A mechanism for decentralized authorization in a distributeddatabase system is presented. This mechanism is an extension of a previously presented concept of the decentralized authorization for a non-distributed data...
详细信息
ISBN:
(纸本)0780304942
A mechanism for decentralized authorization in a distributeddatabase system is presented. This mechanism is an extension of a previously presented concept of the decentralized authorization for a non-distributeddatabase. Three configuration models for the information necessary to perform the validation of an authorization request are proposed. An algorithm for the implementation of the validation process is presented.
The requirements of a PACS database system (PACS DBS), which has been characterized to have large-volume image data, multi-media data and cross-modality reference, suggest the adoption of a distributed approach to PAC...
详细信息
ISBN:
(纸本)0819408069
The requirements of a PACS database system (PACS DBS), which has been characterized to have large-volume image data, multi-media data and cross-modality reference, suggest the adoption of a distributed approach to PACS DBS design. This paper presents the design and the implementation of such a distributed PACS DBS. The design issues of a distributed PACS DBS include distributed transaction management for concurrency/recovery/security control, catalogue management for archiving fragmentation/location/replication transparency, and strategies for the distributed query processing. A prototype distributed PACS DBS that has been implemented and some implications from its evaluation will be discussed.
This paper describes the architecture of a heterogeneous distributeddatabase management system called the distributed Access View Integrated database (DAVID). The DAVID system allows uniform access to distributed dat...
详细信息
ISBN:
(纸本)0897914724
This paper describes the architecture of a heterogeneous distributeddatabase management system called the distributed Access View Integrated database (DAVID). The DAVID system allows uniform access to distributed data stored in different DBMSs that support various data models. The system presents the users with a unified cluster data model and with a uniform high level query language (GSQL). database heterogeneity issues such as external-to-conceptual view translation, view integration, query processing and the definition of a uniform data access language are presented in the context of the DAVID development.
The most important requirement for a heterogeneous distributeddatabase system (HDDBS) is the capability of providing an integrated view of its component databases that is transparent in data distribution and the hete...
详细信息
This paper describes the design of a distributeddatabase for a picture archiving and communications system (PACS). This system consists of several relatively cheap workstations and a large optical archive and distrib...
详细信息
ISBN:
(纸本)0819408069
This paper describes the design of a distributeddatabase for a picture archiving and communications system (PACS). This system consists of several relatively cheap workstations and a large optical archive and distributeddatabase modules. The communication between the modules uses the same network as used to connect the system to the clients. Existing, working, and available standards are used wherever possible. This makes the system open and accessible in a multivendor environment such as hospitals. The distributed approach makes the total system flexible, cheaper, faster, and when designed carefully, more reliable.
The performance of a non-standard distributeddatabase system is strongly influenced by complex objects. The effective exploitation of parallelism in querying them and a suitable structure to store them are required i...
详细信息
The performance of a non-standard distributeddatabase system is strongly influenced by complex objects. The effective exploitation of parallelism in querying them and a suitable structure to store them are required in order to obtain acceptable response times in these database environments where performance tends to be critical. In this paper we use an hierarchical complex object model with object references and define several join operations for these complex objects which we will call tuple-objects. These join queries for tuple-objects can be categorized into materialized, functional and value-based joins. An analytical performance evaluation gives insight into which distributed storage structures for tuple-objects are most effective with regard to executing the different kinds of tuple-object joins.
A model of nested transactions in distributed database systems is presented. The modeling approach is based on conflict serializability extended to accommodate multilevel transactions. Based on these definitions, seri...
详细信息
Since the mid-1980s the authors have been researching the development of query and schema inter-translation tools to facilitate inter-operability between databasesystems at member sites of heterogeneous distributed d...
详细信息
Since the mid-1980s the authors have been researching the development of query and schema inter-translation tools to facilitate inter-operability between databasesystems at member sites of heterogeneous distributeddatabase (HDD) environments, using the automatic tool generation approach known as meta-translation the work has resulted in a query meta-translation system (QMTS) (D.I. Howells et al., 1987; 1988; W.A. Gray et al., 1990), for translating relational queries into non-relational or other relational form equivalents, and a schema meta-translation system (SMTS) (A. Ramfos et al., 1989; 1991), for translating non-relational, particularly object-oriented (O-O), schemas into relational equivalents. The usefulness of the technology developed has also been demonstrated by its successful application in an industrial context. From their experience, the authors are able to propose extensions and consolidations to this technology that will produce a fully integrated inter-site translation support environment (ITSE) for HDDs, which will facilitate complete inter-operability. The authors review previous research and briefly outline the way forward towards realising such a support environment.< >
Allocation and reallocation techniques for resources in a distributeddatabase (DDB) system are discussed. An abstract model of the DDB, which partitions data among a set of nodes in a network, is presented. Initial r...
详细信息
Multi-user applications support multiple users performing a related task in a distributed context. This paper describes Weasel, a system for implementing multi-user applications. Weasel is based on the relational view...
详细信息
ISBN:
(纸本)0897915429
Multi-user applications support multiple users performing a related task in a distributed context. This paper describes Weasel, a system for implementing multi-user applications. Weasel is based on the relational view model, in which user interfaces are specified as relations between program data structures and views on a display. These relations are specified in RVL, a high-level, declarative language. Under this model, an application program and a set of RVL specifications are used to generate a multi-user application in which all issues of network communication, concurrency, synchronization, and view customization are handled automatically. These programs have a scalable distribution property, where adding new participants to a session does not greatly degrade over-all system performance. Weasel has been implemented, and was used to generate all examples in this paper.
暂无评论