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Database Architectures and the Web Session 5

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2 Database Architectures and the Web Session 5
Course Name : Database System Year : 2012 Database Architectures and the Web Session 5

3 Database Architectures and the Web
Chapter 3 Database Architectures and the Web Pearson Education © 2009

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

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

6 Multi-user DBMS Architectures
Teleprocessing Traditional architecture for multi-user systems One computer with a single central processing unit (CPU) and a number of terminals Put a huge burden on the central computer Downsizing Replacing expensive mainframe computers with more cost-effective networks of personal computers

7 Multi-user DBMS Architectures
File-server architecture Processing is distributed about the network Three main disadvantages Large amount of network traffic Full copy of DBMS required on each workstation Concurrency, recovery, and integrity control are complex Multiple DBMSs can access the same files

8 File-Server Architecture

9 Multi-user DBMS Architectures
Traditional two-tier client–server architecture Client process requires some resource Server provides the resource Basic separation of four main components of business application Typical interaction between client and server

10 Traditional Two-Tier Client-Server
Client (tier 1) manages user interface and runs applications. Server (tier 2) holds database and DBMS. Advantages include: wider access to existing databases; increased performance; possible reduction in hardware costs; reduction in communication costs; increased consistency.

11 Traditional Two-Tier Client-Server

12 Traditional Two-Tier Client-Server

13 Multi-user DBMS Architectures
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

14 Three-Tier Client-Server
Client side presented two problems preventing true scalability: ‘Fat’ client, requiring considerable resources on client’s computer to run effectively. Significant client side administration overhead. By 1995, three layers proposed, each potentially running on a different platform.

15 Three-Tier Client-Server
Advantages: ‘Thin’ client, requiring less expensive hardware. Application maintenance centralized. Easier to modify or replace one tier without affecting others. Separating business logic from database functions makes it easier to implement load balancing. Maps quite naturally to Web environment.

16 Three-Tier Client-Server

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

18 Summary of client–server functions

19 Multi-user DBMS Architectures
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

20 Multi-user DBMS Architectures
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

21 Transaction Processing Monitors
Program that controls data transfer between clients and servers in order to provide a consistent environment, particularly for Online Transaction Processing (OLTP).

22 Multi-user DBMS Architectures
Transaction processing monitor

23 Web Services and Service-Oriented Architectures
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

24 Relationship between WSDL, UDDI, and SOAP

25 Web Services and Service-Oriented Architectures
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

26 Traditional vs. SOA Architecture

27 Distributed DBMSs Distributed database
Logically interrelated collection of shared data physically distributed over a computer network Distributed DBMS Software system that permits the management of the distributed database Makes the distribution transparent to users

28 Distributed DBMSs 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

29 Distributed DBMSs Distributed processing
Centralized database that can be accessed over a computer network System consists of data that is physically distributed across a number of sites in the network

30 Data Warehousing 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

31 Typical Architecture of a Data Warehouse

32 Oracle Architecture Oracle’s logical database structure Tablespaces
Schemas Data blocks Extents/segments

33 Relationship between an Oracle Database, Tablespaces, and Datafiles

34 Oracle Architecture Oracle’s physical database structure Datafiles
Redo log files Control files The Oracle instance Oracle processes and shared memory required to access information in the database

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