1.3.4 Web Technologies

Question 1

What are Search engines ?

Answer 1

• are software systems that locate resources on the internet based on clients search criteria
• they rely on an index of webpages to find the page your looking for
• to build an index web crawlers are used

Question 2

Stages of search engine indexing

Answer 2

• crawling
• indexing
• ranking

Question 3

Search engine indexing process

Answer 3

• search engines user software programs called crawlers/spiders to discover webpages [1]
• web crawlers traverse the internet webpage by webpage following linked sites [1]
• web crawlers collect/record information such as keywords and meta tags from the linked sites/webpages and adds this info to the index [1]
• each word in the document is included in the pages index as an entry along with the words position on the page [1]
• the highest quality and most relevant to the user query webpages are returned

Question 4

Meta tags and descriptions

Answer 4

Are a list of keywords or concise phrases specified by the website owner (<meta></meta> tags) that are built into each webpage

Question 5

PageRank algorithm

Answer 5

• ranks each webpage, higher ranked webpages appear first on the search engine

Question 6

Factors determining pageRank of a page

Answer 6

• number of incoming/inbound links it has from other webpages [1]
• the pageRank of the webpages that link to it [1]
• number of outbound links to other webpages [1]

Question 7

Web representation

Answer 7

• the data structure used to represent the web is a directed graph to show which pages link to what websites
• every webpage is a node and any hyperlinks on the page are edges with the edge weightings dependant on the pageRank algorithm

Question 8

Dampening factor

Answer 8

• is a value between 1 and 0 [1]
• is the probability that user will not follow a link [1]

Question 9

Applying the pageRank algorithm

Answer 9

• the pageRank of a page is constantly being recalculated and updated
• this process continues until all the rankings become stable/ converge to a value
• can take hundreds or millions of iterations before the final PR value converges

Question 10

Client and server side processing

Answer 10

In the client-server network model, data may be processed on either side, either by the client computer, the server, or both

Question 11

What is a Server

Answer 11

A device which provides a central point of control/access [1]

Question 12

Client side processing

Answer 12

• is when data is processed on the client computer rather than on the server
• client side processing takes place in the web browser of the device.
• JS is commonly is commonly used for processing data on the client side to validate data before it is sent to the server (eg. Email address)
  1. Provides initial data validation
  2. Provides webpage interactivity
  3. Manipulates UI elements
  4. Applies style (CSS)
  5. Reduces load on server + amount of web traffic

Question 13

Client side processing advantages

Answer 13

• enables users to have interactive and dynamic experiences without constantly requesting data from the server [1]
• webpages can respond immediately to user actions [1]
• websites will execute more quickly for the user [1]
• reduces load on the server [1] (benefit for company)

Question 14

Client side processing disadvantages

Answer 14

• browser won’t run the code if JavaScript ins disabled [1]
• source code is visible allowing it to be copied/ modified [1]
• JavaScript can be amended and circumvented [1]

Question 15

Client side use case

Answer 15

Used for tasks that require :
- immediate user feedback
- realtime interactions
- dynamic user interfaces
- data manipulation within the browser

Question 16

Server Side processing

Answer 16

• the client sends data to a server for it to be processed
• this means no info is processed on the client computer
• SQL or PHP are used for server side processing
  1. Provides further validation
  2. Used to query a database
  3. Updates server database
  4. Performs complex calculations

Question 17

Server side processing advantages

Answer 17

• JS may be circumvented/amended maliciously so server side validation is important to ensure integrity of server data [1]
• does not require plug ins
• can perform large calculations and process data much faster than client computers
• is not browser dependant
• more secure

Question 18

Server side processing disadvantages

Answer 18

• requires continuous server interaction leading to increased load on the server
• slower response times due to latency during communication with the server
• may limit realtime interactivity and responsiveness in web applications

Question 19

API (application programming interface)

Answer 19

• a set of protocols/rules that governs how two applications interact with each other

Question 20

HTML

Answer 20

• HTML defines the structure and content of a web page [1]
• using tags [1]

Question 21

CSS

Answer 21

• defines the style/appearance of a webpage [1]
• using selectors such as classes/IDs etc [1]

Question 22

Why is server side processing needed?

Answer 22

• bc client side processing can be modified [1]
• and can sometimes be disabled on the browser [1]
• to prevent malicious code such as SQL injection [1]

Question 23

Inline CSS

Answer 23

• is entered directly within the HTML body
• is useful for making one off style adjustments that are unlikely to affect any other part of the website

Question 24

Internal CSS

Answer 24

• is placed inside of style tags and is entered directly within the html document
• changes have to be made to every page and it is a lot of work to keep the looks of the site consistent [1]

Question 25

External CSS + benefits

Answer 25

- is placed inside an external style sheet which is linked to the HTML file - content and formatting can be kept separate [1] - changes to the external style sheet affect the whole site [1] - which saves time and prevents the need for duplicate css styles [1] - it also ensures consistency across the website [1]

Question 26

Class

Answer 26

can be assigned to multiple elements [1]

Question 27

ID

Answer 27

is unique/ only a single element can have a given ID [1]

Question 28

JavaScript

Answer 28

- a programming language that runs in a web browser [1] - that can be embedded into HTML with a script tag [1] - to add interactivity to a page [1]

Question 29

Why is JS interpreted rather than compiled ?

Answer 29

- JS is likely to be run on a variety of machines with different processors /architectures [1] - compiled code is machine dependant [1] - whereas interpreters run on high level code which is machine independent [1]

Question 30

Server side processing use case

Answer 30

Better for tasks that involve : - accessing databases - handling sensitive data - complex business logic - server specific operations