A spatio-temporal semantic model for multimedia database systemsand multimedia information systems

As more information sources become available in multimedia systems, the development of abstract semantic models for video, audio, text, and image data is becoming very important. An abstract semantic model has two requirements: it should be rich enough to provide a friendly interface of multimedia presentation synchronization schedules to the users and it should be a good programming data structure for implementation in order to control multimedia playback. An abstract semantic model based on an augmented transition network (ATN) is presented. The inputs for ATNs are modeled by multimedia input strings. Multimedia input strings provide an efficient means for iconic indexing of the temporal/spatial relations of media streams and semantic objects. An ATN and its subnetworks are used to represent the appearing sequence of media streams and semantic objects. The arc label is a substring of a multimedia input string. In this design, a presentation is driven by a multimedia input string. Each subnetwork has its own multimedia input string. Database queries relative to text, image, and video can be answered via substring matching at subnetworks. Multimedia browsing allows users the flexibility to select any part of the presentation they prefer to see. This means that the ATN and its subnetworks can be included in multimedia database systems which are controlled by a database management system (DBMS). User interactions and loops are also provided in an ATN. Therefore, ATNs provide three major capabilities: multimedia presentations, temporal/spatial multimedia database searching, and multimedia browsing     

EXACT: an extensible approach to active object-oriented databases

Active database management systems (DBMSs) are a fast-growing area of research, mainly due to the large number of applications which can benefit from this active dimension. These applications are far from being homogeneous, requiring different kinds of functionalities. However, most of the active DBMSs described in the literature only provide a fixed, hard-wired execution model to support the active dimension. In object-oriented DBMSs, event-condition-action rules have been propo sed for providing active behaviour. This paper presents EXACT, a rule manager for object-oriented DBMSs which provides a variety of options from which the designer can choose the one that best fits the semantics of the concept to be supported by rules. Due to the difficulty of foreseeing future requirements, special attention has been paid to making rule management easily extensible, so that the user can tailor it to suit specific applications. This has been borne out by an implementation in ADAM, an object -oriented DBMS. An example is shown of how the default mechanism can be easily extended to support new requirements. Edited by Y. Vassiliou. Received May 26, 1994 / Revised January 26, 1995, June 22, 1996 / Accepted November 4, 1996     

Overview of multidatabase transaction management

A multidatabase system (MDBS) is a facility that allows users access to data located in multiple autonomous database management systems (DBMSs). In such a system,global transactions are executed under the control of the MDBS. Independently,local transactions are executed under the control of the local DBMSs. Each local DBMS integrated by the MDBS may employ a different transaction management scheme. In addition, each local DBMS has complete control over all transactions (global and local) executing at its site, including the ability to abort at any point any of the transactions executing at its site. Typically, no design or internal DBMS structure changes are allowed in order to accommodate the MDBS. Furthermore, the local DBMSs may not be aware of each other and, as a consequence, cannot coordinate their actions. Thus, traditional techniques for ensuring transaction atomicity and consistency in homogeneous distributed database systems may not be appropriate for an MDBS environment. The objective of this article is to provide a brief review of the most current work in the area of multidatabase transaction management. We first define the problem and argue that the multidatabase research will become increasingly important in the coming years. We then outline basic research issues in multidatabase transaction management and review recent results in the area. We conclude with a discussion of open problems and practical implications of this research.     

Algorithms for integrating PostgreSQL with the semantic web

This paper addresses the integration of the PostgreSQL database management system (DBMS) with the Semantic Web. Integration algorithms based on the use of the DBMS capabilities that do not introduce changes in SQL are proposed. An integration based on one of the algorithms supporting main formats of the Semantic Web is presented. The proposed algorithms can be implemented in different DBMSs supporting triggers (or rules), table functions, and indexing.     

Transaction management in distributed heterogeneous database management systems

Current distributed, heterogeneous database management systems (DBMSs) address the issue of distributed transaction management (DTM) in two different ways: some systems rely solely on unmodified local transaction managers (LTMs), thereby helping preserve local DBMS autonomy, but limit functionality (e.g. allow only unsynchronized retrievals, preclude distributed updates, etc.); others maintain full functionality but require the (re)design of the LTMs to enforce homogeneous DTM across all heterogeneous DBMSs, thereby giving up most of the local DBMS autonomy.

The goal of the work presented here is to establish the minimum set of modifications to LTMs that allow synchronized retrievals and distributed updates (whenever semantic conflicts can be resolved), and will continue to maintain a high degree of local DBMS autonomy. The problems of: (1) distribution of responsibility between DTM and LTMs, (2) concatenation of functionally-equivalent LTM mechanisms, and (3) providing compensation mechanisms for functionally-limited LTMs are introduced. Solutions to the above problems are shown to exist. However, the interconnection of autonomous, heterogeneous DBMSs is significantly more difficult than anticipated, despite communication standardization and current optimism.     

Commit protocols for externalized-commit heterogeneous database systems

In designing a heterogeneous database systems, one of the main technical challenges is developing techniques for ensuring global commit. That is, guaranteeing that a transaction spanning multiple individual database management systems (DBMSs) either commits at all the participating DBMSs or at none of them. Previous work in this area typically assumes that the participating DBMSs do not provide a mechanism for interacting with their commit facilities. While this is true in many cases, in practice there are systems which support a programmatic interface to their commit protocols. We refer to database systems offering such facilities asexternalized commit DBMSs.The focus of this paper is on commit protocols for these systems. We propose two new commit protocols for externalized commit DBMSs. The first may be used to obtain global commit in heterogeneous database systems composed of DBMSs with different 2-phase commit protocols (e.g., centralized and linear). The second protocol is more general, and ensures global commit even if the participating DBMSs employ 3-phase commit protocols. The more general protocol also preserves database autonomy, since it does not block a DBMS upon failure of another system. We describe both protocols in detail and prove their correctness. Recommended by: M. RusinkiewiczThis work was partially supported by an IBM Research Initiation Grant.     

图示操控信息管理系统开发平台的设计与实现

针对当今数据库管理系统(DBMS)和地理信息系统(GIS)的应用现状,提出了一种全新的信息整合、图示操控与管理运用的解决方案——图示操控信息管理系统开发平台。该平台充分运用了近年来在分布式网络数据库技术、图形图像处理技术、多媒体视频音频处理技术和人机接口技术等方面的最新科技成果,提出并引入了地图无限嵌套、数据库树形管理、航摄模拟式地图、时间轴和楼层描述等新的概念和功能,并针对不同应用领域的特点,给出了系统开发平台的设计与实现。     

Method of adaptive controllable parallel execution of operations in object database management systems

The design of parallel database management systems (DBMSs) normally implies using special-purpose multiprocessor computing systems. Most often, a DBMS is supposed to work in an exclusive mode of operation. However, in the class of x86-based multiprocessor computing systems designed for mass usage, the exclusive mode of DBMS operation with respect to other software is often not secured. In addition, the legacy software for this class of computing systems is often not designed for mass parallel usage. When the exclusive mode requirement is ignored and the resources of the computing system are not used in low-load DBMS regimes, the efficiency of using resources of the computing system as a whole reduces. This paper considers a method of program organization of controlled parallelism at the level of internal DBMS operations, allowing for their controlled execution based on the state of the entire computing system. This method made it possible to significantly reduce the time of response for low densities of query arrival in the ODB-Jupiter commercial object DBMS developed in the Inteltec Plus scientific manufacturing center. The method of controlled parallel execution can be used in a wide class of program systems.     

Partial rollback in object-oriented/object-relational database management systems with dual buffer

Partial rollback mechanism has been widely supported by many database management systems (DBMSs). It allows a transaction to be rolled back partially, that is, only back to a certain savepoint set by the user. A partial rollback, however, makes the DBMS buffer management complicated because it requires the DBMS to restore the state of not only the database but also the buffers. There are several literatures addressing such a partial rollback in a relational DBMS (RDBMS), which has page buffer only. However, to our knowledge, there exists no literature addressing it in an object-oriented/relational DBMS (OO/ORDBMS). The RDBMS partial rollback scheme cannot be applied to OO/ORDBMSs directly. The reason is that, unlike RDBMSs, many OO/ORDBMSs use dual buffer which consists of object buffer and page buffer. In this paper, we thoroughly study the partial rollback schemes for OO/ORDBMSs with dual buffer. For this, we propose four different partial rollback schemes which are based on (single) page buffer, (single) object buffer, dual buffer using a soft log, and dual buffer using shadows, respectively. The schemes proposed are practical enough to be implemented in a real OO/ORDBMS. The results of performance evaluations show that the dual buffer-based scheme using shadows achieves the best performance.     

Evaluating Microcomputer DBMSs

The improper use of commercial data base management systems (DBMSs) has been a major problem throughout the history of data base management. With the emergence of microcomputers, the selection of the appropriate DBMS for a user' s particular applications environment can be difficult. This column reviews and discusses approaches toward evaluating a DBMS and provides examples that illustrate the application of these approaches to microcomputer DBMSs. IS managers would benefit by following this column' s three-step evaluation framework     

ADOME: an advanced object modeling environment

ADOME, which stands for ADvanced Object Modeling Environment, is an approach to integrating data and knowledge management based on object oriented technology. Next generation information systems will require more flexible data modeling capabilities than those provided by current object oriented DBMSs. In particular, integration of data and knowledge management capabilities will become increasingly important. In this context, ADOME provides versatile role facilities that serve as “dynamic binders” between data objects and production rules, thereby facilitating flexible data and knowledge management integration. A prototype that implements this mechanism and the associated operators has been constructed on top of a commercial object oriented DBMS and a rule base system     

P2: A Lightweight DBMS Generator

A lightweight database system (LWDB) is ahigh-performance, application-specific DBMS. It differs from ageneral-purpose (heavyweight) DBMS in that it omits oneor more features and specializes the implementation ofits features to maximize performance. Although heavyweight monolithic andextensible DBMSs might be able to emulate LWDB capabilities, they cannotmatch LWDB performance.In this paper, we describe P2, a generator of lightweight DBMSs, andexplain how it was used to reengineer a hand-coded, highly-tuned LWDB usedin a production system compiler (LEAPS). We present results that showP2-generated LWDBs reduced the development time and code size of LEAPS by afactor of three and that the generated LWDBs executed substantially fasterthan versions built by hand or that use an extensible heavyweight DBMS.     

Analyzing the Effects of Hyperthreading on the Performance of Data Management Systems

As information processing applications take greater roles in our everyday life, database management systems (DBMSs) are growing in importance. DBMSs have traditionally exhibited poor cache performance and large memory footprints, therefore performing only at a fraction of their ideal execution and exhibiting low processor utilization. Previous research has studied the memory system of DBMSs on research-based simultaneous multithreading (SMT) processors. Recently, several differences have been noted between the real hyper-threaded architecture implemented by the Intel Pentium 4 and the earlier SMT research architectures. This paper characterizes the performance of a prototype open-source DBMS running TPC-equivalent benchmark queries on an Intel Pentium 4 Hyper-Threading processor. We use hardware counters provided by the Pentium 4 to evaluate the micro-architecture and study the memory system behavior of each query running on the DBMS. Our results show a performance improvement of up to 1.16 in TPC-C-equivalent and 1.26 in TPC-H-equivalent queries due to hyperthreading.     

Audio support for an object-oriented database-management system

We describe the development of the data type audio in an object-oriented database management system (DBMS). The interface of the data type includes operations to store, retrieve, and manipulate audio data. Additionally, a transport protocol supports continuous recording and presentation at the users' workstations in a client-server environment. Design considerations are outlined and lead us to use no compression algorithms and to handle parametrized sample rates and sizes transparently for the user. Specific manipulation operations, such as low-pass filtering and dynamic compression, are described in detail. The implementation of an interactive audio tool shows that the data type audio can be used in the same way as conventional data types. We give an outlook on further built-in support of time-dependent media that a comprehensive multimedia DBMS should offer.     

A structure-based model of semantic integrity constraints for relational data bases

Data base management systems (DBMSs) are in widespread use because of the ease and flexibility with which users access large volumes of data. Ensuring data accuracy through integrity constraints is a central aspect of DBMS use. However, many DBMSs still lack adequate integrity support. In addition, a comprehensive theoretical basis for such support—the role of a constraint classification system—has yet to be developed. This paper presents a formalism that classifies semantic integrity constraints based on the structure of the relational model. Integrity constraints are characterized by the portion of the data base structure they access, whether one or more relations, attributes, or tuples. Thus, the model is completely general, allowing the arbitrary specification of any constraint. Examples of each type of constraint are illustrated using a small engineering data base, and various implemention issues are discussed.     

Rubis: an extended relational system managing events Part I: specification

Dynamic aspects of information systems are taken into account in a lot of conceptual models. However, the dynamic concepts of these models have rarely been fully implemented in database management systems (DBMSs).Rubis is an extended relational DBMS which supports an extended relational schema (including event and operation concepts) and automatic control of the dynamic aspects of applications, i.e. event recognition, operation triggering and time handling.The first part of the paper contains a short presentation of the basic concepts and the specification language used for the extended schema. The second part focuses on the internal mechanisms: the temporal processor, which manages the temporal aspects of specifications and recognizes temporal events; and the event processor which manages events treatment and synchronization. These two mechanisms permit an automatic execution of the extended schema and so provide rapid prototyping capabilities. This last part will be covered in the December issue of this journal.     

Design and implementation of a database inference controller

The Inference Problem compromises database systems which are usually considered to be secure. here, users pose sets of queries and infer unauthorized information from the responses that they obtain. An Inference Controller is a device that prevents and/or detects security violations via inference. We are particularly interested in the inference problem which occurs in a multilevel operating environment. In such an environment, the users are cleared at different security levels and they access a multilevel database where the data is classified at different sensitivity levels. A multilevel secure database management system (MLS/DBMS) manages a multilevel database where its users cannot access data to which they are not authorized. However, providing a solution to the inference problem, where users issue multiple requests and consequently infer unauthorized knowledge is beyond the capability of currently available MLS/DBMSs. This paper describes the design and prototype development of an Inference Controller for a MLS/DBMS that functions during query processing. To our knowledge this is the first such inference controller prototype to be developed. We also describe some extensions to the inference controller so that an integrated solution can be provided to the problem.     

The Role of Visual Fidelity in Computer-Based Instruction

New digital video technologies provide a wide spectrum of multimedia interface capabilities for educational courses running on personal computers. A formal experiment was conducted using a digital video course on code inspection to determine the effects of such capabilities on recall performance and attitude. The findings suggest that the presentation of material as motion video rather than as a slide show within an interactive video course leads to better recall performance. In addition, the presence of motion video in the interfaces and the use of surrogate travel for navigation promote better student opinions toward the subject matter.