Web Programming Resit Exam 2007

Question One

Under the HTTP protocol, a client sends a request to the server and the server sends back a response to the client.

• Describe, in detail, the format of the HTTP response block
• Give three examples of possible response headers that can be included in the response block, along with descriptions of what they are used for.

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

• Describe what is meant by the three tier application architecture and describe what typically runs on each tier in a 3-tier web-based application
• A common way of building and executing a SQL statement that requires information to be supplied at run-time is to use string concatenation. For example, in PHP, the code might be: $pubId = $_POST[“PubId”]; $sqlString = "SELECT title, name FROM books, publishers WHERE books.publisher_id =".$pubId; $sqlString would then be used in the appropriate function to retrieve data from a database. This is a valid approach, but there are problems with using it in web-based applications. What are the problems and what are possible solutions? You are not expected to write any program code here. A general description of possible solutions is acceptable.

Question Four

ASP.NET introduced the concept of server controls and an event driven programming model.

• What are the problems with earlier programming models for the web that the introduction of server controls is intended to solve?
• Describe possible advantages and disadvantages obtained by using server controls.