• Computer workstations (sites or nodes) that form the network system.
• Network hardware and software components that reside in each
workstation.
• Communications media that carry the data from one workstation to
another.
• The transaction processor (TP), which is the software component
found in each computer that requests data. The transaction processor
receives and processes the application’s data requests (remote and local).
The TP is also known as the application processor (AP) or the
transaction manager (TM).
• The data processor (DP). which is the software component residing
On each computer that stores and retrieves data located at the site.
The DP is also known as the data manager (DM). A data processor
may even be a centralized DBMS.
The protocols determine how the distributed database system will:
• Interface with the network to transport data and commands between
data processors (DPs) and transaction processors (TPs).
• Synchronize all data received from DPs (TP side) and route retrieved
data to the appropriate TPs (DP side).
• Ensure common database functions in a distributed system . Such
functions include security, concurrency control, backup, and recovery.
LEVELS OF DATA AND PROCESS DISTRIBUTION
Current database systems can be classified on the basis of how process distribution and data distribution are supported.
SINGLE-SITE PROCESSING, SINGLE-SITE DATA (SPSD)
In the (SPSD) scenario, all processing is done on a single host computer (single-processor server, multiprocessor server, mainframe system) and all data are stored on the host computer’s local disk system. The DBMS is located on the host computer, which is accessed by dumb terminals connected to it. This scenario is also typical of the first generation of single-user microcomputer databases.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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