Alan’s blog

Names and naming have always been a big issue both in computer science and philosophy, and a topic I have posted on before (see “names – a file by any other name“).

In computer science, and in particular programming languages, a whole vocabulary has arisen to talk about names: scope, binding, referential transparency. As in philosophy, it is typically the association between a name and its ‘meaning’ that is of interest. Names and words, whether in programming languages or day-to-day language, are, what philosophers call, ‘intentional‘: they refer to something else. In computer science the ’something else’ is typically some data or code or a placeholder/variable containing data or code, and the key question of semantics or ‘meaning’ is about how to identify which variable, function or piece of data a name refers to in a particular context at a particular time.

The emphasis in computing has tended to be about:

(a) Making sure names have unambiguous meaning when looking locally inside code. Concerns such as referential transparency, avoiding dynamic binding and the deprecation of global variables are about this.

(b) Putting boundaries on where names can be seen/understood, both as a means to ensure (a) and also as part of encapsulation of semantics in object-based languages and abstract data types.

However, there has always been a tension between clarity of intention (in both the normal and philosophical sense) and abstraction/reuse. If names are totally unambiguous then it becomes impossible to say general things. Without a level of controlled ambiguity in language a legal statement such as “if a driver exceeds the speed limit they will be fined” would need to be stated separately for every citizen. Similarly in computing when we write:

function f(x) { return (x+1)*(x-1); }

The meaning of x is different when we use it in ‘f(2)’ or ‘f(3)’ and must be so to allow ‘f’ to be used generically. Crucially there is no internal ambiguity, the two ‘x’s refer to the same thing in a particular invocation of ‘f’, but the precise meaning of ‘x’ for each invocation is achieved by external binding (the argument list ‘(2)’).

Come the web and URLs and URIs.

Fiona@lovefibre was recently making a test copy of a website built using Wordpress. In a pure html website, this is easy (so long as you have used relative or site-relative links within the site), you just copy the files and put them in the new location and they work Occasionally a more dynamic site does need to know its global name (URL), for example if you want to send a link in an email, but this can usually be achieved using configuration file. For example, there is a development version of Snip!t at cardiff.snip!t.org (rather then www.snipit.org), and there is just one configuration file that needs to be changed between this test site and the live one.

Similarly in a pristine Wordpress install there is just such a configuration file and one or two database entries. However, as soon as it has been used to create a site, the database content becomes filled with URLs. Some are in clear locations, but many are embedded within HTML fields or serialised plugin options. Copying and moving the database requires a series of SQL updates with string replacements matching the old site name and replacing it with the new — both tedious and needing extreme care not to corrupt the database in the process.

Is this just a case of Wordpress being poorly engineered?

In fact I feel more a problem endemic in the web and driven largely by the URL.

Recently I was experimenting with Firefox extensions. Being a good 21st century programmer I simply found an existing extension that was roughly similar to what I was after and started to alter it. First of course I changed its name and then found I needed to make changes through pretty much every file in the extension as the knowledge of the extension name seemed to permeate to the lowest level of the code. To be fair XUL has mechanisms to achieve a level of encapsulation introducing local URIs through the ‘chrome:’ naming scheme and having been through the process once. I maybe understand a bit better how to design extensions to make them less reliant on the external name, and also which names need to be changed and which are more like the ‘x’ in the ‘f(x)’ example. However, despite this, the experience was so different to the levels of encapsulation I have learnt to take for granted in traditional programming.

Much of the trouble resides with the URL. Going back to the two issues of naming, the URL focuses strongly on (a) making the name unambiguous by having a single universal namespace;  URLs are a bit like saying “let’s not just refer to ‘Alan’, but ‘the person with UK National Insurance Number XXXX’ so we know precisely who we are talking about”. Of course this focus on uniqueness of naming has a consequential impact on generality and abstraction. There are many visitors on Tiree over the summer and maybe one day I meet one at the shop and then a few days later pass the same person out walking; I don’t need to know the persons NI number or URL in order to say it was the same person.

Back to Snip!t, over the summer I spent some time working on the XML-based extension mechanism. As soon as these became even slightly complex I found URLs sneaking in, just like the Wordpress database The use of namespaces in the XML file can reduce this by at least limiting full URLs to the XML header, but, still, embedded in every XML file are un-abstracted references … and my pride in keeping the test site and live site near identical was severely dented¹.

In the years when the web was coming into being the Hypertext community had been reflecting on more than 30 years of practical experience, embodied particularly in the Dexter Model². The Dexter model and some systems, such as Wendy Hall’s Microcosm³, incorporated external linkage; that is, the body of content had marked hot spots, but the association of these hot spots to other resources was in a separate external layer.

Sadly HTML opted for internal links in anchor and image tags in order to make html files self-contained, a pattern replicated across web technologies such as XML and RDF. At a practical level this is (i) why it is hard to have a single anchor link to multiple things, as was common in early Hypertext systems such as Intermedia, and (ii), as Fiona found, a real pain for maintenance!

1. I actually resolved this by a nasty ‘hack’ of having internal functions alias the full site name when encountered and treating them as if they refer to the test site — very cludgy! [back]
2. Halasz, F. and Schwartz, M. 1994. The Dexter hypertext reference model. Commun. ACM 37, 2 (Feb. 1994), 30-39. DOI= http://doi.acm.org/10.1145/175235.175237 [back]
3. Hall, W., Davis, H., and Hutchings, G. 1996 Rethinking Hypermedia: the Microcosm Approach. Kluwer Academic Publishers. [back]

Fiona @ lovefibre and I have often discussed the worrying decline of language used in many comments and postings on the web. Sometimes people are using compressed txtng language or even leetspeak, both of these are reasonable alternative codes to ‘proper’ English, and potentially part of the natural growth of the language.  However, it is often clear that the cause is ignorance not choice.  One of the reasons may be that many more people are getting a voice on the Internet; it is not just the journalists, academics and professional classes.  If so, this could be a positive social sign indicating that a public voice is no longer restricted to university graduates, who, of course, know their grammar perfectly …

Earlier today I was using Google to look up the author of a book I was reading and one of the top links was a listing on ratemyprofessors.com.  For interest I clicked through and saw:

“He sucks.. hes mean and way to demanding if u wanan work your ass off for a C+ take his class¹”

Hmm I wonder what this student’s course assignment looked like?

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1. In case you think I’m a complete pedant, personally, I am happy with both the slang ’sucks’ and ‘ass’ (instead of ‘arse’!), and the compressed speech ‘u’. These could be well-considered choices in language. The mistyped ‘wanna’ is also just a slip. It is the slightly more proper “hes mean and way to demanding” that seems to show  general lack of understanding.  Happily, the other comments, were not as bad as this one, but I did find the student who wanted a “descent grade” amusing [back]

I’m wondering why people break things when they create new versions.

Firefox used to open a discreet little window when you downloaded papers.  Now-a-days it opens a full screen window completely hiding the browser.

A minor issue, but makes me wonder about both new versions and also defaults and personalisation in general.

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Just scanning a few Google Tech Talks on YouTube.  I don’t visit it often, but followed a link from Rob Style’s twitter.  I find the video’s a bit slow, so tend to flick through with the sound off, really wishing they had fast forward buttons like a DVD as quite hard to pull the little slider back and forth.

One talk was by Stuart Hameroff on A New Marriage of Brain and Computer.  He is the guy that works with Penrose on the possibility that quantum effects in microtubules may be the source of consciousness.  I notice that he used calculations for computational capacity based on traditional neuron-based models that are very similar to my own calculations some years ago in “the brain and the web” when I worked out that the memory and computational capacity of a single human brain is very similar to those of the entire web. Hameroff then went on to say that there are an order of magnitude more microtubules (sub-cellular structures, with many per neuron), so the traditional calculations do not hold!

Microtubules are fascinating things, they are like little mechano sets inside each cell.  It is these microtubules that during cell division stretch out straight the chromosomes, which are normally tangled up the nucleus.  Even stranger those fluid  movements of amoeba gradually pushing out pseudopodia, are actually made by mechanical structures composed of microtubules, only looking so organic because of the cell membrane – rather like a robot covered in latex.

The main reason for going to the text talks was one by Steve Souders “Life’s Too Short – Write Fast Code” that has lots of tips for on speeding up web pages including allowing Javascript files to download in parallel.  I was particularly impressed by the quantification of costs of delays on web pages down to 100ms!

This is great.  Partly because of my long interest in time and delays in HCI. Partly because I want my own web scripts to be faster and I’ve already downloaded the Yahoo! YSlow plugin for FireFox that helps diagnose causes of slow pages.  And partly  because I get so frustrated waiting for things to happen, both on the web and on the desktop … and why oh why does it take a good minute to get a WiFi connection ….  and why doesn’t YouTube introduce better controls for skimming videos.

… and finally, because I’d already spent too much time skimming the tech talks, I looked at one last talk: David Levy, “No Time To Think” … how we are all so rushed that we have no time to really think about problems, not to mention life¹.  At least that’s what I think it said, because I skimmed it rather fast.

1. see also my own discussion of Slow Time [back]

Looked at web stats for this blog for first time in ages.  IE is still top browser in raw hits, but between them Firefox and Mozilla  family have 39% above IE at 36%.  Is this just that there are more Mac users amongst HCI people and academics, or is Mozilla winning the browser wars?

I had been reluctantly considering giving up using Firefox as it crawled to a halt so often on so many sites. To be fair I think it is because I keep lots of tabs open and Firefox did not seem to deal will with pages with many refreshing elements … many air and train ticketing sites were particular problems. However, Firefox 3 has been running continuously for some time now and looking at ‘top’ in terminal window has about 1/3 the real memory footprint compared with Firefox 2 … now it is comparable with Word, Dreamweaver, etc. … I had been sticking with Firefox largely because the Firefox Snip!t bookmarklet works better than the Safari one, so now I can continue to do so without the machine crawling to a halt – well done team Mozilla