Web Transactions

Web-based Transactions Fulvio Corno 08/10/09 Web Transactions 1

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. 08/10/09 Web Transactions 2

Summary  StaticTransactions  Dynamic Transactions  Database-driven Transactions  Rich-Client Asynchronous Transactions 08/10/09 Web Transactions 3

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 08/10/09 Web Transactions 4

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 08/10/09 Web Transactions 5

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 08/10/09 Web Transactions 6

RFC 2616, RFC 2617 HTTP protocol http://www.w3.org/Protoc ols GET /~corno/index.html HTTP/1.0 Accept: text/html Accept: image/gif User-Agent: CornoSoft SuperBrowser 9.45 HTTP/1.0 200 OK Date: Monday, 01-Jan-2001 00:00:00 GMT Server: Apache 1.3.0 MIME-Version: 1.0 Last-Modified: 31-Dec-2000 Content-type: text/html Content-lemgth: 3021 <HTML> . . . 08/10/09 Web Transactions 7

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 08/10/09 Web Transactions 8

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 08/10/09 Web Transactions 9

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 08/10/09 Web Transactions 10

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 08/10/09 Web Transactions 11

Examples www.w3c.org 08/10/09 Web Transactions 12

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 08/10/09 Web Transactions 14

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 08/10/09 Web Transactions 15

URL (HTTP GET) http://www.cad.polito.it/pap/pap.pl?author=Corno Application Parameters CPU Disk Libraries HTML 08/10/09 Web Transactions 16

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 08/10/09 Web Transactions 17

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 08/10/09 Web Transactions 18

Examples  www.sun.com  www.lastampa.it  www.altavista.com 08/10/09 Web Transactions 19

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 08/10/09 Web Transactions 21

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 08/10/09 Web Transactions 22

URL (HTTP GET) http://www.cad.polito.it/pap/pap.pl?author=Corno Application Parameters CPU Disk Libraries HTML Database 08/10/09 Web Transactions 23

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 08/10/09 Web Transactions 24

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 08/10/09 Web Transactions 25

Examples  www.amazon.com 08/10/09 Web Transactions 26

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) 08/10/09 eBWA-www2eB 28

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 08/10/09 XML/JSON Web Transactions 29

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 08/10/09 Web Transactions 30

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 08/10/09 Web Transactions 31

Web Transactions

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