kstruct

Based on the 6th edition of ‘Software Engineering’ by Ian Sommerville, published by Addison Wesley. (amazon.com, amazon.co.uk)

Computer-based system engineering is introduced by Sommerville as a discipline sitting above software engineering and encompassing hardware systems to take a whole system perspective. The introduction of hardware systems bring in a number of aspects such as the physical environment of the system, which need to be considered and controlled. Another key aspect is the consideration of system properties which exist within the system as a whole (emergent properties). Sommerville provides some examples these emergent properties, such as the overall weight of a system (which could be computer from the weights of all the subsystems), and the usability of the system (which would have complex dependencies on the hardware, software the system’s environment and indeed the system’s users).

Though it’s not actually relevant, I’ll wander off on that last point as I’ve always been quite interested in usability (being a Mac user). Simplistic views of usability have always really frustrated me. I remember once reading a really high level requirements specification written by a client which said something along the lines of ‘The system should be user friendly - what more is there to say?’. Actually, there’s a lot. Who are these users? Can we assume they can use a computer? If not, maybe I should be getting out of the way so someone can design a paper based system. What are the usage patterns in the system? A system which users will work on without any training needs to be designed very differently to a system people will use day in and day out. In the end, what the client really meant here was that usability was an important factor for the system, which I would agree with whole heatedly, but downplaying the complexity of usability just makes it more difficult to allocate the time it requires.

(more…)

Another week, another bug.

Earlier this week, I was counting up the number of times I was going to be volunteering at Floriade and came up with a bigger number than expected. Eventually I worked out that the problem was that I was double counting events at the beginning and end of the month because they showed up without indicating they were outside the current month.

(more…)

Our second show is coming up in a couple of weeks time, and it’s also the graduation show for a whole new stage 1 class, so it should be a lot of fun. The stage 2 class, which I will have finished by then, has been great, and hopefully I won’t crash and burn.

Anyway, Sunday October 2^nd at 7:30 pm in the Street Theatre. $15/$12, and by the sounds of it they won’t be able to take cards, so it’s cash only.

There’s also a flyer included in the ‘rest of this entry’.

(more…)

So, another round of Australian iTMS rumours, and with any luck, we’ll get an actual launch this time. I don’t even mind if two of the major record companies aren’t on board.

(Though if I were a band, I certainly wouldn’t want to be with a label who was refusing to be a part of it)

In fact, if it’s Sony BMG and EMI who are the problem, I’ll quite happily boycott them entirely until I can buy their music for an Australian iTMS. Now it’s not as though I buy a lot of CDs to begin with, so I doubt I’ll actually be hurting them in a noticeable way, but at least I can feel like I’m doing something.

Anyone else care to join in?

The main reason being bandied around for why the labels are holding out is that they want a tiered pricing structure, where ‘hit’ songs are more expensive than others. Looking at the current charts, I don’t think I care too much if they do, since I doubt I’d be buying many ‘hit’ songs.

I’m tempted for my bug this week to be “Hey, I entered a bug last week through the public form but still haven’t got my bug tracking number!”, but I guess I’ll give them a bit longer (and I’ve fixed my ADC account, so it shouldn’t be a problem this time).

Anyway, my bug for this week is a UI one I don’t seriously expect to see solved any time soon but happened to annoy me earlier this week.

You can probably already see where I’m going.

(more…)

Being a Mac guy, I really enjoyed Robert X. Cringely’s interview with Andy Hertzfeld (although in retrospect, the video didn’t really add much and if I had my time over I’d probably just get the audio).

There’s too much in there for me to go through it all, but the story of Knuth and the Mac Paint source was great, some of the open source software stuff was really interesting (especially the agrarian revolution point, Robert made) and the idea of Microsoft owning Switcher is quite scary.

I was a little surprised that they both see Adobe as a really strong technical company. I guess Adobe isn’t really on my radar, given that I don’t really do much of that graphics stuff, so that was interesting to hear.

Anyway, it’s worth checking out if you’re interested in that sort of thing (I’m looking forward to the Steve Wozniak one, and hoping Andrew Tridgell gets in at some point). Oh, and if you’re ever in Canberra Andy, I’m sure I could round up quite a few people who’d like to have dinner with you.

Well, I can’t say I’m entirely shocked that others can’t reproduce this, but just to prove my sanity, here’s a screen shot.

Actually getting that screen-shot turned out not to be quite as trivial as I initially expected, since it seems good old Apple-Shift-3 doesn’t capture the cursor (without which that screen shot is kinda meaningless). A quick search turned up the mostly useful Screenshot Hacks for Mac OS X page (I’d completely forgotten about grab.app), which was great until I found Grab didn’t show the cursor. Anyway, to cut to the chase, Grab.app has a preference which lets you choose the cursor to display in the screen shot, which defaults to none. No idea if it’s always been that way.

Anyway, for those who can’t reproduce this, one question. I can reliably drag from the left menus into the right, but never back (or from the right into the left). Do other people see the same, or is it a symptom of the same problem?

Update: Thanks to Simone Manganelli for a useful rundown of what sounds like the same bug. It doesn’t quite explain the inconsistency (i.e. I can sometimes drag from the time menu to the user one as in that screen-shot without a problem), but it sounds like those menus are generally problematic.

I just made my first contribution to ‘Report-an-Apple-Bug Friday‘. The bug is the inconsistent behaviour of the right hand menus (like the time, switch user, battery and volume menus). When selecting one of them and dragging to another, sometimes the other one opens (as expected), and sometimes doesn’t. I haven’t been able to decern a reliable pattern, but playing with them for a minute or so reproduces the problem quite easily (at least for me).

For some reason, my ADC account (admittedly I haven’t used it in quite a while) wouldn’t let me log into the bug reporter so I used the public one but that one hasn’t sent me a bug id yet, but I’ll add it here when it does.

And while we’re on bugs, what’s up with this bit of the form? Maybe that’s one for next week.

I’ve been fiddling with some AJAX functionality at work lately, and was stuck for quite a while on a weird problem. All the input fields were blanked when clicking back into the app, meaning that we lost all the state the user had built up when they clicked out then came back.

It seemed odd to me, but not having done anything with AJAX in the past, I assumed that was normal until I went into research mode and found this outline of AJAX client side session information storage. Of course, that article didn’t help much at first, since it completely contradicted what I was seeing, but that contradiction eventually lead me to dig back through the code.

Anyway, for what it’s worth, it seems that input field values aren’t re-populated when clicking back into a page unless they are contained within a form.

For what it’s worth, having an input outside a form seems to be allowed by the HTML spec (or at least the W3C validator accepts it). In the long run I would have had to add a form to let the app fall-back when there was no javascript, but it looks like I would have saved a bunch of time if I’d done it upfront.