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computer science ocr a level > 1.2.3 software development > Flashcards

1.2.3 software development Flashcards

1
Q

what does SDLC stand for

A

Software/Systems Development Life Cycle

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2
Q

what is SDLC

A
  • number of distinct phases programmers work through when developing a solution to a problem for a computer system
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3
Q

outline the stages of the software development lifecycle (F, R, A+D, I, T, D, E, M). Then explain briefly what is involved in each stage.

A

-Feasibility (is problem solvable)
- Requirements (work out what solution needs to do)
- Analysis + Design (work out how solution needs to do it
- Implementation (code solution)
- Testing (check it works)
- Deployment (install in target environment)
- Evaluation (check with user that solution is complete)
-Maintenance (ensuring it continues to function. improve by patches/updates)

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4
Q

define software development methodology

A
  • arrangement of distinct phases and how programmers move from one phase to another (forwards or backwards)
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5
Q

what are the five methodologies i need to know

A
  • Waterfall
  • Rapid Application Development
  • Spiral
  • Agile
  • Extreme Programming
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6
Q

describe the waterfall lifecycle

A
  • each phase has a well-defined start and end with identifiable deliverables
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7
Q

positives of waterfall lifecycle

A
  • clear responsibilities at each stage
  • simplicity = easy to manage
  • clear deliverables
  • possible for different parts of team to be geographically remote
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8
Q

drawbacks of waterfall life cycle

A
  • if requirements change part way through project, previous stages must be repeated delaying project
  • caries risk
  • end user doesnt see project until end
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9
Q

what type of project is waterfall lifecycle suited to

A
  • large projects with static, well understood requirements and one carrying little risk
  • not suitable for complex projects
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10
Q

how has a slight evolution of waterfall model changed what it allows you to do

A
  • allows you to move back to previous phases as well as forwards (reflects fact that developers often have to rework earlier stages in light of knowledge gained as development progresses)
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11
Q

what is RAD methodology

A
  • involves producing successive prototypes of software until a final version is produced and approved
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12
Q

what follows initial approval of a feasible program (RAD)

A
  • increasingly refined prototypes made with reduced functionality which are designed, coded + tested then evaluated with end user until final working solution is achieved.
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13
Q

what happens if user wants prototype to be improved

A
  • further improvements needed –> starts new iteration (analysis, design, coding, testing, evaluation)
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14
Q

positives of RAD

A
  • continuous feedback from client means solution likely to have good usability
  • requirements dont need to be entirely clear
  • focus groups involving user can be used to gather requirements without need for full formal requirement document upfront
  • can be confident end product meets users needs
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15
Q

drawbacks of RAD

A
  • little attention paid to program efficiency due to focus on usability
  • doesnt scale well
  • can overrun initial budgets due to being agile approach
  • regular contact with client must be maintained
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16
Q

what type of project is RAD suited to

A
  • smaller projects where there is ready access to an end user
  • projects where initial requirements not fully understood as iterative nature prevents side tracking of development
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17
Q

what is the spiral model

A
  • risk-driven development methodology
  • acts as more of a guide for development teams allowing them to adopt elements of one or more other methodologies like waterfall or RAD
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18
Q

what are the 4 stages of the spiral model (each taking up one quadrant of the spiral).

A
  • quadrant 1: Objectives and requirements determined
  • quadrant 2: risks and issues. A prototype is then developed
  • quadrant 3: this prototype tested.
  • After this the project is either complete or if the user wants more the final quadrant works on what will go into the next spiral.
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19
Q

is the spiral model a fixed process that is followed in correct order (true or false)

A
  • false, spiral model order is dependent on project and its unique risks
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20
Q

positives of spiral method

A
  • prioritises risk management and can handle changes in requirements
  • suitable for high risk applications
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21
Q

drawbacks of spiral method

A
  • if risk analysis done badly, project will suffer
  • complex nature of risk analysis increases costs (risk management is a highly specialised skill)
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22
Q

what projects is spiral best suited for

A
  • large, high-risk projects without tight time constraints and one where user doesnt fully understand their requirements upfront
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23
Q

what is agile devlopement

A
  • group of methodologies which focus on idea that requirements will shift and change during development - this can only be dealt with by producing software in an iterative way
  • they’re a more refined form of older concepts behind RAD
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24
Q

what idea is at the core of agile methodologies

A
  • building each iteration in sprint cycles
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25
Q

what are sprint cycles (agile)

A
  • short, time-boxed periods (no longer than 1-4 weeks) when a team has focused goals to complete a set amount of work
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26
Q

positives of agile

A
  • adapts to users needs –> final system tailored to meet end user requirements
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27
Q

drawbacks of agile

A
  • continual collaboration needed between software developers and end users
  • hard to determine timescale and outcomes early on
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28
Q

what types of project is agile best suited to

A
  • projects where initial requirements are hard to determine from outset and in which end user can play active role in development process
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29
Q

what is extreme programming

A
  • not so much of a software methodology as it is a framework that encourages regular, small iterative software releases
  • designed to allow development to
    respond to changing user
    requirements.
  • its an example of an agile software development methodology
30
Q

what does extreme programming aim to produce?

A
  • aims to produce very high quality code and promote developers quality of life by encouraging them to adopt a set of common practices that focus on values of: Simplicity, Communication, Feedback, Courage and Respect
31
Q

what is at the core of extreme programming

A
  • at its core are the concepts of collective ownership and every team member being of equal value
32
Q
  1. how many core XP practices are there
  2. how many of these boost the overall quality of completed solutions for any project
A
  1. 12
  2. 5
33
Q

what are the names of these 5 core XP practices that boost the overall quality of completed solutions for any project

A
  • collective code ownership (everyone in charge of code)
  • continuous integration
  • code standards
  • refactoring (revisiting old code and repurposing)
  • paired programming
34
Q

what is paired programming?

A
  • idea of two programmers sitting side by side at one computer while code is written. One drives + other analyses giving instant feedback. They would switch roles often.
  • Although it sounds expensive it’s claimed this approach produces higher quality code sooner –> saving time + effort later on.
35
Q

how many of the 12 core XP practices can you name

A
  • test-driven development
  • simple design
  • refactoring
  • continuous integration
  • code standards
  • customer tests
  • whole team
  • small releases
  • planning games
  • collective code ownership
  • paired programming
  • sustainable pace
36
Q

give positives about XP

A
  • emphasises programming so quality of code likely to be high
  • core principles and processes promote respect and collaboration leading to productive development team
37
Q

give drawbacks about using XP

A
  • requires team of programmers of close collaboration (hard if team distributed geographically)
  • client must be able to fully commit to having full time representative working with development team
  • paired programming can be costly
38
Q

what project type is extreme programming suited for

A
  • when emphasis of project is on quality of finished code
39
Q

what is an algorithm

A
  • a sequence of steps designed to perform a task
40
Q

what is a flow chart

A
  • one way of representing sequence of steps in an algorithm in diagram form
41
Q

what is pseudocode

A
  • simplified, generic programming code which is an alternative, text-based method of representing the sequence of steps of an algorithm
42
Q

why do we use pseudocode

A
  • allows us to lay down logic of a problem in an “almost-like-real-code” way without worrying about rules and syntax of a particular language
43
Q

what are the flowchart symbols

A
  • oval = terminal
  • rectangle = process
  • arrow = control passing (flow) between connected shapes
  • diamond = decision
  • parallelogram = input/output operations
  • rectangle with lines on either side = subroutine
44
Q

any non-trivial program must be what (beginning with t) and why

A
  • tested to ensure it works as intended
45
Q

to fully test a solution, developers need to adopt a number of different testing strategies.

Name the 4 different testing strategies

A
  • black-box testing
  • white-box testing
  • alpha testing
  • beta testing
46
Q

what is black-box testing

A
  • not concerned with how program works but checks whether every possible input produces expected output
47
Q

fill the gaps:

with ______ - box testing, code ____________ isn’t important as long as ______ return desired ______

A
  • black
  • efficiency
  • inputs
  • outputs
48
Q

what is a drawback of black-box testing

A
  • every possible input can’t always be tested as it’s often not feasible like if there’s an infinite amount of inputs such as numbers
49
Q

if there is an infinite amount of input and you are using black-box testing, how should you test inputs give desired output

A
  • choose appropriate test data to cover a range of situations
50
Q

what is white-box testing

A
  • involves testing algorithms in code and ensuring all parts of those algorithms function as intended
  • also checks overall efficiency of code
51
Q

what does white-box testing focus on

A
  • identifying and testing all possible paths of execution through a program
52
Q

white-box testing:
what happens on each successive test run?

A
  • on each successive test run, the path of execution is noted so it can be compared with other runs
53
Q

when are alpha and beta testing carried out

A
  • when software is nearly ready for release and can be tested as complete solution
54
Q

when should you use alpha and beta testing and why?

A
  • commercial software testing such as games
  • developers want wider community audience to test product
55
Q

what are the 2 differences between alpha and beta testing

A
  • when they take place
  • who performs the testing
56
Q

alpha testing:

  1. when they take place
  2. what state is the software in
  3. who performs the testing
A
  1. occurs first
  2. very early version of finished software is tested so could contain bugs
  3. limited to internal employees and their friends and family
57
Q

beta testing:

  1. when they take place
  2. what state is the software in
  3. who performs the testing
A
  1. occurs after alpha
  2. almost-finished state
  3. testing opened up to wider community through a public beta program
58
Q

what do developers test in beta testing

A
  • developers test areas like load balancing and multiple hardware compatibility
59
Q

what is the order of the testing strategies once development of software started

A
  • start of development
  • white-box testing
  • black-box testing
  • alpha testing
  • beta testing
60
Q

when testing data, what types of data should you test (4 types)

A
  • no data (special case)
  • erroneous / invalid data
  • normal / typical / valid data
  • boundary / extreme / edge data
61
Q

what is erroneous / invalid data

A
  • data that should be rejected by program
62
Q

what is normal / typical / valid data

A
  • data that should be accepted by program, without causing errors
63
Q

what is boundary / extreme / edge data

A
  • data of correct type that is on either edge of accepted validation limits
64
Q

what is tracing execution / performing dry runs

A
  • vital skill for understanding program flow and testing accuracy of an algorithm for logic
65
Q

what does tracing execution / performing dry runs involve you doing?

what should you use in order to track programs flow

A
  • involves examining a printed extract of code and running through program one line at a time
  • trace table
66
Q

what is the purpose of a trace table

A
  • taking each line at a time and writing out the current state of each variable, noting any output program produces in order to track down logic errors in a program
67
Q

in the trace table, what should each variable have

A
  • its own column
68
Q

when should a new row be added to the trace table

A
  • if state of a variable changes
69
Q

when should you gain user feedback

A

at regular intervals throughout development of software

70
Q

why is regular feedback from user about a project being worked on so important

A
  • keeps project focused
  • ensures software being developed for client is the actual system they need
  • provides opportunities for discussion (could push project further)
  • makes user feel part of finished solution

computer science ocr a level (15 decks)

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