2. Evolution
The world wide web, if we analyze the involved
technologies, evolved through 3 main phases:
1.Static and informative Web
2.Dynamic and interactive Web
3.Integrated and application-oriented Web
E-commerce and e-business are a particular
application domain of Phase 3.
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4. Static web transaction
Internet Web HTML
server files
Client
http request path
URL
HTML
display http response
page send
browser TCP/IP server file system
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5. Adopted standards
URL (uniform resource locator) for finding
web pages
HTML (hyper text markup language) for
writing web pages
GIF (graphics interchange format) for
images
HTTP (hyper text transfer protocol) for
client-server interaction
TCP/IP (transmission control protocol over
internet protocol) for data transfer
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6. RFC 2396
URL http://www.w3.org/Addressin
g/
http://elite.polito.it/~corno/index.html
DNS URI Rewriting
130.192.5.26 /home/corno/public_html/index.html
TCP File system
Contact server HTML file contents
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8. Static web transaction
t1 t8 t’1
Browser
t0 t9 t’0
Web t3 t6
server t2 t7
Disk
access t4 t5
server response time user think time
network transfer time
total response time
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9. Response time
t1
Browser
t0
Server
t2
Disk
Browser elaboration time (t0-t1): power uf
the users’ computer
Transmission time for http request (t1-t2):
latency of Internet connection
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10. Response time
t1
Browser
t0 t3 t6
Server
t2 t7
Disk
t4 t5
Server elaboration time (t2-t3, t6-t7): power
of the server and number of simultaneous
accesses
Disk access time (t3-t6): I/O architecture
del server and number of simultaneous
accesses
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11. Response time
t1 t8
Browser
t0 t3 t6 t9
Server
t2 t7
Disk
t4 t5
Transmission time for the HTML page (t7-
t8): size of the page and of the images,
latency, available bandwidth
Visualization time of the page (t8-t9): power
of the users’ computer and complexity of
the page
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14. Dynamic web transaction
Internet Web Application
server
Client
http request com- para-
URL meters
& POST data mand
display logic
http response
page send
HTML
browser TCP/IP server application
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15. Adopted standards
HTTP-POST for sending user-specified data
CGI (common gateway interface), ISAPI
(internet information server application
programming interface), server-side script,
java servlet for integrating application logic
into web servers
ASP (active server pages), PHP, PERL as
new languages for application development
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16. URL (HTTP GET)
http://www.cad.polito.it/pap/pap.pl?author=Corno
Application Parameters
CPU
Disk
Libraries
HTML
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17. Dynamic web transaction
t1 t8 t’1
Browser
t0 t9 t’0
Web t3 t6
server t2 t7
Application
server t4 t5
application time
total server time
total response time
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18. Response time
t1 t8
Browser
t0 t3 t6 t9
Web
t2 t7
Application
t4 t5
Communication time between web server
and application server (t3-t4, t5-t6): speed of
the local network
Execution time of the application (t3-t6):
server power, number of accessese,
complexity of the application
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21. Database-driven transactions
Internet Web Application Database
server
Client
http com- para- query
URL meters
& POST mand
display http
page send data
HTML
browser TCP/IP server application database
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22. Adopted standards
Cookies for storing the state of a session
Java, JavaScript, ActiveX, Flash to program
the user interface on the browser
SQL (structured query language), ODBC
(open database connectivity) to access data
bases
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23. URL (HTTP GET)
http://www.cad.polito.it/pap/pap.pl?author=Corno
Application Parameters
CPU
Disk
Libraries
HTML
Database
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24. Database-driven transaction
t1 t8 t’1
Browser
t0 t9 t’0
Web t3 t6
server t2 t7
Application
server t4 t5
Database
server
application time database time
total server time
total response time
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25. Response time
t1 t8
t’1
Browser t3 t6
t0 t9 t’0
Web
t2 t7
Application
t4 t5
Database
Application: server power, number of
accesses, complexity of application
Database: number of queries, complexity
of queries, size of the database
Communications: local network
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26. Examples
www.amazon.com
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28. Web 2.0
Web applications support social interaction
models
Peer exchange and user-contributed content
instead of rigid publisher/reader pattern
Online communities
Rich,dynamic, interactive user interfaces
Integration of contents across web sites
(mashups)
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29. Rich-Client Asynchronous
Transactions
Web Application
Internet Database
server
Client-side Client
Application http
http com- para- query
URL meters
& POST mand
DOM
display http
page send data
events HTML
runtime browser TCP/IP server application
database
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30. Adopted standards
Dynamic HTML: DOM, Javascript, CSS
JavaScript, Flash to handle a runtime
environment on the browser
DOM (XHTML Document Object Model) to allow
on-the fly modification of the web page
CSS 2.1 to modify attribute and handle objects
AJAX: Asynchronous Javascript and XML
XMLHttpRequest for asynchronous
communication to the server
Data transfer formats: JSON, XML, RDF, RSS,
Atom, FOAF, ...
Mash-up technology
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31. Rich-client transaction
t1 t8 t’1
Browser
t0 t9 t’0
Runtime
Web t3 t6
server t2 t7
Application
server t4 t5
Database
server
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