1. Introduction to Web Applications

Question 1

What is a web application?

Answer 1

A system using web page functionalities on front end and implements server programs in the back-end e.g Amazon, StudyDirect, Facebook, Twitter, Dropbox

Question 2

In web applications, where is this back-end information stored?

Answer 2

Data centers

Question 3

Why use Java Enterprise Edition?

Answer 3

Provides standardization of the services needed to build web applications.

Question 4

What is a Uniform Resource Identifier (URI)?

Answer 4

A compact sequence of characters that identifies an abstract or physical resource

Question 5

What is a URL (Uniform Resource Locator)?

Answer 5

A URI that provides details of the location.

Question 6

What is HTTP?

Answer 6

A stateless, request-response protocol. Application layer protocol running on top of TCP.

Question 7

What is a web page?

Answer 7

A web page consists of objects such as an HTML file, images, JavaScript files, Java applet, Cascading Style Sheets (CSS) etc

Question 8

Describe the client/server model.

Answer 8

Client: requests, receives and displays web objects
Server: sends objects in response to requests (uses HTTP protocol)

Question 9

What is a persistent connection?

Answer 9

Ability to send and receive multiple HTTP requests/responses over a single TCP connection.

Question 10

What is the GET method?

Answer 10

Returns data corresponding to the URI

Question 11

What is the POST method?

Answer 11

Sends data to a server.

Question 12

What is the PUT method?

Answer 12

Transfers data to be stored under the URI.

Question 13

What is the DELETE method?

Answer 13

DELETE removes the specified URI

Question 14

What is the HEAD method?

Answer 14

HEAD returns the headers that would come with GET, but no body

Question 15

Name the status codes 1XX to 5XX.

Answer 15

1XX - informational 
2XX - successful
3XX - additional action to complete the request
4XX - bad requests
5XX - server errors

Question 16

What is a stateless protocol?

Answer 16

A stateless protocol does not retain past session information.

Question 17

Why is HTTP a stateless protocol?

Answer 17

Because each command is executed independently, without any knowledge of the commands that came before.

Question 18

What is a cookie?

Answer 18

A piece of data written by the server that accompanies each client request to the server.

Question 19

What are the four components of a cookie?

Answer 19

1. HTTP response
2. HTTP request
3. A file on the user’s machine associating a cookie with the URI from which it was set
4. An application on the server which can read and write the cookie

Question 20

What is content distribution in networks?

Answer 20

A content delivery network or content distribution network is a geographically distributed network of proxy servers and their data centers.

Question 21

What is DNS redirection?

Answer 21

DNS redirection was the controversial practice of serving a Web page to a user that is different from either the one requested or one that might reasonably be expected.

Question 22

Name 3 URI schemes

Answer 22

1 HTTP
2 FTP
3 MAILTO

Question 23

What is a non-persistent connection?

Answer 23

Allows only one object to be sent over TCP connection

Question 24

Name 2 safe HTTP requests

Answer 24

GET

HEAD

Question 25

What are cookies used for in regards to HTTP?

Answer 25

To extend HTTP functionality and build state.

Question 26

What is a process?

Answer 26

Programs that are running within the host 

Question 27

Whats the difference between User Space and Kernel Space?

Answer 27

User Space is restricted and Kernel Space can do what it wants.

Question 28

Where does TCP code operate?

Answer 28

In the Kernel Space

Question 29

What is Apache HTTPD?

Answer 29

Open source Web server that is designed to be

Question 30

Whats the Apache Portable Runtime (APR)?

Answer 30

A supporting library for Apache consisting of a set of APIs that map to the underlying operating system.

Question 31

What's the Multi-Processing Module | (MPM)?

Answer 31

The interface between the Apache server and the underlying operating system.

Question 32

What is a Servlet?

Answer 32

Java interface that standardises request/response protocol implementations.

Question 33

Name 3 Servlets

Answer 33

- HTTP Servlets - Faces Servlets - Generic Servlets

Question 34

What are the 3 Tier Architectures?

Answer 34

1- Presentation 2- Business Logic Tier 3- Data Tier

Question 35

What is Middleware?

Answer 35

A piece of software that sits on top of other software e.g. J2EE

Question 36

What is the MVC Design Pattern?

Answer 36

A software pattern that is used when developing applications (and web applications)