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1.
A multimedia application involves information that may be in a form of video, images, audio, text and graphics, need to be
stored, retrieved and manipulated in large databases. In this paper, we propose an object-oriented database schema that supports
multimedia documents and their temporal, spatial and logical structures. We present a document example and show how the schema
can adress all the structures described. We also present a multimedia query specification language that can be used to describe
a multimedia content portion to be retrieved from the database. The language provides means by which the user can specify
the information on the media as well as the temoral and spatial relationships among these media. 相似文献
2.
Praveen Seshadri 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(3):130-140
The explosion in complex multimedia content makes it crucial for database systems to support such data efficiently. This
paper argues that the “blackbox” ADTs used in current object-relational systems inhibit their performance, thereby limiting
their use in emerging applications. Instead, the next generation of object-relational database systems should be based on
enhanced abstract data type (E-ADT) technology. An (E-ADT) can expose the semantics of its methods to the database system, thereby permitting advanced query optimizations. Fundamental architectural changes
are required to build a database system with E-ADTs; the added functionality should not compromise the modularity of data
types and the extensibility of the type system. The implementation issues have been explored through the development of E-ADTs
in Predator. Initial performance results demonstrate an order of magnitude in performance improvements.
Received January 1, 1998 / Accepted May 27, 1998 相似文献
3.
Minos N. Garofalakis Banu Özden Avi Silberschatz 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(4):206-225
The Enhanced Pay-Per-View (EPPV) model for providing continuous-media services associates with each continuous-media clip
a display frequency that depends on the clip's popularity. The aim is to increase the number of clients that can be serviced
concurrently beyond the capacity limitations of available resources, while guaranteeing a constraint on the response time.
This is achieved by sharing periodic continuous-media streams among multiple clients. The EPPV model offers a number of advantages
over other data-sharing schemes (e.g., batching), which make it more attractive to large-scale service providers. In this
paper, we provide a comprehensive study of the resource-scheduling problems associated with supporting EPPV for continuous-media
clips with (possibly) different display rates, frequencies, and lengths. Our main objective is to maximize the amount of disk
bandwidth that is effectively scheduled under the given data layout and storage constraints. Our formulation gives rise to
-hard combinatorial optimization problems that fall within the realm of hard real-time scheduling theory. Given the intractability
of the problems, we propose novel heuristic solutions with polynomial-time complexity. We also present preliminary experimental
results for the average case behavior of the proposed scheduling schemes and examine how they compare to each other under
different workloads. A major contribution of our work is the introduction of a robust scheduling framework that, we believe,
can provide solutions for a variety of realistic EPPV resource-scheduling scenarios, as well as any scheduling problem involving
regular, periodic use of a shared resource. Based on this framework, we propose various interesting research directions for
extending the results presented in this paper.
Received June 9, 1998 / Accepted October 13, 1998 相似文献
4.
Wee Teck Ng Peter M. Chen 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(3):194-204
Recent results in the Rio project at the University of Michigan show that it is possible to create an area of main memory
that is as safe as disk from operating system crashes. This paper explores how to integrate the reliable memory provided by
the Rio file cache into a database system. Prior studies have analyzed the performance benefits of reliable memory; we focus
instead on how different designs affect reliability. We propose three designs for integrating reliable memory into databases:
non-persistent database buffer cache, persistent database buffer cache, and persistent database buffer cache with protection.
Non-persistent buffer caches use an I/O interface to reliable memory and require the fewest modifications to existing databases.
However, they waste memory capacity and bandwidth due to double buffering. Persistent buffer caches use a memory interface
to reliable memory by mapping it into the database address space. This places reliable memory under complete database control
and eliminates double buffering, but it may expose the buffer cache to database errors. Our third design reduces this exposure
by write protecting the buffer pages. Extensive fault tests show that mapping reliable memory into the database address space
does not significantly hurt reliability. This is because wild stores rarely touch dirty, committed pages written by previous
transactions. As a result, we believe that databases should use a memory interface to reliable memory.
Received January 1, 1998 / Accepted June 20, 1998 相似文献
5.
K. Selçuk Candan Eric Lemar V.S. Subrahmanian 《The VLDB Journal The International Journal on Very Large Data Bases》2000,9(2):131-153
Abstract. Though there has been extensive work on multimedia databases in the last few years, there is no prevailing notion of a multimedia
view, nor there are techniques to create, manage, and maintain such views. Visualizing the results of a dynamic multimedia
query or materializing a dynamic multimedia view corresponds to assembling and delivering an interactive multimedia presentation
in accordance with the visualization specifications. In this paper, we suggest that a non-interactive multimedia presentation
is a set of virtual objects with associated spatial and temporal presentation constraints. A virtual object is either an object, or the result of a query.
As queries may have different answers at different points in time, scheduling the presentation of such objects is nontrivial.
We then develop a probabilistic model of interactive multimedia presentations, extending the non-interactive model described
earlier. We also develop a probabilistic model of interactive visualization where the probabilities reflect the user profiles,
or the likelihood of certain user interactions. Based on this probabilistic model, we develop three utility-theoretic based
types of prefetching algorithms that anticipate how users will interact with the presentation. These prefetching algorithms
allow efficient visualization of the query results in accordance with the underlying specification. We have built a prototype
system that incorporates these algorithms. We report on the results of experiments conducted on top of this implementation.
Received June 10, 1998 / Accepted November 10, 1999 相似文献
6.
The problem of presenting database query results has not been investigated sufficiently. This work proposes an approach to
identify effective presentations for the results of database queries. This will be done by considering different kinds of
information, such as user goals, the characteristics of the data to be presented, and the relationships among them. Our approach
is based on the definition of composition operations which, on the basis of elementary presentation types, allow us to obtain designs of complex final presentations. Some effectiveness criteria are considered in order to identify
those presentations which best match the user's goals and cognitive abilities. We consider multimedia environments at both
the data and presentation level. 相似文献
7.
Domenico Ferrari 《Multimedia Systems》1996,4(6):299-304
Protocols for multimedia communication are needed to integrate into a single network services intended to satisfy the different
requirements of multiple types of traffic. An essential prerequisite for designing these protocols is that the services to
be offered by the network must be selected and specified in detail. We present the service models proposed, or being developed,
by the Internet community, by the ATM community, and by the Tenet Group. We compare their common characteristics, which reveal
the characteristics of the first integrated services networks are likely to offer. The services referred to in this paper
are those at the network and transport layers, which support the services to be offered to the system's end users. 相似文献
8.
Anastassia Ailamaki David J. DeWitt Mark D. Hill 《The VLDB Journal The International Journal on Very Large Data Bases》2002,11(3):198-215
Relational database systems have traditionally optimized for I/O performance and organized records sequentially on disk pages
using the N-ary Storage Model (NSM) (a.k.a., slotted pages). Recent research, however, indicates that cache utilization and
performance is becoming increasingly important on modern platforms. In this paper, we first demonstrate that in-page data
placement is the key to high cache performance and that NSM exhibits low cache utilization on modern platforms. Next, we propose
a new data organization model called PAX (Partition Attributes Across), that significantly improves cache performance by grouping
together all values of each attribute within each page. Because PAX only affects layout inside the pages, it incurs no storage
penalty and does not affect I/O behavior. According to our experimental results (which were obtained without using any indices
on the participating relations), when compared to NSM: (a) PAX exhibits superior cache and memory bandwidth utilization, saving
at least 75% of NSM's stall time due to data cache accesses; (b) range selection queries and updates on memory-resident relations
execute 17–25% faster; and (c) TPC-H queries involving I/O execute 11–48% faster. Finally, we show that PAX performs well
across different memory system designs.
Received: November 1, 2001 / Accepted: August 29, 2002 Published online: November 22, 2002 相似文献
9.
Gerd Schürmann 《Multimedia Systems》1996,4(5):281-295
Electronic mail for traditional text exchange as asynchronous communication means between computer users is widely built upon
in many application areas. Whereas Multimedia-Mail systems – including text, graphics, still images, audio, video and documents
– were limited to isolated communities – at least two very promising approaches are being under development: the MIME (Multipurpose
Internet Mail Extension), an extension of Internet Mail as well as the Multimedia Teleservice based on CCITT Recommendation
X.400(88) being under development within the BERKOM project funded by the German TELEKOM. The store-and-forward mechanism
inherent to electronic mail is complemented in the later one by an additional exchange mechanism allowing the resolution of
references to message content, e.g. video. Such references may be put into a message in place of the content itself. Internet/MIME
and OSI/X.400, their interworking, asynchronous information server access via Multimedia-Mail, as well as possible future
developments especially in the area of asynchronous Computer Supported Cooperative Work (CSCW) are discussed. 相似文献
10.
Semantic heterogeneity resolution in federated databases by metadata implantation and stepwise evolution 总被引:3,自引:0,他引:3
Goksel Aslan Dennis McLeod 《The VLDB Journal The International Journal on Very Large Data Bases》1999,8(2):120-132
A key aspect of interoperation among data-intensive systems involves the mediation of metadata and ontologies across database
boundaries. One way to achieve such mediation between a local database and a remote database is to fold remote metadata into
the local metadata, thereby creating a common platform through which information sharing and exchange becomes possible. Schema
implantation and semantic evolution, our approach to the metadata folding problem, is a partial database integration scheme
in which remote and local (meta)data are integrated in a stepwise manner over time. We introduce metadata implantation and
stepwise evolution techniques to interrelate database elements in different databases, and to resolve conflicts on the structure
and semantics of database elements (classes, attributes, and individual instances). We employ a semantically rich canonical
data model, and an incremental integration and semantic heterogeneity resolution scheme. In our approach, relationships between
local and remote information units are determined whenever enough knowledge about their semantics is acquired. The metadata
folding problem is solved by implanting remote database elements into the local database, a process that imports remote database
elements into the local database environment, hypothesizes the relevance of local and remote classes, and customizes the organization
of remote metadata. We have implemented a prototype system and demonstrated its use in an experimental neuroscience environment.
Received June 19, 1998 / Accepted April 20, 1999 相似文献
11.
Ivan Herman Nuno Correia David A. Duce David J. Duke Graham J. Reynolds James Van Loo 《Multimedia Systems》1998,6(2):88-101
This paper describes an event-based synchronization mechanism, which is at the core of the inter-media synchronization in
the upcoming standard for multimedia presentation, PREMO. The synchronization mechanism of PREMO is a powerful tool, based
on a small number of concepts, and on cooperation among active objects, and represents a synthesis of various synchronization
models described in the literature. This model can serve as a basis for the implementation of complex synchronization patterns
in multimedia presentations, both purely event-based, as well as time-based. 相似文献
12.
Managing database server performance to meet QoS requirements in electronic commerce systems 总被引:1,自引:0,他引:1
Patrick Martin Wendy Powley Hoi-Ying Li Keri Romanufa 《International Journal on Digital Libraries》2002,3(4):316-324
The performance of electronic commerce systems has a major impact on their acceptability to users. Different users also demand
different levels of performance from the system, that is, they will have different Quality of Service (QoS) requirements. Electronic commerce systems are the integration of several different types of servers and each server must
contribute to meeting the QoS demands of the users. In this paper we focus on the role, and the performance, of a database server within an electronic commerce system.
We examine the characteristics of the workload placed on a database server by an electronic commerce system and suggest a
range of QoS requirements for the database server based on this analysis of the workload. We argue that a database server
must be able to dynamically reallocate its resources in order to meet the QoS requirements of different transactions as the
workload changes. We describe Quartermaster, which is a system to support dynamic goal-oriented resource management in database
management systems, and discuss how it can be used to help meet the QoS requirements of the electronic commerce database server.
We provide an example of the use of Quartermaster that illustrates how the dynamic reallocation of memory resources can be
used to meet the QoS requirements of a set of transactions similar to transactions found in an electronic commerce workload.
We briefly describe the memory reallocation algorithms used by Quartermaster and present experiments to show the impact of
the reallocations on the performance of the transactions.
Published online: 22 August 2001 相似文献
13.
Adaptive piggybacking: a novel technique for data sharing in video-on-demand storage servers 总被引:17,自引:0,他引:17
Recent technology advances have made multimedia on-demand services, such as home entertainment and home-shopping, important
to the consumer market. One of the most challenging aspects of this type of service is providing access either instantaneously
or within a small and reasonable latency upon request. We consider improvements in the performance of multimedia storage servers
through data sharing between requests for popular objects, assuming that the I/O bandwidth is the critical resource in the system. We discuss a novel approach to data sharing,
termed adaptive piggybacking, which can be used to reduce the aggregate I/O demand on the multimedia storage server and thus
reduce latency for servicing new requests. 相似文献
14.
Doug Fang Shahram Ghandeharizadeh Dennis McLeod 《The VLDB Journal The International Journal on Very Large Data Bases》1996,5(2):151-165
An approach and mechanism for the transparent sharing
of objects in an environment of interconnected (networked),
autonomous database systems is presented.
An experimental prototype system has been designed and
implemented, and an analysis of its performance conducted.
Previous approaches to sharing in this environment typically
rely on the use of a global, integrated conceptual database
schema; users and applications must pose queries at this new
level of abstraction to access remote information.
By contrast, our approach provides a mechanism that allows users to
import remote objects directly into their local database transparently;
access to remote objects is virtually the same as access to local objects.
The experimental prototype system that has been designed and implemented
is based on the Iris and Omega object-based database management systems;
this system supports the sharing of data and meta-data objects (information
units) as well as units of behavior. The results of experiments
conducted to evaluate the performance of our mechanism demonstrate
the feasibility of database transparent object sharing in
a federated environment, and provide insight into the performance overhead
and tradeoffs involved.
Edited by
Georges Gardarin. Received October 29, 1992 / Revised
May 4, 1994 / Accepted March 1, 1995 相似文献
15.
16.
As multimedia applications spread widely, it is crucial for programming and design support systems to handle “time” in multimedia
documents effectively and flexibly. This paper presents a set of interactive system support tools for designing and maintaining
the temporal behavior of multimedia documents. The tool set provides mechanisms for anomaly detection, temporal query processing,
and interactive scheduling. It is based on a fast incremental constraint solver we have developed, which can be adapted by
any constraint-based system. The incremental constraint solver provides immediate feedback to the user, supporting a highly
interactive design process. Combined with existing optimal layout generation mechanisms proposed in the literature, our tools
effectively utilize the flexibility provided by constraint-based systems. 相似文献
17.
Transporting QoS adaptive flows 总被引:4,自引:0,他引:4
Distributed audio and video applications need to adapt to fluctuations in delivered quality of service (QoS). By trading
off temporal and spatial quality to available bandwidth, or manipulating the playout time of continuous media in response
to variation in delay, audio and video flows can be made to adapt to fluctuating QoS with minimal perceptual distortion. In
this paper, we extend our previous work on a QoS Architecture (QoS-A) by populating the QoS management planes of our architecture
with a framework for the control and management of multilayer coded flows operating in heterogeneous multimedia networking
environments. Two key techniques are proposed: i) an end-to-end rate-shaping scheme which adapts the rate of MPEG-coded flows
to the available network resources while minimizing the distortion observed at the receiver; and ii) an adaptive network service,
which offers “hard” guarantees to the base layer of multilayer coded flows and “fairness” guarantees to the enhancement layers
based on a bandwidth allocation technique called Weighted Fair Sharing. 相似文献
18.
Recent advances in computer technologies have made it feasible to provide multimedia services, such as news distribution
and entertainment, via high-bandwidth networks. The storage and retrieval of large multimedia objects (e.g., video) becomes
a major design issue of the multimedia information system. While most other works on multimedia storage servers assume an
on-line disk storage system, we consider a two-tier storage architecture with a robotic tape library as the vast near-line
storage and an on-line disk system as the front-line storage. Magnetic tapes are cheaper, more robust, and have a larger
capacity; hence, they are more cost effective for large scale storage systems (e.g., video-on-demand (VOD) systems may
store tens of thousands of videos). We study in detail the design issues of the tape subsystem and propose some novel tape-scheduling
algorithms which give faster response and require less disk buffer space. We also study the disk-striping policy and the
data layout on the tape cartridge in order to fully utilize the throughput of the robotic tape system and to minimize the
on-line disk storage space. 相似文献
19.
Integrated spatial and feature image query 总被引:3,自引:0,他引:3
We present a new system for querying for images by regions and their spatial and feature attributes. The system enables the
user to find the images that contain arrangements of regions similar to those diagrammed in a query image. By indexing the
attributes of regions, such as sizes, locations and visual features, a wide variety of complex joint spatial and feature queries
are efficiently computed. In order to demonstrate the utility of the system, we develop a process for the extracting color
regions from photographic images. We demonstrate that integrated spatial and feature querying using color regions improves
image search capabilities over non-spatial content-based image retrieval methods. 相似文献
20.
B. Riera 《Cognition, Technology & Work》2001,3(1):53-65
Supervision of highly automated processes is an interdisciplinary research area. Knowledge in the fields of automation, process
knowledge, machine engineering, ‘work post’ ergonomics, cognitive ergonomics, working psychology, sociology and so on is necessary
to design efficient supervisory systems. This is because supervision is an activity in which man, despite the increasing automation
of recent years, is still present. Our research concerns monitoring tasks and diagnosis tasks in continuous processes. In
this paper we propose specifications for an advanced human-adapted supervisory system (AHASS) integrating representation characteristics
of the production system, such as functional, structural and behavioural aspects based on cognitive engineering models, with
the use of advanced algorithms of detection and location. The main idea is to design a supervisory system well balanced between
human and technical aspects. Indeed, man–machine system-centred approaches can deal to another extreme like purely technical
approaches. These specifications have been used to design an AHASS for a nuclear fuel reprocessing system that has been evaluated
through experiments with experienced operators. The results show that the approach is interesting because the boarder between
support and assistantship is never crossed. 相似文献