Data Management Layer Design

Abstract

The data link layer (data link level in English) or data link layer is the second layer of the OSI model, which is responsible for the transfer reliable information through a data transmission circuit. Receive requests from the network layer and uses the services of the physical layer .The purpose of the link layer is to make information flow, error-free, between two machines that are directly connected (connection-oriented service). To achieve this objective is to assemble blocks of information (called frames in this layer), provide them with a link-layer address (MAC address), to manage the detection or error correction and address the flow control between equipment (to avoid a faster computer with a slower overflow. When the media is shared between more than two teams must arbitrate the use thereof. This task is performed in the sub layer medium access control.

System architecture ALEPH500

ALEPH500 system is an agent that provides library services through so-called customer service. Application Program Interfaces (APIs). The system architecture is based on the multi-layer client-server model.The exchange of data between client and server is based on the transactional model but ALEPH500 system application servers maintain information about open sessions with clients, which ensures high system performance.ALEPH500 presents a new approach to database design. Each implementation ALEPH500 system consists of interrelated but separate databases: the Standard records, Bibliographic, Library Resources, Administration and Local Data Systems Administrative Data. Implementation ALEPH500 system may consist of multiple databases each of these types of links many-to-many relationship with other databases (Evans, 2007 ). The new model allows a variety of database configurations for a variety of databases and their implementations, including independent installations databases on different servers.The adopted model database has a decisive influence on the scalability of the product to suit your needs.

ALEPH500 system operates on different UNIX platforms ...