Topic 1 - Systems Fundamentals Part 1

System Life Cycle - Stages

Planning and Installation; Design; Building/Development; Implementation (changeover); Evaluation/maintenance/testing

Why are new systems created?

Minimize costs, increase productivity and/or reduce errors.

What are the different kinds of feasibility tests?

TELOS - Technical, Economic, Legal, Operational, Schedule

Change Management

Maximize benefits while making sure things go smoothy during a change from present state to desired state.

legacy system

an old system that is fast approaching or beyond the end of its useful life within an organization

Business Merger

The combining of two or more business entities.

Strategies for Integration

1. Keep both systems and develop them in parallel.
2. Replace both systems with a new one
3. Select the best systems from each company and combine them.
4. Select one company's system and drop the other

SaaS

Software as a Service; a subscription service where you purchase licenses for software that expire at a certain date.

On Premise Software

Software installed on buyer's computers

Change over

The process of putting the new system online and retiring the old one.

Types of Changeover (4)

Parallel
Direct
Pilot
Phased

Parallel Changeover

a changeover approach that includes running the old system, then running both the old and new systems in parallel, and finally fully changing over to the new system after gaining confidence in the working of the new system

Direct Changeover

Immediate removal of an old system and complete replacement with a new IT system.

Pilot changeover

New system is trialed in a small part of business, once it's running correctly then new system is implemented across organisation

Phased changeover

a changeover approach where the older system is broken into deliverable modules; the first module of the older system is phased out using the first module of the new system, then the second module is replaced, and so on until the last module is replaced

Data migration

Transfer of data between different formats, storage types and computer systems.

Problems with Data Migration

Incompatible file formats
Data structure differences
Validation rules
Incomplete data transfers
International conventions on data, currencies & character sets
(I [FF], DS, V, I, IC)

Fundamental Testing

Tests individual commands/text input to confirm that the program functions correctly according to design specs

alpha testing

the firm attempts to determine whether the product will perform according to its design and whether it satisfies the need for which it was intended, done before the product is released.

beta testing

A process that releases commercial software in development to a cross-section of typical users who evaluate the program's features and report any problems or "bugs" in the software before it is released to the public.

Dry Run Testing

Conducted with a pen-and-paper method by the programmer and he/she mentally runs the algorithm in the source code

Unit Testing

tests individual units of code

Integration Testing

The entire system is tested at the same time to verify that all components can work together.

User Acceptance Testing (UAT)

determine if the system satisfies the user and business requirements

Debugging

The process of figuring out why code doesn't behave as expected and eliminating bugs to make it work as desired.

Validation

The process of evaluating whether the data input is appropriate for the program.

verification

Ensuring that the data input is the same as the original source data. When reading from a source(file, db, etc) we make sure that we are reading the correct information.

Purpose of documentation

Providing users with information about how a system works.
Informing other developers of reasons why code was included.

Internal Documentation

Inline code comments, code citations, class/functions headers

User Documentation

highlights how to use the system and how to troubleshoot issues or problems

Why is Proper Training Important?

Hard to take full advantage of new advanced technology
Mistakes can be caused by not understanding the system thoroughly.

Types of User Training

Self Instruction
Formal Classes
Online Training

Data Loss Causes

System Failure,
storage mistake,
incompatible data,
storage negligence,
natural disasters,
hacking.

How do you prevent data loss?

Regular backup of files
Installation of antivirus/protective software.

redudancy

Refers to systems that are either duplicated or that fail over to other systems in the event of a malfunction

Removal Media

CD's, DVDs, USBs, portable SSDs, etc

Failover System

System which will take over the role of a primary system if it fails.

Patches

Updating applications to fix known bugs.

Updates

Improving the product by adding functionality or fixing bugs.

Software Release

The final version of the software that has gone through alpha and beta testing.

Software

A program or instructions that give directions to the computer.

Hardware

The physical components of a computer.

Peripheral device

Devices that communicate with the CPU but are not located directly on the motherboard, such as the monitor, floppy drive, printer, and mouse.

Computer Network

Computers connected together for the purpose of sharing information and resources

Human Resources

People who work to produce goods and services

Client

A person using the services of a professional person or organization.

Router

A device that transfers data from one network to another in an intelligent way

Firewall

Part of a computer system that is designed to block unauthorized access

Client server

Network system that uses servers to store data centrally and client computers to access them.

End User

The person or group who will use the product produced by the project.

External Documentation Forms

User Manuals
Online Documentation
Email Support
Integrated User Assistance
FAQ
Live Chat
Online Portals
Remote Desktop Connections