26-02-2013, 04:41 PM
Distributed computation, analysis, and presentation between PCs
Distributed computation.ppt (Size: 378.5 KB / Downloads: 199)
Unit Structure
Evolution of Client/Server Architecture
Client/Server Model
Characteristics of Client/Server Model
Client/Server Architecture in the Web
Types of Servers
Types of Client/Server Models
Advantages & Disadvantages of Client/Server Model
Evolution of Client/Server Architecture
Mainframes
Dumb Terminals
All processing/data storage on mainframe computer
Large number of users
Expensive
Personal Computers
Single User system
Word Processing, Data Analysis using Spreadsheet
Multimedia Applications & Games
Clients & Server on different computer systems
Local Area Network for Server and Client connectivity
Multiple Users
Distributed computation, analysis, and presentation between PCs
Evolved during 1980s
Heterogeneous hardware and software
Provides greater usability, flexibility, scalability and interoperability
CLIENT / SERVER MODEL
Model or architecture describes the relationship between two computer programs – Client & Server
Client is the requester that makes a service request
Server fulfills the request or services the request
Multiple client programs share the services of a common server program
Servers typically contain data files & applications accessed by multiple clients
Client & Server share the processing load
Client / Server can be on same computer system or on different computer systems
Client/Server model - a convenient way to interconnect programs distributed across different locations
Function of Client / Server
Client
Initiates requests
Waits for and receives replies
Can connect to several servers at the same time
Typically interacts directly with end-users using a Graphical User Interface (GUI)
Server
Waits for requests from clients
Upon receipt of requests, processes them and then serves replies
Usually accepts connections from a large number of clients
Typically does not interact directly with end-users
Database Server
A computer in a LAN dedicated to database storage and retrieval
The database server holds the Database Management System (DBMS) and the databases
Upon requests from the client machines, it searches the database for selected records and passes them back over the network
APPLICATION SERVER
Application server runs the programs and processes the data
Application servers are typically used for complex transaction-based applications
Application server performs the business logic functions and some data access
An application server provides middle tier processing between the user's machine and the database management system (DBMS)