[Year 12 SofDev] usability - NF requirement or constraint or both???

Robert Timmer-Arends timmer at westnet.com.au
Mon Dec 7 17:47:21 AEDT 2015


Hello all
>>>As for Mark's question about "something that is not a requirement still 
>>>could be in scope?"

A couple of perhaps silly examples:

  FR: we need the (modified) software to calculate the blah blah
  NFR: the calculation process has to involve minimal input from the 
operator
  Constraint: the calculation must take no longer than ...
  Scope: we will only modify the software; user documentation will not be 
included.

  FR: we need an on-line purchasing system that can blah blah
  NFR: it needs to cater for vision-impaired people
  Constraint: it must allow for all major credit cards
  Scope: we will only get it working in the Chrome browser

There is a lot of definitional slippage amongst these terms - rephrasing the 
scope statements above could make them a constraint or a non-functional 
requirement. Part of the difference, as someone has alluded to, is the 
difference between 'it must/must not' and 'we will/will not'.

Whatever the distinctions, the point of the exercise is to have a clear idea 
of what is going to be addressed by the solution and what is not, especially 
between user and developer. One of the main reasons for project failure is 
'scope creep'.

Regards
Robert T-A



----- Original Message ----- 
From: "Claudia Graham" <claudia.graham at overnewton.vic.edu.au>
To: "Year 12 Software Development Teachers' Mailing List" 
<sofdev at edulists.com.au>
Sent: Sunday, December 06, 2015 11:33 PM
Subject: Re: [Year 12 SofDev] usability - NF requirement or constraint or 
both???


Hi Heath,

Be careful the new study no longer has ‘benefits’ within ’scope’

  *   Determining the scope of the solution. The scope states the boundaries 
or parameters of the solution. It identifies the area of interest or what 
aspects of the problem will and will not be addressed by the solution.

Was teaching it last week and had to reteach – had students that did Apps in 
2015 and they kept talking about benefits.

Regards
Claudia
**********************************************************
Claudia Graham
VCE Coordinator
@ClaudiaG_Aus
9334 0049 (direct)

From: 
<sofdev-bounces at edulists.com.au<mailto:sofdev-bounces at edulists.com.au>> on 
behalf of Heath Matheson 
<Matheson.Heath.A at edumail.vic.gov.au<mailto:Matheson.Heath.A at edumail.vic.gov.au>>
Reply-To: Year List <sofdev at edulists.com.au<mailto:sofdev at edulists.com.au>>
Date: Sunday, 6 December 2015 11:07 pm
To: Year List <sofdev at edulists.com.au<mailto:sofdev at edulists.com.au>>
Subject: Re: [Year 12 SofDev] usability - NF requirement or constraint or 
both???

I’m often asked by students: “ I feel constrained by your requirements so 
does that make them constraints?”  I tell them something like “You may feel 
constrained, but a project can’t be constrained by what it has to do”. But I 
too find it pretty murky.

I think that since useability is “making something useable” it is a 
requirement. Constraints are either items you wish you had more of or laws 
you must follow. So security would be a requirement to meet a legal 
constraint.

I’ll just stick to my VCE IT motto and “don’t think too deep” which means I 
can rephrase and answer Mark’s question with scope has “benefits to users”, 
FR and NFR do not. :)

Heath Matheson
Mount Beauty

From: sofdev-bounces at edulists.com.au<mailto:sofdev-bounces at edulists.com.au> 
[mailto:sofdev-bounces at edulists.com.au] On Behalf Of Esther Andrews
Sent: Sunday, 6 December 2015 1:34 PM
To: Year 12 Software Development Teachers' Mailing List
Subject: Re: [Year 12 SofDev] usability - NF requirement or constraint or 
both???


I am glad I am not the only one who is confused about the overlap in these 
aspects.



When it comes to scope I ask the students to try to think of items that the 
client might WISH for (or even expect) but are NOT included, so they are 
like a list of Functional Requirements that will NOT be happening - probably 
because of constraints. It is necessary to ovoid conflict later in the 
project when the client says "Why didn't you do X/Y/Z ? I assumed it would 
be done!"



A constraint is something that will prevent you from implementing all of the 
things you would like to do. So I would say that usability could be a 
constraint if it means that there are features that will have to be left out 
of the Functional Requirements list because they are too complex for the 
special needs of the user (ie there's no possible way to implement that 
Feature so that it meets a NFR of usability).



As for Mark's question about "something that is not a requirement still 
could be in scope?"

Nope. That's too much for me on a Sunday... !

Anyone else?


Esther Andrews | Admin Systems Developer, IT and Maths Teacher
Bendigo Senior Secondary College
Box 545 | BENDIGO | Victoria  3552   Australia
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________________________________
From:sofdev-bounces at edulists.com.au<mailto:sofdev-bounces at edulists.com.au> 
<sofdev-bounces at edulists.com.au<mailto:sofdev-bounces at edulists.com.au>> on 
behalf of Mark <mark at vceit.com<mailto:mark at vceit.com>>
Sent: 06 December 2015 12:39
To: Year 12 Software Development Teachers' Mailing List
Subject: Re: [Year 12 SofDev] usability - NF requirement or constraint or 
both???

Hi Katherine.

I can see 'usability' being listed as an NFR in the sense that: 'The 
finished solution must be usable.'
It could also appear as a constraint on design choices for the same reason: 
'The solution must be designed in a way that makes it very usable for the 
end-user.'

Much of a muchness. There is some natural overlap in theory concepts.

For example, I still can't work out how scope is different to defining all 
FR and NFR.
If you have defined ALL requirements, is the scope not also defined?
Anything that does not appear as a requirement must be - by definition - not 
in scope.

Otherwise, listing things that are not in scope could go on til the crack of 
doom.

e.g.

Solution: A toaster

In Scope:
- Scorch bread.
- Scorch muffins.
- Scorch crumpets.

Not in scope:
- Train elephants.
- Predict hurricanes.
- Solve crosswords.
- Blend mangoes.
- Pat the cat.
- Take the wife out dancing.
etc

Can anyone give an example of how something that is not a requirement still 
could be in scope?

Regards
Mark



On 6 December 2015 at 08:59, Young, Katherine A 
<young.katherine.a at edumail.vic.gov.au<mailto:young.katherine.a at edumail.vic.gov.au>> 
wrote:
Hi all,

I’ve attached a graphic organizer that will hopefully get my kids thinking 
more carefully during their analysis of a problem, need or opportunity. Do 
others use something similar? I’d love to hear your feedback.

However, in doing so I realized that usability is listed as both a 
non-functional requirement AND a constraint. My brain had been thinking that 
a social constraint such the users’ level of expertise or some other 
"audience characteristic" would impose a non-functional requirement in 
relation to the usability of a solution.

Could someone please explain the difference between usability as a 
constraint and as a NF requirement? I know that I WILL be asked the same 
question :-/

Thank you!



Regards,


[cid:image001.jpg at 01D13075.E4756220]


Katherine Young
11C Mentor
Mathematics & Information Technology Teacher

Castlemaine Secondary College
Etty Street Campus
Etty Street
Castlemaine VIC 3450
T: (03) 5479 4222   |  F: (03) 5479 4230



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