Computer Science-System Fundamentals

Reasons to create a new system

\-it is outdated ,inefficient or redundant

\-in order to increase the productivity or quality of the system

\- reduce the errors and flaws of the existing

one

planning a new system

the process of thinking about various details and organizing the activities required to achieve the desired goal

*Planning should anticipate potential organization issues*

impact of planning

Lack of

-stakeholder and end user anticipation

-guiding organisational and business strategies

-attention to various organisation issues, such as culture

\-attention to required training

-end user ownership to a system

what is the feasibility report/study

Evaluates and analyses a project and its potential ,based on various technical, economical ,legal, operational and scheduling criteria. This is used to decide whether the proposed project should be pursued

Technical and Economic feasibility

TF: can existing technology work in the new system

EF: will it be cost effective

Legal and Operational Feasibility

\-does it follow the regulations/laws(i.e. GDPR)

\-do the existing organizational practices and procedures support the maintenance and operation of the new system

Schedule feasibility

how long will we wait

Systems Life Cycle stage 1-existing systems analysis

already existing systems are analysed for potential issues and how they can be solved with a new/ improved system

Systems Life Cycle stage 2-specification

The elements needed for the new system are identified and put into a specification that outlines what is required for the final system

Systems Life Cycle stage 3-software design

Different versions of the software are designed and then evaluated to see which one is best. The best design is then chosen for creation

Systems Life Cycle stage 4-testing and debugging

The product is tested for issues within the software, if these are found then they are fixed

Systems Life Cycle stage 5-Maintainance

The system is checked often to see if there are any issues. If issues are found, these are fixed

What is change management

the process of moving organisations, teams, individuals and departments from the present state to a desired state

why is change management needed

maximise benefits and limit the negative impacts of change on individuals

Legacy System

an old technology, hardware, computer system and application program. Some systems in this category can still be important in organizations.

Why are Legacy Systems Used

Data cannot be converted to newer formats

Apps cannot be updated

The exchange of data between new and legacy systems is a factor that the administration needs to pay special attention to

Business merger

the merging of 2 or more business entities

4 strategies for integration

\-Develop both information systems to have the same function(high maintenance)

\-Replace both information systems to a new one(increased initial cost)

\-Select the best information systems from each and combine them (difficult for employees)

\-Select one and drop the other(policy issues)

Parallel Changeover

both systems work in parallel for a period of time-this allows for gradual change from the old system to the new system, method is very popular due to limited risk

\-pos: if the new system fails the company can revert to the old system

\-neg: running 2 systems simultaneously isn’t cost efficient, method may not also be efficient if the 2 systems are completely different

Big Bang/Direct Changeover

the old system is terminated and the new one is implemented at the same time

\--it is important to make sure staff are trained before implementing the new system

\--may also be issues if the new system doesn’t work as expected

neg: very risky method for the company, should only be done if the system isn’t critical

Pilot

only used in larger organisations with multiple sites. the system is tried out at one of them, if they are satisfied it is implemented to all the other sites over time (usually with direct changeover)

Phased

the system is changed one module at a time, meaning different parts are converted at different times

neg: very slow, adoption of the new system takes longer

Changeover Definition

the process of removing/retiring the old system and implementing the new one

Locally hosted System

a server used for business software to operate, this works on larger and more complex systems

Remote hosted system

a server used for business software to operate, this works on systems that don’t require hardware equipment

What is SaaS (software as a service)

a service that allows software and data to be managed centrally on a remote datacentre; Users pay a subscription for this, this is usually on the cloud and requires internet connection

3 benefits of SAAS

\-cheaper than other options

\-requires few it technicians and few software updates

\-compatible with lots of devices/ a wide range of devices support it

3 drawbacks of SaaS

\-the performance of a web browser is lower with SaaS

\-there is data loss if a SaaS provider goes out of business

\-SaaS integration with other SaaS solutions or software is difficult

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what happens without proper user documentation

\-programs and systems may become increasingly complex as their aim becomes more and more complicated

\-the product functions may not be as clear to the user as the users way of thinking may be different to the developers

\-this may lead to serious problems in the implementation/operation stages of the systems life cycle

\-users may not know how to use the product to its full capacity and even specialists may struggle

List 6 things user documentation should include

\-appropriate use of constant identifiers

\-appropriate comments

\-appropriate code structuring and indentation

\-useful and meaningful variable names

\-appropriate use of data types defined by the user

\-appropriate module headers

List 6 methods of user documentatio

-Email support

-live chat sessions

-FAQ’s

-embedded/integrated user assistance

-manuals

-Online/web portals

Verification vs Validation

Validation: the process of evaluating whether data input follows appropriate specifications and is in reasonable limits

Verification: the process if ensuring the data input is the same as the original source.A way of ensuring this data verification is double entry

Types of testing: Functional Testing, Data Testing,

Functional Testing: Tests each element individually to confirm that they perform and function correctly.

Data testing: normal, abnormal and extreme data is put into the system

Normal:data should be accepted

Data at the limits:data at the boundary of being accepted

Extreme-data that is outside the normal limits, should be rejected when tested

Abnormal:data that is not expected to be entered

Alpha, Beta and Dry-run Testing

-done before the software is made available to the general public, will be carried out by the company that develops the software

-includes comments and suggestions of the users, users outside the company are involved too, this feedback is valuable and can also be used to fix defects and errors

-conducted by hand, the programmer mentally runs the algorithm, they then examine the source code and decide on an output

Integration, User-Acceptance Testing and Debugging

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

-determines if the system satisfies the customer needs and is conducted in user premises before accepting transfer of ownership

-the process of finding and correcting the number of bugs in a computer program, there are computer programs that automatically

Different methods of delivering user training

self instuction, formal classes or online training

→ the developers of the new system have to create clear educational material for solving any question that a user may have

→the ways that it may be executed depends on: number of students, availability of instructors, the size of the business and the training budget

Data Loss (Definition)

an error condition where data is lost or destroyed due to systems failure , storage negligence, or even transmission or processing errors 

List 4 causes of data loss

-Accidental Deletion

-Physical damage

-Administrative errors

-Data Corruption

2 consequences of data loss

Retrieval can be time consuming

Retrieval may not be possible or can be impractical in some cases

Preventing data loss

-Regular System Backup

-Firewall installation

-Install antivirus

-Storing data in multiple locations

Ways in which updates can be made available

Patches-update software by fixing known bugs and vulnerabilities.However, they have side effects such as introducing new bugs

Updates-update software by adding new fuctionalities of fixing known bugs.Mostly free.

Upgrade- always contain novel functionalities or characteristics as well as cumulative bug fixes.Mostly need to be bought

Releases-final woring versns of software. These have alrady gone through alpha and beta software testing

Hardware and Software

-the physical elements of a computer e.g screen, monitor, CPU etc.

-a series of instructions that can be understood by a CPU, it is comprised of both programs and data

Peripherals

any auxillary device that can communicate and work with a computer e.g mouse, keyboard, printer etc

Computer Networks and Human Resources

-A series of computer systems that are interconnnected and share resources and data eg LAN

-People who are used or could be in use in an organisation,business or economy

Roles that a computer can take in a network Client, thin client and email server

client: recieves data via the network

thin client: a relativeky low performance terminal, which is heavily dependent on the server

email server-manages the flow of email in and out of a network, essentiallly an epost office

Roles that a computer can take in a network Firewall, Router,DNS server, Dumb terminal

Firewall- hardware/software controls data flow access among network entities

Router- a networking device that accepts incoming quantities of devices

DNS server-attributes names to network addresses and therefore resolves namnes by assigning them to the appropriate network entity

Dumb Terminal-a device that usually consists oof a keyboard, a monitor and a network card that is connected to a server or powerful computer

Stakeholders(Definition)

-individuals, groups, teams or organisation that have an interest in the realisation oof a project or might be affected by its outcome

-can also be someone that uses the system often.They will be able to identify flaws and issues in the current system and propose improvements that can be vital to the update of the system

Applications Software (Definition)

Programs designed for the end user that ennable the completion of various tasks in order to increase productivity

Word Processors and Spreadsheets

- Used for the production of any document, and has tools for composition, editing, formatting and printing of documents

-used for the organisation and analysis of data, which is represented in cells organised in rows and collums

Database management systems and Web Browsers

-manages databases (an organised collection of data) and is designed to provide an interface between users and a database

-Used to access, retrieve and present content on the world wide web. Things acessed on web browsers may be identified with URLs, which connect to web servers and requests wanted information and send it back to the web browser

Email

allows for the sending and receiving of digital messages from a single author to one or more recipients.In order for an email to be transferred SMTP is used

Computer Aided Design and Graphic processing software

-A software application that assists engineers to create, modify, analyse and optimise a design.It’s purpose is to increase productivity of the designer and the quality of the design.

-allows a user to manipulate visual images on a computer.Users can manipulate images in various ways such as moving, cropping and scaling

What is Data Migration

Transferring data between formats, storage types and/or computer systems when switching to a new system/ changing/ upgrading/ merging

4 types of incompatibility issues that can arise due to data migration

-Non-recognisable data structures and formats- result in a mismatch of data, e.g. in  customer records 

-Data lost or corrupted during transfer due to transmission faults/lack of adequate storage. Not usable at destination 

-Data misinterpretation due to conventions in different countries e.g. date, measurements,  currencies 

-Different validation rules between companies- could lead to inconsistent/incorrect results  Might not be able to use data while transferring, problem if it's large and takes long

Explain 3 methods of user documentation

-Help files: Easy to access, cheap, can't be misplaced, no internet needed

-Online documentation: Easier to use and search through, can have email support and  can update documentation later. However, access limited by internet connection

- Manuals: Printed manuals can be accessed any time (even if system not yet installed) and  not restricted by internet connection but can't be updated. Digital manuals more cost efficient and eco-friendlier but online ones restricted by internet connection.

Data Loss (Definition)

an error condition where data is lost or destroyed due to systems failure , storage negligence, or even transmission or processing errors 

List 6 causes of data loss

Accidental Deletion

-Firmware corruption

-Physical damage

-Continued use after signs of failure

-Administrative errors

-Data Corruption

2 consequences of data loss

Retrieval can be time consuming

Retrieval may not be possible or can be impractical in some cases

Preventing data loss

-Regular System Backup

-Firewall installation

-Install antivirus

-Storing data in multiple locations