Case Study 2011 - Dynamic Website - Three Tier Architecture

Client Side v Server Side Client side e.g. JavaScript Tasks localized to users interface. E.g. image rollover or page transition effect. Server side script used to access server resources e.g. database or external files. Perform more sophisticated tasks e.g. store users shopping cart in a database. Available again the next time the user logs on, irrespective as to which computer. Majority of server sided scripts are related to either getting information from the user and saving it somewhere or retrieving information from somewhere and presenting it. The somewhere is a database.

Three Tier Architecture Software Dynamic Website Three Tier Architecture Software Client Side Software HTML Browser HTML + JavaScript PHP Server Side Software Unix Operating System or Linux OS Apache Web server PHP processor/interpreter Module Database Software MySQL Apache is generally recognized as the world's most popular Web server (HTTP server). Originally designed for Unix servers, the Apache Web server has been ported to Windows and other network operating systems (NOS). The Apache Web server provides a full range of Web server features, including CGI, SSL, and virtual domains. Apache also supports plug-in modules for extensibility. Apache is reliable, free, and relatively easy to configure. Databases Many dynamic websites have a database 'back end' that stores data that can be retrieved by the scripting language and written into the content of a page.  For example, a site that sells products probably has all of the details about products (product name, description, price, etc.) stored in a database.  When the ID for that product is passed in, as in the above example, the scripting language will look up all the details for that particular product in the database and place that information in the product details template before serving the file. PHP For this purpose, PHP code is embedded into the HTML source document and interpreted and executed by a web server with a PHP processor module, which generates the web page document. The PHP code is executed on the server, independently of the browser. It is open source, easy to use, powerful and allows for quick development. It also interfaces very well with MySQL which is also opensource. MySQL High performance, multiuser relational database management system. Widely used, think Google, Yahoo, Cisco, NASA & HP. Fast, reliable

What Happens MySQL Apache PHP SQL Query Web Browser Client Server Result Set Windows/Mac Unix/Linux 1. PC user opens web browser and enters URL for website. After establishing the domain the browser sends a HTTP request to the corresponding server IP address. 2. Apache web server handling HTTP requests for the domain notes the URL ends in a .php suffix. Server is programmed to automatically redirect all such requests to the php layer. The php interpreter receives the named file. 3. Interpreter parses the file and executes the code which is in php tags. If this code includes database queries the php interpreter opens the client connection to the MYSQL database and executes the code. 4. The results returned by the interpreter are transmitted to the web browser by the Apache Web-Server. Cut short, with respect to the given syntax or language (XML in this case), parsing is the action by which one can properly recognize/decipher/acquire the significant data (and commands) from a sequence, and then act on the particular data.

Three Tier Architecture Software Dynamic Website Three Tier Architecture Software Client Side Software HTML Browser HTML + JavaScript PHP Server Side Software Unix Operating System or Linux OS Apache Web server PHP processor/interpreter Module Extras Shopping Cart e.g. Zencart + Payment Merchant facility e.g. Nochex, Eway, Paypal. Database Software MySQL