The Web: an architectural view. Browser Render HTML Get URL Send HTML Get HTML file HTTPD File System The primitive Web model.

The Web:The Web:aan architectural viewn architectural view

•Browser

•Render HTML

•Get URL

•Send HTML

•Get HTML file

•HTTPD

FileSystem

The primitive Web modelThe primitive Web model

http

d

The primitive Web model

Inte

rnet

HTTP Get

Client

Browser

Server

File System

•Browser

•Render HTML

•Get URL with Params

•Send HTML

•Execute CGI(params)

•Build HTML on the fly

•HTTPD •CGI Process

A simple interactive Web modelA simple interactive Web model

http

d

A simple interactive Web model

Inte

rnet

HTTP Get

Cgi-bin

proc

ess

Client

Browser

Server

File System

•Browser

•Render HTML

•Get URL with Params

•Send HTML

•Execute CGI(params)

•Build HTML on the fly

•HTTPD •CGI Process •DB

•Run Sql query

•Send query results

An evolved interactive Web modelAn evolved interactive Web model

http

d

An evolved interactive Web model

Inte

rnet

HTTP Get

Cgi-bin Query SQL

proc

ess

DB

Data

Client

Browser

Server

File System

http

d

The Bottlenecks

Inte

rnet

HTTP Get

Cgi-bin Query SQL

proc

ess

DB

Data

Client

Browser SLOW!

SLOW!

Server

File System

http

d

The Bottleneck – part I

Inte

rnet

HTTP Get

Cgi-bin Query SQL

proc

ess

DB

Data

Client

Browser SLOW!

Server

File System

http

d

The solution:

Inte

rnet

HTTP Get

Cgi-bin Query SQL

proc

ess

DB

Data

Client

Smartbrowser

How? How? Including code in HTMLIncluding code in HTML

Server

File System

reduce net traffic by having a smarter client!

Programming languagesProgramming languages

• JavaJava

Enabling technologies

Client

Smartbrowser

Scripting languagesScripting languages• JavascriptJavascript• VbscriptVbscript• PerlscriptPerlscript• PythonPython• … …

Interpreted:

Source code travels

Compiled:

Executable travels

(must be

HW-OS-Browser

independent!)

http

d

The Bottleneck – part II

Inte

rnet

HTTP Get

Cgi-bin Query SQL

proc

ess

DB

Data

Client

BrowserSLOW!

Server

File System

http

d

The solution:

Inte

rnet

HTTP Get

Query SQL

Function

DB

Data

Client

Browser

Server

File System

integrate the service into the httpd process

Enabling technologies

• MultithreadingMultithreading• DLLDLL• ServletsServlets

Using…Using…

•Scripting languagesScripting languages•Programming languagesProgramming languages

Function

http

dServer

How? How? Including code in HTMLIncluding code in HTML

File System

(depending on server implementation)

mixed client- and server-side scripting

<HTML><HTML>……<SCRIPT LANGUAGE=VBScript RUNAT=SERVER><SCRIPT LANGUAGE=VBScript RUNAT=SERVER>……VBScript Commands…VBScript Commands…</SCRIPT></SCRIPT>……<%VBScript Commands%><%VBScript Commands%>……<SCRIPT LANGUAGE=JavaScript><SCRIPT LANGUAGE=JavaScript>……JavaScript Commands…JavaScript Commands…</SCRIPT></SCRIPT>……</HTML></HTML>

Code executed Code executed by the Server by the Server BEFORE the BEFORE the page is page is transferred transferred over the Netover the Net

Code transferred to the clientCode transferred to the clientand interpreted by the Browserand interpreted by the Browser

ASP SyntaxASP Syntax

The state problem

Inte

rnet

Client

1

Server

+CGI

http

d

Data User 1

Data User 2

Data User 3

Client

3

Client

2

??

A typical solution

Inte

rnet

Client

1

Server

+CGI

http

d

Data User 1

Data User 2

Data User 3

Client

3

Client

2

CookieCookie

CookieCookie

CookieCookie

Supported

by Java & JavaScript

http

d

A more radical solution

Inte

rnet

HTTP GetCgi-bin

proc

ess

Client

Browser

Server

Java

ap

plet proc

ess

Startup

Sta

rtup

Socket connection

Supported

by Java

http

d

An even more radical solution

Inte

rnet

HTTP GetCgi-bin

proc

ess

Client

Browser

Server

Java

ap

plet proc

ess

Startup

Sta

rtup

CORBAMiddle Tier

Supported

by Java

WAP - Cenni

Client Client (cellular phone)(cellular phone)MicroBrowserMicroBrowser

Gateway WAPGateway WAPRichiesta WDP + WTSL

(Wireless Datagram Protocol)Wireless Transport Security Layer

Server HTTPServer HTTPDescrizione delle pagine:

Wml (Wireless Markup Language, in XML)Hdml (HandhelD Markup Language, variante di HTML

9600 baud (*)

(*) con GPRS fino a 56 Kbit/sec, conUMTS fino a 2 Mbit/sec (Universal Mobile Telecommunication System)

More info: www.wapforum.org

XML Enabled HTTP Server

Client Client DocumentDocument

Server Server HTTPHTTPServer Server

XSLTXSLTProcessor Processor

HTTP request

StylesheetStylesheetServer Server

Get document

XML document Get SS

XSL stylesheet

XML + XSL

HTML documentHTML

document

The Web: an architectural view. Browser Render HTML Get URL Send HTML Get HTML file HTTPD File System The primitive Web model.

Documents

httpd process slide

java slide

html server file system

server implementation

html file httpd file

html file system

cgi httpd data user

browser render html