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CS Department Bakhter university Kabul Afghanistan CS Department Bakhter university Kabul Afghanistan

CS Department Bakhter university Kabul Afghanistan - PowerPoint Presentation

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CS Department Bakhter university Kabul Afghanistan - PPT Presentation

1 System modeling Requirement Modeling u secase diagram activity diagram Content modeling c lass diagram state machine diagram Navigation modeling Presentation modeling CS Department Bakhter university Kabul Afghanistan ID: 782682

university bakhter afghanistan kabul bakhter university kabul afghanistan department web server application architecture layer data system business client software

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Slide1

CS Department Bakhter university Kabul Afghanistan

1

Slide2

System modeling

Requirement Modeling

u

se-case diagram, activity diagram

Content modelingclass diagram, state machine diagramNavigation modelingPresentation modeling

CS Department Bakhter university Kabul Afghanistan

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Slide3

Software system architecture

Specifics of web application architecture

Layered web architecture

2-layered architecture

3-layered architectureN-layered architectureCS Department Bakhter university Kabul Afghanistan

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Slide4

The

architecture

of a computer system is the high-level (most general) design on which the system is

based

Architectural features include:ComponentsCollaborations (how components interact)Connectors (how components communicate) CS Department Bakhter university Kabul Afghanistan

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Slide5

CS Department Bakhter university Kabul Afghanistan

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Key

attributes

of an architecturearchitecture describes structurearchitecture forms the

transition from analysis to implementation

different

viewpoints

(

conceptual, runtime, process and implementation

)

m

akes a system

understandable

Slide6

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Factors

influence

the system architecture

Architecture

Quality considerations with

Performance

Scalability

Reusability

Other?

Functional Requirements

Clients

Users

Other Stakeholders

Slide7

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Factors

influence

the system architecture

Architecture

Experience with

Existing Architecture

Patterns

Project Management

Other?

Technical Aspects

Operating

System

Legacy Systems

Other?

Slide8

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A number of

architectures

for specific requirement in several application domain have been developedFor web application architecture, usually we consider

layering aspect: to implement the principle of

‘separation of concerns’

d

ata aspects:

to support processing of structured and non-structured data

Slide9

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For web applications

quality requirements

are more demanding as compared to desktop applicationsperformance, security, scalability, and availability etc

.Need specific

technical infrastructures

both for the development and

the operation

of

web

applications

Slide10

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we have to

consider

web infrastructure architecture (WPA)web application architecture

(WAA)Web application architecture (WAA) depends on the problem domain of the application, therefore we focus on web platform architecture

(WPA)

Slide11

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In

particular WPAs provide a wide range of functionalities

to solve common problems and they define the context in which web applications (WAA)

may evolve.

Slide12

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The following section gives an overview of common components of Web platform architectures and shows how these architectures

support

the development of Web applications

Slide13

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Client:

generally a browser (user agent) is controlled by a user to operate the w

eb applicationthe client’s functionality can be expanded by installing

plug-ins

Firewall:

a

piece of software

regulating

the communication between insecure

networks(e.g

.,

the

Internet) and secure networks (e.g., corporate

LANs)

t

his

communication

is

filtered

by access rules

Slide14

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Proxy:

A

proxy is typically used to temporarily store web pages in a cache

Web server: A Web server is a piece of software that supports various Web protocols

like HTTP

, and HTTPS, etc., to process client

requests

Slide15

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Database server:

this

server normally supplies data in structured form, e.g., in tables

Legacy application: A legacy application is an older system that should be integrated as an internal or external component

Slide16

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Media server:

This

component is primarily used for content streaming of non-structured bulk data (e.g., audio or video)

Application server:An application server holds the functionality required by

several applications

Slide17

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C

lient

Browser

Plug -In

Firewall

proxy

Web-server

HTML, XML

Database server

Application server

Legacy application

Media server

Slide18

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Presentation tier:

Every web application needs

to

communicate

with external entities, human users or other computers

allows

these entities to

interact

with the system

implemented

as a

GUI interface

How

the data should appear to the

user

Slide19

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Application tier:

Web applications

do more than information delivery, they perform data

processing

(Business Logic & calculation) behind the results being delivered

This

tier is often referred to as

Services

Business logic

Slide20

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Data layer:

Web applications

needs

data

to work with

Data can reside in

databases

or other

information repositories

Deals

with and implements different data sources of Information Systems

Slide21

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Presents architecture in two layers:

Layer

1: Client platform, hosting a web browserLayer 2: server platform, hosting all server software

componentsAlso called client/server architectureClient directly send request to the server

Server respond to the client request

Static or dynamic requests

Slide22

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Client

Web/App Server

Database

Services

Dynamic HTML

Static HTML

Client

Server

Slide23

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Advantage:

Inexpensive

(single platform)Disadvantages:

Interdependency (coupling<Dependency> B/Z of single layer) of components

No

redundancy (no duplication)

Limited

scalability

Typical

application:

10-100 users

Small company or

organization

Slide24

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Usually implemented in 3 layers

Layer

1: DataLayer 2:

ApplicationLayer 3:

presentation

Additionally, security mechanism

(Firewall)

and caching mechanism

(Proxies)

can be added

Slide25

25

Application Server

(Business Logic, Connectors,

Personalization, Data Access)

DBMS

Backend

(Legacy Application,

Enterprise Info System

)

Business Layer

Data Layer

Client

Presentation Layer

Firewall

Proxy

Web Server

CS Department Bakhter university Kabul Afghanistan

Slide26

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Advantages:

Improved

performance

Decreased coupling of software components

(because there are two server)

Improved

scalability

Disadvantages:

No

redundancy

Typical

Application:

100-1000 users

Small business or regional organization, e.g., specialty retailer, small college

Slide27

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A multitier (

N-layer)

architecture is an expansion of the 3-layer architecture, in one of several different possible ways

Replication of the function of a layer

Specialization

of function within a

layer

Slide28

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Replication:

Application

and data servers are replicatedServers share the total workload

Slide29

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Specialization:

Servers are specialized

Each server handles a designated part of the workload, by function

Slide30

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Slide31

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Advantages:

Decoupling

of software componentsFlexibility to add/remove platforms in response to load

ScalabilityRedundancy(repeat same server)

Disadvantages:

Higher costs (maintenance, design, electrical load, cooling

)

Typical

Application:

1000+ users

Large business or organization

Slide32

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2-Tier

3-Tier

N-Tier

10

100

1000

users

large e-commerce, business, or organization

small e-commerce, regional business or organization

local business or organization

capacity

scalability

redundancy

cost

Slide33

33

Application Server

(Business Logic, Connectors,

Personalization, Data Access)

DBMS

Business Layer

Data Layer

Client

Presentation Layer

Web Server

Media

Server

CS Department Bakhter university Kabul Afghanistan

Slide34

Software system architecture

Specifics of web application architectureLayered web architecture2-layered architecture

3-layered architecture

N-layered architecture

CS Department Bakhter university Kabul Afghanistan 34

Slide35

Chapter 4

,

Kappel

, G.,

Proll, B. Reich, S. & Retschitzegger, W. (2006). Web Engineering, Hoboken, NJ: Wiley & SonWeb-based application development,

Ralph F Grove , J and B publishers,

(www.jbpub.com)

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