Damian Brady’s Blog

I found this article by Steve Yegge claiming that the Singleton pattern is stupid and evil.  I know it’s old, but I found it via reddit (which I’ve been getting into a lot more than Digg lately - probably more on that later) and despite having his blog on my feed, I hadn’t gone back that far into his archives.

I read about half of the article before I decided I’d write my own post pointing out that he’s actually attacking not the singleton pattern itself, but its use in inappropriate circumstances.  I use the pattern occasionally, and I’d like to think I use it when it should be used or at least when it’s useful.  The examples he gives throughout represent inappropriate uses for the singleton pattern, not a failure of the concept.

Then I read the rest of it, including the final note which says:

Note: I think there are some good uses for the Singleton pattern, but it’s so incredibly overused, and serves as such a convenient crutch for people who don’t understand OOP, that I figured I’d just take the stance in this article that it’s basically Evil.)

Huh.  So here I am writing a post about nothing.

If you’ve visited here before, you’ll have noticed that the template I’m using has changed.

While the old one looked good to me for a while, the more I looked at it, the more I thought it just looked too busy.  There were borders all over the place and gradients and background textures and all sorts of things.  It was too much.

So I’ve gone the minimalist approach and have chosen a template that’s very simple.  I hope you like it.  I think it makes the posts easier to read.

Damo

It’s great when software is designed and implemented with careful planning and plenty of documentation so someone can pick it up when it falls down.  Unfortunately, it’s often the case that a) You’re working on an existing project that has no documentation, or b) You’re working on an existing project that has documentation that is now out of date.

I’m doing the former right now.  The software is old.  Like 12 years old.  It has no documentation.  It has duplicated code, code where it shouldn’t be, hard-coded values, code that does the wrong thing before being corrected by other code.  Think of an anti-pattern and it’s in there.

The application is being phased out, but it must be supported until it’s completely gone.  It’s also in an environment where changes are inevitable and legally mandated so there’s no chance of a complete code-freeze.  The original programmers are long gone.  It’s not fun to work with.

Now don’t get me wrong.  I don’t go in and make changes that just add to the spaghetti - I refactor when it’s practical.  If I’m changing some code that’s repeated in three places, I’ll pull it out into its own method.  If there are hard-coded values that could change, I’ll set them up so they’re configurable.  In short, I’ll do some cleanup, but I’m not going to do it all.  Refactoring everything would mean nearly rewriting the thing from scratch, and that’s been done (hence the phase out).

So what about documentation?  Writing detailed UML for this software is just not practical.  For one thing, it’d be obscenely hard to do, but more important is the fact that this program is unlikely to be in use in 12 months time.  Priority doesn’t go to documenting legacy software.  The fact of the matter is that it’s just not worth the time and effort to pull the thing apart to work out how every little piece ticks.

So I’ve come up with my own alternative.  I call it Post-traumatic Documentation.

I’ve set up a document that I’ve titled the Application Body of Knowledge.  Every time I dive in to make a change or fix a bug, I’ll absorb a whole lot of information about how the application fits together.  There are basic things like which files do what, but most of the important stuff is in the details.  I might spend half an hour working out that some assignments in method A get overridden in certain cases when method B is called, or that a class called ABC actually provides functionality for DEF and perhaps doesn’t get called at all.  I learn these things the hard way and I make notes as I go.

Whenever I finish one of these traumatic quests to change something small, I go through my notes and add anything of interest to my Application Body of Knowledge.  There’s a section dealing with the overall architecture of the application, one for each of the main modules, one for deployment, and one for general notes.  It’s deliberately heavy on keywords and jargon to facilitate searching.

This document is obviously far from complete, but it is immensely helpful to me when I next have to make a change, and it’ll be even more helpful to the guy who takes the reigns from me when I get hit by that programmer-killing bus.

Damo

Let me preface this post by saying that I haven’t played it. In fact I don’t even own a console that is able to play it. I’ve never even seen anyone play it, and I’ve watched maybe one trailer about halfway through.

So why am I writing about GTA IV having had no hands-on experience and no exposure?

Well, I’ve been absolutely inundated by the flood of reports, articles, blog posts, editorials and reviews about GTA IV. I spend a lot of time on the web and I watch my share of TV and listen to the radio, so I’m fairly up to date with what’s being talked about online and in the media.

So here’s what I’m aware of so far. Despite the massive success and constant positive reviews of the recently-released Ironman movie, its revenue is likely to pale in comparison to sales of the latest Grand Theft Auto game. The media is jumping all over reports that Hollywood is (once again) scared that computer games are going to seriously eat into their profits.

It’s been said before, and it’s a fairly legitimate fear. It’s worth noting though, that movies and computer games compete in the entertainment market only indirectly. Sure, there’s some overlap, but $100 million in movie revenue will not be replaced directly with $100 million in computer game sales. There is room for both. Motion picture industry revenues certainly haven’t experienced the same massive growth as the computer game industry, but there haven’t been many huge changes in movies in the last few years. Computer games on the other hand have improved out of sight in a short number of years. There are still brand new technical advancements being made (think Wii) while movies now have slightly better special effects than a few years ago. It’s an unfair fight and this result isn’t really surprising.

Anyway, it seems that this game is a very big deal. It’s apparently got a very complex storyline; one that competes with big plot-based Hollywood movies. The big difference is that being as interactive and immersive as the GTA games are, it’s infinitely more interesting and longer-lasting than a movie. There’s little doubt that the $100 million it cost to make will be well worth it. The real question will be whether the other games companies will continue to pump out the same games with better graphics, or whether they’ll go the way of Rockstar and start releasing games that are more like fully interactive movies.

Damo

Every few months, my bank card decides it’s not going to work.  Usually generic ATMs or those of other banks refuse to accept it, but this time it was an ATM belonging to the bank I’m with.  Once again, I walked inside the branch and arranged for another card to be sent to me.

In addition to ordering me another card, the customer service rep offered to link my Visa card to my savings account so I could use it to withdraw money from my main account.  I’ve never had problems with the Visa, so this may be a more permanent solution.  Regardless, I needed to choose a new PIN for this to work.

Here’s where it gets interesting.  I was asked to type in a new four-digit PIN with various obvious restrictions such as no birth dates or other important dates, but also with no consecutive double digits.  My initial reaction was that it was an unusual requirement (given that I’ve had PINs with double digits assigned to me by the same bank in the past), but I didn’t think much of it.  That was my initial reaction.  As I considered it more, I thought, wouldn’t this would have the opposite of the desired effect?

Now my probability mathematics is a little rusty, but here goes.  There are 10,000 possible four digit PINs.  If a truly random PIN is chosen, the probability of guessing it on the first try is one in ten thousand.  Given you usually only get three tries before the machine swallows your card, the odds aren’t good.  If you let people choose their own PIN with no restrictions, it could be a little easier - you’d probably try their birth date, or an anniversary or something like that.  Let’s face it, people need to be able to remember this number so they’ll have to choose something that relates to them.  The odds of guessing a PIN like this are a lot better.

I was asked to choose a PIN that didn’t correspond to any important dates, so given that restriction, we’ll make an assumption that the PIN isn’t guessable.  Brute force (albeit three attempts) is really all that’s left, so we’re back to one in ten thousand.  But if you add a rule that says you can’t have double digits, then the number of options available decreases to 7,290.  A person who finds my card has a better chance of guessing my PIN than if this rule didn’t exist.

This seems like a case of implementing decisions that sound good without any real analysis.  Have I got this totally wrong?  Does this seem silly to anyone else?

Damo

I read a Coding Horror post in March about testing localisation code for Turkey to make sure it’s correct.  Apparently Turkey has one of the hardest languages to write Internationalisation code for.

Anyway, it appears that a localisation fault on a mobile phone in Turkey has resulted in two deaths and three jailings.  Warning - bad language in this link!

Wow.  That’s a very bad side-effect…

From a few places comes news that CNN is selling t-shirts with news headlines on them.  An interesting/unusual idea, sure, but they’ve done one thing very wrong.

The text on the shirt is part of the URL.

All of which means I can presumably order (but at least create an image of) a shirt that says, “CNN slept with your mum” or “I like short shorts”.  The shirts come with a line underneath the headline that says, “I just saw it on CNN.com” and the date of the news story.  A person could have fun with that…

Now I’m all for RESTful architecture when it’s appropriate, but there should really be some checking to make sure the headline exists…

Damo

Two of my favourite blogs have announced in the last few hours the upcoming launch of www.stackoverflow.com and I, for one, am excited.

The site will be a combined effort by two of the legends in the software design world, Jeff Atwood and Joel Spolsky.  Jeff runs the well-known Coding Horror blog, and Joel is chief guy for the Joel on Software blog as well as CEO of Fog Creek.  They’ve decided to combine forces to start a community site that’s essentially a free programming Q&A site.

Every programmer knows the recurrent problems encountered when searching for a programming dilemma in Google with the hopes of finding an answer.  There are a couple of problems that haunt me constantly.  Joel mentions in his blog post the situation where you find your exact problem and potential answers on sites that require registration and payment.  Experts Exchange is a classic for that; so much so that I generally use some google-fu to remove any Experts Exchange pages from my search results when searching for solutions.  Don’t get me wrong, I’m sure Experts Exchange has some fantastic content, but I can’t justify spending that much money to save me a few hours every few months.

The other problem I encounter time and time again are the forum posts with no solutions.  Often, when I search for a specific problem in Google, I’ll get a ton of results that appear to exactly match my particular issue.  Excitedly, I’ll open them all up in new tabs and go through them looking for the bit of code that will be my saviour.  Far too often, the threads don’t provide answers at all - just a community of people lamenting the same fault and looking for cures.  Even more frustrating are the instances when the initial poster finishes up the thread with a post along the lines of, “Thanks everybody, but I found out how to do it” without providing the solution.

Hopefully, this site will hasten a timely death for these frustrations.  If there’s anyone I’d want on the case, it’s these two guys.

Damo

Slashdot today carries a link to a story claiming that the CAPTCHA algorithm for Hotmail (or Windows Live Hotmail or whatever it’s called now) has been defeated by a spambot and the exploits have started.  So that’s Gmail, Yahoo Mail, and now Hotmail.

CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a great idea, but if it doesn’t work, then it doesn’t work.

CAPTCHAs were developed to tell humans apart from software.  They’re essentially a Turing Test across a very limited domain, and because of the limited domain, they’re much easier to attack.  In the case of a standard warped-text CAPTCHA, the attacker knows that the challenge will be an image with a certain number of letters and/or numbers, and that it will be warped in one or more ways.  The software can be written with this in mind.  Additionally, even if there is only a miniscule success rate, it’s often worthwhile for a spammer, particularly if attempts can be automated and run several times a second.

So what’s the solution?

Slashdot made a tongue-in-cheek reference to Kitten Auth, suggested in 2006.  It may have been a playful suggestion, but I think they’re on the right track.  Kitten Auth basically presents the user with a number of pictures of cute fluffy animals, and tells the user to select all the kittens.  The premise is the same as the text-based CAPTCHAs - easy for humans, hard for computers - but it doesn’t use text, making OCR useless.

Something like Kitten Auth could work as long as there’s no predictability.  If the same images are repeatedly used, a brute force attack would work.  If you needed to select three kittens out of nine pictures, all you need is one random success and bam, you have copies of three images that are kittens.  Given enough time, the software could learn enough images to be viable as a solution.

Alternatively, if OCR can be trained to learn letters and numbers that are very warped and modified, then why not pictures of kittens?  It’s harder, sure, but if we mere mortals can tell a kitten apart from a possum, then why not a computer? These spammers and malware authors are pretty determined you know.

So what else?

Maybe the problem with CAPTCHAs is the “CA” part.  Completely Automated.  What about PAPTCHA? Partially Automated. Sure, it ruins the contrived acronym, but it might be more effective.

Arguably, Kitten Auth is already an PAPTCHA.  The pictures of kittens can’t really be completely automated unless there are 3D models of kittens rendered from different angles with different lighting each time… hmm… that’s an idea… but I digress.

If Microsoft and Google and Yahoo were to put some effort into changing their “PTCHA” regularly, by real people, maybe there’s a solution.

Here’s how it could work:

• Twenty people, armed with cameras, walk the streets for a few hours taking photos of random objects or scenery.
• They get back to the office and upload the photos to today’s collection.
• They link each photo to some standard questions (e.g. “what is the main object in this photo?”) and provide acceptable responses.
• They provide additional specific questions for each photo (e.g. “How many white horses are there in the field?”) and provide acceptable responses.
• One or more other staff members look at the photo and each question for quality control.  They can add more acceptable answers, remove them, or reject photos or questions outright.
• Photos are retired after a time to prevent them being learned.

As a very rough estimate, I’d expect that a person would be able to add at least fifty photos with ten questions each every day.  With 20 people, that equals 10,000 new PTCHAs every day - 50,000 per working week. Surely that’d be enough.  Is 20 people too many?  Even with five people you’d have 12,500 new challenges every week.  If you expire the questions after a month, you’d still have an incredibly large number to choose from.

Current CAPTCHAs effectively have an infinite number of possibilities, however they’re still in a narrow domain.  By expanding the domain to include any question about any photo, there’s no pattern to learn - no possible algorithm to solve the problem.

Is it foolproof?  Definitely not.  However, I’d suggest that implemented properly (and that means a lot of QA), it would be a lot harder to break than current CAPTCHA methods.

There could be a business in this you know… I’d be interested to know what you think!

Damo

Edit: I’ve been having a discussion with a friend of mine who has outlined exactly why 50,000 new challenges per week is not enough.  In short, if x people are creating these challenges, then some fraction of x can be employed to decipher them (answering is quicker than asking).  The answers get added to a massive database along with copies of the images, and there’ll be enough solutions saved to give some malicious code a decent success rate.  If the image and question match one in the database, then the answer will be there.

Repetition of challenges is therefore a significant problem.  A challenge that presents an “image and question” that is repeated every 200,000 requests (4 weeks of 50,000 per week) is far too repetitive.  If the malicious code runs one request every fifteen minutes on 1,000 nodes, you’d have seen every challenge in just over 2 days.

So to overcome this, here are some ideas:

• Use existing CAPTCHA technology such as warping the question text and putting it directly on the photo in a semi-random place.  You’d get no exact repeats.  The obvious problem is that this may still allow a malicious program to recognise sections of the photo that haven’t been altered.  With every photo and answer saved, there’s still a one in ten chance (given 10 questions per photo) of getting the question right.  Very unacceptable.
• Warp not only the text, but the image as well.  Obviously it’d still need to be recognisable, so overlaying a random, semitransparent pattern or something might be all you could do.  It might be enough to slow down matching of the image though.
• Include a bevy of questions that bear no relation to the image.  These could be added to any of the images.  For example, you could have a picture of a field of horses which renders with the question, “How many legs are most people born with?”

So now I have a system where a modified image is rendered with an overlayed warped-text question which may or may not have anything to do with the image.

Of course all I’m really doing is adding complexity, but as long as it’s complex enough to withstand attacks for the length of time it’s used (one month in my example), it should work.

My other suggestion, the CG kittens, got more interest.  In this case, there would be essentially no repeated images.  You’d probably only need a handful of animal models with a few variables set at random to make it feasible.  Perhaps fur colour, lighting, camera position, and some posture or face variables.

Every now and then I’ll get an email from someone that’s been addressed to a number of people. I can tell how many and who they are because all of our email addresses are listed in the “To:” header. My email address has been sent to a list of people I don’t know.

There are a couple of reasons I don’t want my email address broadcast to the world.

Spam et. al.

I often don’t know many of the other people on the list, and more to the point, I don’t know anything about their computers. It’s possible, probably likely, that in an email addressed to 20 people, at least one of them has a fairly insecure computer and probably has at least one virus or a trojan. When the insecure computer receives the email, my email address going to be visible to this malware.

In short, I can have the best and most robust security on my computer, and I can ensure my email address is never published on the web, but all of this is useless if a single person sends my email address to a compromised machine.

Email addresses can be personal

I may be in the minority here, but I maintain a large number of email addresses. Having my own domains means that I can set up separate email addresses for job applications, friends and family, work, web enquiries, and so on. Right now, off the top of my head, I can think of about twenty email addresses that I use regularly. Most are simply forwarders, but they allow me to categorise incoming emails efficiently.

The other thing this lets me do is control communication. If I am wary about giving a company or a person my email address, I’ll create a new one. If I start getting emails I don’t want, or if for some reason I don’t want them to contact me any more, I can delete the email address.

Now you can see the dilemma. If I’ve given a particular email address to one company and they broadcast it to other people in a group email, I lose control.

Easily Fixed

If you’re reading this blog, I’d be surprised if you didn’t know about BCC, but I’ll summarise just in case.

When sending an email, you can put recipients’ email addresses into the “To:” field, the “CC:” field, or the “BCC:” field. “To:” and “CC:” behave the same, but “CC:” indicates that the person is being given a “carbon copy” - a legacy name from the paper days.

“BCC:” stands for “blind carbon copy”. These people will still receive the email, but the email addresses in this section will not be included in the header. They will be kept private.

The problem of sending everyone’s email addresses out with the email is obviously easily fixed. Just put all the email addresses in the “BCC:” section. For emails amongst groups of friends and family, it’s often not a big deal, but in business it’s frankly unprofessional.

Design flaw

People still don’t know about BCC. I sometimes feel compelled to educate the sender of a group email about BCC and the usual response is surprise. They usually aren’t even aware of this function.

I think the problem is deeper than just a lack of education. There are fundamental design flaws here. Now, email is old - Wikipedia claims that it’s been around since about 1965. So I’m not going to suggest any fundamental technical changes. Such changes would be infeasible in a system that a) works, and b) is older than the Internet.

A significant part of the problem is that it’s called “BCC”. What the hell does that mean to the average person? Even expanding it to “blind carbon copy” doesn’t really help - it doesn’t describe its behaviour.

“Carbon copy” is relatively easy to understand. It’s at least reasonably clear that the people in this section will be getting a “copy” of the email - it’s not directly addressed to them, but they’ll see it anyway. But what does “blind” mean? That it will be invisible? It’ll be transmitted in Braille? People won’t know what BCC does until they’re told.

The other problem I can see is that “BCC:” isn’t presented as a default field in many email clients. The main email clients I use are Outlook and Gmail. In both cases, “BCC:” must be explicitly turned on.

Solutions

1. Change the name.
   “BCC” doesn’t mean anything - even when it’s expanded to “blind carbon copy” it doesn’t mean anything.
   Obviously, this change can’t be fundamental, but it can be cosmetic. If an email client changed “BCC:” to “Discreetly To:” or something similar, it might help with people’s understanding.
2. Change the behaviour.
   In an office environment, group emails to external domains should, by default, include everyone in the “BCC:” field rather than the “To:” field. If that’s too extreme, it should prompt the user, suggesting that perhaps they don’t want to share the list of email addresses with all the recipients. At the very least, hiding email addresses from the other recipients should be a very visible option.

In the meantime? Teach your staff about BCC. Make sure they use it when it’s appropriate.

Damo