Web Programming Resit Exam 2008

Question One

Describe in as much detail as possible, the communication process that takes place between a web browser and a web server to retrieve a simple web page from the server and display it to the user. Your answer should make reference to the different parts of the HTTP protocol.

Question Two

A cookie is a piece of text that a web server can request to be stored on a client machine. Describe:

• The different pieces of information that make up a cookie request
• The mechanism by which a cookie is set on a client machine
• How and when the content of a cookie is sent back to a web server.

Question Three

A PHP script contains the following section of code: $firstName = $_POST[“firstname”]; echo “Hello $firstName”; where “firstname” refers to the contents of a text entry field on the form that caused the PHP script to be executed when the submit button was pressed.

• Describe, ideally using an example, why such code can leave the web site vulnerable to malicious attacks.
• How would you fix this code to ensure that the site is not vulnerable to attack and how does your fix solve the problem?

Question Four

When programmers are developing web applications, they often combine both mark-up and business logic in the same script files.

• What are the problems that can arise when applications are structured like this?
• Describe different programming approaches that can be used to reduce these problems in both PHP and ASP.NET. What are the advantages and disadvantages of using these approaches?