Date post: | 23-Dec-2015 |
Category: |
Documents |
Upload: | angel-holland |
View: | 214 times |
Download: | 0 times |
Client/Server Computing Information processing is distributed
among several workstations and servers on a network, with each function being assigned to the environment that is best suited to perform it. The client initiates the requests and the server responds.
Consolidate the virtues of traditional time-shared mainframe and mini-computer paradigms with the advantages of personal computers, workstations, and local area networks
Components of Client/Server Computing Three interrelated components
Client - the front-endServer - the back-endNetwork - the middle ware
M:N relation between clients and servers.
Client/Server Architecture The client is any computer process that
requests services from the server. It is also known as the front-end application.
The server is any computer process providing services to the clients. The server is also known as the back-end application.
The communication middleware is any computer process(es) through which clients and servers communicate. It is also known as middleware or communications layer.
Two levels of communications middleware The physical level deals with the
communications between client and server computers (computer to computer).
The logical level deals with the communications between client and server processes (process to process).
Database Middleware Components Application programming interface
(API) interfaces with the client application.
The database translator translates the SQL requests into the specific database server syntax.
The network translator manages the network communications protocols.
Three Main Benefits of Using Middleware Access multiple databases Database server-independent Network protocol-independent
Typical Logic Component Placement
The presentation logic is always placed on the client side.
The I/O processing logic may be placed on the client side or on the server side, but more commonly on the client side.
The business logic can also go either to the client or the server, but usually on the client side.
The data management logic can also be placed on either the client or the server side, but normally on the server side as part of the application code.
The data manipulation logic is most commonly located on the server side.
Microsoft SQL Client/Server Connection
MicrosoftSQL(server version)
MicrosoftSQL(workstation version)
LAN
Client PC ServerComputer
Microsoft SQL Client/Server Connection
At the server site, DBA creates a SQL database for the user
At the client site, the user can make remote registration and logon to access SQL database stored on the server
MicroSoft SQL Server SQL Server registration
local and remote servers SQL Server security control
Windows NT authenticationSQL user authentication
User access privilege specification
SQL Client/Server Connection
Buscom SQLserver
Local SQL server
MGD B106 Computer or your own PC
Remote SQL server registration
User authentication using
your user name and password
Local SQL server registration
Import/export
Backup disk
Backup/restore
Yourdatabase created by DBA
You create your own
database
Linking to SQL Server from Access
MicrosoftSQL
MicrosoftAccess
Internet
ODBC
Client 1 DB Server
MicrosoftAccess
ODBC
Client 2
LAN
ODBC
Web Server
ASP
ODBC Open Database Connectivity DBMS-independent means for
processing relational database data ORACLE SYBASE INFORMIX
Page 342
ODBC Terminology Data source: the database, its
associated DBMS, operating system, and network platform
Driver manager: intermediary between the application and DBMS drivers
Driver: processes ODBC requests and submits SQL statements to a data sourcePage 343