In regard to the scalable service control platform needed for realization of future mobile communication service, a new method of efficiently accessing distributed databases (DB) is proposed. Previously, as an access ...
详细信息
In regard to the scalable service control platform needed for realization of future mobile communication service, a new method of efficiently accessing distributed databases (DB) is proposed. Previously, as an access system plan to distributed DBs, a unicast-type system in which the access request to a DB received from the network is transferred to the destination DB (System A) and a multicast system with multicast delivery (System B) have been proposed. In the former, the increased size of the destination decision table puts pressure on main memory. In the latter, multicast communication applies pressure every time on processor process capacity. Hence, sufficient scalability has not been obtained in either method. In the present paper, the existence of locality in the requirement for DB access among users is recognized. A hybrid system (System C) is proposed here in which unicast communication is applied for access by a few users with high access frequency, but multicast communication is used for access, by the other, majority users. A system control parameter is introduced to select these communication methods. By choosing the value of this parameter optimally, the user accommodation limits in the conventional system are resolved. It is shown quantitatively that operation with a minimum amount of equipment is possible in a wide accommodation range. (C) 2003 Wiley Periodicals, Inc.
Real-time database applications are distributed in nature. Incorporating distributed data into a real-time database framework incurs complexity, associated with transaction concurrency control and database recovery in...
详细信息
ISBN:
(纸本)0769513212
Real-time database applications are distributed in nature. Incorporating distributed data into a real-time database framework incurs complexity, associated with transaction concurrency control and database recovery in a distributed context. This article presents an algorithm that manages soft real-time transactions in a distributed database. It uses a specific causal-ordering protocol to ensure the precedence relationships between transactions. Our algorithm is based on a technique, which subdivides transactions into sets. Then the protocol virtually serializes the executions on distributed servers by, using causal phase ordering properties. Causal phases are created according to transactions conflicts that may occur between transactions sets. Transactions of the same phase are scheduled according to their criticality, and transactions of two successive phases are ensured to commit in a causal partial order. This strategy, permits to reduce the execution time, allowing more transactions meeting their deadlines.
This paper presents new research and development of an integrated peer-to-peer(P2P) platform comprising of a network of distributed and decentralized peer devices connected directly with one another in an ad-hoc virtu...
详细信息
This paper presents new research and development of an integrated peer-to-peer(P2P) platform comprising of a network of distributed and decentralized peer devices connected directly with one another in an ad-hoc virtual group *** platform is built upon an extended version of the Sun Microsystem's Project JXTA and the Jabber's XMPP (Extensible Messaging and Presence Protocol) protocols. The proposed P2P platform has a comprehensive set of application programming interfaces(APIs) that provide a high-level encapsulation of many core P2P platform services, security control and policies,online presence management, data management and transfer,*** the application layer. By using these platform APIs,we have developed a number of essential tools targeting distributed e-Education and e-Collaboration environments,such as integrated secure chat, digital asset management,sharing,searching and retrieval, synchronized calendaring and contacts management,and scalable multimedia *** core vision and strategy here is to enable a truly distributed means for multiparty communications and collaboration in an ad-hoc peer group eco-system without the need for centralized systems,file servers,databases and corporate networks setup (such as extranets and virtual private networks).The platform's flexible plug-in and XML web services architecture allows easy development and integration of many new applications and services *** employing a 100% Java implementation,the platform is OS-independent and has been shown to work well on Windows,Macintosh,and Linux.
In this paper,we discussed the case of deadlock in a distributed database management *** emphasis is how to detect or resolve deadlock in a dike safety detection management information system.
In this paper,we discussed the case of deadlock in a distributed database management *** emphasis is how to detect or resolve deadlock in a dike safety detection management information system.
A comprehensive system management has been developed to solve the problem of difficulty and low security. By multi-user management, directory and parameter maintaining, data backuping and restoring, this method can co...
详细信息
A comprehensive system management has been developed to solve the problem of difficulty and low security. By multi-user management, directory and parameter maintaining, data backuping and restoring, this method can control multi-subsystem altogether, so the management becomes simple and safe. A distributed decision support system to show the advantage is demonstrated.
Data replication can be used to improve the availability of data in a distributed database system. In such a system, a mechanism is required to maintain the consistency of the replicated data. Grid structure (GS) tech...
详细信息
Data replication can be used to improve the availability of data in a distributed database system. In such a system, a mechanism is required to maintain the consistency of the replicated data. Grid structure (GS) technique based on quorum is one of the latest solutions for performing this while providing a high availability of the system. It was shown in the previous study, that it still requires a bigger number of copies be made available to construct a quorum. So it is not suitable for the large systems. In this paper, we propose a technique called the binary vote assignment on grid (BVAG) technique by considering only neighbors have the replicated data. In comparison to the GS technique, BVAG requires lower communication cost for an operation, while providing higher data availability, which is preferred for large systems.
The blocking phenomena in two-phase commit (2PC) reduces the availability of the system as the blocked transactions keep all the resources until the recovery of the coordinator. The three-phase commit (3PC) protocol i...
详细信息
The blocking phenomena in two-phase commit (2PC) reduces the availability of the system as the blocked transactions keep all the resources until the recovery of the coordinator. The three-phase commit (3PC) protocol involves an extra round of message transmission to resolve the blocking problem. In this paper, we propose a backup commit (BC) protocol to reduce the blocking problem by attaching multiple backup sites to the coordinator site. In BC, after receiving responses from the participants, the coordinator quickly communicates the final decision to the backup sites, before it sends the final decision to the participants. When blocking occurs, the participant sites can terminate the transaction by consulting a backup site of the coordinator. The BC protocol resolves the blocking in most of the coordinator site failures without involving an expensive communication cycle as in 3PC. The simulation experiments indicate that the throughput performance of BC is close to 2PC. (C) 2002 Elsevier Science B.V. All rights reserved.
This paper presents a distributed parallel system for face recognition. The face database in this system is so huge (more than 1,000 thousand faces) that matching and recognition processes can not be carried out on on...
详细信息
ISBN:
(纸本)0780378407
This paper presents a distributed parallel system for face recognition. The face database in this system is so huge (more than 1,000 thousand faces) that matching and recognition processes can not be carried out on only one computer. So cluster system must be used to improve the matching speed. But many current clusters existing have some problems and can not fit our system. A special distributed parallel system was developed to complete face query and recognition. The concept of parallel virtual machine and a kind of linked table structure adopted in this system not only decreased lots of moving overhead of adding or deleting nodes in the array structure but also truly realized the infinite extensibility. Furthermore, key techniques such as distributed database, buffer and synchronization techniques in communication and multithreading in control flow were adopted to guarantee the normal running. Practical results proved that this parallel system can improve the matching speed for more than 4 times. Moreover, the greatest advantage of this system is not only increasing matching speed but breaking the upper limit of face data capacity. Consequently, the face data capability of this system can be extended to arbitrary figure as bigger as possible.
Digital images are being generated at a phenomenal rate. Currently, the most common method by far for searching digital image databases is based on employing index terms which are entered manually. Content based image...
详细信息
ISBN:
(纸本)1892512459
Digital images are being generated at a phenomenal rate. Currently, the most common method by far for searching digital image databases is based on employing index terms which are entered manually. Content based image retrieval (CM) systems are required to effectively and efficiently use the information that is intrinsically stored in these image databases. However, CBIR on multiple image databases is a slow process that needs performance improvement. In this paper, we present a distributed approach to CBIR, an image retrieval scheme that retrieves images based on segmentation and signature in a distributed environment.
暂无评论