Use of a semantically grained database system for distribution and control within design environments

This paper presents a technique to share the data stored in an object-oriented database aimed at designing environments. This technique shares data between two related databases, called the Original and Product databases, and is composed of three processes: data separation, evolution and integration. Whenever a block of data needs to be shared, it is spread into both databases, resulting in a block on the original database, and another into the Product database, with special links between them controlled by the Object Manager. These blocks do not need to be maintained identical during the evolution phase of the sharing process. Six types of links were defined, and by choosing one, the designer control the evolution and reintegration of the block in both databases. This process uses the composite object concept as the unit of control. The presented concepts can be applied to any data model with support to composite objects.

A medical information system to manage a cancer database

Cancer is the second main cause of death in Brazil, and according to statistics disclosed by INCA - National Cancer Institute 466,730 new cases of the disease are forecast for 2008. The storage and analysis of tumour tissues of various types and patients' clinical data, genetic profiles, characteristics of diseases and epidemiological data may provide more precise diagnoses, providing more effective treatments with higher chances for the cure of cancer. In this paper we present a Web system with a client-server architecture, which manages a relational database containing all information relating to the tumour tissue and their location in freezers, patients, medical forms, physicians, users, and others. Furthermore, it is also discussed the software engineering used to developing the system.

Optimization of query results in peer-to-peer database supported by semantics

The development of new technologies that use peer-to-peer networks grows every day, with the object to supply the need of sharing information, resources and services of databases around the world. Among them are the peer-to-peer databases that take advantage of peer-to-peer networks to manage distributed knowledge bases, allowing the sharing of information semantically related but syntactically heterogeneous. However, it is a challenge to ensure the efficient search for information without compromising the autonomy of each node and network flexibility, given the structural characteristics of these networks. On the other hand, some studies propose the use of ontology semantics by assigning standardized categorization of information. The main original contribution of this work is the approach of this problem with a proposal for optimization of queries supported by the Ant Colony algorithm and classification though ontologies. The results show that this strategy enables the semantic support to the searches in peer-to-peer databases, aiming to expand the results without compromising network performance. © 2011 IEEE.

The design of robust protocols for distributed real-time systems

Modern distributed control systems comprise of a set of processors which are interconnected using a suitable communication network. For use in real-time control environments, such systems must be deterministic and generate specified responses within critical timing constraints. Also, they should be sufficiently robust to survive predictable events such as communication or processor faults. This thesis considers the problem of coordinating and synchronizing a distributed real-time control system under normal and abnormal conditions. Distributed control systems need to periodically coordinate the actions of several autonomous sites. Often the type of coordination required is the all or nothing property of an atomic action. Atomic commit protocols have been used to achieve this atomicity in distributed database systems which are not subject to deadlines. This thesis addresses the problem of applying time constraints to atomic commit protocols so that decisions can be made within a deadline. A modified protocol is proposed which is suitable for real-time applications. The thesis also addresses the problem of ensuring that atomicity is provided even if processor or communication failures occur. Previous work has considered the design of atomic commit protocols for use in non time critical distributed database systems. However, in a distributed real-time control system a fault must not allow stringent timing constraints to be violated. This thesis proposes commit protocols using synchronous communications which can be made resilient to a single processor or communication failure and still satisfy deadlines. Previous formal models used to design commit protocols have had adequate state coverability but have omitted timing properties. They also assumed that sites communicated asynchronously and omitted the communications from the model. Timed Petri nets are used in this thesis to specify and design the proposed protocols which are analysed for consistency and timeliness. Also the communication system is mcxielled within the Petri net specifications so that communication failures can be included in the analysis. Analysis of the Timed Petri net and the associated reachability tree is used to show the proposed protocols always terminate consistently and satisfy timing constraints. Finally the applications of this work are described. Two different types of applications are considered, real-time databases and real-time control systems. It is shown that it may be advantageous to use synchronous communications in distributed database systems, especially if predictable response times are required. Emphasis is given to the application of the developed commit protocols to real-time control systems. Using the same analysis techniques as those used for the design of the protocols it can be shown that the overall system performs as expected both functionally and temporally.

The implementation of a functional query language front-end to a relational database system. Available in 2 volumes.

Database systems have a user interface one of the components of which will normally be a query language which is based on a particular data model. Typically data models provide primitives to define, manipulate and query databases. Often these primitives are designed to form self-contained query languages. This thesis describes a prototype implementation of a system which allows users to specify queries against the database in a query language whose primitives are not those provided by the actual model on which the database system is based, but those provided by a different data model. The implementation chosen is the Functional Query Language Front End (FQLFE). This uses the Daplex functional data model and query language. Using FQLFE, users can specify the underlying database (based on the relational model) in terms of Daplex. Queries against this specified view can then be made in Daplex. FQLFE transforms these queries into the query language (Quel) of the underlying target database system (Ingres). The automation of part of the Daplex function definition phase is also described and its implementation discussed.

Semantic wrapping for heterogeneous database management

Query processing is a commonly performed procedure and a vital and integral part of information processing. It is therefore important and necessary for information processing applications to continuously improve the accessibility of data sources as well as the ability to perform queries on those data sources. ^ It is well known that the relational database model and the Structured Query Language (SQL) are currently the most popular tools to implement and query databases. However, a certain level of expertise is needed to use SQL and to access relational databases. This study presents a semantic modeling approach that enables the average user to access and query existing relational databases without the concern of the database's structure or technicalities. This method includes an algorithm to represent relational database schemas in a more semantically rich way. The result of which is a semantic view of the relational database. The user performs queries using an adapted version of SQL, namely Semantic SQL. This method substantially reduces the size and complexity of queries. Additionally, it shortens the database application development cycle and improves maintenance and reliability by reducing the size of application programs. Furthermore, a Semantic Wrapper tool illustrating the semantic wrapping method is presented. ^ I further extend the use of this semantic wrapping method to heterogeneous database management. Relational, object-oriented databases and the Internet data sources are considered to be part of the heterogeneous database environment. Semantic schemas resulting from the algorithm presented in the method were employed to describe the structure of these data sources in a uniform way. Semantic SQL was utilized to query various data sources. As a result, this method provides users with the ability to access and perform queries on heterogeneous database systems in a more innate way. ^

Database As A Tool For Hospitality Management

In his discussion - Database As A Tool For Hospitality Management - William O'Brien, Assistant Professor, School of Hospitality Management at Florida International University, O’Brien offers at the outset, “Database systems offer sweeping possibilities for better management of information in the hospitality industry. The author discusses what such systems are capable of accomplishing.” The author opens with a bit of background on database system development, which also lends an impression as to the complexion of the rest of the article; uh, it’s a shade technical. “In early 1981, Ashton-Tate introduced dBase 11. It was the first microcomputer database management processor to offer relational capabilities and a user-friendly query system combined with a fast, convenient report writer,” O’Brien informs. “When 16-bit microcomputers such as the IBM PC series were introduced late the following year, more powerful database products followed: dBase 111, Friday!, and Framework. The effect on the entire business community, and the hospitality industry in particular, has been remarkable”, he further offers with his informed outlook. Professor O’Brien offers a few anecdotal situations to illustrate how much a comprehensive data-base system means to a hospitality operation, especially when billing is involved. Although attitudes about computer systems, as well as the systems themselves have changed since this article was written, there is pertinent, fundamental information to be gleaned. In regards to the digression of the personal touch when a customer is engaged with a computer system, O’Brien says, “A modern data processing system should not force an employee to treat valued customers as numbers…” He also cautions, “Any computer system that decreases the availability of the personal touch is simply unacceptable.” In a system’s ability to process information, O’Brien suggests that in the past businesses were so enamored with just having an automated system that they failed to take full advantage of its capabilities. O’Brien says that a lot of savings, in time and money, went un-noticed and/or under-appreciated. Today, everyone has an integrated system, and the wise business manager is the business manager who takes full advantage of all his resources. O’Brien invokes the 80/20 rule, and offers, “…the last 20 percent of results costs 80 percent of the effort. But times have changed. Everyone is automating data management, so that last 20 percent that could be ignored a short time ago represents a significant competitive differential.” The evolution of data systems takes center stage for much of the article; pitfalls also emerge.

An Intelligent Distributed System for Environmental Management

Environmental management is a complex task. The amount and heterogeneity of the data needed for an environmental decision making tool is overwhelming without adequate database systems and innovative methodologies. As far as data management, data interaction and data processing is concerned we here propose the use of a Geographical Information System (GIS) whilst for the decision making we suggest a Multi-Agent System (MAS) architecture. With the adoption of a GIS we hope to provide a complementary coexistence between heterogeneous data sets, a correct data structure, a good storage capacity and a friendly user’s interface. By choosing a distributed architecture such as a Multi-Agent System, where each agent is a semi-autonomous Expert System with the necessary skills to cooperate with the others in order to solve a given task, we hope to ensure a dynamic problem decomposition and to achieve a better performance compared with standard monolithical architectures. Finally, and in view of the partial, imprecise, and ever changing character of information available for decision making, Belief Revision capabilities are added to the system. Our aim is to present and discuss an intelligent environmental management system capable of suggesting the more appropriate land-use actions based on the existing spatial and non-spatial constraints.

Static detection of anomalies in transactional memory programs

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do Grau de Mestre em Engenharia Informática

Information flow analysis using data-dependent logical propositions

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

Scaling In-Memory databases on multicores

Current computer systems have evolved from featuring only a single processing unit and limited RAM, in the order of kilobytes or few megabytes, to include several multicore processors, o↵ering in the order of several tens of concurrent execution contexts, and have main memory in the order of several tens to hundreds of gigabytes. This allows to keep all data of many applications in the main memory, leading to the development of inmemory databases. Compared to disk-backed databases, in-memory databases (IMDBs) are expected to provide better performance by incurring in less I/O overhead. In this dissertation, we present a scalability study of two general purpose IMDBs on multicore systems. The results show that current general purpose IMDBs do not scale on multicores, due to contention among threads running concurrent transactions. In this work, we explore di↵erent direction to overcome the scalability issues of IMDBs in multicores, while enforcing strong isolation semantics. First, we present a solution that requires no modification to either database systems or to the applications, called MacroDB. MacroDB replicates the database among several engines, using a master-slave replication scheme, where update transactions execute on the master, while read-only transactions execute on slaves. This reduces contention, allowing MacroDB to o↵er scalable performance under read-only workloads, while updateintensive workloads su↵er from performance loss, when compared to the standalone engine. Second, we delve into the database engine and identify the concurrency control mechanism used by the storage sub-component as a scalability bottleneck. We then propose a new locking scheme that allows the removal of such mechanisms from the storage sub-component. This modification o↵ers performance improvement under all workloads, when compared to the standalone engine, while scalability is limited to read-only workloads. Next we addressed the scalability limitations for update-intensive workloads, and propose the reduction of locking granularity from the table level to the attribute level. This further improved performance for intensive and moderate update workloads, at a slight cost for read-only workloads. Scalability is limited to intensive-read and read-only workloads. Finally, we investigate the impact applications have on the performance of database systems, by studying how operation order inside transactions influences the database performance. We then propose a Read before Write (RbW) interaction pattern, under which transaction perform all read operations before executing write operations. The RbW pattern allowed TPC-C to achieve scalable performance on our modified engine for all workloads. Additionally, the RbW pattern allowed our modified engine to achieve scalable performance on multicores, almost up to the total number of cores, while enforcing strong isolation.

Tietojärjestelmien tietokantojen jatkuva tietojen varmistaminen

Tietokantoja käyttävien tietojärjestelmien kriittisyys tietoyhteiskunnan eri osille ja toiminnalle on merkittävä. Tietojenkäsittelyn jatkuvuus ja tietojärjestelmien korkea käytettävyys on pyrittävä turvaamaan mahdollisimman kattavasti joka hetkellä ja vikatilanteista on kyettävä toipumaan työskentelyn ja liiketoiminnan jatkamiseksi. Työn tarkoituksena oli selvittää erilaisia menetelmiä näiden tietokantojen jatkuvaan tiedonvarmistukseen sekä paikallisilla palvelinjärjestelmillä että tietoverkon välityksellä ylläpidettävillä varajärjestelmillä. Paikallisella hyvin suunnitellulla tiedonvarmistuksella vikaantunut tietokanta ja sen tietosisältö kyetään palauttamaan mihinkä tahansa ajanhetkeen ennen vikaantumista. Varajärjestelmät puolestaan voidaan ottaa välittömästi käyttöön kokonaisen konesalin käytön estyessä tai vikaantuessa. Lisäksi useammat konesalit ratkaisusta riippuen voivat palvella käyttäjiään samanaikaisesti tasaten tietojärjestelmän kuormaa, tarjoten lisämahdollisuuksia tietojenkäsittelyyn ja niiden avulla sama tieto voidaan tuoda lähemmäksi palvelemaan käyttäjiään. Työn mielenkiinto kohdistuu lähinnä Oracle-tietokantoja käyttävien tieto-järjestelmien tarjoamiin varmistusvaihtoehtoihin. Kyseiset tietokantajärjestelmät ovat laajassa käytössä niin yritysmaailmassa kuin julkisellakin sektorilla.

On Implementing Joins, Aggregates and Universal Quantifier in Temporal Databases using SQL Standards

A feasible way of implementing a temporal database is by mapping temporal data model onto a conventional data model followed by a commercial database management system. Even though extensions were proposed to standard SQL for supporting temporal databases, such proposals have not yet come across standardization processes. This paper attempts to implement database operators such as aggregates and universal quantifier for temporal databases, implemented on top of relational database systems, using currently available SQL standards.

Abbildung von XML-Dokumenten auf SQL:2003-konforme Datentypen

Die Auszeichnungssprache XML dient zur Annotation von Dokumenten und hat sich als Standard-Datenaustauschformat durchgesetzt. Dabei entsteht der Bedarf, XML-Dokumente nicht nur als reine Textdateien zu speichern und zu transferieren, sondern sie auch persistent in besser strukturierter Form abzulegen. Dies kann unter anderem in speziellen XML- oder relationalen Datenbanken geschehen. Relationale Datenbanken setzen dazu bisher auf zwei grundsätzlich verschiedene Verfahren: Die XML-Dokumente werden entweder unverändert als binäre oder Zeichenkettenobjekte gespeichert oder aber aufgespalten, sodass sie in herkömmlichen relationalen Tabellen normalisiert abgelegt werden können (so genanntes „Flachklopfen“ oder „Schreddern“ der hierarchischen Struktur). Diese Dissertation verfolgt einen neuen Ansatz, der einen Mittelweg zwischen den bisherigen Lösungen darstellt und die Möglichkeiten des weiterentwickelten SQL-Standards aufgreift. SQL:2003 definiert komplexe Struktur- und Kollektionstypen (Tupel, Felder, Listen, Mengen, Multimengen), die es erlauben, XML-Dokumente derart auf relationale Strukturen abzubilden, dass der hierarchische Aufbau erhalten bleibt. Dies bietet zwei Vorteile: Einerseits stehen bewährte Technologien, die aus dem Bereich der relationalen Datenbanken stammen, uneingeschränkt zur Verfügung. Andererseits lässt sich mit Hilfe der SQL:2003-Typen die inhärente Baumstruktur der XML-Dokumente bewahren, sodass es nicht erforderlich ist, diese im Bedarfsfall durch aufwendige Joins aus den meist normalisierten und auf mehrere Tabellen verteilten Tupeln zusammenzusetzen. In dieser Arbeit werden zunächst grundsätzliche Fragen zu passenden, effizienten Abbildungsformen von XML-Dokumenten auf SQL:2003-konforme Datentypen geklärt. Darauf aufbauend wird ein geeignetes, umkehrbares Umsetzungsverfahren entwickelt, das im Rahmen einer prototypischen Applikation implementiert und analysiert wird. Beim Entwurf des Abbildungsverfahrens wird besonderer Wert auf die Einsatzmöglichkeit in Verbindung mit einem existierenden, ausgereiften relationalen Datenbankmanagementsystem (DBMS) gelegt. Da die Unterstützung von SQL:2003 in den kommerziellen DBMS bisher nur unvollständig ist, muss untersucht werden, inwieweit sich die einzelnen Systeme für das zu implementierende Abbildungsverfahren eignen. Dabei stellt sich heraus, dass unter den betrachteten Produkten das DBMS IBM Informix die beste Unterstützung für komplexe Struktur- und Kollektionstypen bietet. Um die Leistungsfähigkeit des Verfahrens besser beurteilen zu können, nimmt die Arbeit Untersuchungen des nötigen Zeitbedarfs und des erforderlichen Arbeits- und Datenbankspeichers der Implementierung vor und bewertet die Ergebnisse.

The Web 2.0 Development Survival Guide

Building software for Web 2.0 and the Social Media world is non-trivial. It requires understanding how to create infrastructure that will survive at Web scale, meaning that it may have to deal with tens of millions of individual items of data, and cope with hits from hundreds of thousands of users every minute. It also requires you to build tools that will be part of a much larger ecosystem of software and application families. In this lecture we will look at how traditional relational database systems have tried to cope with the scale of Web 2.0, and explore the NoSQL movement that seeks to simplify data-storage and create ultra-swift data systems at the expense of immediate consistency. We will also look at the range of APIs, libraries and interoperability standards that are trying to make sense of the Social Media world, and ask what trends we might be seeing emerge.