Paper 1 - Comp Sci Topics 1-7

SaaS (Software as a Service)

SaaS (Software as a Service)

Software distribution model in which applications are hosted by a vendor or service provider and provided to customers over a network

Four types of system changeover

Parallel running, pilot running, direct changeover and phased conversion

Parallel Running

Both the old and new system run at the same time

Pilot Running

One section of the business is trying out the new software while one keeps using the old one

Direct Changeover

Moving straight from the old to new system

Phased Conversion

Slowly implementing the new software

Debugging

Identifying and removing errors from computer hardware and software

User documentation

Documentation to support users of computer systems including hardware and software

Methods of user documentation

• Manuals

• Live Chat

• Remote Desktop Connection

• Embedded Assistance

• Email Support

• FAQs

• Web Portals

Possible causes of data loss

• Power Outages

• Defective Hard-Drives

• System Crashes

• Malicious Activities

• Human Error

• Physical Damage

• Data Corruption

• Firmware Corruption

Consequences of data loss to individual users

Can lose personal information (ex. address, social security number, health information or bank account information)

Consequences of data loss to companies

Can lose reputation/customers, may be sued/have to pay fines

Methods of Prevention of Data Loss

• Failover Systems ('ready-to-go' server with backups if old one goes offline)

• Redundancy (data duplication i.e. RAID systems)

• Removable Media

• Offsite Storage

• Online Storage

• Physical Security

• Antivirus

Strategies for managing/releasing updates

Automatic updates, manual updates

Hardware

Anything within a computer that you can physically touch

Software

A collection of programs and instruction that control the computer

Peripheral

Devices attached to the computer that allow interation and the exchange of information (ex. keyboard, mouse, screen)

Network

A group of computers connected together to share resources such as documents and printers

Human Resources

The humans operating the computer

Operating system

Help people interact with the computer system and manage how the hardware, programs and data interact

Client

A computer accessing resources hosted by another computer/the server

Server

A computer hosting resources to be shared across the network

Firewall

Protects the network traffic, decides what gets access and what doesn't

Benefits of surveys

(Research) Little time, simple, large amounts of data

Drawbacks of surveys

(Research) Hard to ask the right questions

Benefits of interviews

(Research) Detailed information, customizable questioning

Drawbacks of interviews

(Research) Time consuming, demand characteristics

Benefits of direct observations

(Research) First hand, unbiased information

Ergonomics

The study of people's efficiency in their working environment

Accessibility

How the system can be accessed for information exchange and operation

Ways to improve the accessibility of a system

Touch screens, voice recognition, text to speech, braille keyboards, braille printers

System

A set of interacting parts that operate together to achieve some objective or purpose.

Three Stages of a System

Input Process Output

Factors organizations need to consider when changing computer systems

needs, limitations, user roles, cost, underlying technologies.

Why change management is required

Accomplishes change in the most efficient manner while minimizing the impact on an organization. Provides training and support for staff. Ensures that a consistent approach to change is used. Ensures that proper planning, designing, and testing of proposed change has occurred. Lowers the total cost of IT services.

Legacy system

Is an outdated computer system, programming language or application software that is used instead of available upgraded versions

Legacy system compatibility issues

Will legacy software run on new hardware? Is the format of the legacy system data compatible with new software? Can the legacy system be used with new technologies?

Business merger compatibility issues

Is the data from each company compatible? How is the data from each system going to be integrated? Transformation of data from one system to another. Companies may not be using same application software. Businesses may not have same change management policies.

Considerations for Systems Analysts

• legacy system & its flaws

• purpose of new system

• hardware/software requirements

• ethical implications

Change Management

a structured approach to ensure that changes to a system are thoroughly and smoothly implemented and focuses on the impacts on change on the end user in order to minimise any issues related to the change

On-premise Software

unlike SaaS, this type of systems implementation involves the software being installed / hosted locally on company machines located within their facility as opposed to externally

Two categories of Documentation

• User Documentation

• Technical Documentation

Types of Data Testing

• Normal (regular, should be accepted)

• Boundary (at the limits of acceptability)

• Extreme (unacceptable to system, should fail)

• Abnormal (data in a wrong form i.e. a string instead of integer)

Types of System Testing

Alpha, Beta, Dry-run, Unit, Integration, User Acceptance

Alpha Testing

Carried out by the developer in a 'laboratory type' environment on test subjects, not real end users

Beta Testing

Having potential consumers examine a product prototype in a real-use setting to determine its functionality, performance, potential problems, and other issues specific to its use

Dry-run Testing

Pen-and-paper method by the programmer that mentally runs the algorithm in the source code to check if the program achieves the same result

Integration Testing

Verifies that separate parts of the system can work together

User Acceptance Testing

To determine if the system satisfies the user and business requirements

Methods of user training

• Self-instruction

• Formal classes

• Remote/online training

Release

The initial launch / version of a software package

Update

A software file that contains fixes for problems found by users or the software developer or small improvements

Patch

Type of software update that fixes problems in an existing software program. Usually meant as a temporary solution until a more comprehensive update can be released

Continuous Delivery

A methodology that focuses on making sure software is always in a releasable state throughout its lifecycle

Agile Development

A software development methodology that delivers functionality in rapid iterations, measured in weeks, requiring frequent communication, development, testing, and delivery

DevOps

The practice of blending the tasks performed by the development and IT operations groups to enable faster and more reliable software releases

Server

A computer that provides client stations with access to files and printers as shared resources to a computer network

Client

A computer that requests data stored on a server.

Hub

the connection point for devices on a single network. network devices and computer systems connect to a hub using Ethernet cables that attach to a port.

Switch

the connection point for multiple devices on a single network. unlike a hub, the switch can identify which network device is connected to which port.

Router

a more sophisticated device than both a hub and a switch. its use is to join multiple networks and serve as an intermediary between these networks so that data can be exchanged effectively.

LAN

Local Area Network. A small group of computers connected, usually over a very small area. Copper cables. high data transfer rates

MAN

Metropolitan Area Network. Networks over a larger area, city-size, connecting computers and LANs. Sometimes with fibre optics.

WAN

Wide Area Network. Network over large geographical areas, often across continents. Most common WAN is the internet. Connects to many computers.

VLAN

Virtual Local Area Network. Computers behave as if in LAN but in reality they are far apart in different network, where they tunnel into a virtual LAN. Done when playing online computer games.

WLAN

Wireless LAN, just with radio wave connections instead of wires. Slower than LAN.

GAN

Global Area Network. The nodes are spread out globally.

WPAN

Wireless Personal Area Network. (Bluetooth). Consists of computers, phones, tablets, etc.

Extranet

Your home computer can access your work network. Can be considered a restricted internet in a certain environment.

Intranet

In a school. We can see out to internet, but internet cannot see in. (Like one way mirror)

Internet

The name for world wide web.

P2P

Peer to peer. All computer systems in the network are decentralized and are both clients and servers at the same time, consuming and supplying resources from and to the other computer systems on the network.

SAN

Storage Area Network. Network which provides dedicated access to storage. (own storage device, not wider network) appears as a device to OS.

LAN vs WLAN Similarities

Both act on a local level. Both allow communication. Both used to connect devices. Both allow sharing of resources.

LAN vs WLAN Differences

They use different transmission medium. LAN is safer. LAN is faster. WLANs offer greater flexibility.

LAN vs VLAN Similarities

Both act on a local level. Both have same attributes. Both allow communication. Both used to connect devices. Both allow sharing of resources.

LAN vs VLAN Differences

VLAN delivers better performance. VLAN is safer. Formation of virtual workgroups is easy. VLANs offer greater flexibility. VLANs are independent on the medium and the physical topology. Sometimes the management/administration of a VLAN is complex.

Standards

Common rules providing "international language" enables compatibility for all computer systems around the world

OSI Model

Open system interconnection model defines a networking framework to implement protocols in seven layers. (to communicate)

Physical (Layer One)

Provides mechanic, electric and functional help to activate and deactivate physical connections. How a bit is transferred across a medium, transmits as 0s and 1s.

Data Link (Layer Two)

Ensure faultless transmission of data. Error handling of physical transmission. Amends transmission rates according to buffer of receiver.

Network (Layer Three)

Handles routing of packets across a network through devices to reach destination.

Transport (Layer Four)

End to end connections. Definition of data segments - assignment of numbers - data transfer - reassemble of data at the destination.

Session (Layer Five)

Manages sessions between two users.

Presentation (Layer Six)

Provides data format information, data compression information and data encryption information to the application.

Application (Layer Seven)

Performs various services for the applications used by the end users.

Please Do Not Teach Students Pointless Acronyms

Physical, Data (Link), Network, Transport, Session, Presentation, Application

TCP/IP Model

Describes all the functions that take place at each layer of protocols within the TCP/IP suite. Hierarchical model protocol that models and represents all the functionality required for successful communication between users.

OSI and TCP/IP

The OSI Model and the TCP/IP Model are two separate network protocol models. They can be used separately or together.

VPN

A virtual private network makes a "tunnelled" connection through the Internet or any other public network.

Hardware and Software of VPN

Internet Access, VPN Software, VPN Routers, VPN Appliances, VPN Concentrators.

Secure VPN

All traffic must be encrypted, authenticated and then sent along virtual tunnels.

Internet protocol security protocol (IPsec)

Secure transmission over public IPs. Standard encryption algorithm provide confidentiality Authentication via digital certificates.

Secure Socket Layer or Transport Layer Security

Doesn't need special client software. All web servers and browsers support this method of providing a VPN.

Remote access VPN

Connects individual hosts to private networks and facilitate teleworkers who need to access their company's network securely using the Internet.

Use of a VPN

VPNs gave rise to home offices as it allowed workers to connect to a company's internal network. For example, a mother can work from home that their own speed in time to pick her kids up from school.

Benefits of a VPN

Communication is easier, companies take advantage to provide secure connections, improves overall productivity, offers flexibility to remote offices.

Protocol

a set of rules that defines the rule and conventions for communication between network devices.

Data packet

A unit of data in a form suittransfer between computers that communicate on a network.

Source integrity

• Identity of sender has been validated

• Digital signatures verify identity.