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1 Database Driven Web Application Clients Application Servers including web servers Database Server Traditional client-server (2-tier architecture): client: user interface database server: stores data. business logic: resides on both Three or multi-tier architecture: Presentation layer: client, browser Business layer: web server, handles web requests and actual functionality Database layer: database server, stores data Slide 2 2 Three-Tier Architecture Slide 3 3 Benefits of Web Applications Standard & thin client: web browser Easy maintenance both server and client Easy upgrade both server and client Fast development Mature technologies and platforms Security https, password protection, firewall transparent Limitations Compatibility of different web browsers Limited functionalities Slide 4 4 Web Technolgies Client-side HTMLCSS (Cascading Style Sheets) XML (Extensible Markup Language) JavaScriptVBScript FlashJava applet Server-side oPHP PERL / CGI oASP (Active Server Pages) & ASP.NET oJSP (Java Server Pages)Java Servlets oC++/C Database ODBC, JDBC MS SQL, Oracle, DB2, my sql Slide 5 5 Web Application Option1: LAMP LAMP LAMP Linux OS Linux OS Apache Web Server Apache Web Server MySQL Database MySQL Database PHP scripting (Hypertext Preprocessor) PHP scripting (Hypertext Preprocessor) Advantage Advantage Free Free Open source Open source Proved to be one of the most reliable ways for web development Proved to be one of the most reliable ways for web development Disadvantage Disadvantage Tech support Tech support Higher HR cost Higher HR cost Slide 6 6 Web Application Option2: Microsoft Microsoft technologies Microsoft technologies Windows 2003 / vista OS Windows 2003 / vista OS IIS (Internet Information Server) Web Server IIS (Internet Information Server) Web Server SQL Database SQL Database ASP.NET scripting (Active Server Page) ASP.NET scripting (Active Server Page) Advantage Advantage Tech support Tech support Fast development Fast development Lower HR cost Lower HR cost Continuous improvement on reliability and security Continuous improvement on reliability and security Disadvantage Disadvantage Commercial software Commercial software Not open source Not open source Security, reliability and stability Security, reliability and stability Slide 7 7 Web Application Option3: Java Java technologies Java technologies Unix / Linux OS Unix / Linux OS Apache + Tomcat / Websphere / Weblogic Web Server Apache + Tomcat / Websphere / Weblogic Web Server Oracle / Sybase / DB2 / Mysql Database Oracle / Sybase / DB2 / Mysql Database JSP scripting (Java Server Page) and Servelet JSP scripting (Java Server Page) and Servelet Advantage Advantage Proved to be one of the most reliable and secure ways for web development Proved to be one of the most reliable and secure ways for web development Many third party software Many third party software Disadvantage Disadvantage High development cost High development cost High HR cost High HR cost Future unclear Future unclear Slide 8 HTML www.w3schools.com 8 Slide 9 9 Forms HTML and forms are used to build front-end application CGI/ASP/PHP/JSP are used to build the back-end application A Form A Text Input Box A Radio Button A Check Box A Hidden Varible A Submit Button Slide 10 10 Apache, MySQL and PHP Integration Slide 11 11 PHP Error Turn on php error reporting: For development server, very useful; for production server, dont do that. php.ini display_errors = On error_reporting = E_ALL & ~E_NOTICE httpd.conf php_flag display_errors on php_value error_reporting 2039 Slide 12 12 PHP Overview Open Source server-side scripting language designed specifically for the web. Conceived in 1994, now used on +10 million web sites. Outputs not only HTML but can output XML, images (JPG & PNG), PDF files and even Flash movies all generated on the fly. Can write these files to the file system. Supports a wide-range of databases (20 + ODBC). PHP also has support for talking to other services using protocols such as LDAP, IMAP, SNMP, NNTP, POP3, HTTP. Easy learning curveEasy learning curve Syntax Syntax Perl- and C-like syntax. Relatively easy to learn. Large function library Embedded directly into HTML The separation of HTML design and PHP tagsThe separation of HTML design and PHP tags Interpreted, no need to compile Slide 13 On server, save it as e3.php in $HOME/.WWW-orion/, On client browser, visit http://orion.csl.mtu.edu/~yourid/e3.php Slide 17 17 Control Structures Conditional structures (e.g. if/else) Repetition structures (e.g. while loops). Example if/else if/else statement: if ($foo == 0) { echo The variable foo is equal to 0; } else if (($foo > 0) && ($foo