138 research outputs found
TEMPOS: A Platform for Developing Temporal Applications on Top of Object DBMS
This paper presents TEMPOS: a set of models and languages supporting the manipulation of temporal data on top of object DBMS. The proposed models exploit object-oriented technology to meet some important, yet traditionally neglected design criteria related to legacy code migration and representation independence. Two complementary ways for accessing temporal data are offered: a query language and a visual browser. The query language, namely TempOQL, is an extension of OQL supporting the manipulation of histories regardless of their representations, through fully composable functional operators. The visual browser offers operators that facilitate several time-related interactive navigation tasks, such as studying a snapshot of a collection of objects at a given instant, or detecting and examining changes within temporal attributes and relationships. TEMPOS models and languages have been formalized both at the syntactical and the semantical level and have been implemented on top of an object DBMS. The suitability of the proposals with regard to applications' requirements has been validated through concrete case studies
The exploration of a category theory-based virtual Geometrical product specification system for design and manufacturing
In order to ensure quality of products and to facilitate global outsourcing, almost all
the so-called “world-class” manufacturing companies nowadays are applying various
tools and methods to maintain the consistency of a product’s characteristics
throughout its manufacturing life cycle. Among these, for ensuring the consistency of
the geometric characteristics, a tolerancing language − the Geometrical Product
Specification (GPS) has been widely adopted to precisely transform the functional
requirements from customers into manufactured workpieces expressed as tolerance
notes in technical drawings. Although commonly acknowledged by industrial users as
one of the most successful efforts in integrating existing manufacturing life-cycle
standards, current GPS implementations and software packages suffer from several
drawbacks in their practical use, possibly the most significant, the difficulties in
inferring the data for the “best” solutions. The problem stemmed from the foundation
of data structures and knowledge-based system design. This indicates that there need
to be a “new” software system to facilitate GPS applications.
The presented thesis introduced an innovative knowledge-based system − the
VirtualGPS − that provides an integrated GPS knowledge platform based on a stable
and efficient database structure with knowledge generation and accessing facilities.
The system focuses on solving the intrinsic product design and production problems
by acting as a virtual domain expert through translating GPS standards and rules into
the forms of computerized expert advices and warnings. Furthermore, this system can
be used as a training tool for young and new engineers to understand the huge amount
of GPS standards in a relative “quicker” manner.
The thesis started with a detailed discussion of the proposed categorical modelling
mechanism, which has been devised based on the Category Theory. It provided a
unified mechanism for knowledge acquisition and representation, knowledge-based
system design, and database schema modelling. As a core part for assessing this
knowledge-based system, the implementation of the categorical Database
Management System (DBMS) is also presented in this thesis. The focus then moved
on to demonstrate the design and implementation of the proposed VirtualGPS system.
The tests and evaluations of this system were illustrated in Chapter 6. Finally, the
thesis summarized the contributions to knowledge in Chapter 7.
After thoroughly reviewing the project, the conclusions reached construe that the
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entire VirtualGPS system was designed and implemented to conform to Category
Theory and object-oriented programming rules. The initial tests and performance
analyses show that the system facilitates the geometric product manufacturing
operations and benefits the manufacturers and engineers alike from function designs,
to a manufacturing and verification
Visually querying object-oriented databases
Bibliography: pages 141-145.As database requirements increase, the ability to construct database queries efficiently becomes more important. The traditional means of querying a database is to write a textual query, such as writing in SQL to query a relational database. Visual query languages are an alternative means of querying a database; a visual query language can embody powerful query abstraction and user feedback techniques, thereby making them potentially easier to use. In this thesis, we develop a visual query system for ODMG-compliant object-oriented databases, called QUIVER. QUIVER has a comprehensive expressive power; apart from supporting data types such as sets, bags, arrays, lists, tuples, objects and relationships, it supports aggregate functions, methods and sub-queries. The language is also consistent, as constructs with similar functionality have similar visual representations. QUIVER uses the DOT layout engine to automatically layout a query; QUIVER queries are easily constructed, as the system does not constrain the spatial arrangement of query items. QUIVER also supports a query library, allowing queries to be saved, retrieved and shared among users. A substantial part of the design has been implemented using the ODMG-compliant database system O₂, and the usability of the interface as well as the query language itself is presented. Visual queries are translated to OQL, the standard query language proposed by the ODMG, and query answers are presented using O₂ Look. During the course of our investigation, we conducted a user evaluation to compare QUIVER and OQL. The results were extremely encouraging in favour of QUIVER
An object query language for multimedia federations
The Fischlar system provides a large centralised repository of multimedia files. As expansion is difficult in centralised systems and as different user groups have a requirement to define their own schemas, the EGTV (Efficient Global Transactions for Video) project was established to examine how the distribution of this database could be managed. The federated database approach is advocated where global schema is designed in a top-down approach, while all multimedia and textual data is stored in object-oriented (O-O) and object-relational (0-R) compliant databases.
This thesis investigates queries and updates on large multimedia collections organised in the database federation. The goal of this research is to provide a generic query language capable of interrogating global and local multimedia database schemas. Therefore, a new query language EQL is defined to facilitate the querying of object-oriented and objectrelational database schemas in a database and platform independent manner, and acts as a canonical language for database federations. A new canonical language was required as the existing query language standards (SQL: 1999 and OQL) axe generally incompatible and translation between them is not trivial. EQL is supported with a formally defined object algebra and specified semantics for query evaluation.
The ability to capture and store metadata of multiple database schemas is essential when constructing and querying a federated schema. Therefore we also present a new platform independent metamodel for specifying multimedia schemas stored in both object-oriented and object-relational databases. This metadata information is later used for the construction of a global schemas, and during the evaluation of local and global queries.
Another important feature of any federated system is the ability to unambiguously define database schemas. The schema definition language for an EGTV database federation must be capable of specifying both object-oriented and object-relational schemas in the database independent format. As XML represents a standard for encoding and distributing data across various platforms, a language based upon XML has been developed as a part of our research. The ODLx (Object Definition Language XML) language specifies a set of XMLbased structures for defining complex database schemas capable of representing different multimedia types. The language is fully integrated with the EGTV metamodel through which ODLx schemas can be mapped to 0-0 and 0-R databases
Modeling Relationships Using The Relational And Object-Oriented Data Models
We compare the performance of naive data modelers in modeling association, generalization, and aggregation relationships with the relational and object-oriented data models. We first develop research hypotheses based on the properties of expressiveness, minimality, and unique semantic interpretation to analyze the effectiveness of the two models. We then test our hypotheses in anexperiment with 22 naive modelers. The findings of our study support the notion that, to be effective, a data model should satisfy these three propertie
The LCG POOL Project, General Overview and Project Structure
The POOL project has been created to implement a common persistency framework
for the LHC Computing Grid (LCG) application area. POOL is tasked to store
experiment data and meta data in the multi Petabyte area in a distributed and
grid enabled way. First production use of new framework is expected for summer
2003. The project follows a hybrid approach combining C++ Object streaming
technology such as ROOT I/O for the bulk data with a transactionally safe
relational database (RDBMS) store such as MySQL. POOL is based a strict
component approach - as laid down in the LCG persistency and blue print RTAG
documents - providing navigational access to distributed data without exposing
details of the particular storage technology. This contribution describes the
project breakdown into work packages, the high level interaction between the
main pool components and summarizes current status and plans.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 5 pages. PSN MOKT00
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