BTEC IT Revision Booklet.pdf
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BTEC iCT Unit 1 – The Online World My Theory Booklet Introduction 1 Online Services 1 Mark __ /8 2 Online Services 2 Mark __ /8 3 Online Advertising Mark __ /11 4 Online Documents – Compression Mark __ /7 5 Online Software & Backups Mark __ /11 6 Collaborative Working Online Mark __ /8 7 Online Comm...
BTEC iCT Unit 1 – The Online World My Theory Booklet Introduction 1 Online Services 1 Mark __ /8 2 Online Services 2 Mark __ /8 3 Online Advertising Mark __ /11 4 Online Documents – Compression Mark __ /7 5 Online Software & Backups Mark __ /11 6 Collaborative Working Online Mark __ /8 7 Online Communication 1 Mark __ /7 8 Online Communication 2 Mark __ /7 9 Voice Over Internet Protocol Mark __ /13 10 Cloud Computing Mark __ /7 11 Ubiquitous Computing Mark __ /9 12 The Internet - Hardware Mark __ /8 13 The Internet – Network Diagrams Mark __ /5 14 Connection Methods Mark __ /12 15 The Internet - Protocols Mark __ /9 16 World Wide Web Mark __ /8 17 HTML Mark __ /6 18 URLs Mark __ /8 19 Search engines Mark __ /8 20 Email – Purposes & Uses Mark __ /16 21 Email - Protocols Mark __ /7 22 Data Exchange – Packet switching Mark __ /10 23 Data Exchange – Transmission Mark __ /11 24 Wired Transmission Methods Mark __ /14 25 Wireless Transmission Methods Mark __ /8 26 Client-side Processing Mark __ /12 27 Server-side Processing Mark __ /9 28 Database Theory Mark __ /9 29 Databases in practice Mark __ /15 30 Threats to Data Mark __ /6 31 Protection of Data Mark __ /15 32 Legislation Mark __ /11 33 Key Terms OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review OK Must review 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 Getting Online We’ll see how services work & their benefits, such as saving travel costs We’ll look at how people get online, like using superfast ‘fibre’ broadband Cloud Services Email We’ll see how storing files online lets staff work together on docs We’ll see how it works using special rules or protocols & email servers Online Software Web We’ll see how working online saves hassle, such as installing software We’ll see how sites are built & how Web data travels across the Internet Networks Search engines We’ll see why local and wide area networks are vital for organisations We’ll see how Google etc. collect & store details of billions of web pages Server Computers Online Ads & Shopping We’ll see how these special machines help power networks We’ll look behind the scenes at how companies advertise & sell online Databases Social Media We’ll see how businesses store info on products, staff & customers We’ll look at all the different ways people can communicate online Security Wi-Fi We’ll see what kind of threats make security such a big deal today 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 Services that provide up-to-date info That means moving data in the form of text, photos, video and audio 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 Commerce Government Commerce means business so these services involve money in some way. These involve ‘official’ public services eg online shopping & banking 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 1 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 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 2 Online Services 2 Entertainment Download Means services for leisure and fun Means LEGAL download services, such as for games, music & movies 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 Business Means companies using websites to increase efficiency & save money Examples 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 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! Email 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 3 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 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 way of working is becoming more and more common This is a traditional way of working Advantages to Online Software Backup & Restore Automatic Updates Pay Monthly Having a back-up Getting an upgrade You don’t need to pay online means a copy used to mean a full price for a of your files are getting a new CD. software product on stored on web But online a CD. Instead, you servers, so you can software is can ‘pay monthy’ so restore the files if updated the software is more there’s a problem. automatically. affordable. Save on Hardware 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… 5 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 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 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 IM/Chat? Who Uses Chatroom? Who Uses Podcasts? Media channels sharing TV & radio shows Musicians and comedians sharing gigs Businesses for promotion 7 Friends sharing updates Professionals linking with colleagues about work Businesses sharing news and product information Celebs in touch with fans 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 8 Online Communication 2 Communicating online includes instant messaging (IM). Online communication also requires rules and involves users in developing a profile for their online presence 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. 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 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 Advantages 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 9 Disadvantages 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 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 Processors are built into running kit to track distance, heartbeat etc. Processors built into GPS/satnav to direct the driver Buildings Appliances People Processors built Processors in into fire alarms washers control to detect smoke different & set-off alarms programmes, and and contact the monitor load size, fire brigade 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 This cap flap only opens for As a tagged product is placed an animal wearing the inside, this fridge can correct RFID chip automatically read the RFID embedded in collar. Pets chip and use the data to also get RFID microchips monitor & order groceries. Shops 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 13 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 14 Connection Methods You need to know these three connection methods Dial-Up Broadband Wireless Is a wired connection via modem & phone wires Means a wired connection via a broadband supplier Connects without using cables 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 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 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 14 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 Internet Protocol TCP is responsible for: Breaking data into packets Assembling the packets again when they arrive 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 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 Hyperlinks 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 Web Servers 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 16 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 Make a heading on a webpage Welcome to my website! Make a paragraph of text My website is about Tim Berners-Lee Make text bold I think Tim is a legend! Make text italic You know why, don’t you? Underline text That’s right – Tim invented the Web! Create a line break Some textMore text Insert an image src means ‘source’ It tells the browser what file to display Click here Create a hyperlink 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: 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 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 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. Smart Searching With Operators Use Quotes “ ” “happy days” Search for an exact word or set of words 19 Use Minus jaguar -car Exclude all results that contain a certain word Use Star * *plastic Find all variations of a word (called a wildcard) Use OR chimp OR gorilla Find one keyword or another, use the term OR (in CAPITALS) 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 Send Attach CC – Send a copy to another person Advantages High/Low Priority Address Book Disadvantages Attachments Junk Email - Spam You can attach multiple files, such as images or documents Spam or ‘junk’ email has become a massive problem Copy Phishing Use cc to send copy to other people Or bcc to hide addresses from others Fake emails designed to trick people to give personal details Contacts Viruses (from attachments) ‘Address books’ store contacts & you can also use distribution lists to email lots of people simultaneously Attachments can contain code designed to harm your computer Delivery Speed Delayed Reply Emails usually arrive in seconds – much faster than traditional post Email isn’t real time so you can’t expect an instant response Webmail No Access Gmail & Hotmail use cloud servers so can access email anywhere Not everyone has email – or they might not logon regularly 20 21 Email - Protocols 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 IMAP handles receiving webmail SMTP handles sending 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’ 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 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 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 21 Emails downloaded to client machine + Can access them, even if not online + Client software has more features - Emails lost if computer crashes 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 Advantages Packets chose different routes so traffic flow is efficient Big files can still be sent but don’t clog network Receiver’s computer re-assembles data & decodes the data Disadvantages 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… 23 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 Bits of data are transferred simultaneously – a whole byte can be transferred at the same time Parallel Faster because more bits transferred per second Only for shorter distances eg 5 meters 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 Contains pairs of copper wires twisted together Used for LANs Is solid copper wire with thick shielding Used to connect TV with aerial 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 Disadvantages Slow Low capacity Used over short distances Susceptible to interference, which means data can be interfered with if near another digital device Advantages Reliable Disadvantages Slow Low capacity Used over short distances Thick and physically inflexible Susceptible to noise Fibre Optic Strands of glass carry data as light Used for backbone of network Advantages Fast Used over long distances Little interference Disadvantages 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 Uses infrared light to transmit data That’s very high frequency light Microwave Uses waves with short wavelengths to transmit data Satellite Uses satellites in space to relay data between points on earth eg GPS eg GPS Advantages Reliable Disadvantages Short range Devices must be in line of sight Can suffer from interference Advantages Good for medium distances Disadvantage Can suffer from interference from other devices eg a microwave oven that’s near to a computer device 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 Advantages Good for very long distances Disadvantages Very expensive 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 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 Disadvantages 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 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 27 Disadvantages 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). 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 This SupplierID is not really product data So it’s called a Foreign Key Its purpose is to link to the Supplier table 28 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… 29 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 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 Sample Principles Offences Data must be accurate & up to date. It must be kept safe & secure. (1) Unauthorised access (2) Then UA with intent (3) Then unauthorised altering data 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 27% of software in use is illegal in the UK You have the right to access information stored about you by public organisations. 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 CCTV cameras record movements GPS in phones tracks your location Travel data eg airport passenger lists Communications Authorities monitoring emails & web Search engines logging your keywords Sites using cookies to track browsing 32 33 Key Terms 33 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 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 35 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 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
