Syntax diagrams (by alaric)

I've always liked syntax diagrams as a way of describing languages. They make it clear what options are legal in any given situation.

However, drawing them by hand is tedious, so after a moment's thought, I realised it would be pretty trivial to design a reasonable layout algorithm to generate them automatically.

And so, on a train journey, banterpixra was born!

It's quite simple. It takes a BNF-esque grammer, encoded in s-expressions like so:

(rule
 . (choice
    rule-label
    literal
    (seq "(elidable" " " literal ")")
    (seq "(optional" " " rule ")")
    (seq "(zero-or-more" " " rule ")")
    (seq "(one-or-more" " " rule ")")
    (seq "(seq" (one-or-more (seq " " rule)) ")")
    (seq "(choice" (one-or-more (seq " " rule)) ")")
    (seq "(optional-choice" (one-or-more (seq " " rule)) ")")
    (seq "(comment" " " literal " " rule ")")))

...and it turns it into a nice syntax diagram, rendered as an SVG file. I found producing an SVG to be a very easy way of generating vector images - SVG is quite a decent format to generate, and inkscape will happily convert .svg files to .png and .pdf from the command line, so it's easy to automate rendering.

The layout algorithm is quite easy. The BNF is parsed, and a tree of layout objects generated from the bottom up. Layout objects may contain other layout objects, recursively, and cover a rectangular extent of the two-dimensional plane. New layout objects are created at the origin, and then the parent layout looks at the sizes of the child layouts within it, and relocates them to appropriate locations within itself. When the layout object tree has been generated, it's processed top-down to generate actual SVG. Each different type of layout object renders its children recursively (unless it's a terminal, in which case it just renders itself at the chosen location), then it adds the arrows and lines that join the children together.

That's really all there is to it.

The output is quite decent, if your browser supports SVG!

Society (by alaric)

It's easy to sit and complain that Society Is Going To The Dogs, and hardly any harder to come up with somebody to blame (these days, immigrants and politicians are popular), and still well within the mental capacity of the average Daily Mail reader to come up with some satisfying-sounding radical proposals for what to do about it.

However, a society is a very complex system, and every change you make has complex consequences; nothing is quite as simple as it seems. Further complicating the situation is that any attempt to make your system of laws or government institutions more complex further complicates the analysis of subsequent changes; and, perhaps most pertinently, a society is not some beaker full of bubbling chemicals - the components of a society are sentient, some of them are even intelligent, and they are highly incentivised to make the best of their situation. In other words, people will figure out how to exploit systems, rather than working happily within the spirit of them.

People who are familiar with my approach to engineering solutions to problems will not be surprised to find that I suggest:

1. Forgetting all the cruft and historical baggage, and sitting down and carefully enumerating what you actually want from the system

2. Making the system as simple as possible (but no simpler), to reduce the scope for unexpected consequences

3. Using self-reinforcing negative feedback loops to maintain stability, while injecting noise to prevent stagnation in local maximae

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User Interfaces for Event Streams (by alaric)

Reading Phil Gyford's post about the reasoning behind his Todays Guardian app reminded me of an old interest of mine - the design of user interfaces that show people streams of events.

I hate the fact that I have several systems that have reason to throw notifications at me:

1. Incoming email (with multiple accounts)
2. Twitter (with multiple accounts)
3. RSS feeds I follow
4. Voicemails/SMSes
5. Notification of server failures and other such technical problems
6. Incomng phonecalls, Skype calls, etc
7. IMs and DMs in IRC, and people mentioning my name in IRC channels
8. People talking in channels I'm following in IRC
9. Scheduled alarms (time to stop working and eat!)
10. Batch processes have finished (I often start a long compilation/test sequence going then browse the Web for five minutes while it runs - then get distracted and come back twenty minutes later)

Many of these event sources are capable of producing events of different levels of urgency, too. It's really quite complex. Some things shout in my face (incoming skype messages cause a huge window to pop up over what I'm doing, for example) while some need to be manually checked (such as email; I get too much spam for the "you've got mail!" noise to mean much to me), and this has little correlation with the relative importance of them.

Obviously, the first thing to do is to have some standard mechanism in the user interface system for notifying me of events. Growl is a start, but it's focussed on immediate notifications, rather than handling a large backlog of events. What I want is something like my email inbox, that has a searchable, scrollable, history, and notifies me when new events come up. But I also want richer metadata than Growl has; I want all IMs, emails, and whatnot from the same person to be tied to that 'source' of events, so I can filter them into groups. I want to have Personal, Work, and Systems events, and to have Personal deprioritised during working and Work deprioritised during personal time. And so on.

The BlackBerry OS goes someway towards this with its integrated Messages system. Any app can register to put messages into the message stream, so when I get emails, BlackBerry IMs, notifications of new versions of software being available, etc. they all appear in the same time-stream and I get a 'new message' notification. I want something similar on my desktop, but with much more advanced filtering and display capabilities. My design for 'user agent' entities in ARGON involves using a standard "send an object to an entity protocol" for all email/IM/notification activities - the same protocol that is used to send print jobs to a printer, files to a backup system or removal storage device, orders to an automated process, and so on; it's roughly the equivalent of "drag and drop" in a desktop GUI. Incoming objects from 'elsewhere' are then combined inside the UA with internal events such as calendar alarms and situations the user agent might poll for, such as things appearing in RSS feeds, into a centralised event stream, by the simple process of translating all internal events into incoming objects like any other; but actually designing a user interface for displaying that is something I look forward to doing...

Phil's analysis of the newspapers interests me, because it's a very similar challenge. You have a stream of events, and the user may want to skim over them to see what's relevant then zoom into particular ones. How do you present that, and how do you help the user deal with an inundation of events, by applying heuristics to guess the priority of them and suitably de-emphasising or hiding irrelevant events, or making important events intrude on their concentration with an alarm? Priority is mode-dependent, too; if you're in an idle moment, then activity in your interest/fun RSS feeds should push out work stuff entirely - apart from important interruptions. And some events will demand my attention to respond to them, in which case they should offer me links to the tools I need to do that - a notification of a problem on a server, ideally, should carry a nice button that will open me up a terminal window with an ssh connection to that server. But some things might require my attention, but I can't give it yet - so I need to defer the task, so it doesn't then clutter my inbox, yet in such a way that it reappears when all higher-priority tasks are done. There are elements of workflow, where events need an initial "triage" to be categorised into "read-and-understood, do now, do later today, do whenever" and maybe prioritised, then later, deferred tasks need to be revisited.

Also, some event streams are shared. Perhaps an event should be handled by the first member of a team to be free, such as a shared office phone ringing, or a bug to be fixed or feature added to a software product. There needs to be some system for shared event pools, with support for events to be "claimed" from the pool by a person, or put back. Perhaps personal event systems should be able to contain proxy objects that wrap events stored in a shared pool somewhere, so they can be managed centrally as well as appearing in personal event streams along with events from other sources. Standard protocols would be required to manage this.

Looking at the relatively crude support for this kind of thing in even the supposedly integrated and smart combined email/calendar apps, I think there's a lot of fun research to be done!

Economic Crises hits the Public Sector (by sarah)

I'm very happy with Jean's school but yesterday we get a letter say that they do not have enough money to replace the teacher who retired nor to keep all the current stuff on full time. So the teachers have had to take an hours cut and the afternoon will see two classes instead of three.

They do not think there will be an increase in funding and infact there are cuts and expenses will continue to rise. Friends who are teachers are finding they are loosing their jobs as departments in secondary schools are honned down to a minimium. Graduate teachers are being employed as they are cheaper but as soon as they become experienced they to will find there are no jobs.

It would appear that 20 years experience is not needed and everybody will be fine with inexperienced teachers who though maybe good teachers are still very much going to be learning the ropes and now those colleges that could guide them through it are being turffed out of the system. Am I the only one who sees this as dangerous and damaging to our children's education?

More - if class numbers are rising in the village then what of the already stupid class sizes in the towns and cities? Are they going to be doing the same?

Large classes means that children can be lost in the mass and struggling or excelling get lost and not noticed. The children themselves see the school and teachers as a system around them rather than being apart of it - this leads to disruptive behavoiur as they develop the old US and THEM complex. Then we come to the safety issue - more children means more furniture cramped into the rooms and this means that regurdless of the fire door not being obstructed - there are more things to crash into, less room to move about - more territory disputes amongst the kids.

And of course the larger numbers results in a breeding ground for bullying - I am talking about education in general here.

I thought it was telling that the school can't see a change to these circumstances for the next 3 odd years.

I am wondering how Nurses, police and fire departments are fairing? I have already found out that most of the fire fighters are sort of part time hobbyist - ie they do it because they want to save lives on top of their actual job 🙁

Foundary to Close (by sarah)

Basically my favourite bar and art gallery in London is closing - this was where I had my 25th birthday (or was it the 26ths?), it is where Alaric used to take me to meet up with geeky people who knew when transits of space stations where going to happen and were to look even in the built up area. It is where my friends have had their art work displayed and where I was concidering doing an exhibition 🙁

Sucky sucky - and why? Is it not doing well? No! The site its on is being developed into a hotel and yet another main stream gallery - like we need any more of them especially in London :/

Anyway you can read more about it here.