1 Software Testing and Quality Assurance Lecture 32 – SWE 205 Course Objective: Basics of Programming Languages & Software Construction Techniques

2 Lecture Outline Web Applications and Web Servers Introduction to HTTP Introduction to HTML

3 Role of HTTP Web applications are different than traditional desktop applications. A production level web application will always involve at least two networked machines. The machines must agree upon a particular protocol to determine How to send and receive data. Hypertext Transfer Protocol (HTTP)

4 Role of HTTP A client launches a web browser An HTTP request is made to access a particular resource (e.g. *.aspx file or.html file) located on a server machine. HTTP is a text-based protocol Build on request/response.

5 Role of HTTP If we navigate ( The browser software access Domain Name System (DNS), which converts the registered URL into IP address. Browser opens a socket connection (typically port 80), and sends the HTTP request to the default page at the KFUPM website.

6 Role of HTTP Hosting web server receives the incoming HTTP request, May use client supplied input to format a proper HTTP response. Web programmers can use any technology (e.g. ASP.NET,JSP) to dynamically generate content. Finally, client renders the HTML received from the web server.

7 Role of HTTP Client – side Browser Display HTML obtained from HTTP response Web Server Web Application (any number of Server – side resources such as *.asp, html files) Incoming HTTP request Outgoing HTTP Response

8 Web Applications and Web Servers Web Applications A collection of files (*.html, *.asp, etc.) and related components (.NET) Stored within a particular directory on a given web server. Web Server Software product in charge of hosting your web applications; and typically Provides a number of related services security etc.

9 Internet Information Server (IIS) ASP.NET web applications interacts with IIS. IIS can host numerous web applications, each of which resides in a virtual directory. Each virtual directory is mapped to a physical directory on the local hard disk.

10 Internet Information Server (IIS) For example, we create a virtual directroy ‘CarsAreUs’ Naviagte using The virtual directory maps to a physical directory such as C:\TheCarsSite, which contains set of files that constitute the web application. Creating ASP.NET web applications using Visual Studio, automatically creates a new virtual directory for the project.

11 Role of HTML Hypertext Markup Language (HTML) is used to describe how Text, images, external links etc are rendered by the client-side browser. A HTML file consists of a set of tags that describe the look and feel of a web page. For example, *.html file open and close with and tags; typically followed by section, ……. HTML is not case sensitive

12 HTML - Example This is a Car Web Site

13 HTML - Example This is Cars web site The cars login page Please enter your user name and password.

14 HTML - Example User Name: Password:

15 Key Points Web Applications are different than traditional desktop applications. HTTP is build on request/response text based protocol. HTML is used to describe how text, images etc. are rendered by a web browser.