Memoria para optar al Título Profesional de Médico Veterinario / La presente memoria de Título estima el valor económico que otorgan los usuarios del patrimonio natural y servicios ambientales entregados por la Reserva Natural Altos de Lircay, ubicada en la VII Región, Chile. Se aplicó el método de valoración contingente (MVC) para valorar esta área silvestre protegida. En la determinación de la disposición a pagar (DAP) se realizaron encuestas diseñadas con un formato de preguntas mixto. Dado el total de 2540 visitantes adultos anuales promedio de los últimos 5 años, se determinó aplicar 333 encuestas. A pesar de no llegar al tamaño muestral el estudio se realizó con un total de 243 encuestas, las que se distribuyeron en los diferentes sectores que conforman la reserva. Las encuestas fueron administradas durante el mes de Febrero del año 2004. Los resultados muestran que los visitantes a la reserva son mayoritariamente chilenos, jóvenes, en su mayoría hombres y cuyas principales razones para visitar la reserva es disfrutar del paisaje y hacer caminatas. La DAP de los visitantes por acceder a los beneficios de la reserva fue de $ 2.587 por visita/año, siendo el excedente del consumidor calculado de $ 1.287 por visita/año, que es un valor mucho mayor a lo que se paga actualmente por acceder a los servicios recreativos y ambientales de la reserva. Las variables ingresos, edad, ni cantidad de visitas realizadas a la reserva por los encuestados demostraron ser explicativas de la DAP. La Curva de Demanda obtenida permitió revelar que las personas que realizan un mayor número de visitas a la reserva, no necesariamente están dispuestas a pagar un mayor valor por la entrada a ella

<p>Distributed real-time database systems demand consistency and timeliness. One approach for this problem is eventual consistency which guarantees local consistency within predictable time. Global consistency can be reached by best effort mechanisms but for some scenarios, e.g. an alarm signal, this may not be suffcient. Bounded delay replication, which provides global consistency in bounded time, ensures that after the local commit of a transaction updates are propagated to and integrated at any remote node within bounded time. The DRTS group at the University of Skövde is working on a project called DeeDS, which is a distributed real-time database prototype. In this prototype, eventual consistency with as</p><p>soon as possible (ASAP) replication is implemented. The goal of this dissertation is to further develop replication in this prototype in coexistence to the existing eventual consistency which implies the extension of both the theory and the implementation.</p><p>The main issue with bounded time replication is to make all parts, which are involved in the replication process predictable and simultaneously support eventual consistency with as soon as possible replication.</p>

Distributed real-time database systems demand consistency and timeliness. One approach for this problem is eventual consistency which guarantees local consistency within predictable time. Global consistency can be reached by best effort mechanisms but for some scenarios, e.g. an alarm signal, this may not be suffcient. Bounded delay replication, which provides global consistency in bounded time, ensures that after the local commit of a transaction updates are propagated to and integrated at any remote node within bounded time. The DRTS group at the University of Skövde is working on a project called DeeDS, which is a distributed real-time database prototype. In this prototype, eventual consistency with as soon as possible (ASAP) replication is implemented. The goal of this dissertation is to further develop replication in this prototype in coexistence to the existing eventual consistency which implies the extension of both the theory and the implementation. The main issue with bounded time replication is to make all parts, which are involved in the replication process predictable and simultaneously support eventual consistency with as soon as possible replication.

Replikation kann helfen, in einem verteilten System die Fehlertoleranz und Datensicherheit zu verbessern. In Systemen, die über Weitverkehrsnetze kommunizieren oder mobile Endgeräte einschließen, muß das Replikationssystem mit großen Kommunikationslatenzen umgehen können. Deshalb werden in solchen Systemen in der Regel nur asynchrone Replikationsalgorithmen mit schwach-konsistenter Änderungssemantik eingesetzt, da diese die lokale Annahme von Änderungen der Daten und deren Koordinierung mit anderen Replikaten entkoppeln und somit ein schnelles Antwortverhalten bieten können. Diese Dissertation stellt einen Ansatz für die Entwicklung schwach-konsistenter Replikationssysteme mit erweiterten kausalen Konsistenzgarantien vor und weist nach, daß auf seiner Grundlage effiziente Replikationssysteme konstruiert werden können. Dazu werden Mechanismen, Algorithmen und Protokolle vorgestellt, die Änderungen an replizierten Daten aufzeichnen und verteilen und dabei Kausalitätsbeziehungen erhalten. Kern ist ein Änderungsprotokoll, das sowohl als grundlegende Datenstruktur der verteilten Algorithmen agiert, als auch für die Konsistenz der lokalen Daten nach Systemabstürzen sorgt. Die kausalen Garantien werden mit Hilfe von zwei Algorithmen erweitet, die gleichzeitige Änderungen konsistent handhaben. Beide Algorithmen basieren auf der Beobachtung, daß die Divergenz der Replikate durch unkoordinierte, gleichzeitige Änderungen nicht unbedingt als Inkonsistenz gesehen werden muß, sondern auch als das Erzeugen verschiedener Versionen der Daten modelliert werden kann. Distributed Consistent Branching (DCB) erzeugt diese alternativen Versionen der Daten konsistent auf allen Replikaten; Distributed Consistent Cutting (DCC) wählt eine der Versionen konsistent aus. Die vorgestellten Algorithmen und Protokolle wurden in einer Datenbankimplementierung validiert. Mehrere Experimente zeigen ihre Einsetzbarkeit und helfen, ihr Verhalten unter verschiedenen Bedingungen einzuschätzen. / Data replication techniques introduce redundancy into a distributed system architecture that can help solve several of its persistent problems. In wide area or mobile systems, a replication system must be able to deal with the presence of unreliable, high-latency links. Only asynchronous replication algorithms with weak-consistency guarantees can be deployed in these environments, as these algorithms decouple the local acceptance of changes to the replicated data from coordination with remote replicas. This dissertation proposes a framework for building weak-consistency replication systems that provides the application developer with causal consistency guarantees and mechanisms for handling concurrency. By presenting an integrated set of mechanisms, algorithms and protocols for capturing and disseminating changes to the replicated data, we show that causal consistency and concurrency handling can be implemented in an efficient and versatile manner. The framework is founded on log of changes, which both acts the core data structure for its distributed algorithms and protocols and serves as the database log that ensures the consistency of the local data replica. The causal consistency guarantees are complemented with two distributed algorithms that handle concurrent operations. Both algorithms are based on the observation that uncoordinated concurrent operations introduce a divergence of state in a replication system that can be modeled as the creation of version branches. Distributed Consistent Branching (DCB) recreates these branches on all participating processes in a consistent manner. Distributed Consistent Cutting (DCC) selects one of the possible branches in a consistent and application-controllable manner and enforces a total causal order for all its operations. The contributed algorithms and protocols were validated in an database system implementation, and several experiments assess the behavior of these algorithms and protocols under varying conditions.

This thesis compares different approaches of creating a collaborative editing application using different methods such as OT, CRDT and Locking. After a comparison between these methods an implementation based on CRDT was done. The implementation of a collaborative graphical network was made such that consistency is guaranteed. The implementation uses the 2P2P-Graph which was extended in order to support moving of nodes, and uses the client-server communication model. An evaluation of the implementation was made by creating a time-complexity and a space complexity analysis. The result of the thesis includes a comparison between different methods and by an evaluation of the Extended 2P2P-Graph.

<p>In a distributed database system, pessimistic concurrency control is often used to ensure consistency which implies that the execution time of a transaction is not predictable. The execution time of a transaction is not dependent on the local transactions only, but on every transaction in the system.</p><p>In real-time database systems it is important that transactions are predictable. One way to make transactions predictable is to use eventual consistency where transactions commit locally before they are propagated to other nodes in the system. It is then possible to get predictable transactions due to the fact that the execution time of the transaction only depends on concurrent transactions on the local node and not on delays on other nodes and delays from a network.</p><p>In this report an investigation is made on how a replication protocol using eventual consistency can be designed for, and implemented in, DeeDS, a distributed real-time database prototype. The protocol consists of three parts: a propagation method, a conflict detection algorithm, and a conflict resolution mechanism. The conflict detection algorithm is based on version vectors. The focus is on the propagation mechanism and the conflict detection algorithm of the replication protocol.</p><p>An implementation design of the replication protocol is made. A discussion on how the version vectors may be applied in terms of granularity (container, page, object or attribute) and how the log filter should be designed and implemented to suit the particular conflict detection algorithm is carried out. A number of test cases with focus on regression testing have been defined.</p><p>It is concluded that the feasibility of the conflict detection algorithm is dependent on the application type that uses DeeDS.</p>

In a distributed database system, pessimistic concurrency control is often used to ensure consistency which implies that the execution time of a transaction is not predictable. The execution time of a transaction is not dependent on the local transactions only, but on every transaction in the system. In real-time database systems it is important that transactions are predictable. One way to make transactions predictable is to use eventual consistency where transactions commit locally before they are propagated to other nodes in the system. It is then possible to get predictable transactions due to the fact that the execution time of the transaction only depends on concurrent transactions on the local node and not on delays on other nodes and delays from a network. In this report an investigation is made on how a replication protocol using eventual consistency can be designed for, and implemented in, DeeDS, a distributed real-time database prototype. The protocol consists of three parts: a propagation method, a conflict detection algorithm, and a conflict resolution mechanism. The conflict detection algorithm is based on version vectors. The focus is on the propagation mechanism and the conflict detection algorithm of the replication protocol. An implementation design of the replication protocol is made. A discussion on how the version vectors may be applied in terms of granularity (container, page, object or attribute) and how the log filter should be designed and implemented to suit the particular conflict detection algorithm is carried out. A number of test cases with focus on regression testing have been defined. It is concluded that the feasibility of the conflict detection algorithm is dependent on the application type that uses DeeDS.

Les systèmes décentralisés sont par nature extensibles mais sont également difficiles à coordonner en raison de leur faible couplage. La réplication de données dans ces systèmes géo-répartis est donc un défi inhérent à leur structure. Les deux contributions de cette thèse exploitent l'hétérogénéité des besoins des utilisateurs et permettent une qualité de service personnalisable pour la réplication de données dans les systèmes décentralisés. Notre première contribution Gossip Primary-Secondary étend le critère de cohérence Update consistency Primary-Secondary afin d'offrir des garanties différenciées de cohérence et de latence de messages pour la réplication de données à grande échelle. Notre seconde contribution Dietcoin enrichit Bitcoin avec des nœuds diet qui peuvent (i) vérifier la validité de sous-chaînes de blocs en évitant le coût exorbitant de la vérification initiale et (ii) choisir leur propres garanties de sécurité et de consommation de ressources. / Decentralized systems are scalable by design but also difficult to coordinate due to their weak coupling. Replicating data in these geo-distributed systems is therefore a challenge inherent to their structure. The two contributions of this thesis exploit the heterogeneity of user requirements and enable personalizable quality of services for data replication in decentralized systems. Our first contribution Gossip Primary-Secondary enables the consistency criterion Update consistency Primary-Secondary to offer differentiated guarantees in terms of consistency and message delivery latency for large-scale data replication. Our second contribution Dietcoin enriches Bitcoin with diet nodes that can (i) verify the correctness of entire subchains of blocks while avoiding the exorbitant cost of bootstrap verification and (ii) personalize their own security and resource consumption guarantees.

La collaboration en temps réel est un cas spécial de collaboration où les utilisateurs travaillent sur le même élément simultanément et sont au courant des modifications des autres utilisateurs en temps réel. Les données distribuées doivent rester disponibles et consistant tout en étant répartis sur plusieurs systèmes physiques. "Strong Consistency" est une approche qui crée un ordre total des opérations en utilisant des mécanismes tel que le "locking". Cependant, cela introduit un "bottleneck". Ces dix dernières années, les algorithmes de concurrence ont été étudiés dans le but de garder la convergence de tous les replicas sans utiliser de "locking" ni de synchronisation. "Operational Trans- formation" et "Conflict-free Replicated Data Types (CRDT)" sont utilisés dans ce but. Cependant, la complexité de ces stratégies les rend compliquées à intégrer dans des logicielles conséquents, comme les éditeurs de modèles, spécialement pour des data structures complexes comme les graphes. Les implémentations actuelles intègrent seulement des data linéaires tel que le texte. Dans ce mémoire, nous présentons CollabServer, un framework pour construire des environnements de collaboration. Il a une implémentation de CRDTs pour des data structures complexes tel que les graphes et donne la possibilité de construire ses propres data structures. / Real-time collaboration is a special case of collaboration where users work on the same artefact simultaneously and are aware of each other’s changes in real-time. Shared data should remain available and consistent while dealing with its physically distributed aspect. Strong Consistency is one approach that enforces a total order of operations using mechanisms, such as locking. This however introduces a bottleneck. In the last decade, algorithms for concurrency control have been studied to keep convergence of all replicas without locking or synchronization. Operational Transformation and Conflict free Replicated Data Types (CRDT) are widely used to achieve this purpose. However, the complexity of these strategies makes it hard to integrate in large software, such as modeling editors, especially for complex data types like graphs. Current implementations only integrate linear data, such as text. In this thesis, we present CollabServer, a framework to build collaborative environments. It features a CRDTs implementation for complex data types such as graphs and gives possibility to build other data structures.

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-09-02T14:30:50Z No. of bitstreams: 1 Gisele Aparecida Bovolenta.pdf: 4981306 bytes, checksum: 7208f20080b6dfd8c292dfc861b44f59 (MD5) / Made available in DSpace on 2016-09-02T14:30:50Z (GMT). No. of bitstreams: 1 Gisele Aparecida Bovolenta.pdf: 4981306 bytes, checksum: 7208f20080b6dfd8c292dfc861b44f59 (MD5) Previous issue date: 2016-04-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study investigates the scenery and the history of progress and challenges, continuities and changes in the recognition of the Brazilian government potential benefits (BE). BE are under the responsibility of the social welfare policy since 1993 and are a social assistance right in the sector of distributive social protection. BE have established a public state duty to support citizens in view of life cycle events, such as birth and death, and day-to-day hardships, such as temporary vulnerability, lack of social protection and public calamity. The cities, states and the Federal District are responsible for ensuring such right, thus it is necessary to consider the cooperation agreement regarding management, regulation and funding signed by these organizations before the Federative Agreement. Based on real-life data and through evidence-based, theoretical, documentary and legal analyses, this research sought to rebuild the history of such benefits, identify previous forms of care, investigate their elements and make a few considerations about the current BE provided. Finally, this study aims to perform an evidence-based reality analysis of the city and the state of São Paulo, highlighting the lack of cooperation among the organizations responsible for ensuring such social assistance right, which is part of the social protection sector of the Brazilian Unified Social Assistance System (SUAS) / Este estudo investiga o cenário e o histórico de avanços e desafios, permanências e mudanças, no reconhecimento do benefício eventual (BE). Sob a incumbência da política de assistência social desde 1993, como um direito socioassistencial no campo da proteção social distributiva, o BE institui o dever público estatal no apoio ao cidadão em face das eventualidades do ciclo da vida, como o nascimento e a morte, e das adversidades cotidianas, como as vulnerabilidades temporárias, desproteções sociais e calamidades públicas. O dever de garantir essa atenção centra-se junto aos municípios, estados federados e Distrito Federal, o que requer considerar a relação de cooperação quanto a gestão, regulamentação e financiamento firmada entre esses entes ante o Pacto Federativo. A partir dos dados da realidade, das análises empírica, teórica, documental e legal, a pesquisa buscou reconstruir o histórico desse benefício, identificar formas de atenção que o precederam, investigar os elementos de sua natureza e tecer algumas considerações acerca das modalidades de BE asseguradas atualmente. O trabalho tem, por fim, São Paulo (cidade e estado) como realidade empírica a ser examinada, destacando a inexistência de cooperação entre esses entes responsáveis em garantir esse direito socioassistencial, o qual é parte do campo de proteção social do Sistema Único de Assistência Social