Software development

Question 1

What are the 5 stages of software development in the Software Development Life Cycle?

Answer 1

1. Analysis
2. Design
3. Implementation
4. Evaluation
5. Maintenance

Question 2

What is the analysis stage of the SDLC?

Answer 2

• this is where the problem to be solved is defined + system requirements
• for any problem takes into consideration: data to be used, procedures, problems with current solution and any future plans
• documentation produced = systems specification or user requirements - outlines what the system will do but not how to make it
• info gathered using interviews, questionnaires, observation at current system + looking at existing documentation

Question 3

what is the feasibility study?

Answer 3

• part of analysis stage
• assessment of whether the project is practical and makes sense to do
• considers: is there appropriate tech, can it be operated + maintained easily after production, can it be financed, is it legal, does it have a market, can it be produced reasonably quick
• useful as it identifies any issues and resolves them or drops the project completely if it isn’t deemed worth it

Question 4

what is requirements analysis?

Answer 4

• part of analysis stage
• outlines the requirements of the project
• gathered through interviews with users, questionnaires, observation of current system usage + looking at current system documentation
• important because it clearly and unambiguously defines what the user wants the software to do and creates a specification
• analyse strengths and weaknesses in the current system + consider inputs, outputs, stored data and amount of data

Question 5

what is the design stage of the SDLC?

Answer 5

• it’s when info gathered during the analysis stage is translated into a blueprint for programmers to follow during implementation
• test plan is formed here
• key aspects: description, database format, inputs, outputs, security features, hardware features and user interface
• features high level and low level design

Question 6

what is high level design?

Answer 6

• system architecture is defined
• components (modules) of the system are identified + relationships between them established
• descriptions of hardware + software interfaces + UI

Question 7

what is low level design?

Answer 7

• detailed guide formed after high level design
• much more comprehensive - covers specifics of each module + goes through each one’s logic in detail
• addresses different algorithms, data structures + interfaces
• ensures accurate + efficient implementation of required functionality

Question 8

what is the implementation stage of the SDLC?

Answer 8

• when code for the software is written, it is tested and installed on user’s machines
• can be very long or short depending on methodology used - complete when all code has been written to achieve required functionality
• problem is divided into modules that perform an individual task and assigned to a team member to code in the appropriate programming language
• code will continue to be edited until testing is complete

Question 9

what are some testing strategies?

Answer 9

• black box testing
• white box testing
• alpha testing
• beta testing

Question 10

what is black box testing?

Answer 10

• carried out independently of code (not using internal structure)
• produce and test a set of test data that covers all potential input and program functions based on specification and checks that outputs are valid
• done by company or end-users from user perspective
• good to check all requirements are satisfied + non-specialist can use it

Question 11

what is white box testing?

Answer 11

• test data is derived from source code (focus on structure not function)
• tests that program logic works throughout and makes sure that every possible path through the code is tested at least once
• good to make sure program works and is at peak efficiency
• doesn’t help find missing functions - you can only test what has been written

Question 12

what is alpha testing?

Answer 12

• done by in-house software development team + user
• reveals errors + omissions in system requirements definition or misunderstandings of requirements by the developer
• software might do something the user doesn’t want it to do
• aims to find and fix unspotted bugs before being released to the public

Question 13

what is beta testing?

Answer 13

• used when commercial software is being tested (eg. Windows, Word, etc)
• testing an unreleased program with a teeny bit of the intended audience - users agree to report any issues to developers
• good because it exposes product to real world and find bugs programmers didn’t find
• afterwards product is modified + further beta testing until satisfied
• done towards the end of testing period

Question 14

what is deployment?

Answer 14

• part of implementation stage
• done once other testing is complete to a satisfactory level
• product is installed on user systems + more testing is done
• any new issues are corrected
• may be done in a graduated manner so not all users face issues simultaneously
• do this when all target users get access to the product

Question 15

what is the evaluation stage of the SDLC?

Answer 15

• aka acceptance testing
• often involves post-implementation review - 6 months after product release
• delay between deployment + evaluation to allow users to get used to the product
• this and month end reviews allow the chance to see whether the product has fulfilled original requirements + identifies any shortcomings
• product can be adjusted if any issues found
• solution should be evaluated based on effectiveness, usability and maintainability

Question 16

What are the 3 types of maintenance?

Answer 16

• corrective maintenance
• adaptive maintenance
• perfective maintenance

Question 17

What is corrective maintenance?

Answer 17

This is when any bugs found after software is released to the general public have to be patched - this will always happen no matter how much testing is done

Question 18

What is adaptive maintenance?

Answer 18

This is when software is adapted to adjust to changing user requirements, for example as a result of development of new technology

Question 19

What is perfective maintenance?

Answer 19

This is when software is improved in non-essential ways even if the software still works - for example by improving functionality, UI, etc

Question 20

What is the waterfall software development methodology?

Answer 20

• one of the oldest models - not quite redundant but nearly there
• mainly used for small projects where requirements are well defined and there is no changing technology
• follows all the steps of the SDLC but only moves onto the next stage once the previous stage is done and documentation is produced
• it is possible to go back to a previous stage if needed but you can’t skip any

Question 21

What are the advantages of the waterfall model?

Answer 21

• it’s simple to understand and straightforward to manage the project
• self contained stages mean team members clearly know what to do

Question 22

What are the disadvantages of the waterfall model?

Answer 22

• time consuming + expensive to go back and fix an issue
• not much client input beyond analysis stage so they may end up with a product that doesn’t satisfy their requirements
• no working software produced until late into the cycle

Question 23

What is the spiral model?

Answer 23

• made up of 4 basic steps: analyse, design, implement, evaluate
• repeatedly go through these steps and produce a prototype at the end of each iteration
• evaluating each prototype helps produce a plan for the next prototype
• requirements are defined at the start and each successive loop around the spiral produces a more refined product until it’s complete
• mainly used for medium to high risk objects with evolving or complex requirements and for long term projects

Question 24

Advantages of the spiral model?

Answer 24

• well defined steps make it easy to manage
• software is produced at an early stage - issues identified quickly + easily
• user feedbacks fairly often - changes made early on + end result is closer to what they expected

Question 25

Disadvantages of the spiral model?

Answer 25

- time consuming + expensive to do each iteration and produce a prototype - not good for small projects - needs a large team

Question 26

What is the agile software development methodology?

Answer 26

- often used for smaller projects as a faster more efficient variation of the spiral model - software is developed in rapid incremental cycles known as sprints - each version builds on the previous version and is thoroughly tested - doesn't need much planning to get started - lack of emphasis on documentation since client is heavily involved - best used for small projects that are part of a bigger project or in developing business where customer needs are constantly changing - 4 stages: plan, develop, test, demonstrate

Question 27

What are the advantages of the agile model?

Answer 27

- rapid continuous delivery of useful software + lots of engagement between customers, developer and testers = high customer satisfaction - much quicker than other methodologies - software is produced in weeks, not months - high customer involvement = software produced makes the customer happy

Question 28

what are the disadvantages of the agile model?

Answer 28

- requires an experienced team of programmers (novices must be mentored) - lack of emphasis on documentation can become an issue - customer dissatisfaction if they haven't been clear about requirements - can't incorporate features that would be good for later because the focus is on what is needed now

Question 29

what is extreme programming software development methodology?

Answer 29

- type of agile software development but working in even shorter cycles where working code "releases" are made rapidly and the user feedbacks on it - the speed aims to improve productivity + quality + introduce checkpoints here new/changed customer requirements can be introduced - 5 values: courage, simplicity, communication, feedback, respect - 5 rules: planning, managing, designing, coding, testing (emphasis on coding stage) - you need a really small team of up to 12 people for this to work - best for large projects with a short deadline and changing requirements

Question 30

what are the advantages of extreme programming model?

Answer 30

- saves money + time on project realisation - focus on delivering products, not producing documentation - simpler methodology - code can be improved at any point - constant feedback from customer - they get a product they are happy with quicker

Question 31

what are the disadvantages of extreme programming model?

Answer 31

- lack of focus on design + documentation may lead to issues with code + mistakes being repeated in the future - doesn't really work if programmers are separated geographically

Question 32

what is rapid application development (RAD) software development methodology?

Answer 32

- short development cycles with a focus on making working software and a prototype more refined than the previous one (refined based on user feedback) - workshops and focus groups gather requirements - no formal requirement document - each part of the system will be produced in a short time frame - not perfect, but good enough - reuse any software components possible - best used for long projects with both user and technology requirement changes - it is much easier to incorporate changes at a late stage with this methodology

Question 33

advantages of RAD model?

Answer 33

- cheaper - fewer developers needed - faster - reuseable components of code higher customer satisfaction - their feedback is incorporated - shorter development cycles make it easier to incorporate changes

Question 34

disadvantages of RAD model?

Answer 34

- uses powerful tools to speed up development process - needs skilled professionals + too expensive for small projects - if there are no reusable components to e project could fail - if the project can't be modularised properly RAD can't be used

Question 35

what could go wrong during a long project?

Answer 35

- personnel change - requirements change - technology changes - costs increase - project could get cancelled

Question 36

What is an algorithm?

Answer 36

A set of instructions to solve a problem or complete some well defined task in a finite number of steps Eg. making a cup of tea

Question 37

what are the properties of a good algorithm?

Answer 37

- clear and precise steps that produce the correct outputs for any valid input - should allow for invalid inputs - must terminate at some point - execute efficiently in as few steps as possible - should be designed in such a way that other people would be able to understand it and modify it if necessary

Question 38

what are some examples of computational algorithms?

Answer 38

- Internet related algorithms - to manage and manipulate all the data stored on the internet - route-finding algorithms - eg. to find the best route to transmit packets of data from A to B over a network when there are 1000s of options - compression algorithms - used to compress data files so they can be transmitted faster or held in a smaller amount of storage space - eg. MP3 files - encryption algorithms - you have to encrypts someone's personal details when they do online shopping to make sure it isn't intercepted or read because it's sensitive data

Question 39

What is a trace table?

Answer 39

- it is used to dry run a program and see how the algorithm flows - the table has columns for each variable + processes + output - as you go through the algorithm in the way the computer does, note down in the trace table what values change and how