneity has traditionally made it difficult to compare different approaches, and the area lacks in general commonly agreed benchmarks that could be used not only for such comparisons but also for improving OBDA support. In this paper we compile data, dimensions and measurements that have been used to evaluate some of the most recent systems, we analyse and characterise these assets, and provide a unified set of them that could be used as a starting point towards a more systematic benchmarking process for such systems. Finally, we apply this initial benchmark with some of the most relevant OBDA approaches in the state of the art.

Captura y transformación de grafos para análisis de redes sociales

Hoy en día las redes sociales se han convertido en una parte importante en la vida de muchas personas. No sólo porque les permite mantener el contacto con familiares y amigos, sino porque también pueden mostrar al mundo sus opiniones, inquietudes, estilo de vida, habilidades, ideas… Una de las redes sociales que ha adquirido mayor importancia en los últimos años es Twitter. Actualmente cuenta con más de 320 millones de usuarios activos al mes. En ella los usuarios pueden publicar información y acceder a información publicada por otros usuarios. Se ha convertido en el medio de comunicación y difusión de noticias más rápido del mundo. Éstas son algunas de las razones por las que existe un gran interés por el análisis de datos de esta red social. En particular, el análisis de tendencias a través de redes de interacciones entre sus usuarios. Un ejemplo este tipo de redes en Twitter es una red de retweets sobre una etiqueta o hasthtag concreto. Estas redes se pueden representar como grafos, donde los nodos representan a los usuarios y las aristas los retweets entre usuarios. Aunque existen varias aplicaciones que permiten transformar y visualizar grafos a partir de un fichero, es difícil encontrar librerías de programación o aplicaciones que recopilen los datos de twitter, generen los grafos, los analicen y los exporten a ficheros concretos para poder visualizarlos con alguna aplicación. Este trabajo tiene como finalidad crear una librería en el lenguaje de programación Java que permita recopilar datos de twitter, transformar dichos datos en grafos, aplicar algoritmos para analizarlos, y exportar los grafos a ficheros con formato GEXF para que puedan ser visualizados con la aplicación Gephi. Esta librería incluye un programa para probar todas sus funcionalidades.---ABSTRACT---Today, social networks have become an important part in the life of many persons. Not only because they allow them to keep in contact with relatives and friends but also because through them they can express their opinions, interests, life- styles, hobbies or ideas to the wide world. Twitter is one of the social networks which in the last few years has achieved a particular importance. Right now, it counts with more that 320 millions of active monthly users who exchange, or have access, through it to a wide variety of informations. Twitter has become the fastest way in the world to communicate or diffuse news. This explains, among other reasons, the growing interest in the analysis of the data in this specific social network, particularly the analysis of trends through the web of interactions between its users. An example of this type of networks in Twitter is the network of retweets on a specific label or hashtag. These networks can be represented as graphs where nodes represent users and edges the retweets between users. Although there exist aldeady several applications that allow for the transformation and visualization in graphs of the contents of a data file, it is difficult to find libraries or applications to compile data from twitter, to generate graphs from them, to analyze them and to export them to a specific file that will allow its visualization with the use of some application. The purpose of this work is the creation of a library in Java language that will make posible to compile data from twitter, to transform them in grafos, to apply algorythms to analyze them and to export the graphos to files with a GEXF format, which will allow their visualization with a Gephi application. This library will include a program to test all its features.