Architecture of the web Client Server retrieved or generated web page

Activities on the Client Client Generate a request Manage loading of web content Translates Web Pages into DOM Render HTML, CSS, Images Renders SVG Graphics interpret JavaScript, VBScript Manipulate the DOM using JavaScript, VBScript Stores Cookies, Bookmarks, History, Form Data and local datastores using a database (SQLite) AJAX requests using JavaScript, VBScript Maintains “sandbox” security (SOP, CORS) Interprets XML+XSLT A container for video and audio codecs A container for Java Applets

Activities On The Server Server Listens for Requests Loads modules in mods-enabled Translates directory refs in sites-enabled (root directory for system and per-user web accounts) Moves uploaded files into /tmp Passes QUERY_STRING, par Sends the output of the following Requests files from the OS Returns error page if the file is not found Requests execution of CGI scripts by the OS Interprets PHP Logs web page access and errors Requests JSP (Java) execution from a secondary server

Activities On The Server The Server DOES NOT talk directly to an SQL Database Engine!!! Communication with a database is done either through the PHP-MYQL library or through a library in some other server based language such as Java, Python, Ruby, PERL or some variation of C. All of the above can also talk to the OS to read and write files. The database does not have to be resident on the same machine CSS, Script, Images or other included files in a web page are loaded by the Client, NOT the server. Apache or IIS Server mod-php5 mod-ruby mod-cgi jsp redirect Operating System: port 80

n-Tier Client/Server Apache or IIS Server mod-php5 mod-ruby mod-cgi jsp redirect Operating System: port 80 Database Server Request Response Local Database JSP Server

Interaction with the File System Apache or IIS Server mod-php5 Request for file File or Error code Request for Error Page request for include or data file handle File handle Request Response PHP File PHP Output

Interaction with the Database Apache or IIS Server mod-php5 library function call Result Set, record count or errror code Request with form data Response Client Library function call (Java, VB) using sockets for communication Result Set, record count or errror code