Ipt Hsc Notes

IPT HSC Notes
Chapter 6 - Multimedia systems
Characteristics of media types
Text and Numbers:
Text:
Most common methods for digitally representing text ASCII (American standard code for information interchange) e.g. Unicode systems, and EBCDIC (extended binary coded decimal interchange code) IBM mainframe and mid-range computers, together with devices communicate with these machines use EBCDIC.
The Unicode system of coding text is used more widely and has become the standard for representing text digitally.
Standard ASCII represents the English language characters using decimal numbers in the range from 0 to 127 and requires 7 bits per character. Unicode systems extend ASCII characters to include characters from other languages.
Number:
Number media types is used to represent integers (whole numbers), real numbers (decimals), currency, Boolean and dates and times.
Boolean: uses a single bit, 1 represents true and 0 false
Both text and numbers are displayed as images using fonts. Each font describes how each character will be rendered when displayed.
Two types of broad font: outline fonts and raster fonts
Outline fonts: describe characters using mathematical descriptions of the lines and curves within each character. (vector) doesn’t become pixelated when enlarged, Lossless
Raster Fonts: Stores a bitmap of each character (bitmap) Lossy
RLE and Huffman are both examples of lossless compression

Hyperlinks: Hyperlinks are text, images, audios or videos that are linked and can be selected in order to move to another node of data.
Hypertext: a term used to describe bodies of text that are linked in a non-sequential manner.
Hypermedia: a term used to describe different media types including images, sound and video
Hypertext mark up language: used to organise hypertext for the WWW, specifies how text, graphics and sound are displayed on a web page.
Hyperlink HTML tag: <a href=”URL”</a>
Summary:
* All HTML document are stored as text files * Pair of tags are used to specify hyperlinks and other instructions * Tags are text that have no meaning until analysed by a web browser * Tags are specified using angled brackets <> * Web browsers the meaning of each HTML tag

Audio:
The audio media type is used to represent sounds
All sounds are transmitted through the air as compression waves
File formats for storing audio include MP3 and WAV, WMA for sampled sounds and MID which represents individual notes.
All waves have two components frequency and amplitude.
Frequency: The number of times per second that a complete wavelength occurs, measured in hertz (Hz)
Amplitude: determines the volume or level of sound, measured in decibels (db)

How audio data is represented as binary: * Sampling the actual sound at precise intervals of time e.g. converting real sound to digitalised sound. * Describing the sound in terms of the properties of each individual note e.g. computer generated sound (music notes)
Sampled Rate: Samples are joined to approximate the original sound wave
Accuracy and quality can be affected be the number of sound samples per second and the number of bits used to represent each of these samples.
Individual Notes: Traditional music scores are represented digitally as a series of individual notes. The most common storage is MIDI (musical instruments digital interface)
(sample rate * Sample Size * Time) *Channel
Images: represent data that will be displayed as visual information
Bitmap: represents each pixel in the picture separately as a binary digit. (Lossy)
Morphing: transforming one image to another
Distorting: changing the natural look of an object
Bit depth/image colour: The number of bits per pixel. The larger the bit depth the greater quality and size of the image.
Resolution: determines how clear or detailed the image appears. Determined by pixel width and height.
To calculate the uncompressed storage requirements:
Vertical pixels*horizontal pixels*bit depth
(8*1024) =kB
Vector: Represent each portion of the image mathematically. Represented as separate editable shapes (lossless)

Animations: A sequence of images/frames one after the other.
Onion skinning: process of placing a series of cels on top of each other
Cel-based animation: a sequence of cels with small changes between each cel.
Path-based animation: a line is drawn which the character the follows.
Animated GIF: a sequence of frames displayed on the web
Flash (SWF): organised as a sequence of definition tags, control tags and actions.

Video: Combines images and sound together to create movies or animations

File size = number of frames per second * file size for each frame
Number of frames per second = frame rate * time in seconds
File size for each frame = horizontal * vertical * bit depth
Example
Calculate the file size in kilobytes of a 15-minute movie at 24fps.
Each frame is 600 * 800 with 24 bits per pixel.
Number of frames= 24 * 60 * 15
= 21600frames
File size for each frame=600*800*24
=11520000 bits

File Size = 21600 * 11520000 (8*1024)
File Size = 30375000 KB = 30 .37 MB
H.264 codec: Compression and decompression is included in MPG, MOV, AVI, WMV
Compressing video involves: removing repetitive data and also removing data from parts of images that the human eye does not perceive. Most common compression is blocked based coding.
Hardware for creating and displaying Multimedia:
Screen/display: information for display is received by the video system via the system bus. The video system is composed of a video card and the screen. The video card translates the data into a form that can be understood and displayed on the screen.
Video cards: contains a processor chip, random access memory called video ram or VRAM and a digital to analog converter DAC. AGP (advanced graphics port) is dedicated to transmission of video only.
DVI (digital visual interface) operate with digital screens, HDMI is also used (High definition Multimedia interface)
CRT (cathode ray tube) based monitors:
Electrons rush from the negative cathode to the positive anode, the anodes are used to focus the electron beam accurately towards the opposite end of tube which is coated with coloured phosphors which produces colour when hit by the electrons. * Refresh rate/frequency: the rate at which the screen is drawn/refreshed each second. * Multisync: automatically detect and respond to signals with various refresh, resolution and colour-depth settings. The software driver for the video card, allows changes to be made to the refresh rate, resolution and colour-depth.
LCD (liquid crystal display) based monitors:
Liquid crystals are used to alter the polarity of light as it passes through the molecules. LCD monitors require a light source (small fluorescent light)
A filter containing red, green and blue is contained between the polarizing panels
Thin Film transistors (TFT): a two dimensional grid of connections supplies electrical current to the transistor located at the intersection of a particular column and row.
Plasma Screens: when an electrical charge is applied to a plasma substance it gives off light.
Touch screens:
Components: touch sensor panel that overlays the screen, a controller that converts signals from the sensor panel into a form suitable for collection via serial or USB and a software driver to allow communication with the touch panel. * Primary technologies used to create touch screen sensors:
Resistive: contains two electrically conductive layers separated by a gap, when pressure is applied the gap closes and an increased of electrical current flows at that point.
Capacitive: a single electrically charged panel coated with conductive coating detects the charge of your finger through sensors in each corner. The controller determines the position of where your finger touched the screen.
Surface acoustic wave (SAW): generate ultrasonic waves that travel from transducers via reflectors and into receivers on the other side. When the screen is touched the wave is interrupted at that point causing a corresponding change in the received wave pattern.
Digital projectors:
Transmissive projection: direct light through a smaller transparent image.
Reflective projection: reflect light off a smaller image.
Three technologies used to generate small reflective images within reflective projectors include:
LCOS (liquid crystal on silicon), DMD (digital micromirror devices) and GLV (grating light valves)
LCOS: A traditional LCD where the transistors controlling each pixel are embedded within a silicon chip underneath the LCD.
DMD: composed of minute mirrors that can tilt, each mirror measures just 4 micrometres by 4 micrometres and are space approximately 1 micrometre apart. Also known as DLP (digital light processing)
GLV: 1 million times faster than LCDs.
Head-up Display: allows the user to keep their head up and looking forward

Audio Display:
Sound card: (DAC) can be attached through a PCI expansion slot. The purpose of a sound card is to convert binary digital audio samples from the CPU into signals for the use by speakers and other audio devices. Digital audio files are first converted to analog signals before being output to speakers.
Speakers: has a diaphragm attached to a wire coil, as the diaphragm vibrates so too does the coil of wire. (ADC)
Head-set: integrate a microphone and speakers into a single device worn on the head. Allow the user to immerse themselves in sound without interrupting others.
Audio visual (AV) headsets add video and images to sound. Commonly used to view traditional movies and music videos.
Virtual reality (VR) head-sets add sensors to monitor the position of the users head. Totally immerses the user as they explore virtual worlds.
Optical storage:
Retrieving data has to processes:
Spinning the disk and moving the read head assembly:
Reading and translating reflected light into electrical signals:
A laser generates a beam which gets diffracted to make to smaller beams which are used to ensure the main beam accurately tracks over the pits and lands. Diffraction causes dispersion of the beams, to correct dispersion the three beams pass through a collimator lens which makes the beams parallel. The beams then proceed through a focusing lens which focuses the beams onto the disc. The reflected light returns back through the focussing and collimator lenses and then is reflected by a prism onto an opto-electrical cell. The cell converts optical data into electrical signals. The electrical signal is then passed through a DSP where it’s converted back to its original form. It’s then placed into the drive’s buffer where it’s retrieved via an interface to the computer’s RAM. * Constant angular velocity (CAV): the spindle motor rotates at a steady speed. A consequence of CAV drives is that they have variable rates of data transfer. Data located further from the centre of the disk is read more rapidly. * EFM (eight to fourteen modulation): converts each 8 bit byte binary into 14 bit such that all the bit patterns include at least two but less than ten consecutive zeros . * DSP (digital signal processor) removes merge bits converted by EFM
Software for creating and displaying multimedia:
Presentation software: is used to produce high quality multimedia presentations designed for display to groups of participants
Apple’s iWork keynote: Mac based an extensive collection of 3 dimensional transitions and effects. It also produces spread sheet like tables that can be used as charts and graphs. It is also able to produce high-resolution display for high definition projectors.
Microsoft PowerPoint: mac and PC, software included within Microsoft Office suite. Most widely used presentation software application.
OpenOffice.org’s Impress: open source product which is able to create flash files (SWF) and rad PowerPoint files.

Applications such as word processors with sound:
Two techniques for combining information of different types and from different sources:
Embedding: importing a source file into a destination file. The source file becomes part of the destination file.
Destination file: the existing file
Source file: file being imported
Linking: establishes a connection between a source and destination file. Alterations to the source file will be reflected in the destination file.
Differences between print and multimedia: * Higher resolution of print compared to screen display * Interactive nature of multimedia compared to static nature of printed output * Ability to use hyperlinks, sound, animation and video in multimedia systems * Printed output can’t be altered * Printed output doesn’t require any information technology

Authorising Software:
Multimedia authorising software packages are used to design and create multimedia systems. They import and combine different media types into a single interactive system.
Articulates Quizmaker: creates graded and surveyed type quizzes as flash files. The quiz can be uploaded to a learning management system (LMS) where students tests are automatically delivered and results recorded.
Neosoft’s Neobook: creates fully compiled and self-contained windows applications as either executable EXE files, screensavers or as browser plug-ins. Interactive multimedia programs such as electronic books, brochures, games and many more can be developed without learning any programming code.
Adobe Flash CS3 professional: leading authorising software package for creating rich interactive Flash files for the web.

Animation software:
Xara3D: used to create 3 dimensional animations using a combination of text and/or vector images. Animations can be saved as animated GIFs, flash files, AVIs and screensaver files
Toon Boom studio: produces quality carton style animations. Creates high quality animations for films, television, games, websites and many other applications.

Web browsers and HTML editors:
Browsers provide the human interface between users and the vast store of information out there in cyberspace.
Window’s Notepad: is a simple text editor included with all versions of Microsoft windows operating system
Coffee Cup HTML Editor: develops and distributes a number of inexpensive web design software application including Flash Firestarter, web video player and an FTP client
Adobe Dream Weaver CS3: WYSIWYG (what you see is what you get) interface, code can also be used and edited. CSS (Cascading style sheet) allows the design and the content to be separated. CSS files can be reused on many pages.

Examples of Multimedia Systems:
Education and training: Multimedia systems are used to enhance education and training within homes, schools, universities and businesses.
Preschool and infants: large buttons, bright colours and often a game style format.
LMS (learning management systems): used in schools, universities and commercial training organisations to manage the distribution of multimedia and other learning resources to their students. Examples Moodle
Businesses: use multimedia to train there staff. Examples occupation health and safety, customer support, communication, sales skills and computer skills.
Software: one of the most common forms of online multimedia training. Assists users develop skill to use their product effectively.

Leisure and entertainment: games are now implemented on a variety of hardware devices including personal computers, game consoles, mobile phones etc.
Genres include
Action games: users reflexes to control the action in real time
Role playing Games: player controls one or more characters which each possess different characteristics
Massively Multiplayer Online (MMO) Games: ongoing virtual world hosted on a dedicated and powerful server. Consists of thousands of players
Platform games: the player causes a character to travel between onscreen platforms
Simulation games: mimic a real world situation.

Provision of information: the integration of a variety of different media types makes multimedia systems well suited to the delivery of information
Information Kiosks: dedicated multimedia systems
Multimedia brochures, reports, presentations and business cards: created and distributed on CD-ROM
Multimedia encyclopaedias: uses hyperlinks and different media types, distributed on CD-ROM, DVD and over the internet.

Virtual Reality and Simulation: Allow participants to experience an environment as close as possible to the real world environment being simulated
Aircraft flight simulator: allows pilots to experience and deal with aircraft failure and other possible disasters.
Medial schools: using simulators as a training method before performing procedures on patients.
Surgeons: to assist during many surgical procedures.
Walkthroughs: designs can be created and analysed prior to construction
Tours: used to view houses, buildings etc.
Military: used for training, planning and during actual operations.

Expertise required during the development of multimedia systems:
Project managers coordinate and manage the activities of all these personnel.
Systems designers create the overall design of the multimedia system and oversee the entire operation to ensure the development remains true to their design in terms both content and use of technology.
Content providers: provide ready to use content, specialise in the provision of stock photographs, animations, video and also text articles. Act on behalf of the copyright holders and negotiate fees so the content can be legally used.
System designers: work through the stages of the system development cycle, they identify the purpose of the system; make decisions on the most suitable and feasible solution and design the overall system. This all include determining the hardware and software that will be used and also preparing specifications that detail the information processes that will form part of the solution.
Project managers: develop the project plan and ensure it is followed during development.
Writers: produce the textual content within multimedia systems; they also create storylines upon what the aspect of the system will be based on
Video production: a crew comprised of a director, camera operator, sound engineer and perhaps actors and editors is required.
Audio production personnel: sound engineers specialise in the recording and editing of audio.
Illustrators and animators: artists who draw figures and scenes
Graphic designers: improve the readability of multimedia by enhancing the visual appeal of the presentation.
Technical personnel: ensure the final system will operate correctly on the user’s machines. Considerations and tasks performed by technical personnel: * Multimedia delivered over the internet is reliant on the speed of the user’s internet connection. * Required codecs are present on the end-users computer (decompress CD files) * Copy protection and product registration techniques.

Other information processes when designing multimedia systems:
Organising presentations using storyboards:
Story boards describe the layout of each individual screen together with any navigational links between scenes. * Structure must convey the information to the users in the manner intended by the author * Users must be should be able to locate information without being forced to manually search through irrelevant information.
Linear: used when there is a strict logical sequence or order to the presentation
e.g. PowerPoint presentations

Non-linear: A non-linear layout has no particular structure; the user moves between different sections in any direction.

Hierarchical: A user starts at the home page and move down through the system, layer by layer.
e.g. format of web pages

Composite: uses a combination of the layouts

Collecting Multimedia content:
Text and numbers are inputted using a keyboard.
Collecting audio, video and images requires the raw analog data to be converted to digital.

Scanners: collect light as raw analog data and transform it into binary digital data. Barcode scanners operate by reflecting light off barcode images. This digital data may then be analysed, organised and processed using optical character recognition software into numbers or text.

CCDs (charged coupled device) in barcode scanners operate by LEDs reflecting light off the image back to the mirror. The mirror reflects the light onto a lens that focuses the image at the CCD. Each photocell in the CCD transforms the light into different levels of electrical current that are fed into an ADC.

Flatbed scanners:
Collect image data in the form of bitmaps.
Collect colour by reflecting red, then green, then blue light off the image.
CCDs in flatbed scanners convert electrical current from each photocell into a binary number using ADC (analog to digital converter).
8 bit output range from 0 to 225, black=0 and white=225
The led lamp, mirror, lens and CCD are all mounted on a single carriage call the scan head.

Digital Camera: detect lights and transform it into electrical currents.
Either based on CCD or CMOS (complementary metal oxide semiconductors).
CCDs have better quality but cost more to produce and operate.
CMOS technology is used in security and phone cameras. CMOS chips combine the image sensing and ADC functions into a single integrated chip.
Unlike scanners who generate their own light source, cameras must control the amount of light used to generate the image. Digital cameras are classified according to the number photosites on their CCD. A Bayer filters alternate red and green rows with blue and green rows. Most photos are stored as JPEG a lossy technique.

Microphone and sound card:
Microphones are used to collect data from sound waves. They convert compression waves into electrical energy. This analog electrical energy is converted using ADC (analog to digital converter) into a series of digital sound samples.
Two types of microphones dynamic and condenser: Both contain a diaphragm which vibrates in response to incoming sound waves. A dynamic microphone has its diaphragm attached to a wire coil, as the diaphragm vibrates so too does the coil of wire. Condenser microphones alter the distance between two plates. The diaphragm is the front plate; it vibrates in response to incoming sound waves, whereas the backplate remains stationary. The electrical current produced by a microphone is the same raw analog signal output from all types of audio devices. This makes it possible to connect any different audio sources to one of the analog input ports on a computers sound card.
Processes taking place once the analog signal from the microphone reaches the computer’s sound card. The analog signal is fed through ADC which converts the signals into binary. The output from the ADC is then fed into the DSP (Digital signal processor) which filters and compresses the samples. The final samples are then placed on the computer’s data bus. The data bus then feeds the samples to the main CPU where they are then sent to a storage device.
Video cameras:
Combine image collection with audio collection which results in a sequence of images that includes a sound track. Analog and digital camcorders use CCDs to capture light and microphones to capture sound. Video camcorders must be able to collect 25 to 3o images every second. This is accomplished through the use of two layer sensors, one behind another. The front layer collects the light and then transfers the electrical current to the lower layer. Whilst the lower layer is being read the upper layer is collecting the next image.

Analog to digital conversion:
Constantly samples the magnitude of incoming electrical current and converts these samples to binary digital numbers. ADCs contain DAC on the surface; DAC is much simpler than ADC.

Storing and retrieving multimedia content:
The end user must be able to decompress and display the selected formats and the display must occur in a timely fashion.
Bitmap image file formats:
JPEG (Joint Photographic Expert Group): Lossy, 8bit grey scale and 24-bit true colour bit depths
BMP (Windows Bitmap): Lossless, default bitmap format, bit depths 1,4,8 & 24 bits/pixel are supported.
GIF (Graphics Interchange Format): Lossless, 8 bits/pixel in grey scale or colour, compressed using LZW lossless compression.
PNG (Portable Network Graphics): Lossless, 16bit grey scale and 48bit true colour, graphic can be semi transparent
TIFF(Tagged image file format): Lossless, used for storing professional quality images, all bit depths up to 48bits/pixel are supported.

Vector image file formats:
Metafile: users a variety of different text tags like HTML
WMF (windows metafile): a Microsoft format that can be used by many operating systems.
PDF (Portable Document format): used to distribute electronic versions of printed material.
SVG (Scalable Vector Graphics):developed by W3C (World Wide Web Consortium) to become predominant format for vector graphics on the web.
SWF (Small Web Format): a flexible metafile format that can be used for vector images, animation and video.

Audio file formats:
WAV (Waveform Audio Format): a metafile format able to include raw or compressed audio data. Codecs include PCM (lossless) and MPEG-1 layer 3 (Lossy)
AIFF (Audio Interchange File Format): used on Macintosh, contain raw and compressed sound samples (lossy & lossless)
MP3 (MPEG-1 Audio Layer 3): compressed format (Lossy) for electronic distribution of commercial music files. Removes sounds not noticed by people.
WMA (Windows media audio): Microsoft format designed to be a competitor to mp3. (lossy)
MID (Musical instrument Digital interface): used to communicate with synthesisers and digital instruments.

Video and animation file Formats:
Container formats: contain data compressed using any of a variety of available video codecs.
MPEG (motion Picture Experts Group): Lossy, contains video compressed using MPEG video codecs
MP4 (MPEG-4 layer 14): Lossy, supports a large variety of resolution and frame rates, e.g. iPods.
AVI (Audio Video Interleave): container format created by Microsoft and IBM
QT (QuickTime): Apple format from which the current MP4 standard was developed.
WMV (Windows media video): Lossy, Microsoft format used for streaming video data
GIF (animated GIF): Lossless, used for small animations on websites without any audio.
SWF (Small Web Format): can contain video, animations and interactive features, requires flash player
FLV (Flash Video): Lossy, delivers streamed videos over the web for display within Flash Player.

Processing To integrate Multimedia content:
Software applications are used to combine and link all the multimedia content into an integrated and interactive multimedia presentation.
Tasks performed to combine and link all the multimedia content include: * Import existing content into the application * Create screens, add and format content and create hyperlinks * Create the final file or files required for distribution and display.

Issues Related to multimedia systems:
Copyright Issues: copyright laws are used to protect the legal rights of authors of original works. The copyright act 1968 details the laws governing copyright in Australia. Copyright laws are designed to encourage the creation of original works by limiting their copying and distribution rights to the copyright owner.
Integrity of source data: need to acknowledge all data sources (references)
Current and emerging trends in Multimedia systems: * RSS (Real Simple Syndication) and podcasts. * GPS and Mp3 functions on phones * Software download over the internet * Virtual worlds (second life)

Chapter 3 Communication systems:
Enables people and systems to share and exchange data and information electronically.
Occurs between transmitting and receiving hardware and software over a network.
Each device is called a node.
As each message leaves its source encoded into a form suitable for transmission along the communication medium. When the message is received it’s decoded.
Switches decide based on MAC address while routers use IP address
For communication to be successful requires components to agree on a set of rules known as protocols
Handshaking: establishing and negotiating and agreeing on which protocols will be used between devices.
OSI model (open systems interconnection): defines 7 layers, where each layer is expanded into sub layers
IPT levels:
Application: Organises the data into a form for transmission
7. Application:
6. Presentation:
Communication and control: A connection established which allows packets to be directed to
5. Session: there destination
4. Transport:
3. Network:
Transmission: Physical transfer occurs
2. Data link:
1. Physical:

Communication occurs in both directions (acknowledge receipt/request more data)

Characteristics of communication systems:
Overview of protocol levels:
Software is used to control and direct hardware. The transmitter and receiver must agree on how the hardware will be used to transfer messages
Application Level:
7. OSI Application Layer: The data to be transmitted is created by a software application, the data is organised into a format understood by the application that will receive the data
6. OSI Presentation Layer: the data is reorganised into a form for subsequent transmission. Commonly part of the application or is executed directly by the application and is often related to the requirements of the operating system. Protocols include HTTP,DNS, FTP, SMTP, POP, IMAP, SSL
Communication and Control:
5. OSI Session Layer: communication with the network is established, commences and is maintained. Determines when a communication session starts and ends.
4 OSI Transport Layer: Manages the correct transmission of each packet of data. (TCP)
3 OSI Network Layer: Packets are directed to their destination. (IP)
Transmission level:
2. OSI Data Link Layer: defines how transmission media is actually shared. Determine the final size of transmitted packets, the speed of transfer and other physical characteristics. Switches and Ethernet protocols cooperate at this level directing messages based on MAC address (Media Access Controller-address hardware on a device). Other protocols include token ring, SONET, FDDI.
1. OSI Physical Layer: performs the actual physical transfer (hardware). Converts the bits in each message into signals that are transmitted down the transmission media.

Overview of how messages are passed between sources and destination:
Message creation: compiled at the source in preparation for sending.
Examples of message creation: * A user writing an email using an email client such as Outlook * Pressing the delete key to remove a file stored on a file server.
Organisation of packets at the interface between source and transmitter:
The header and trailer contain data relevant to the protocol operating at the layer. The protocol operating at the next lower layer considers each entire packet from the prior layer to be data and adds its own header and trailer./
Headers and trailers are added in preparation for transmission and removed after a message is received.
Usually multiple packets are created based on the requirements of individual protocols being applied.
Routers determine where to send each datagram based on the destination IP address
Signal generation by the transmitter:
Transmitter: is the physical hardware that encodes the data onto the medium creating a signal.
Receiver: decodes the signals on the medium.
Examples that include transmitter: NICs, switchers, routers, ADSL, cable modems
Transmission: occurs as the signal travels through the medium.
Synchronising the exchange: To accurately decode the signal requires the receiver to sample the incoming signal using precisely the same timing used by the transmitter during encoding. This process ensures each waveform/symbol is detected by the receiver.
Commonly used to assist with synchronising process: * Preamble: initial synchronisation of the senders and receiver’s clocks. * Included/embedded within data: used to ensure synchronisation is maintained throughout transmission of each frame
Frame delimiter: alternates the 1s and 0s that end with a terminating pattern
Addressing and routing:
Each packet must ascend the stack until it reaches the addressing or routing protocol and then descends the stack as it is prepared for transmission down the next path.
Ethernet and other transmission level protocols use the receivers Mac address to determine the path leading to the receiver
Error detection and correction:
As a message descends the stack protocols calculate checksums or CRC (Cyclic Redundancy check) values and include them with their headers or footers.
Whenever an error is detected virtually all protocols discard the entire packet
Security and management: many protocols restrict messages based on user name and password or encrypting messages.

Protocols:
Protocol: a formal set of rules and procedures that must be observed for two devices to transfer data efficiently and successfully.
Handshaking: The process of negotiating and establishing the rules of communication between two or more devices.
HTTP (Hypertext Transfer Protocol): Operates in the Application layer and within layer 6 (Presentation layer) of the OSI model. Used by web browsers to communicate and retrieve web pages from web servers.
Three methods used by the browsers:
Get: receives entire documents
Head: retrieves just the header information for the file.
Post: sends data from the browser to a web server
Transmission Control Protocol (TCP): Communication and Control within (Transport layer 4)
TCP together with IP are the protocols responsible for the transmission of most data across the internet. TCP ensures messages are actually delivered correctly.
TCP requires IP to be operating. TCP considers elements of the IP header. Often called TCP/IP
A TCP packet is called a segment. Each TCP segment includes a header that includes the sequence of bytes contained within the segment and a checksum
DNS (domain name server): A server that determines the IP address associated with a domain name.
Segment: includes a string of bytes forming part of the data to be sent. (Error checks within and sliding windows)
Sliding Windows: controls the flow of data and ensures every byte of data is acknowledged once it has been successfully received. Allows the receiver to adjust the rate of data it receives.

Internet Protocol (IP): protocol that causes data packets (datagrams) to move from sender to receiver. IP operates at the OSI Network layer 3. * Doesn’t guarantee datagrams will reach their destination and makes no attempt to acknowledge datagrams that have been received. IP is known as a connectionless protocol.
Only error check that is needed is checksum of the bytes within the header.
UDP (user datagram protocol) can be used on layer 4 when speed is high priority then accuracy. * IP can reroute messages over the most efficient path to their destination.
IP is composed of four bytes(32 bits)
The header of every IP datagram includes the sender’s IP address and the destination’s IP address.
Every IP address is composed of a network ID and a host ID. The network ID is a particular number of bits starting from the left had side of the binary IP address, the remaining bits form the host ID.

Ethernet: Operates at layer 1, 2 (transmission level)
Ethernet packets are known as frames.
The Ethernet uses a system called Carrier Sense Multiple Access with Collision Detection (CSMA/CD) to deal with data collision.

Measurements of Speed:
Bps (bits per second): the number of bits transferred each second. The speed of binary data transmission.
Baud rate: The number of signal events occurring each second along a communication channel.
Bandwidth: The difference between the highest and the lowest frequencies in a transmission channel.

Error Checking Methods:
When an error occurs the receiver may drop the data packets (IP), acknowledge correct packets (TCP) or specifically request that packets containing errors be resent (Ethernet)

Parity bit check: a single bit attached before or after data so that the total number of ones is either odd or even.
Parity options: even, odd, none, mark and space.
Odd and even are the only two that provide error checking. If the checking method was even and number of 1s added to 3 then another 1 would be added to make it 4/even.
Problems: if 2 bits of data is lost the error will not be detected.
Checksum: calculated by summing or adding up.
Problems with checksum: If problem occurs it is revered. If all data being sent is zeros this is solved by reversing off the 0 to 1 & 1 to 0.
MSB (Most significant bits-left hand side) if the two MSB were corrupted during transmission error the no error will be detected because the bits are discarded.
Cyclic Redundancy Check (CRC): Part of Transmission level in layer 1 and 2. Both Checksum and CRC are calculated and included within the header and trailer of each message packet by the sender. The receiver calculates the CRC value and compares it to the CRC value within the received message packet. CRC values are calculated using division whilst checksums use addition. Divided by the generator polynomial
When adding and even number of 1s then the answer is 0 and adding an odd number of 1s results in 1. 0+0=0, 0+1=1, 1+0=1, 1+1=0
A XOR gate performs precisely this process.
CRCs are stronger than checksums because they are able to detect many of the more common types of transmission errors. Checksum are unable to detect 2 bits within one column of the addition has been corrupted 99.9% of errors are detected.

Examples of communication Systems:
Internet: a worldwide packet switch public network based on the Internet Protocol where all data moves between nodes within IP datagrams.
PSTN (Public switch Telephone Network: carries traditional telephone calls through the world. Designed for real time (synchronous, dull duplex) voice communication using telephones as the collection and display devices.
Intranet: a Private network maintained by a company or government organisation and is based on the Internet on the Internet Protocols (IP) e.g. LANs & WANs
Extranet: allow access to customers and other users outside the organisation

Teleconferencing: A multi-location, multi-person conference where audio, video and/or other data is communicated in real time to all participants. (Synchronous)
Business meeting system, sharing audio over the PSTN:
Environment/Boundaries:
Purpose:
Data/information:
Participants:
Information Processes:
Advantages/Disadvantages:

Messaging Systems: 1. Traditional Phone and Fax:
Telephones:
* Connected using copper wire * Additional features (call waiting, voice mail, caller id, 3 way calls) are required to implemented at the telephone exchange * The hardware to connect many PSTN telephone lines to a computer is known as a Telephony board
Facsimile (Fax):

2. Voice mail & phone information services:
After a predefined number rings the call is diverted to the voice mail system. The voice main answers the call and plays a pre-recorded outgoing message (OGM)
The OGM welcomes the caller and provides instruction on how to leave a message.
The voice mail system then digitally records the users voice and stores it within the customers voice mailbox * A hierarchical system of OGMs
Feature within Phone Information Services: * Voice mail management of many users, support for incoming/outgoing lines (VoIP), TTS (text to speech), call logging to databases, automated ordering and surveys. * #: restricts data input, stop recording or move to next step * *: stops current action and will return caller back to previous step * 0: quickest way to speak to an operator

3. Voice Over Internet Protocol (VoIP):
VoIP also known as IP telephony transfer voice call over the public internet.
Provides an interface to the PSTN, allows VoIP calls to be made to any normal telephone across the globe.
VoIP includes audio codecs to digitise and compress the analog voice data and then decompress and convert it back to analog at the receiving end.
Soft phone: when a VoIP software application operates on an existing analog internet connected computer
RTP & UDP at the Transport layer 4 and IP and network layer 3
RTP (real time protocol) is used to control streaming of data packets, including management of a constant speed and keeping packets in correct sequence.
UDP (User Datagram Protocol) is also used rather than TCP as UDP fires packets more rapidly without the overhead of error checking and flow control.
Advantage of VoIP compared to PSTN: * Low cost distance calls, no added cabling costs, additional digital services(voice mail)
Disadvantage of VoIP compared to PSTN * Congestion can occur and some packets may be lost which can cause poor quality audio, VoIP calls can’t be made when there is a power failure

4. Electronic Mail:
During transmission all email messages are composed of two broad components
Envelope: contains the information required to transfer the message to its destination. Used by SMTP serves to relay email messages to other SMTP serves and finally to their destination.
Contents component: contains various headers together with the actual message. SMTP examines and adds to these headers; however it doesn’t alter the actual message.
Email contents components: contains the actual message data together with various header fields used to specify the sender, receiver, date/time, subject and relationship of message to other related messages.
Destination Address Fields: header fields include To:, Cc: and Bcc:.
Originator Fields: include data:, From:, Sender: and Replay-To:
Identification Fields: headers are used to identify individual messages and to allow email applications to maintain links between a thread of messages. Message-ID= @
Information Fields: include familiar subject: header together with comment: keywords: header fields.
Resent, Trace and Optional Fields:
Recent: added to the start of a message each time that an existing message is submitted by a user for transmission.
Trace: added to various SMTP servers who deliver messages across the internet (describe the path the message has taken from sender to receiver.
Optional Fields: added to provide additional functionality such as virus checking and specifying MIME (multipurpose Internet Mail Extensions) headers.
MIME (multipurpose Internet Mail Extensions): protocol used to code non-textual data and attachments into ASCII so that it can be transmitted within email messages. Encoded in 7 bit ASCII, 6 binary digits.
Transmitting and Receiving Email Messages:
Uses Application level protocols
SMTP (Simple Mail Transfer Protocol): used to send email messages from an email SMTP client application to an SMTP sever

Emails are received by an email client application server listed below
POP (Post Office Protocol): used to download emails from an email server to an email client
IMAP(Internet Message Access Protocol):

Electronic Commerce: 1. Automatic Teller Machine (ATM):
Display devices include: the screen (CRT/LCD), receipt printer, speaker, keypad and screen buttons, cash dispenser, magnetic card stripe reader 2. Electronic funds transfer at point of sale (EFPOS) 3. Internet Banking:
Server side: CGI(Common Gateway Interface) & ISAPI (Internet Server Application Programmers Interface) 4. Trading over the Internet: (Ebay)
Virtual organisation: An organisation or business whose members are geographically separated. They work together using electronic communication to achieve common goals

Network Communication concepts:
Client-server Architecture: Servers provide specific processing services for clients. Clients request a service, and wait for a response while the server processes the request.
Authentication: The process of determining if someone, or something, is who they claim to be.
Thin client: connects to a NOS on the local server which runs all the applications
Fat client: applications are installed and executed by the CPU within the machine

Network Topologies:
Topology: the way a the nodes on a network are connected
Physical Tropology: The physical layout of devices on a network and how the cables and wires connect these devices
Physical Bus Topology: all nodes are connected to a single backbone with a terminator at each end. Each node attached listens for data present on the backbone cable via a T-connector
Physical star Topology: all nodes connect to a central node using their own dedicated cable
Advantage: has its own cable (can be connected/disconnected), easy to find faults (disconnect node)
Disadvantage: more cabling is required, if central node has a fault all the nodes connected are disabled
Physical Ring topology: data packets pass through each node as they circulate the ring
Physical Hybrid/tree topology: connect multiple bus, star and/or ring topologies such that a single path exists between each node.
Physical Mesh Topology: include more than one path between individual nodes.
Logical Tropology: How data is transmitted and received between devices on a network regardless of their physical connections.
Logical Bus Topology: All transmissions are broadcast simultaneously in all directions to all attached nodes.
CSMA/CD: Carrier sense Multiple Access with collision Detection
CSMA/CA: Carrier sense Multiple Access with collision Avoidance
Logical Ring Topology: each node receives frames from one node and transmits frames to one node.
Self-healing rings: able to divert data packets around problem areas in a virtual instant.
Logical Star Topology: each node has its own connection to a switch that is the central node.

Encoding and decoding Analog and digital signals:
Transmitting: involves the sender encoding the message and transmitting it over the medium
Receiving: involves the receiver understanding the organisation of the encoded message
Analog Data to Analog signal: waveform varies, points are significant. Transmitted along PSTN telephone lines.
Digital Data to Digital Signal: produced when digital data is encoded onto analog waves. Encoded as a digital signal through the process of modulation or voltage changes.
QAM (Quadrature Amplitude Modulation): amplitude and phased modulation scheme
Digital Data to Analog Signal: DAC performs the process. Digital to analog conversion estimates intermediate waveforms between each known digital data point. Audio CDs use PCM (Pulse code modulation) to encode the original analog music as a sequence of 16 bit digital sound samples.
Analog Data to Digital Signal: ADC performs the process. At precise intervals the incoming analog signal is fed into a capacitor

Network Hardware:
Transmission Media: can be bound or unbounded, part of the physical layer
Bound/wired: Twisted pair, coaxial cable and optical fibre
Unbound: wireless connections (satellite links, mobile phones and wireless LANs)
Bound: can be shielded or unshielded, shielded is more expense and but prevents electronic forces from affecting the signal.
Twisted pair: includes STP (shielded twisted pair) and UTP (unshielded twisted pair) 16MHz
Coaxial cable: used for cable TVs and broadband networks. 30MHz to 3GHz
Optic Fibre Cable: used on aircrafts and as a backbone on a network. Can support much larger bandwidth and has faster transfer rates. Operates by the light reflecting off the glass cladding as it moves through the glass core. 200,000GHz to 350,000GHz
Unbound: uses the atmosphere as the carry medium to carry electromagnetic waves between nodes
Point-to-Point Terrestrial Microwave: used to relay wireless signals across large distances. A direct and uninterrupted line of sight between the transmitter and the receiver is required.
Satellite: use microwaves to carry digital signals from and to both ground based stations and also between satellites.
Wireless LANs (WLANs): communicate using microwaves
Bluetooth: used for short ranged transmission, uses CRC error checking, asynchronous.
Infrared: require a direct line of sight, short distances
Mobile phones: split into cell areas, cell contains central based station that transmits and receives data to and from individual mobile phones.

Network Connection Devices:
NIC (Network Interface Card): convert data between the computer into a suitable form for transmission across the network. Has its own unique MAC address
Repeater: any device that receives a signal, amplifies it and then transmits the amplified signal down another link. Increase the physical range of the transmission media.
Hub: sends data to call attached nodes
Bridge: separates a network into separate segments to reduce network traffic
Switch: Determines the MAC address of the sender and intended receiver that precedes each message.
Gateway: connects two networks together. (LAN & WAN)
Wireless Access Point (WAP): central nodes on wireless LANs, security includes WEP (wired Equivalent Privacy) & WPA (Wi-Fi Protected Access)
Modem:
* Modulation: the process of encoding digital information onto an analog wave by changing its amplitude, frequency or phase * Demodulation: The process of decoding a modulated analog wave back into its original digital signal
ADSL modems: (asymmetrical digital subscriber lines) Use existing copper telephone lines to transfer broadband signals. Allow for faster transmission by using higher frequencies.
DMT (Discrete Multi-tone): specifies the channels that are used for actual data transfer.
Cable modems: used to connect to a broadband coaxial network. Commonly the network is shared with cable television.

Servers: provide specific processing services to other nodes
File server: manages storage and retrieval of files and application software in response to client requests.
Fault Tolerance: The ability of a system to continue operating despite the failure of one or more of its components.
Print server: controls access to one or more printers for many clients. Receives all print requests and places them into an ordered print queue
Database Server: run DBMS. Provides connection to the database and ensures the rules defined for the database are maintained.
Mail Servers: Emails are received by an email client application from a POP or IMAP server.
Web Servers: provides service to web browsers, allow web pages to be uploaded, edited and deleted.
Proxy Servers: Sits between clients and real servers. Performs requests on behalf of a server. Keeps requests and responses within a large cache to speed up the access. Proxy servers that operate between clients and the internet are also gateways. Provide connectivity between the LAN and the Internet. They are also as a web filter to block sites

Network Software:
NOS (Network Operating system): the NOS is installed on one or more servers where it provides various services to secure and support the network’s resources and users
Network Administration tasks: network administrators are the personnel responsible for the ongoing maintenance of network hardware and software.
Adding/removing users: each user has an individual account with set policies and privileges.
Assigning printers:
Assigning file access rights: ACL (access control list),
Directory/folder permissions:
File permissions:
Installation of software and sharing with users:
Client installation and protocol assignment:

Issues Related to communication systems:
Internet fraud: spam, identity theft
Power and Control: installing internet filtering software
Removal of physical boundaries:
Interpersonal Issues: people overdo themselves online compared to reality.
Work and Employment Issues: team members don’t physically meet, it’s all through phones, email etc.

Current & emerging trends in communication:
Blogs: a journal made public by placing it on the web
Wikis: a website were users are able to add new content and edit existing content
RSS Feeds (Really simple syndication): contain a combination of audio, video, images and text.
Podcasts: an audio RSS feed
Online radio, TV and Video on demand (VOD): displayed in real time using streaming media player.
3G mobile networks: 3rd generation mobile communication networks.

Chapter 1
Project management: A planned and ongoing process that guides all the development tasks and resources throughout a project’s development
The project triangle: If one side of the triangle is altered, the remaining two sides are affected. Quality is affected by each of the three sides.

Money Scope/tasks Quality Time
Techniques for managing a project:
Communication Skills:
Active Listening: time spent listening to people
Techniques include:
Mirroring: Repeating back some of the speaker’s key words. Indicates that you are interested and want to understand more.
Paraphrasing: listener users their own words to explain what they think the speaker has just said. Listener acknowledges the speakers feelings and reflects their own words
Summarising: responses are commonly used to refocus or direct the speaker to some important topic or reach agreement so the conversation can end.
Clarifying questions: neglecting or glossing over important details.
Motivational responses: encourages the speaker and reinforce in their mind that you are indeed listening and interested in what they have to say.
Conflict Resolution: working together to solve disputes. (scheduling tasks, different goals)
Negotiation Skills:
Interview Techniques: used to identify problems with existing systems, obtain feedback during development and also to recruit and assess staff performance.
Team Building: Being able to achieve more as a team then alone
Advantages of a team: more productive, and the system is of higher quality
Disadvantages of a team: financial loss, employment loss and missed opportunities.
Team Building skills and techniques: (Tuckman’s four stages) 1. Forming: team members get to know each other 2. Storming: people are beginning to feel comfortable 3. Norming: team member know recognise their differences 4. Performing: team is now operating as an effective productive unit

Project management tools:
Document and communicate: * What each task is * Who completes each task * When each task is to be completed * How much time is available to complete each task * How much money is available to complete each task
Gantt charts for scheduling tasks:
Journals and diaries:
Funding management plan: aims to ensure the project is developed within budget
Communication management plan: how communication will take place.

Social and ethical issues related to project management: * Work environment has to be healthy and provide safety, (ergonomic design of furniture, appropriate lighting, noise levels, etc.) which resolves OHS problems * Security of data/information * Copyright issues * Respecting the rights and needs of an individual team member.

System development:
SDLC:
* Understanding the problem * Planning * Designing * Implementing * Testing, evaluating and maintaining

Understanding the Problem: determines the purpose and requirements of a new system.
System analyst is a person who analyses systems, determines requirements and designs new information systems.
The outcome of this stage is to produce a Requirements Report.
Requirements: features, properties or behaviours a system must have to achieve its purpose.
Requirements Report determines what needs to be achieved to make the system a success. Interview/survey users of the existing system: interviews and surveys collect user’s experiences and problems with the existing system
Interview/survey Participants of the existing system:

Requirements Prototypes: a working model of an information system, built in order to understand the requirements of the system.
Requirements for a new system: specifies the inputs and outputs together with their relationships to each other.
The requirements report is used to determine possible solution options and their feasibility.

Planning:
To decide which possible solution should be developed and then decide how it should be developed and managed.
Feasibility study: a study that analyses possible solutions and recommended solutions which is used to determine if the development should commence
Feasible: capable of being achieved using the available resources and meeting the identified requirements
Technical Feasibility: * Do we currently possess the necessary technology * Is the technology available * How widely used is the technology * Are existing users of the technology happy with its quality and performance * Will the technology operate with other existing and possible future new or emerging technology
Economic Feasibility: * Development costs * Ongoing operational costs * Tangible benefits * Intangible benefits
Issues Cost-benefit analysis:
NPV (Net Present Value) A measure of the predicted real cost benefits of an investment. The higher the NPV the better. The time before the break-even points is called the payback period.
Schedule Feasibility: * How can the solution be monitored to verify deadlines are being met
Operational Feasibility: * Will the solution work in practice rather than whether it can work.

Choosing a system Development Approach:
Traditional/structured: step by step stages. Each stage must be complete before progressing to the next stage. Disadvantage: doesn’t allow for requirement changes.
Outsourcing: the contracting of outside specialists to complete a particular task. Disadvantage=Cost
Prototyping: verifies and determines the requirements for a new system. Acknowledge the changing nature of requirements. Disadvantage time
Customisation: Altering an existing solution to suit specific needs and requirements
Participant development: The same people who use and operate the final system develop the system. Doesn’t require detailed user documentation to be produced.
Agile methods: remove the need for detailed requirements and complex design documentation. It encourages cooperation and team work. Acknowledge the changing nature of requirements

Designing: The actual solution is designed and built
System design tools for understanding explaining and documenting the operation of the system:
Context diagram: represent the entire system as a single process.
Process: A single process representing the entire system
External entity: Any input (source) or output (sink) that provides data to the system or receives data from the system Data flow representing the flow of data between the single process and external entities
Data Dictionaries: used to detail each of the data items used by the system. Include field name, data type and description, etc.
Data store
Data store
DFD (data flow diagram): describe the movement and changes in data between processes. (same as context diagram) have identical data flow entering and leaving the system as context diagram. A location where data is stored. It can be in computer format or non-computer format

Decision Tree: A diagrammatic way of representing all possible combinations of decisions and their resulting actions. It represents the decisions made within a system as the branches of a tree. For every condition, there is an action/ outcome.
Decision Tables: Decision tables represent all possible conditions and the actions that will result. It indicates the alternatives for different conditions and actions based on the rules.
Storyboards: tools for designing the user interface within software. They document the layout of elements on individual screens and also the connections between screens.
User Interface: Part of a software application that displays information for the user. The user interface provides the means by which user interact with software.

Designing the information technology: * Is it maintainable, user friendly,

Building/creating the system: The system will actually be created and built is determined by the chosen system development approach and specifies of each individual system.
Refining Existing Prototypes: Existing prototypes can be refined such that they evolve into final software solution.
Guided Process in Application Packages: Wizards or assistants that guide the user as they perform common tasks.

Implementation: the system is installed and commences operation.
Implementation Plan: * How and when will the participants be trained to operate the new system * The method of conversion between old and new system * How the system will be tested. * Conversion of data for the new system
Methods of conversion:
- Direct conversion - directly drop old and start new
- Parallel conversion - run both for a period of time
- Phased conversion - gradual introduction of new system
- Pilot conversion - system installed for some users to learn and evaluate, then install for all.
Implementing training for participants and users:
Training techniques include
Traditional group training sessions: the trainer can be a member of the system development team or an outsourced specialist trainer.
Peer training:
Online training such as tutorials and help systems: (usually sample files)
Operation manuals

Testing, Evaluating and Maintaining: Aspects of this stage continues throughout the life of the system
Testing to ensure the system meets the requirements:
Acceptance tests: Formal tests conducted to verify whether or not a system meets its requirements. It enables the client to determine whether or not to accept the new system
Volume data: test data designed to ensure the system performs within its requirements when processes are subjected to large volumes of data
Simulated data: tests the performance of systems under simulated operational conditions.
Live data: the actual data that is processed by the operational system.

Trialling and using operation manuals:
Operation manual: a step-by-step description of each task and decision that should be accomplished to perform specific system processes

Ongoing evaluation to monitor performance:
Evaluation: the process of examining a system to determine the extent to which it is meeting its requirements
Technical performance: evaluates the continuing achievement of the systems evolving requirements
Financial performance: evaluating the extent to which the new system is achieving its economic goals

Ongoing evaluation to review the effect on users participants and people within the environment:
Decreased privacy:
Changes in the type and nature of employment:
Health and safety concerns: ergonomics: The study of the relationship between human workers and their work environment
Little or no sense of accomplishment:
Deskilling:
Loss of social contact

Maintaining the system to ensure it continues to meet requirements 1. Regular maintenance 2. Repairs when faults occur

Information Systems and databases:
Information system: produces information from data for use by the system’s end-users
Purpose: the aim or objectives of the system. Fulfils the needs of the users.
Environment: circumstances and conditions that surround an information system. Everything that influences or is influenced by the system
Participants: people who perform or initiate information processes (use the system)
Information Technology: the hardware and software used by an information system to carry out its information processes
Information processes: the steps of operation required to transform data into useful information.
Honour
Organisation Methods:
Organising: The information process by which data is structured into an appropriate format for the use of other information processes.

Organisation of Flat-file Databases:
Flat-file database: A single table of data stored as a single file. All rows (records/tuple) are composed of the same sequence of fields/attributes
Data types: Data type | Description | Size | Integer | Exact whole number | | Decimal/ Fixed – Point | Exact fixed decimal point number | | Real /Float | Fractional numbers with a very large scale | | Money/currency | Exact integer scaled to four decimal places | 8 bytes | Boolean/ bit | Yes/no, true/false | 1 bit | Date/time | A number representing a specific date | 8 bytes | Text/character | String data represented as individual characters | Each character = 1 byte | Binary/ BLOB(binary large object | Raw binary data, used to store non-numeric data | |

What to consider when deciding between text or numeric:
Is arithmetic operation going to be performed?
The data type determines how the data will be stored and processed
Will be sorted alphabetically or numerically
Text data:
Is there a limit to the number of characters that will be entered?
Unicode or ASCII, Unicode 2 bytes – used for foreign language symbols, ASCII 1 byte
Numeric data:
Will it be an integer? Are the values currency
Non-computer Examples of Flat-files:
Telephone book, filing cabinet

Relational databases: a collection of two-dimensional tables where the organisation of each table is almost identical to a simple flat file database.
The logical organisation of relational databases:
Tables: the basic building block of all relational databases
Tables are also known as entities or relations
Primary key: a field or combination of fields that uniquely identifies each record (usually single integer field) e.g. ID
Candidate key: Any single field or combination of fields that uniquely identifies a record
Composite key: more than one primary key

Relationships: creates a join between the primary key in one table and a foreign key in another.
Foreign keys: contain data that must match data from the primary key of another table.
Database schemas/ERD(Entity Relationship Diagrams): technique for displaying the relationships within a relational database.
One to One: rarely used, used to improve performance and reduce storage. One record is associated with another
One to many (1:m): For each record in the primary key’s table there can exist multiple records in the foreign key’s table.
Many to many(m:m): resolved by creating a joint table with to 1:m relationships
Recursive relationships: when an attribute of a table is joined to the primary key within the same table
Referential Integrity: ensures each foreign key matches its primary key.

Normalising Databases:
Normalisation: The process of excluding redundant data
Redundant Data: Unnecessary duplicate data
First Normal Form (1NF): removal of repeating attributes across horizontal rows and ensured each field holds single data items (Full name to first and last name)
Second Normal Form (2NF): removes redundant data within vertical columns or fields (uses ID, assigning primary key)
Third Normal Form (3NF): further removes redundant data within vertical columns or fields. (Creating tables and assigning new primary keys)

SQL: A programming language that uses a set of commands to extract information form database files.
Insert: used to create new records as part of the collecting information process.
Delete: used to delete record and record data
Update: used to change specific data items at the same time in many places
Metadata: data defining data
Meta tag: describes data within a web page

URLs (uniform resource locators): used to identify individual files and resources on the internet. http://www.w3.org/ protocols /overview.html
Protocol Domain Name Subdirectory path filename

Protocol: identifies the format and method of transmission to be used
Domain name/host name: name of the website
Storage and retrieval:
Data independence: The separation of data and its management from the software applications that processes the data
Storage Hardware:
Direct access: ability to go to any data item in any order e.g. DVD
Sequential access: data must be received in a linear sequence e.g. magnetic tape
Online storage:
RAID (redundant array of independent disks)
Includes striping and mirroring
Striping: splits data across hard disks
Mirroring: backing up data on more than one disk.

Securing Data:
Aims to: * Prevent data loss or corrupted * Prevent unauthorised access.

Encryption & Decryption:
Keys: used to encrypt and/or decrypt
Symmetrical/single key encryption: same key for encryption and decryption
Asymmetrical/public key encryption: the public key is shared and used for encryption; the private key is never shared and used for decryption.

Search: To look through a collection of data in order to locate required data
Sort: to arrange a collection of items in some specified order.
Logical operators: AND, OR, NOT

QBE (Query by Example): A visual method for specifying a query

Centralised databases: A single database under the control of a single DBMS. All users and clients applications connect directly to the DBMS
Distributed: A set of connected databases stored on multiple computers that appears to users as a single computer

Screen report and design principles:
Consistency of design:
Grouping of information:
Use of white space:
Sensible use of colour and graphics:
Legibility:
Data validation: A check, at the time of data collection to ensure the data is reasonable and meets criteria
Effective Prompts:
Issues related to information systems:
Acknowledgement of data sources:
Access, ownership and control of data:
Accuracy and reliability of data: * Data integrity: A measure of how correct and accurately data reflects its source. The quality of data * Data verification: A check to ensure the data collected and stored matches and continues to match the source of the data

Current and emerging trends:
Data warehouse: A large, separate combined copy of different databases used by an organisation. It includes historical data, which is used to analyse the activities of the organisation
Data mining: The process of discovering non-obvious patterns within large collections of data
Online Analytical Processing (OLAP): provides statistical evidence based on passed trends. (Products, customers & dates)
Online transaction Processing (OLTP): allow transaction to be processed immediately by remote users. E.g. PayPal

TPS (Transaction Processing Systems):
Transaction: multiple events that must all succeed or must all fail. Events perform actions that create and/or modify data.
Characteristics of TPS:
Automation of manual system:
Disadvantage of manual system: * Time consuming * Human errors can occur * Redundant data can occur * Difficult to manage * No backups
Advantage of Automated system: * Faster * No calculation errors * Backups and restores can be performed
Disadvantage of Automated system: * Expensive start-up costs * Training is required * Component failures
Components of TPS:
Participants: anybody who directly interacts with the transaction processing system (operators/customers) Data/information: data is transformed into information by the system’s information processes. A transaction log stores details of the transaction and prior to the transaction. Can be used to roll back system
Transaction file: store data collected prior to batch processing A master file is actual live data.
Information Technology: * Hardware: screens, tape drives, tape libraries, CD/DVD burners, NICs * Software: client application, DBMS software, TPM (Transaction Processing Monitor)- mange transactions that span multiple databases, systems and client applications

ACID Properties: transactions must obey ACID
Atomicity: To ensure transactions succeed completely or fail completely e.g. Bank withdrawal
Consistency: data is never inconsistent
Isolation: transactions don’t affect each other
Durability: Results of a completed transaction are permanent

Real Time (online) Processing (RTP)or OLTP: The immediate processing of data e.g. library loan system * Must be completed within a few seconds otherwise the user will abort. * Require fast direct or sequential access to secondary storage, more secure communication links and more processing power than batch processing.

UPC (Universal Product code): a 12 digit number printed with an equivalent barcode on the products packaging. Uniquely identifies different products.

Batch Transaction Processing: The collection and storage of data for processing at a scheduled time or when there is sufficient data.
Transactions will be stored (usually on magnetic tape or paper) until it is convenient or economical to process them
Advantage:
* Can run on a regular schedule, without human operators * Set-up costs are lower and processing is not as demanding in batch systems. Updating data only when all data is ready keeps costs minimal whilst personnel need is greatly reduced. Carried at times when resources are least used such as night.
Disadvantage:
* All processes must wait until a predetermined schedule time * If an error occurs in one of the tasks it will halt immediately * Errors cannot be corrected during processing. The batch process must be restarted from the beginning to correct errors. * Must have exclusive access over files, they cannot be shared with any other operator * Sorting data is expensive and time consuming * Doesn’t provide data that is fully current

User interaction includes: * Preparing and/or collecting data prior to batch processing commencing * Correcting errors after batch processing has completed * Scheduling when batch jobs she be performed

Backup and Recovery:
Backup: to copy files to a separate secondary storage device as a precaution in case the first device fails or data is lost
Recovery: Whereby a backup copy of the data is restored or copied back into the operational system.

Full and Partial Backups:
Full Backup: a complete copy of all data within the system. Longer period to backup but easier to restore
Partial backups: 2 types
Incremental Backup: making partial backups that copy all files that have changed or been created since the last full or partial backup. Faster, uses less space.
Differential Backup: uses partial backups to make copies of all files that have been altered or created since the last full backup.

Backup media:
Magnetic tape: slow and sequential but inexpensive and portable.
Hard disks:
Optical media:
Online systems: data is transferred via the internet to a secure remote location.

Backup Procedures:
Grandfather, Father, Son (GFS): Each time a new backup is made it become the “son” and the previous “son” becomes the “Father” and the previous “Father” becomes the “Grandfather” and the previous “Grandfather” is either archived or recycled
Round Robin: The rotations of a number of tapes sequentially.
Towers of Hanoi: To move all disks to the third pole, however you can only move one disk at a time and larger disks cannot be placed on top of smaller disks.

Collection Hardware In TPS:
RFID (radio frequency identification): electronic system for identifying items using radio waves. E.g. toll roads, keyless entry systems etc. allow individual items to be tracked e.g. post and courier systems. Greater advantage over barcode system because RFID tag can be hidden within the product but have to be in rage for RFID reader. * MICR (magnetic Ink Character Recognition): used by banks to read account number on cheques. Characters are printed using magnetic ink that contains magnetised particles. Magnetic sensor. Either waveform or matrix. Waveform for low speed MICR readers. Matrix for high-speed MICR readers. * Magnetic stripe Readers: Have 3 parallel tracks, magnetic sensor. Use (LRC) Longitudinal redundancy check which calculates an odd parity bit in each character within the data
Track 1: contains same as track to plus the card holders name 210bpi (Bits per Inch) 7bits per character
Track2: contains primary account number and other details unique to the card issuer. 75bpi 5bpc
Track3: rarely used, contains rewritable data e.g. details of offline transactions. 210bpi 5bpc

Collection from forms:
Form: document used to collect data from a person
Paper Form: Written on to provide data and then processed
Onscreen Form: Usually completed for data entry to populate databases
Web Form: For users wanting to purchase products off the internet
Screen design for online data collection: * Drop down menus, radio buttons, command buttons, check boxes. * Use of colour, alignment, white spaces, images etc.
Analysing data in which output is used as input in other system:
Management Information Systems (MIS): transforms data within transaction processing systems into information to assist in the management of business operations. E.g. sales performance, payroll, budgets. The MIS shares the data from a TPS, which is then manipulated to create reports/forecasts.
Decision Support Systems (DDS): assist people in making decisions by providing information, models and other analysis tools.
Enterprise Systems: Any system that performs processes central to the overall operation of an enterprise.

Issues Related to TPS:
The changing Nature of work: workers are required to learn new skills and complete ongoing training or face being replaced by a more skilled worker.
The need for alternative non-computer procedures: must be checked and tested.
Bias in data collection: Bias unfairly influences the outcome
Data security issues: protects systems against accidental or deliberate damage * Passwords * Backup copies * Physical barriers * Encryption * Firewalls
Data integrity issues: quality/accuracy of data * Data validation * Data Verification * ACID properties * Minimising data redundancy
Data quality issues: the reliability and effectiveness of the data * Data quality assurance (DQA) standardises the definition of data and includes processes that scrub or cleanse existing data so it meets these data quality standards
Control and its implications for participants: the act of influencing or directing activities.