Chapter3 Database Architecuture and the Web

Chapter3 Database Architecuture and the Web

3.1.6Middleware

is a generic term used to describe software that mediates with other software and allow for communicationbetweendisparate applications in a heterogeneous System.

3.1.7 TP Monitor

A program that control data transfer between clients and server in order to provide a consistent environment. Complex application are often built on the top of several resource managers(such as DBMS,operating system , user interface,and messaging)...

3.2.2 Service-Oriented Architectures(SOA)

A business-centricsoftware architecture for building applications that implement business processes as a set of services published at a granularity relevant to the service consumer.

3.3Distrbuted DBMS

Distributed database:A logically interrelated collection of shared data .

Distributed DBMS:The software that permits the management of the distributed database are makes the distribution transparent to users.

*it is important to make a distinction between a distributed DBMS and distributed processing.If the data is centralized,even through other users may be accessing the data over the network,we do not consider this to be a DBMS simply.

3.4 Data Warehousing

A consolidated/integrated view of corporate data drawn from disparate operational data sources and a range of end-user access tools capable of

supporting simple to highly complex queries to support decision making.

3.5 Components of a DBMS

• Query processor: transforms queries into a series of low-level instructions directed to the database manager.

• Database manager:The Dm interface with user-submitted application programs and queries.The DM accept queries and examines the external
and conceptual  schemas  to determine what conceptual records are required to satisfy the request.

• File manager:The file manager manipulated the underly storage files and manager the allocation of storage space on disk.

• DMS preprocessor: This module convert DML statement embedded in an application into standard function calls in the host language.

• DDL complier: converts DDL statements into set of tables containing metadata. These tables are then stored in the system catalog while control information is stored in data file headers.

• Catalog manager:manage access and maintain the system catalog. 

The major software component for the database manager are as follows:

• authorization control.

• Command processor

• Intergiry checker

• Query optimizer

• transation manager

• scheduler:responsible for ensuring that concurrent operation on the

database proceed without conflicting with one another.

• Recovery manager

• Buffer manager:responsible for the transfer of data between main

   memory and secondary storage.