Embed Size (px)
Citation preview
BTEC iCT Unit 1 – The Online World
My Theory Booklet
Introduction
1 Online Services 1 Mark __ /8
OK Must review
2 Online Services 2 Mark __ /8
OK Must review
3 Online Advertising Mark __ /11
OK Must review
4 Online Documents – Compression Mark __ /7
OK Must review
5 Online Software & Backups Mark __ /11
OK Must review
6 Collaborative Working Online Mark __ /8
OK Must review
7 Online Communication 1 Mark __ /7
OK Must review
8 Online Communication 2 Mark __ /7
OK Must review
9 Voice Over Internet Protocol Mark __ /13
OK Must review
10 Cloud Computing Mark __ /7
OK Must review
11 Ubiquitous Computing Mark __ /9
OK Must review
12 The Internet - Hardware Mark __ /8
OK Must review
13 The Internet – Network Diagrams Mark __ /5
OK Must review
14 Connection Methods Mark __ /12
OK Must review
15 The Internet - Protocols Mark __ /9
OK Must review
16 World Wide Web Mark __ /8
OK Must review
17 HTML Mark __ /6
OK Must review
18 URLs Mark __ /8
OK Must review
19 Search engines Mark __ /8
OK Must review
20 Email – Purposes & Uses Mark __ /16
OK Must review
21 Email - Protocols Mark __ /7
OK Must review
22 Data Exchange – Packet switching Mark __ /10
OK Must review
23 Data Exchange – Transmission Mark __ /11
OK Must review
24 Wired Transmission Methods Mark __ /14
OK Must review
25 Wireless Transmission Methods Mark __ /8
OK Must review
26 Client-side Processing Mark __ /12
OK Must review
27 Server-side Processing Mark __ /9
OK Must review
28 Database Theory Mark __ /9
OK Must review
29 Databases in practice Mark __ /15
OK Must review
30 Threats to Data Mark __ /6
OK Must review
31 Protection of Data Mark __ /15
OK Must review
32 Legislation Mark __ /11
OK Must review
33 Key Terms
Introduction – What Is The Online World?
Imagine a business with thousands of staff & customers in many countries
Unit 1 is about looking behind the scenes at many different parts of this online world…
Inside the Business (Staff) Outside the Business (Customers)
Video conferencing We’ll see how services work & their benefits, such as saving travel costs
Cloud Services We’ll see how storing files online lets staff work together on docs
Online Software We’ll see how working online saves hassle, such as installing software
Networks We’ll see why local and wide area networks are vital for organisations
Server Computers We’ll see how these special machines help power networks
Databases We’ll see how businesses store info on products, staff & customers
Security We’ll see what kind of threats make security such a big deal today
Getting Online We’ll look at how people get online, like using superfast ‘fibre’ broadband
Email We’ll see how it works using special rules or protocols & email servers
Web We’ll see how sites are built & how Web data travels across the Internet
Search engines We’ll see how Google etc. collect & store details of billions of web pages
Online Ads & Shopping We’ll look behind the scenes at how companies advertise & sell online
Social Media We’ll look at all the different ways people can communicate online
Wi-Fi We’ll see how data travels online, such as wired & wireless methods
Introduction – The Exam
The Unit 1 exam will be your biggest challenge on this course.
That’s because to do well you need to be able to:
Handle basic questions, such as giving the meaning of technical terms
But also expand your answers in more challenging questions, such as to discuss the advantages & disadvantages of technologies or evaluate the impact on people & business.
Basic Expand Answer Success!
+
=
So being able to expand your answers is the key to coping with different types of exam questions:
So you MUST develop the basic knowledge PLUS the expanded understanding.
That’s why you’ll need this booklet, then make your own notes & then do practice questions…
1
Online Services 1
Communication Real-time Information
Services that let people keep in touch That means moving data in the form of text, photos, video and audio
Services that provide up-to-date info They are constantly updated for people who need to get the latest information
Examples & Pros/Cons Examples & Pros/Cons
Examples: Email, instant messaging, social networks, blogging, micro-blogging, online conferencing
Pros: Easy for extended families and friends to keep in touch
Cons: Cyber-bullying & trolls
Examples: Train timetables, traffic reports, flight updates, weather & news services
Pros: Can save people time & trouble, such as when catching trains and planes
Cons: Downtime damages public image, such as for airports and train companies
Commerce Government
Commerce means business so these services involve money in some way. eg online shopping & banking
These involve ‘official’ public services eg local councils & national government collecting taxes
Examples & Pros/Cons Examples & Pros/Cons
Examples: Online shopping (eg Tesco), auctions (eg eBay), banking (eg NatWest), publishing (eg Kindle e-books on Amazon)
Pros: Convenience of home delivery for online shopping
Cons: Security eg credit card fraud
Examples: paying personal taxes online, paying car tax, paying student loans
Pros: Cuts cost of government because it reduces the need for people to process paperwork
Cons: Not everyone has online access
1
2
Online Services 2
Entertainment Download Business
Means services for leisure and fun
Means LEGAL download services, such as for games, music & movies
Means companies using websites to increase efficiency & save money
Examples Examples Examples
Examples: Catch-up TV services, radio players and music streaming sites
Pros: Services can be accessed on the move
Cons: Need broadband for media services
Examples: iTunes for music, or Steam for games
Pros: Legal so not piracy. No need for ‘old’ methods such as waiting for DVDs in post
Cons: Need fast Internet to download large files
Examples: Using Skype or using special ‘internal’ websites called Intranets
Pros: Cuts travel costs for staff & Intranet is secure way to share files & info
Cons: Staff need training
Education VLEs ‘SaaS’
Involves workplace training for businesses as well as learning for schools
Services that provide virtual classrooms for students and teachers
‘Software As A Service’ lets you use applications online so you only pay for ‘software on demand’
Examples Examples Examples
Examples: Online training for construction trades, or online learning eg Bitesize
Pros: Users can work online at their own pace
Cons: Must have Net access
Examples: Moodle is a Virtual Learning Environment or VLE
Pros: Upload work for feedback & share via forums
Cons: Set-up/training costs
Pros: Cuts costs since use ‘cloud’ service instead of in-house IT set-up
Get automatic updates
More reliable backups
Cons: Must be 100% reliable
2
3
Online Advertising
Pay Per Click
A host website (eg Facebook) displays an ad for another company (eg Adidas)
If a visitor clicks the ad, they are sent to the advertiser’s site (eg Adidas.com)
The host website earns money for each visitor who clicks on the advert
This process is called pay per click
Also called the affiliate model (since the companies act as partners, or affiliates)
Types of Online Advertising
Sponsored Links Banners Pop-Ups Email
Companies want to be listed first by search
engines – so they pay to get their links at the top
Banners go at the top of pages so you can’t miss them! Other ads can be all over a page.
These appear in new
windows so you can’t miss
them!
Marketing emails go direct to
customers’ inbox (not illegal SPAM)
Why Companies Choose to Advertise Online
Multimedia Targeting & Cookies Links
Online ads use video and audio plus
animation to get your attention
People’s online behaviour is tracked using small text files called cookies. Sites access
cookies to display ads based on your interests shown by searches & page views.
Online ads try hard to get you to click links direct to the advertiser’s site
How Ads Can Be Annoying
Personal Privacy Not everyone is
happy with use of cookies & history
Adware Type of malware that generates unwanted ads, often as popups
Auto-play Video Some ads play
video as soon as the page loads
Distraction Ads can take your
attention from what you’re trying to do
3
4
Online Documents – File Compression
Why use Compression?
Compression is squeezing data to reduce file sizes for storage and sending.
Compression is done using an algorithm.
Files are zipped
Afterwards, they are unzipped or extracted
People use compression because:
1) File sizes can be reduced so it saves memory space
2) Smaller file sizes mean faster downloads
3) If you need to send lots of files via email, you can send in just one compressed folder so saves time & effort
Example of using ‘zip’ compression
Some email services limit the number or file size of attachments.
One solution is to zip lots of files in one folder to send
The receiver can then unzip or extract or expand the folder to access all the files.
How Compression Algorithms Work
Each compression tool uses an algorithm
That means a method to reduce the data
One method for reducing the size of text files is to cut all repeating words
An index is then created to store the position of all the cut words
So later, the index can be used to put the original text back together
4
5
Online Software & Backups
Online Software – v – Standalone Software
Standalone software is installed on your computer, from a CD or downloaded Key advantage: it’s on your hard-drive so runs fast & doesn’t need the Internet
Online software is accessed over the Internet via your web browser Key advantage: you can access the software on all devices eg PC, Mac & tablet
This is a traditional
way of working
This way of working is becoming more and more common
Advantages to Online Software
Backup & Restore
Automatic Updates
Pay Monthly
Save on Hardware
Having a back-up online means a copy
of your files are stored on web
servers, so you can restore the files if there’s a problem.
Getting an upgrade used to mean
getting a new CD. But online software is
updated automatically.
You don’t need to pay a full price for a
software product on a CD. Instead, you
can ‘pay monthy’ so the software is more
affordable.
A business doesn’t need to buy its own servers because the software & files will be stored online. So
this saves the business money.
But there are also risks…
Reliability: If your online software service is unavailable, you can’t access your files Security: Your online service could be at risk from hackers wanting to access files
5
6
Collaborative Working Online
Advantages of Working Together
Online services allow people to work on the same project, or even the same document, so:
Staff can collaborate online, even if they’re in different places or countries So they don’t need to travel, which saves money & helps the environment You only need one version of a document, which everyone can edit
Online Software
Levels of Access
File Permissions
Version Control
Restrictions are set at logon: Staff can access areas
depending on their role Students & teachers see
different parts of network
Settings that control what users can do to a file: Read: View only Read/Write: View & edit Full control: Also delete
When lots of people can edit a document, it’s vital to show which is latest version eg filenames can use numbers or dates.
6
7
Online Communication 1
Online Communities
An online community or network of friends is a group that only exists online
An example is social networking sites that connect people with similar interests
Another example is a virtual world, such as Second Life that only exists online
Some need members to be online at same time eg online gaming Others can interact at different times, eg learning community on a VLE
Blog & Vlog Micro-Blogging Wikis A web log or online journal or video blog (vlog) that’s meant
to be updated often
A website or app where short messages are exchanged
(eg Twitter)
Sites where authorised users can logon to add or
edit content
Who Blogs? Who MicroBlogs? Who Uses Wikis?
Businesses promoting news & product info
‘Fans’ using blog or vlog
Creative professionals showcasing their work
Journalists sharing stories
Friends sharing updates
Professionals linking with colleagues about work
Businesses sharing news and product information
Celebs in touch with fans
Teams who want to collaborate on a central pool of information
People with a shared interest or hobby
Podcasts Instant Messaging Chatroom Audio or video files that are
usually published in instalments
Form of ‘chat’ where people are online at same time & post
messages in ‘real time’ (live)
A place on the web where many users online at same
time can communicate ‘live’
Who Uses Podcasts? Who Uses IM/Chat? Who Uses Chatroom?
Media channels sharing TV & radio shows
Musicians and comedians sharing gigs
Businesses for promotion
Businesses offering online support to customers
People on social networks eg using chat window
People with shared interests eg football
Professionals who work in same industry
7
8
Online Communication 2
Netiquette Profile & Avatar Emoticons
Netiquette is a set of rules for users online
e.g. avoid UPPER CASE. (‘Etiquette’ means a code
of behaviour.)
Is a user’s online presence, such as on social media.
People decide what to show & how much is TRUE! An avatar is an image to represent you.
Also known as smileys, emoticons
are images that represent emotions.
Communicating online includes instant messaging (IM). Online communication also requires rules and involves users in developing a profile for their online presence
Instant Messaging (IM)
Is a way to exchange messages instantly between two or more users
Usually software is used to make connections between users and provide an environment to chat or share files, such as images, and use emoticons.
Client & Server Roles
The chat program is processed on the user’s computer, which is called the client
Each person chatting holds a local copy on their computer
Other processing may be carried out on the server, eg when users log-on
8
9
Voice Over Internet Protocol - VoIP
Advantages Disadvantages
Uses Internet only so no additional costs (unlike phone)
Able to connect anywhere – but only if have Internet connection
Reduces travel costs, such as staff in different countries having a ‘video conference’, not flying
Better for collaboration since can also show documents on-screen
Relies on Internet connection so it can be slow & ‘buffer’ or it can cut out
Data exchanged online is at risk of security threats, such as hackers, which is especially relevant to a business working with confidential information
Voice quality can be affected since the audio is being converted to digital and then transmitted over the Internet
What is Voice over Internet Protocol?
VoIP is a method of real-time communication over the Internet eg Skype
It began as a way to make free calls over the Internet but now does video
So audio and video data is transmitted between computers
The computers are connected via their unique IP addresses
An example IP address is 125.76.23.003 – like a phone number for a computer
In business, VoIP is used for online meetings called ‘video conferencing’
Hardware Needed For Individual Use
For the video, you need a webcam, either standalone or built into your computer, laptop or tablet
For audio, you need a mic plus speakers, or an individual headset
9
10
Cloud Computing
Cloud Storage
Cloud computing is where you use external servers instead of your hard drive.
The external servers are called hosts and are owned by a hosting company
Some well-known hosting companies are Dropbox , Google & Microsoft
Users can access software, data and storage from their hosting company
You access all that using your web browser
Advantages Disadvantages
Cost Savings
‘Anytime, Anywhere’
Reliability & Speed
Security
You only pay for the storage you use,
rather than having to buy & maintain
all the server hardware.
You can access your files and software from anywhere in
the world, as long as there is an Internet
connection
A poor hosting service can mean
the servers are slow, or they crash and the
service goes down
You have to trust the hosting company to keep your files safe, otherwise there is a risk from hackers.
10
11
Ubiquitous Computing
Ubiquitous computing is where processors are built into everyday objects that are connected online
Clothing Vehicles Buildings Appliances People
Processors are built into
running kit to track distance, heartbeat etc.
Processors built into
GPS/satnav to direct the
driver
Processors built into fire alarms to detect smoke & set-off alarms and contact the
fire brigade
Processors in washers control
different programmes, and monitor load size,
water etc.
Pacemakers are fitted to
regulate heartbeat
RFID
Radio Frequency Identification Chips (RFID) are a way to embed processors into everyday objects
Used to identify & track products for stock control Like a barcode, but doesn’t need to be scanned
Animals Home - Fridge Shops
This cap flap only opens for an animal wearing the
correct RFID chip embedded in collar. Pets also get RFID microchips
As a tagged product is placed inside, this fridge can
automatically read the RFID chip and use the data to
monitor & order groceries.
An RFID scanner by the door of a shop can read the chips
as they pass thru – and sound an alarm if the
product is stolen
The Internet of Objects
As more objects have processors built-in, they can be connected online
So we’ll start to see an Internet that connects ‘things’ rather than just computers
This Internet of Objects can include ‘smart’ products and even people!
11
12
The Internet - Hardware
The Internet
The Internet is a global network of interconnected computers that allows ‘packets’ of data to be exchanged between computers and devices.
Internet Hardware
Client A computer/device that uses services provided by a server
The computer you use to access the Internet is a client
Routers Devices that route (direct) data traffic through a network
They are intelligent and will try to find the best routes
Backbone A ‘big’ cable (often fibre optic) that connects a large
number of devices in the ‘core’ of the Internet
Server Runs special software to serve other computers
Different types include file, print, web and email servers
Cables Form the connections between all this hardware
Includes all kinds of cable, such as fibre & telephone lines
Internet Service Providers (ISPs)
An ISP allows connection to the Internet
IT would be too expensive to connect to the Internet directly so the ISP gives an easy way for a connection
An ISP may provide connection to one ‘client’, or a network of clients. For example, a home network or a business network.
ISPs can also provide additional services for a fee, such as website development and tech support.
12
13
The Internet – Network Diagrams
Network diagrams show how pieces of technology connect together
Two terms are vital when labelling a network diagram:
POP
A Point of Presence (POP) is an access point to the Internet.
An ISP may have several PoPs to allow good access to the Internet
NAP
A Network Access Point (NAP) is where different networks interconnect, such as your home network onto the Internet
Sample diagrams
LANs & WANs
Two types of network
Local Area Network Wide Area Network
Is a network on one site, like a school, or one building, such as an office block
Is a network that spans a whole region, or country or globe, eg the Internet
13
14
Connection Methods
You need to know these three connection methods
Dial-Up Broadband Wireless
Is a wired connection via modem & phone wires
Advantages Can use existing
telephone wires
Gives connection where broadband is not available
Disadvantages
Older technology and can give poor reception
Usually slower than other methods
Conversion between digital and analogue can cause errors
Means a wired connection via a broadband supplier
Advantages
Better reception and speed than dial-up
Disadvantages
Wired, so has to be used on a stationary computer
Broadband is not available in many rural areas
Connects without using cables
Advantages Not fixed to a
stationary computer Can be used
whenever wireless
Internet is available
(eg wi-fi hotspot) Disadvantages
Needs to have wireless Internet available
Can be less secure than wired
Tends to be slower than wired
Bandwidth
Is how we measure the speed of Internet connection.
Bandwidth is how much capacity (space) there is to carry digital data as 1s and 0s
Measured in bits per second High bandwidth means more
data can be moved, so giving a faster Internet connection and a higher transmission rate
142
15
The Internet - Protocols
Protocols are rules that allow computer systems to connect with different systems to transfer data.
This is important because the Internet involves many different types of devices.
How the Internet uses Packets
All data on the Internet is split into packets & the traffic is managed by TCP/IP
TCP IP
Transmission Control Protocol
TCP is responsible for:
Breaking data into packets Assembling the packets again
when they arrive
Internet Protocol
IP is responsible for:
Handling the routing of packets
That’s addressing, sending and receiving packets over the Net
File Transfer Protocol - FTP
Protocol which allows files to be transferred between two computers or devices. It is usually used to upload or download files to a server. (See page 18.)
15
16
World Wide Web
Think of the Web as content on the Internet
That content includes web pages plus multimedia files & other data.
How the Web works…
Browser Hyperlinks Web Servers
Web pages are accessed through browsers
These are applications which allow a user to enter a URL and view a webpage
Your browser reads the HTML code and displays the page
The Web works because of hyperlinks
They connect web pages together
When a hyperlink is clicked, a user is taken to another page on the site, or taken to another website
Websites are stored on web servers
When you access a webpage through a browser, the page is temporarily downloaded onto your computer
It is the web server’s job to deliver the web page requested
162
17
HTML
HTML is the language for making webpages
It uses special ‘tags’ to tell the browser how to display the content of a webpage
Example of Hypertext Markup Language
Tag Function Example
<h1> Make a heading on a webpage <h1>Welcome to my website!</h1>
<p> Make a paragraph of text <p>My website is about Tim Berners-Lee</p>
<b> Make text bold <b>I think Tim is a legend!</b>
<i> Make text italic <i>You know why, don’t you?</i>
<u> Underline text <u>That’s right – Tim invented the Web!</u>
<br> Create a line break
<p>Some text</p><br><p>More text</p>
<img> Insert an image
<img src=“photo.jpg”>
src means ‘source’
It tells the browser what file to display
<a> Create a hyperlink
<a href=“www.argos.co.uk”>Click here</a>
href means ‘hyperlink reference’
It tells the browser what site to open
Meta-tags Special tags at the start of a page that are used to give details about its content, such as: <meta name="description" content="Information about Queen Elizabeth School">
17
18
URLs & Web Protocols
A URL is an address for a webpage.
URL stands for Uniform Resource Locator
Protocol Domain Name Path
Tells the browser what to do with the URL
This is the name of the website
This points to a specific webpage
Web Protocols
There are several protocols or rules for handling all the data for webpages. They are included in the URL so that the browser knows how to handle that page.
FTP HTTP
File Transfer Protocol
An old protocol that was invented even before the Web was born
It is still used to upload and download files from a server
It is often used by web developers to transfer files to their web server
But to use FTP, you usually need a username and a password
Hypertext Transfer Protocol
HTTP is the set of rules that handle what we do on the Web
It handles your REQUEST to load a page from a web server
It also handle the RESPONSE to download the web page and all its files to your computers
Secure HTTPS
The ‘S’ in HTTPS means secure. Data in the webpage is scrambled
before sending across the Internet So if data is intercepted, it can’t be
understood Protects privacy from ‘hackers ‘
18
19
Search Engines
Smart Searching With Operators
Use Quotes “ ”
Use Minus -
Use Star *
Use OR
“happy days”
jaguar -car
*plastic
chimp OR gorilla
Search for an exact word or set of words
Exclude all results that contain a certain word
Find all variations of a word (called
a wildcard)
Find one keyword or another, use the term
OR (in CAPITALS)
How Search Works
Search engines are special websites that allow users to find data on the Internet. Examples include Google and Bing.
A user enters keywords into the search engine
The search engine searches its Index, which is its database of web pages
The results are displayed in order of popularity
Don’t forget that the ‘sponsored links’ will also be placed at the top
The more a company pays, the more likely it is to appear in search results
19
To collect details of
websites, the search
engines use
automated
programs (or ‘bots’)
called Web Spiders
or Web Crawlers.
They look around
the Web, looking for
new or updated
pages and log them
in the search
engine’s database
called the Index.
20
Email – Purposes & Uses
Emails are stored on servers & then forwarded to the receiver – so it’s called ‘store & forward’
Emails are sent from an sender’s Outbox and received in a recipient’s Inbox
The sender & recipient do not have to be online at the same time
That’s great when sending emails to people in different global time zones
This applies to staff in a big company, as well as families & friends
Advantages Disadvantages
Attachments You can attach multiple files, such as images or documents
Copy Use cc to send copy to other people Or bcc to hide addresses from others
Contacts ‘Address books’ store contacts & you can also use distribution lists to email lots of people simultaneously
Delivery Speed Emails usually arrive in seconds – much faster than traditional post
Webmail Gmail & Hotmail use cloud servers so can access email anywhere
Junk Email - Spam Spam or ‘junk’ email has become a massive problem
Phishing Fake emails designed to trick people to give personal details
Viruses (from attachments) Attachments can contain code designed to harm your computer
Delayed Reply Email isn’t real time so you can’t expect an instant response
No Access Not everyone has email – or they might not logon regularly
20
Send Attach
Address Book
High/Low Priority
CC – Send a copy to another person
21
Email - Protocols
Webmail –v– Email Client
Not everyone uses webmail services such as Gmail & Hotmail. Some people use software applications called ‘email clients’
All your messages stay on the server + Can access email
on many devices + Email backed-up - You must have Net
connection - Slow service
Emails downloaded to client machine + Can access them,
even if not online
+ Client software has more features
- Emails lost if computer crashes
Learn Three - SMTP, POP3 & IMAP
A protocol allows different software & devices to communicate so you can send email on a computer and it is received on a tablet or phone
21
SMTP handles sending Simple Mail Transfer Protocol
It pushes outgoing email to a server
If ever a problem sending, them SMTP will keep trying until it’s sent
IMAP handles receiving webmail Internet Message Access Protocol
Lets you access your email on a server
When logon, you pull email from server
So you can access ‘anytime, anywhere’
POP3 also handles receiving messages Post Office Protocol 3
POP originally came before webmail when people used ‘email client software’ eg MS Outlook
You downloaded emails from the server
Then emails could be deleted from the sever
22
Data Exchange - Packet Switching
Parts of a Packet
Packet switching is the process of data being broken into ‘packets’ before being sent through a network and then re-assembled at the other end.
Trailer Data Header Used to check
that packets are reassembled correctly
This core is the most important part of the packet!
The ID is vital to putting all the packets back in order
Addresses tell where going & where come from
VoIP and Packet Switching
VoIP uses a special computer program called a CODEC to speed-up the transmission of the audio and video by enCOding and DECoding all that digital data as packets:
Sender uses microphone & webcam
Message converted to digital data & broken into packets to be sent across the Internet
Receiver’s computer re-assembles data & decodes the data
Advantages Disadvantages Packets chose different
routes so traffic flow is efficient
Big files can still be sent but don’t clog network
Packets give security benefit because if intercepted, the hacker will only have one part of a file
If one or more packets are lost or corrupted during transmission, the whole file will not be received correctly
22
23
Data Exchange - Transmission Modes
Modes
Transmission modes are the ways devices on a network communicate & transmit data
Simplex – One Way
Signals go in one direction at a time
Duplex – Two Way
Signals go in both directions at same time
½ Duplex - Take Turns
Signals go in both directions but not simultaneous
Transmitting Bits
Two ways of transmitting digital data as a stream of bits…
Method Data Transfer Benefit Limitation
Serial
Bits of data are transferred one at a time over a wire
Good over large distances
Complex because data has to be broken into individual bits
Parallel
Bits of data are transferred simultaneously – a whole byte can be transferred at the same time
Faster because more bits transferred per second
Only for shorter distances eg 5 meters
23
24
Wired Transmission Methods
Learn Three Types of Cable
When transmitting data, the aim is to reduce latency, which is the delay between sending and receiving data over a network (think ‘late’).
UTP/STP Co-axial Fibre Optic
Contains pairs of copper wires twisted together
Used for LANs
Is solid copper wire with thick shielding
Used to connect TV with aerial
Strands of glass carry data as light
Used for backbone of network
Advantages Advantages Advantages
Cheaper than other methods
Reliable
Under plastic coating, the shielded (STP) cable has protective layer around the copper wires to protect data signal from interference
Reliable
Fast
Used over long distances
Little interference
Disadvantages Disadvantages Disadvantages
Slow
Low capacity
Used over short distances
Susceptible to interference, which means data can be interfered with if near another digital device
Slow
Low capacity
Used over short distances
Thick and physically inflexible
Susceptible to noise
Used for backbone of network
24
25
Wireless Transmission Methods
Using Invisible Waves
Data is transmitted wirelessly using different types of waves from the electromagnetic spectrum…
Infrared Microwave Satellite
Uses infrared light to transmit data
That’s very high frequency light
Uses waves with short wavelengths to transmit data
Uses satellites in space to relay data between points on earth eg GPS
eg GPS Advantages Advantages Advantages
Reliable
Good for medium distances
Good for very long distances
Disadvantages Disadvantage Disadvantages
Short range
Devices must be in line of sight
Can suffer from interference
Can suffer from interference from other devices eg a microwave oven that’s near to a computer device
Very expensive
NICs & NAPs
Devices using wireless networking need a NIC
Network Interface Card
It’s the hardware for receiving wireless signals
It’s built-into modern devices eg tablets & phones
The NIC connects to a NAP
Network Access Point
Lots of places offer NAPs, such as cafes & libraries.
25
26
Client-side Processing
Client Scripts = Interactivity
Client side is viewing webpages on your client device (e.g. a tablet or PC)
Today’s webpages have lots of features that are interactive
Interactivity is achieved using client scripts written in a language called JavaScript
These client scripts are run by your browser to display the interactive effect
Example 1 – Hover Image
On some webpages, images change when you move your mouse pointer over them. This ‘hover’ effect and is achieved using code in a client script.
Example 2 – Slider
Another common interactive feature on websites is a ‘slider’ where you click or swipe to scroll through images. This is created using code in a client script.
Advantages Disadvantages
Speed Processing is faster on the client because data does not have to travel back to the sever across the Internet
Security Data cannot be intercepted on the client in the same way it can be when data is transmitted back to the server across the Internet
Browser-specific Different browsers process client scripts in different ways, therefore a web developer cannot be sure how their website will appear on a screen on the client side
Computer speed The web developer is relying on the speed of the client computer to deliver the interactive features, so if that is slow then the processing will be slow
26
27
Server-side Processing
Server = ‘Back end’ Processing
Server side means processing data at the ‘back end’ on the web server
That’s all the nerdy work that ordinary people never think about!
It’s done using special server scripts written in server-side languages such as PHP
All this usually happens after you’ve done something on a webpage…
Example 1 – Submitting a web form
After you click SUBMIT your data is sent back to the web server for processing, such as storing your personal details on the website’s database.
Example 2 – Submitting a web search
After you click SEARCH your keywords are sent back to the web server for processing, such as finding matches on the database or Index. Then the results are send back to you.
Advantages Disadvantages
Servers are powerful computers A web server is likely to be way more powerful than a client computer, so it can process data faster
No browser involved Servers don’t use Browsers so there are none of the difficulties you get on the client with different brands
Efficient Everything is done on the server, so no need to wait for downloads etc
Security When data is send back from the client, it has to travel across the Internet where there is more risk of security threats
Overloading If a lot of users are asking the webserver to process data, it could overload the server and cause it to crash (eg when thousands of people try to book gig tickets).
27
28
Database Theory
What is a Database?
A database is a structured collection of data
A table stores a set of data e.g. details of all the students in school
A record is one row that stores data about a single item eg a student’s details
A field are the columns in a table eg forename, surname, gender, date of birth
The primary key is a special field with a unique identifier eg a student ID
Data Types
Says what kind of data is going to be stored in a field
Text Any kind of characters, including letters & numbers eg LA6 2HJ
Number Numerical values eg 1.5
Date/Time Dates and times 01/04/2014
Boolean One of two values, such as Yes/No or True/False Yes
Relational Databases Most databases need more than one table to store all the data
So the tables need to be linked (or ‘related’) to create a relational database.. s
28
This SupplierID is not really product data
So it’s called a Foreign Key
Its purpose is to link to the Supplier table
29
Databases in Practice
Local & Online Databases
Local means a database held inside a network to keep it secure Online means a database that could be accessed around the world
Shops such as Argos plus search engines & social networks all use databases
The database is stored server-side
And the data is sent with the webpage when you load it
Database Management System A DBMS is software that allows you to create & use your own database
It creates tables and fields and allows you to search and sort data
It handles security to prevent un-authorised access
It can also allow for different levels of access for different users
SQL
SQL is the language used by a DBMS to actually create & search a database
It has a Data Definition Language (DDL) to set-up the tables
And it has a Data Manipulation Language (DML) for updates & search queries
Data Validation Validation means checking data on input to see if it meets certain rules These validation rules check that the data is sensible (but can’t check if correct) Here are some different kinds of validation rules…
Presence Check to see if data has been entered & not left blank
Range Check values are in sensible range eg effort grades between 1 & 5
Format Check that data is in required format eg a date is DD/MM/YY
Check digit Use digits in a code to check the data is right eg a barcode
29
30
Threats to Data
Opportunity Threats
A company’s network security can be breached by people who take a random opportunity, such as an unattended PC
Computer Viruses
Viruses are malicious programs designed to replicate and spread across a computer or a network to damage or corrupt files & data
Other Malware
Malware is the name for several other types of malicious software, such as Trojans, worms, adware, spyware and other nasty software that aims to cause damage to files or to steal data
Phishing
Means when hackers use fake emails or fake websites to trick people into clicking links and then entering their personal data, such as bank passwords
Accidental Damage
This could include floods, or fire or hurricanes or damage from untrained users
Hackers
Means people who purposefully try to gain unauthorised access to a computer or a network. But bear in mind that a high proportion of hackers are people who actually work for an organisation.
30
31
Protection of Data
Physical Barriers
Means protection such as locks on doors, or CCTV & even turning computers off at night
Password control of access
A strong password is at least 8 characters and includes uppercase & lowercase letters plus numbers and symbols
Access Levels
Ensures people only have access to the parts of the system they need. (Staff would also need training before gaining greater access.)
Anti-virus Software
Software that works by scanning your files & then deleting a virus or put safely in quarantine.
Firewall
Software that monitors data coming in and out of a network to protect it from viruses, malware and hackers. It puts a ‘wall’ around a network.
Encryption
Means scrambling data to turn it into a secret code before sending it over a network, or the Internet so hackers can’t decode & understand it.
Backup & Recovery
A backup is a copy of data kept in a different location. Recovery is replacing the data, such as copying the backup files to the original location.
Personal Privacy Settings
Security settings can be used on social networking sites to protect users’ privacy.
31
32
Legislation
Know Four Law
Data Protection Act
Computer Misuse Act
Forces organisations to protect the data they store about people
Lays down 8 principles – see above
Can be fined if don’t follow them
Targets hackers and virus-makers
Focused on ‘un-authorised access’
Starts with access, then intention to do more harm & then altering data
Copyright, Designs & Patents Act
Freedom of Information Act
Aimed at preventing piracy
Protects rights of the makers of software, photos, music, films etc
So use without permission is illegal
Gives people the right to see data stored about them by public sector organisations eg government, councils
Anyone can make a ‘FOI’ request
Technology & Monitoring
Today’s technologies can be used to monitor people’s movements and
communications and that has an impact on our freedoms & privacy…
Movements Communications
CCTV cameras record movements
GPS in phones tracks your location
Travel data eg airport passenger lists
Authorities monitoring emails & web
Search engines logging your keywords
Sites using cookies to track browsing
32
Sample Principles Data must be accurate & up to date.
It must be kept safe & secure.
Offences (1) Unauthorised access (2) Then UA with intent (3) Then unauthorised altering data
27% of software in use is illegal in the UK You have the right to access information stored about you by public organisations.
33
Key Terms
Page Term Meaning
6 Access levels Restricted access to files, depending on your role & training
3 Adware Malware that displays unwanted ads, often as pop-ups
4 Algorithm (file compression) Method of reducing data to make size of file smaller (compress)
31 Anti-virus software Utility software that scans files & deletes or quarantines viruses
20 Attachment File(s) that is sent along with an email e.g. documents & images
33 Avatar Image selected to represent someone e.g. on social media.
5, 31 Backup A copy of data kept in a different location so can be restored
14 Bandwidth Speed of an Internet connection, measured in ‘bits per second’
20 BCC Send email to many people but hide addresses from each other
7 Blog An online journal or diary that’s meant to be updated regularly
28 Boolean (Data Type) Type of data in a database field that can be True or False, or Yes/No
14 Broadband A high speed Internet connection that’s ‘always on’
16 Browser Software application for viewing webpages e.g. Google Chrome
20 CC Email terms for sending copies of messages
29 Check digit (validation) Use digits in a code to check the data is right e.g. in a barcode
12 Client Means the computer you use to view webpages e.g. on a tablet
26 Client-side processing Means interactive parts of webpages made using code scripts
10 Cloud storage Keeping your files on an online server, not your own computer
24 Co-axial Solid copper wire with thick shielding that connects TV & aerial
22 CODEC Computer program that speeds transmission of audio & video
6 Collaborative working People working together on same document stored on the Cloud
32 Communication monitoring Use of technology to track people’s messages e.g. by the Police
4 Compression (files) Reducing the amount of data in a file for storage & sending
32 Computer Misuse Act Anti-hacking law that’s focused on ‘un-authorised’ access
32 Cookie Small file stored on computer used to track online behaviour
32 Copyright, Designs & Patents Act Anti-piracy law to protect rights of makers of music, movies etc.
32 Data Protection Act Privacy law to force organisations to look after personal data
28 Database A structured collection of information e.g. for products in a shop
28 Date/Time (Data Type) A type of data that can be stored in a database e.g. date of birth
29 DBMS Software that allows you to create & use your own databases
14 Dial-up Old fashioned way to connect to Internet via modem & phone
18 Domain name (URL) The name of a site & the main part of the address e.g. Nike.com
33
34
Key Terms
Page Term Meaning
23 Duplex Transmission where data goes in both directions at same time
31 Encryption Scrambling data before sending online so hackers can’t decode
21 Email client software Dedicated email application or program , such as MS Outlook.
24 Fibre optic Cable made from strands of glass that carry data as light
28 Field (Database) One item of data in a database, such as a Surname field
6 File permissions Control what you can do to a file: Read, Read/Write, Full Control
31 Firewall Software that monitors data coming in and out of a network
28 Foreign Key (Relational Db) Special field that links two tables in a relational database
29 Format check (Data Validation) Check that input data is in required format e.g. date is DD/MM/YY
32 Freedom of Information Act Law gives the right to see data stored about you by public sector
18 FTP (File Transfer Protocol) Old set of rules to handle uploads & downloads from a server
6 Full control (file permission) Lets you delete a file, as well as read (view) & write (edit)
23 Half-Duplex Data transmits in both directions but not simultaneous
17 HTML Coding language used to create webpages using tags
18 HTTP (URL) Set of rules that controls loading webpages
18 HTTPS (secure webpages) Rules for secure webpages where data is scrambled for privacy
21 IMAP (webmail) Set of rules that handles webmail for access ‘anytime, anywhere’
4 Index (File compression) Stores details of all the cut words so a document can be remade
19 Index (Search engine) Special database that stores details of billions of webpages
25 Infrared Transmitting data using very high frequency light e.g. TV remote
8 Instant Messaging Real-time communication between people online at same time
11 Internet of Objects ‘Smart’ products with processors built-in & connected online
15 Internet Protocol - IP The part of TCP/IP that handles the routing of data packets
12 Internet Service Provider (ISP) Company that charges you a fee for your Internet connection
13 LAN Local Area Networks are restricted to a single site e.g. a school
24 Latency The delay between sending & receiving data over a network
30 Malware Malicious software designed to damage or corrupt files & data
17 Meta-tag Special tag used to give details of a web page
25 Microwave Use of radio waves with short wavelengths to transmit data
13 Network Access Point (NAP) Provides a wireless hotspot for people to use e.g. in a library
8 Netiquette Code for behaviour online, such as not using UPPER CASE
25 Network Interface Card (NIC) Hardware for receiving wireless that’s built into today’s computers
34
35
Key Terms
Page Term Meaning
28 Number (Data Type) A basic type of data that can be entered into a database field
29 Online & local database Local means on your computer; online means used on websites
7 Online community Group of people with shared interest e.g. in a virtual world
5 Online software Version of an application that is hosted & used on the Cloud
22 Packet Header Vital part of an Internet package that contains the package ID
22 Packet switching All Internet data is broken into ‘packets’ before being transmitted
18 Path (URL) End part of a web address that points to a specific webpage
23 Parallel Transmission Where bits of data are transferred simultaneously together
3 Pay per click Websites only get paid for adverts if users click on them
30 Phishing Using fake emails or sites to trick people to give personal data
7 Podcast Audio or video file designed for download in regular instalments
13 Point of Presence (POP) Is an access point to the Internet
21 POP3 (email) Old protocol that ‘pulls’ emails from server when requested
29 Presence check (data validation) Check that required data has been entered and not left blank
28 Primary Key (database) Special field that acts as a unique identifier, such as a StudentID
15 Protocol Technical term for sets of rules for handling & sending data
31 Quarantine (anti-virus software) How suspicious files are stored to stop them infecting computer
29 Query (database) Is the technical term for doing a search in a database
29 Range check (data validation) Check that input data is within set of values e.g. between 1 & 100
6 Read-Only & Read/Write access Read means you can view a file; Write means you can also edit.
28 Record (database) One row in a database table that stores data about a single item
28 Relational Database Stores data in more than one table to make it more efficient
5, 31 Restore What you do with a backup of a file to make it usable again
11 RFID RFID chips are a way to embed processors into everyday objects
1 Real-time information Anything that happens in ‘real time’ basically means ‘live’
12 Router Devices that route (direct) data traffic through a network
25 Satellite transmission Use of space satellites to relay data to points on earth e.g. GPS
26 Script Code written in special scripting languages for use on webpages
19 Search operator Use of symbols for smarter web searches e.g. minus symbol.
23 Serial Transmission Where bits of data are transferred one at a time over a wire
27 Server-side processing Processing data on the web server e.g. put info in a database
23 Simplex Data can only transmit in one direction at a time e.g. TV remote
35
36
Key Terms
Page Term Meaning
21 SMTP (email protocol) Handles sending email by pushing outgoing email to a server
2 Software As A Service (SAAS) Use of Cloud-based applications to give ‘software on demand’
20 Spam Unwanted junk emails that most people put in Spam folder
3 Sponsored link When companies pay for links to appear first on search results
30 Spyware Type of malware that tracks your activity on a computer
29 SQL (Structured Query Language) Language used to actually create & search a database
5 Standalone Software Has been installed on your PC (as opposed to online software)
20 ‘Store & forward’ model Emails are stored on servers & forwarded to the receiver
24 UTP/STP Types of networking cable that contain pairs of copper wire
2 Streaming Way of delivering multimedia to computer connected online
31 Strong Password Min. 8 characters with mixed case letters, numbers & symbols
28 Table Is where information is stored in a database
17 Tag (HTML) Special words that tell the browser how to display a webpage
15 Transmission Control Protocol (TCP) Part of TCP/IP that breaks data into packets & reassembles
28 Text (Data Type) A basic type of data that can be entered into a database field
11 Ubiquitous Computing Everyday objects with processors built-in & connected online
18 URL (web address) Technical name for web address – Uniform Resource Locator
29 Validation (database) Checking data on input to see if it meets certain rules
6 Version control (documents) Managing which is the latest version of a shared document
2 Video conferencing Online meeting that uses video, usually in a business
30 Virus Programs designed to replicate & corrupt or damage files
2 VLE (eg Moodle) Virtual Learning Environment used in schools & Universities
9 VoIP Online communication that uses real-time video e.g. Skype
13 WAN Wide Area Networks span whole regions or countries
19 Web crawler/spider Programs used by search engines to collect details of webpages
16 Web server Powerful type of computer that ‘hosts’ or stores a website
21 Webmail Services such as Gmail where emails are stored on the Cloud
7 Wiki Sites where authorised users can logon to add or edit content
14 Wi-fi hotspot Location where you can get wireless Internet, often for free
24 Wired Transmission Methods Ways to transmit data using cables e.g. UTP or fibre optic.
25 Wireless Transmission Methods Ways to transmit data with NO cables eg infrared & microwave
4 Zip A way to compress or reduce file size for storage & sending
36
