Chapter 3 Database Architectures and the Web Pearson Education © 2009

Chapter 3 - Objectives u The meaning of the client–server architecture and the advantages of this type of architecture for a DBMS u The difference between two-tier, three-tier and n- tier client–server architectures u The function of an application server u The meaning of middleware and the different types of middleware that exist u The function and uses of Transaction Processing (TP) Monitors Pearson Education © 2009

Chapter 3 - Objectives u The purpose of a Web service and the technological standards used u The meaning of service-oriented architecture (SOA) u The difference between distributed DBMSs, and distributed processing u The architecture of a data warehouse u The software components of a DBMS u About Oracle’s logical and physical structure

Pearson Education © 2009 Summary of client–server functions

Pearson Education © 2009 Multi-user DBMS Architectures u Three-tier client–server architecture –User interface layer –Business logic and data processing layer –DBMS –Many advantages over traditional two-tier or single-tier designs

Pearson Education © 2009 Multi-user DBMS Architectures u N-tier architectures –Three-tier architecture can be expanded to n tiers u Application servers –Hosts an application programming interface (API) to expose business logic and business processes for use by other applications

Pearson Education © 2009 Multi-user DBMS Architectures u Middleware –Software that mediates with other software –Communication among disparate applications –Six main types »Asynchronous Remote Procedure Call (RPC) »Synchronous RPC »Publish/Subscribe »Message-Oriented middleware (MOM) »Object-request broker (ORB) »SQL-oriented data access

Pearson Education © 2009 Multi-user DBMS Architectures u Transaction processing monitor –Controls data transfer between clients/servers –Provides a consistent environment, particularly for online transaction processing (OLTP) –Significant advantages »Transaction routing »Managing distributed transactions »Load balancing »Funneling »Increased reliability

Pearson Education © 2009 Multi-user DBMS Architectures Transaction processing monitor

Pearson Education © 2009 Web Services and Service-Oriented Architectures u Web service –Software system that supports interoperable machine-to-machine interaction over a network –No user interface –Examples of Web services –Uses widely accepted technologies and standards

Pearson Education © 2009 Relationship between WSDL, UDDI, and SOAP

Pearson Education © 2009 Web Services and Service-Oriented Architectures u Service-Oriented Architectures (SOA) –Architecture for building applications that implement business processes as sets of services –Published at a granularity relevant to the service consumer –Loosely coupled and autonomous services –Web services designed for SOA different from other Web services

Pearson Education © 2009 Traditional vs. SOA Architecture

Pearson Education © 2009 Distributed DBMSs u Distributed database –Logically interrelated collection of shared data physically distributed over a computer network u Distributed DBMS –Software system that permits the management of the distributed database –Makes the distribution transparent to users

Pearson Education © 2009 Distributed DBMSs u Characteristics of DDBMS –Collection of logically related shared data –Data split into fragments –Fragments may be replicated –Fragments/replicas are allocated to sites –Sites are linked by a communications network –Data at each site is controlled by DBMS –DMBS handles local apps autonomously –Each DBMS in one or more global app

Pearson Education © 2009 Distributed DBMSs u Distributed processing –Centralized database that can be accessed over a computer network u System consists of data that is physically distributed across a number of sites in the network

Pearson Education © 2009 Data Warehousing u Data warehouse –Consolidated/integrated view of corporate data –Drawn from disparate operational data sources –Range of end-user access tools capable of supporting simple to highly complex queries to support decision making –Subject-oriented, integrated, time-variant, and nonvolatile

Pearson Education © 2009 Typical Architecture of a Data Warehouse

Pearson Education © 2009 Components of a DBMS u Major components of a DBMS: –Query processor –Database manager (DM) –File manager –DML preprocessor –DDL compiler –Catalog manager

Pearson Education © 2009 Components of a DBMS u Major software components for database manager –Authorization control –Command processor –Integrity checker –Query optimizer – Transaction manager – Scheduler – Recovery manager – Buffer manager

Pearson Education © 2009 Oracle Architecture u Oracle’s logical database structure –Tablespaces –Schemas –Data blocks –Extents/segments

Pearson Education © 2009 Relationship between an Oracle Database, Tablespaces, and Datafiles

Pearson Education © 2009 Oracle Architecture u Oracle’s physical database structure –Datafiles –Redo log files –Control files u The Oracle instance –Oracle processes and shared memory required to access information in the database