Transcript Database - McMaster University

Client/Server Computing
Client/Server Computing
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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 timeshared mainframe and mini-computer
paradigms with the advantages of personal
computers, workstations, and local area
networks
Components of Client/Server
Computing
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Three interrelated components
Client - the front-end
Server - the back-end
Network - the middle ware
M:N relation between clients and
servers.
A Basic Client/Server Computing Model
Client/Server Architecture
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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.
How Client And Server Components Interact
Two levels of communications
middleware
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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).
Interaction Between Client/Server
Middleware Components
Database Middleware
Components
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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.
Database Middleware Components
Three Main Benefits of Using
Middleware
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Access multiple databases
Database server-independent
Network protocol-independent
Middleware Accessing Multiple Database Servers
Application Functional Logic Components
Typical Logic Component
Placement
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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.
Functional Logic Splitting In Four Client/Server
Architectural Styles
Microsoft SQL Client/Server
Connection
Client PC
Server
Computer
Microsoft
SQL
Microsoft
SQL
(workstation
version)
(server version)
LAN
Microsoft SQL Client/Server
Connection
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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
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SQL Server registration
local and remote servers
SQL Server security control
Windows NT authentication
SQL user authentication
User access privilege specification
SQL Client/Server Connection
Remote SQL server registration
User authentication using
your user name and password
MGD B106
Computer or
your own PC
Buscom SQL
server
Import/export
Local SQL
server
Local SQL server
registration
Backup/restore
Backup disk
Your
database
created by
DBA
You
create
your own
database
Linking to SQL Server from Access
DB Server
Client 1
Microsoft
Access
ODBC
LAN
Client 2
Microsoft
Access
ODBC
Internet
Microsoft
SQL
Web Server
ASP
ODBC
ODBC
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Open Database Connectivity
DBMS-independent means for
processing relational database data
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ORACLE
SYBASE
INFORMIX
ODBC Terminology
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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
source
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ODBC Architecture
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Figure 13-5
© 2000 Prentice Hall