Client-Server Architecture

Network Operating Systems

• There are two major types of network operating systems: Peer-to-Peer and Client/Server

Peer-to-Peer Network

• Allows users to share resources and files located on their computers and access shared resources on other computers
• All computers are considered equal and have the same abilities to use resources available on the network
• Designed primarily for small to medium local area networks
• Advantages:
  • Less initial expense
  • No need for a dedicated server
• Disadvantages:
  • Decentralized, no central repository for files and applications
  • No security available on a client/server network

Client/Server Network

• Allows the network to centralize functions and applications in one or more dedicated file servers
• File servers become the heart of the system, providing access to resources and security
• Individual workstations (clients) have access to resources available on the file servers
• Advantages:
  • Centralized, resources and data security are controlled through the server
  • Scalable, elements can be replaced individually as needs increase
  • Flexible, new technology can be easily integrated into the system
  • Interoperable, all components work together
  • Accessible, server can be accessed remotely and across multiple platforms
• Disadvantages:
  • Requires initial investment in dedicated server
  • Maintenance, large networks require a staff to ensure efficient operation
  • Dependence, when server goes down, operations will cease across the network

Client-Server Architecture

• A computing model in which the server hosts, delivers, and manages most resources and services to be consumed by the client
• Also known as a networking computer model or client-server network
• Shares computing resources

Components of Client-Server Architecture

• Servers:
  • Software that sits around listening or waiting for a request
  • Provided with special functionalities
  • Manage access structures, query evaluation, and optimization, concurrency control, and recovery
• Clients:
  • Personal computers or workstations
  • Devices with software that knows how to make a request from a server and knows what to do with the response returned by the server
  • Run on one or more client machines
  • Provide the user with an interface to utilize the servers and local processing power to run local applications

Application Architecture

• Presentation Layer:
  • Concerned with presenting the results of a computation to system users and with collecting user inputs
• Application Processing Layer:
  • Concerned with providing application-specific functionality
• Data Management Layer:
  • Concerned with managing the system databases

Types of Client-Server Architecture

• One-Tier Architecture:
  • All client/server configuration, user interface environment, data logic, and marketing logic system exist on the same system
  • Reliable but difficult to handle because they contain all data in different variance
• Two-Tier Architecture:
  • Similar to a basic client-server model
  • Application at the client end directly communicates with the database at the server side
  • Client can be THIN CLIENT or FAT CLIENT
• Three-Tier Architecture:
  • Each of the application layers may execute on a separate processor
  • Allows for better performance and is simpler to manage
  • More scalable architecture – as demands increase, extra servers can be added
  • Intermediate layer acts as a medium for exchange of partially processed data between server and client
  • Used in case of large web applications

Three-Tier Architecture Layers

• Client layer:
  • The part of the application visible to the user
  • Enables input of requirements and presentation of results
• Application layer:
  • The middle layer of the model (middleware)
  • Assures calculations and operations performed between input-output requirements and data
  • Also known as the application server
• Data layer:
  • The lowest layer of the model
  • Ensures all operations with data, i.e., database management system and basic database operations for functional storage, selection, aggregation, processing, integrity, and data audit

This quiz covers the basics of client-server architecture, its components, and types. It also touches on network operating systems and their role in managing networks.