CHAPTER 1 - SYSTEM FUNDAMENTALS Flashcards
System life cycle
The stages through which the development of a new system passes through
5 stages of system life cycle
Analysis, Design, Implementation, Operation, Maintenance
Why is new system created
To replace inefficient old system, fix default/defects, increase quality of output/productivity of the system
Requirements needed for a new system
Internet, RAM, operating system, hardware, software
Limitation of new system
- end users not being able to use the system properly
- data migration is time consuming
- memory issues and data clashes when system is developed/tested
- maintenance is costly overtime
Potential organizational issues in planning of a new system
- lack of attention to required training
- lack of attention to organizational issues
- lack of stakeholder and end-user participation
Whats a feasibility study
study that evaluates and analyzes a project and its potential based on TELOS criteria: Technical, Economical, Legal, Operation and Scheduling
Planning
process of thinking about various details and organizing the activities required to achieve the desired goal
Whats TELOS criteria
Technical: Is existing technology appropriate to implement proposed system
Economical: Is it cost-effective
Legal: Is it against any laws/regulations
Operational: Is existing organizational practices sufficient to maintain and operate system
Scheduling: How long will we wait
What is change management
Involves various parameters and is the process of shifting existing individuals, teams and departments from an existing to desired state; goal is to maximise benefits and minimize negative impacts of the change on individuals
What is a legacy system
Old technology, hardware or computer system
Why are legacy systems still used
- Data cannot be converted to newer formats/applications cannot be upgraded
- System provides users needs even if newer systems exists
Outline one problem of maintaining legacy systems
Continuous patching, updating and upgrading of the old system to look out for any bugs/errors
4 strategies to integration
- Replace both information systems with a new one (high initial cost)
- Keep both information systems and develop them to have the same functionality (high maintenance cost)
- Select one company’s computer system and discard the other (policy problems)
- Select best info system from each company and combine them (workers may have difficulties working with a system from another company)
Software incompatibility
a situation where 2 different software systems cannot operate cooperatively/individually in a same computer or different computer linked by a LAN/WAN (network)
SaaS “Software as a Service”
a contemporary delivery method that allows software and data to be hosted & managed centrally on a remote datacenter.
Example: Powerschool/Netflix; basically just a software that offers a service
Features of SaaS
- Subscription: users have to pay to access services provided
- Uses a multi-tenancy model: single software and its supporting infrastructure can serve multiple customers
- Uses cloud service to store customer data (which reduces data loss risks)
Limitations to SaaS
- Possible data loss if SaaS provider goes out of business
- Involvement of a third party i.e. SaaS provider which risks user data privacy
- Uncertainty of data’s location: customers have lower access to their personal data; usually stored away in datacenter
- Risk of identity theft: the providers often require credit card payments for subscription; may not provide better identity management security/poor firewall
- Connectivity requirement: SaaS model is based on web delivery, if internet service fails, loses access to software data
- Access management: if design of the access control system is inefficient, a single act of accessing the cloud service can expose confidential data
Distinguish between Phased and Direct changeover
Phased conversion method is when the new system is implemented/introduced per module to the whole company. If the particular program/module is proven satisfactory, another module will be introduced until the system is introduced completely. With this approach, the training period is extended and the adoption of the new system takes longer since it is implemented separately at different times. On the other hand, direct changeover is very risky since the company replaces their old system with a new one immediately. With this approach, all users require proper training before the switch takes place, in order to use the new information system efficiently.
Direct/Big Bang changeover
instant from old to new
Parallel changeover
old and new is run side by side; only when output of new is proven satisfactory then the old system is terminated
Pilot changeover
the whole system is introduced to one branch/department of the company and its performance accessed before being introduced elsewhere in the company
Phased changeover
the new system is introduced per module to the whole company, only when its proves satisfactory then the next part is introduced - until the old system is fully replaced
Data migration
transfer data between different formats, storage types, computer systems; It usually takes place when a business changes, upgrades, or merges its computer systems
Possible problems during data migration
- Data loss: due to incomplete data transfers/ errors because of differences in International conventions concerning data time and measurement units
- Data incompatibility: information during data migration may not retransferred due to parameters such as incompatibility with the new systems/non recognizable data structures
2 types of main testing
Functional testing = test whether or not the features of the program (menu functions, individual commands, text input) perform according to design specifications. For example, the programmer wishes to test if the system’s function “add to client” brings them to the add client module
Data testing = involves using normal, abnormal and extreme data to test the system. For example, normal data “75” is used to test whether or not the output of the school’s marking system (with 60 as the middle range) will show “pass” or fail” messages appropriately
Alpha testing
- Testing the software before the product s released to public
- Tests by the company in lab type environment and not by end users in their usual workplaces
Beta testing
- include comments and suggestions from end users
- their feedback valuable to fix defects/errors of the program & contribute to the preparation of support teams who will deal with expected problem
Dry run test
conducted using pen-paper by programmer; run the algorithm mentally and decides on what the output of a run should be (execution)
Unit test
individual parts of the system are tested seperately
Integration test
entire system is tested at the same time to verify that all components work together
User acceptance test
determine if system meets user needs and conducted within the users premises before accepting transfer of ownership
Debugging
process of identifying and correcting errors/faults in a new system
Business merger
combining 2 or more businesses into a single corporation
Internal documentation
code comprehension features and details provided as part of the source code itself; example: appropriate module headers, appropriate code indentation, appropriate code structuring
External documentation
written as a separate document from the program itself; provided through various types of user supporting documents; user guide, software requirements specification document etc
Methods of providing user documentation
manuals, email support, live chat sessions, FAQs
Methods of delivering user documentation
online training, formal classes, self study
Data loss
error-condition where data is lost or destroyed due to system failure, storage negligence, or even transmission or processing errors
Methods to prevent data loss
regular backup of files, firewall installation, antivirus program
Reasons for data loss
Accidental deletion, building fires, computer viruses
Types of removable media used as fast data backups
Blu-ray discs, CDs, DVDs, USB
Failover system
a computer system which is on standby capable of switching to a spare computer system upon hardware, network failure or software malfunction; automatic and handles abnormal situations without human interference
Patches
used by software companies to update applications by fixing known bugs and vulnerabilities
Upgrades
contain novel/complex functionalities or characteristics, as well cumulative bug fixes
Updates
improves a product in a minor way by adding new functionalities or fixing known bugs
Releases
final, working versions of software applications
software
programs that control computer system/set of instructions guiding computer to perform specific tasks
hardware
physical elements of a computer
peripheral device
any auxiliary device that can communicate and work with a computer; extends capabilities of the computer system it is connected to
computer network
a set of computer systems that are interconnected and share resources and data
human resources
people who are used in an organization
firewall
hardware or software network infrastructure that controls data flow access among network entities
client
receives data via the network; average computer/terminal used to access a computer-based system
Domain Name System Server
attributes names to network addresses and therefore resolves names by assigning them to appropriate network entity; allows you to types names in to address bar of your web browser “mit.edu” then the web browser automatically finds that address on the Internet
server
program/computer that provides services requested by clients connected over a network
MFA (Multi-factor authentication)
authentication technique used to control computer access; authentication factors:
- something you know = passwords
- something you have = ATM cards
- something you are = biometrics
IT subjects of social and ethical significance
- reliability = how well an IT system functions
- security = protection of hardware, software, and computer networks from unauthorized access (biometrics, proprietary tokens, passwords etc)
- digital divide and equality of access = growth and use of IT systems have not developed at the same rate for all countries; even in advanced countries there are people who lack access to IT infrastructure
Stakeholders; mention the examples
Individuals, team, groups/organizations that have an interest in the realization of a project/affected by the outcome; e.g. end-user, manager, specialists, frequent user
Advantages and disadvantages of students having unrestricted access to PC
pros:
- allows students to learn at their own speed
- allows students to access information to help with their studies
cons:
- some sites do not give accurate information
- some sites encourage and facilitate illegal/inappropriate activities
Methods of obtaining requirements from stakeholders
- questionnaires
- interview
- direct observation
Describe one advantage and one disadvantage of using observations to gather information when planning a new system
Advantage: Direct observations makes the collection of different types of data and information possible. This is because the analysts are directly spending time on different departments, facilitating involvement of all activities and processes
Disadvantage: Observations are very time-consuming and expensive as you need to hire specialists to carry them out
What are questionnaires? What are closed/restricted and what are open/unrestricted?
carefully constructed questions that draw out unambiguous responses; survey methodology = domains of applied statistics that focuses on taking samples from a population and improve various data collection techniques
- closed/restricted questionnaires:
short response questions (yes/no), facilitates statistical analysis - open/unrestricted questionnaires:
free response questions, difficult to summarize and make statistical analysis impossible; yield more reliable information
What is interview? What is the difference between structured and unstructured interview?
direct fact-to-face procedure that focuses on obtaining reliable and valid data in the form of verbal responses from a person/group of stakeholders
structured: strictly standardized; presented in the same manner to each stakeholder
unstructured: flexible; encourage to express their thoughts and personal beliefs freely
What is direct observation
involves spending time in different departments and show where procedures and processes could be made more efficient or make the collection of different types of data and information possible
pros: familiarizes analyst with the project/case study
cons: time-consuming; hires analyst/specialist (extra cost)
System flowchart
a way of displaying how data flows in a system and how decisions are made to control events
Online processing
data processing performed by a single processor through the use of equipment that it controls; e.g. airline reservation
Real time processing
data processing performed on the fly in which the generated data influences the actual process taking place, e.g. aircraft control
Batch processing
data processing performed on data that have been composed and processed as a single unit, e.g. payroll
2 high-level computer languages that support modularity
Java, JavaScript
Prototype
a working/non-working preliminary version of the final product used as part of the design phase to demonstrate how the final product will work
Functions of prototype
- provides just enough of the concept for investors to decide if they want to fund the full production or not
- helps in the identification of problems with the efficiency or design
- increases system development speed
Iteration
repetition of a set of instructions for a specific number of times until operations yield a desired result
Accessibility
potential of a service, product, device or environment to serve and meet needs of as many individuals as possible
Usability
potential of a product, application, or website to accomplish user goals
Ergonomics
design of safe and comfortable products, systems or processes
state 2 usability problems
- buttons too small
- excessive keyboard used may lead to RSI (Repetitive Strain Injury) syndrome
- bright screens may cause eyesight problems
Methods to improve accessibility of systems
- touchscreens
- voice recognition
Environmental implications of interaction between humans and machines
- printed paper waste
- electronic waste contains chemicals that are harmful for the environment; ends up in landfills
Economic implications of interaction between humans and machines
digital divide between high and low income households (those who can and cannot afford) -> increased inequality & reduced opportunities for education, entertainment and income
Ethical implications of interaction between humans and machines
machines make human lazy and overusing can affect our mental and physical health
Moral implications of interaction between humans and machines
computers carry false information to humans without realising
Social implications of interaction between humans and machines
concerns that advancements in technology leads to unpredictable and dangerous situations which reduces involvement of humans; cause humans to become enclosed in virtual environments/limiting socialization
