SERVER ARCHITECTUREServer Architecture is nothing but the way our server layers(server ,network connectivity and other components connected to it) are connected to one another. It depends on :-1.The architecture depends on type of application and network layer.2.based on targeted users.3.Firmware and midware.4.Any 3rd party application usage.

Objectives• Explain the essential principles of client-

server architecture.• Explain the differences between 2-tier, 3-tier,

and multitier architectures, including their features and relative capacities.

• Recognize 2-tier, 3-tier, and multi-tier architectures.

• Contrast the client-server architecture with centralized and distributed architectures.

Types of application:- 1.Stand-alone application – usually has

single tier architecture. 2.Client-Server architecture – usually has

two tier(client and server) to multi-tier(n-tier) architecture depending on concurrent load.

3.Web-server architecture - usually has single tier to multi-tier(n-tier) architecture depending on concurrent load.

System Architecture• The architecture of a computer system is the

high-level (most general) design on which the system is based.

Architectural features include:• Components.• Collaborations (how components interact)• Connectors (how components communicate)

SYSTEM ARCHITECTURE

Common architectural patterns include• Client-Server• Layered• Peer-to-peer• Pipes and Filters• etc.

Client-Server Architecture• Each component of a client-server system has

the role of either client or server.

–Client: a component that makes requestsclients are active initiators of transactions

–Server: a component that satisfies requestsservers are passive and react to client requests

Representation of client-server

ClientPresentation Logic

Business Logic

ServerBusiness LogicDatabase Logic

DBMS

DataBase

Centralized / Distributed• The client-server architecture can be thought

of as a median between

–Centralized processing: computation is performed on a central platform, which is accessed using “dumb” terminals.–Distributed processing: computation is

performed on platforms located with the user.

Centralized Client / Server Distributed

• The Web is a client-server system• Web browsers act as clients, and make

requests to web servers• Web servers respond to requests with

requested information and/or computation

Client-Server Architecture

Server

Server

ServerClient

Client

ClientClient

Client request

Tiered Web Architectures• Web applications are usually

implemented with 2-tier, 3-tier, or multitier (N-tier) architectures

• Each tier is a platform (client or server) with a unique responsibility

2-Tier C-S Architecture• Tier 1: Client platform, hosting a web

browser• Tier 2: server platform, hosting all server

software components

2-Tier Characteristics

• Typical application– 10-100 users.– Small company or organization, e.g., law office, medical

practice, local non-profit.

• Advantage:– Inexpensive (single platform)

• Disadvantages– Interdependency (coupling) of components.– No redundancy.– Limited scalability.

3-Tier C-S Architecture• Tier 3 takes over part of the server function from tier

2, typically data management.

3-TIER CHARACTERISTICS

• Advantage:– Improved performance, from specialized hardware. – Decreased coupling of software components.– Improved scalability.

• Disadvantages– No redundancy.

• Typical application– 100-1000 users.– Small business or regional organization, e.g., specialty

retailer, small college

MULTITIER C-S ARCHITECTURE

• A multitier (N-tier) architecture is an expansion of the 3-tier architecture, in one of several different possible ways– Replication of the function of a tier. – Specialization of function within a tier.– Portal services, focusing on handling incoming web traffic.

REPLICATION

• Application and data servers are replicated.• Servers share the total workload.

SPECIALIZATION

• Servers are specialized• Each server handles a designated part of the

workload, by function.

PORTAL SERVICES

• Portal servers handle incoming traffic, reducing application server load.– e.g., firewall, load balancer, transaction processing

manager.

MULTI-TIER CHARACTERISTICS

• Advantage:– Decoupling of software components. – Flexibility to add/remove platforms in response to load.– Scalability.– Redundancy.

• Disadvantages– Higher costs (maintenance, design, electrical load,

cooling)

• Typical Application– 1000+ users.– Large business or organization.

CHARACTERISTICS SUMMARY

2-Tier

3-Tier

N-Tier

10

100

1000users

•Large e-commerce, business, or organization

•Small e-commerce, regional business or organization

•Local business or organizationCapacity

ScalabilityRedundancyCost

SAMPLE ARCHITECTURE

SAMPLE ARCHITECTURE

TYPICAL DETAILS OF WINDOWS IIS SERVER AND APACHE SERVER