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PRO-MOTION: Mobile Transaction Processing Infrastructure
We developed a complete characterization of the mobile client and stationary database server interactions based on the notion of agreements which is a generalization of the escrow ideas in traditional distributed systems. Agreements allow sharing of data among mobile and stationary clients in a controlled fashion by specifying restrictions, obligations, and privileges which accompany the shared data.
We defined a canonical model for agreement based mobile transaction processing consisting of three functional components, namely, an agreement manager at the level of the server, mobility data manager at each mobility support station, and an agreement agent at each mobile computer. The agreement manager is responsible for all data and transaction management on a mobile computer. Using this canonical model, we developed a pro-active protocol for fragmentable objects which allows transactions to unilaterally commit on the mobile computer within the conditions of an agreement. |
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The Implicit Yes Vote Protocol
The Implicit-Yes Vote protocol is an atomic commit protocol that has been proposed for the future gigabit-networked distributed databases employing strict two-phase locking for concurrency control. By exploiting the network bandwith, IYV eliminates the first phase of the two-phase commit protocol, hence reducing the time required to commit a distributed transaction during normal processing, at the expense of independent recovery of failed participant sites. |
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PowerMedia Database Network
Panos Chrysanthis and Daniel Mosse are developing a system architecture for distributed multimedia system, with the provisory name of PowerMedia Database Network or Networld. The NETWORLD architecture was developed for the information access and retrieval in physically and logically distributed networks. |
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WANDS: Wide Area Networked Database Systems
This project's goal is to study the impact of the new capabilities of high-speed networks on the design and performance of data management protocols. In particular, the focus is on high-speed wide-area networks (WANs) where the propagation latency is the dominant communication cost, the migration of large amounts of data is not an issue, and efficient multicasting and guarantees on network Quality of Service (QoS) parameters are available. In this project, existing concurrency control, commit and recovery protocols are being evaluated with respect to performance scalability under the new network assumptions. Further, new protocols are being developed that utilize the huge bandwidth and minimize the number of sequential phases of messages exploiting the multicasting capability and the provision of QoS guarantees such as bounded end-to-end packet delay and packet loss. At the same time, because of the need to scale to thousands of clients and servers, not all of which may be operational at any given time, the new WAN data management protocols are designed to achieve higher site autonomy in a cooperative manner, reducing global synchronization and supporting disconnected operations. The various protocols are empirically evaluated using computer simulation under different scenarios. |
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Query by Icon
Query By Icon (QBI) is a query processing facility developed by Antonio Massari. It allows users to query a database through the use of icons. The icons and choices that the users are presented come from semantic knowledge about the structure of the underlying databases. This knowledge is presented to the user using a data model called the Complete Object Model. By clicking on these icons, the system will automatically compose and present the user a query in natural language. In order to achieve this, information about the underlying database is internally represented, graphically, using a semantic data model called the Binary Graph Model. |
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