New Adventures in Software by Dan Dyer

Twelve months on from my first visit to the UK edition of Droidcon, I was back in Islington this week for this year’s version. The format was the same: barcamp on day 1, conference proper on day 2. I’m not sure the distinction between the two days is all that worthwhile. After the initial hour of pitching and organising, the first day proceeds along similar lines to the second, with four tracks of presentations. I’d vote for just having two normal conference days with the programme for both days published in advance, which appears to be how the Dutch Droidcon works. If there is a need to democratise the programme, this could be done online beforehand.

Anyway, while it’s all still fresh in the memory, here are some of the things I thought worth noting. These may or may not be of interest to other Android developers. If you want to watch some of the talks, keep an eye on the Skills Matter website as I suspect the videos will start appearing on there shortly.

Proguard author Eric Lafortune talked about obfuscation and optimisation of Android apps. I’ve been using his Java obfuscator for many years, since well before it became an integral part of the Android tool set, so it was good to speak to him and finally put a face to the name. Eric’s start-up has another Proguard-based obfuscator/optimiser, called DexGuard, with extra Android-specific features, which may be of interest to app developers who need stronger protection and are willing to pay for it.

Erik Hellman made using OpenCV for computer vision on Android look reasonably painless. I’d previously discarded a good app idea that required this kind of functionality as too complicated and too processor-intensive. Might need to revisit that.

David Teitelbaum of Apkudo showed step-by-step how to crack an APK and inject code. He was able to cheat at one of Zynga’s word games by reverse-engineering the obfuscated code. It was an eye-opening demo and may well have caused a few app developers to seriously consider DexGuard as an extra line of defence against this kind of attack.

Jenkins contributors Christopher Orr and Jørgen Tjernø spoke about the plugins that are available for continuous integration on Android projects. If you have the server resources to dedicate to it, you can use Jenkins to automatically build and test your app with an emulator for every combination of Android version, screen size and configuration that you are interested in. A long time ago I wrote why you should use Jenkins for general Java projects, or Hudson as it was then (technically Hudson still exists as a separate Oracle-backed project but the community has moved en masse to the Jenkins fork). Christopher and Jørgen made the case for using it to improve the quality of your Android apps.

James Hugman gave an updated overview of Kirin, a hybrid approach to cross-platform app development that uses native-specific UIs and Javascript for logic. This was one of the more interesting topics from last year but I never got around to actually trying it out. It was interesting to see how the project has progressed. It now seems to be based around Node.js.

Given my interest in artificial intelligence, the session I was most interested in attending was the one called “Integrating AI into your app”. Unfortunately this was a complete waste of time and served only to prevent me from taking an earlier train home. It was nothing more than an advert for some tool for building expert systems. Neither the tool itself nor the generated systems had anything to do with Android. You expect some degree of being advertised at from the fee-paying keynote speakers who are subsidising the event but at least they have the decency not to stray too far from the main theme of the conference.

That’s the type of session I’d like to see fewer of but I’d like to see more like the preceding session by Anders Ericsson. He delivered a live-coding demo of a fairly clean approach to applying animation to custom views. The results were impressive (the approach is also outlined in this blog post) and the presentation followed on nicely from Chiu-Ki Chan‘s earlier talk on developing custom views. A couple of people pointed out that the new animation features in Android 3.0 and later can be used to achieve similar effects but this approach also works on the large number of Android devices that are still running Android 2.x. This session and David Teitelbaum’s APK cracking were probably the two best talks and are the kind of things I’d like to see if I attend next year.

A couple of months ago I purchased an O2 Mobile Broadband USB dongle so that I could continue working during an ADSL outage. Once the ADSL was back on I had no further use for it. Seeing as I also had a 3G-enabled Samsung Galaxy Tab 10.1 without a SIM, I thought it would make sense to use the remaining data allowance on that. However I was initially unable to find the right settings to make the tablet connect to O2’s network.

Having given it another shot before the unused data expires, I have eventually stumbled upon the correct settings, which I’ll document here for anyone who might need to achieve the same. Previously I was trying the device’s default O2 access point configurations and the APN settings I found on the web. The problem with these is that they are for pay-monthly and pay-as-you-go SIMs sold specifically for use in phones and tablets. The settings for the mobile broadband SIMs are different. You need to use the m-bb.o2.co.uk APN rather than payandgo.o2.co.uk or mobile.o2.co.uk. The full working settings from my Galaxy Tab are shown to the right (the obscured password is, predictably, ‘password’).

Update (30/1/2013): After the remaining data had expired, I didn’t use the 3G functionality of the tablet for a while, during which time I updated the tablet to Android 4.0.4. For whatever reason, the settings shown here no longer worked after adding more credit to the SIM. Eventually I discovered that the “APN type” field had to be set to “default” rather than “internet”. I also switched to using the “o2bb” username that the OS X connection manager software uses with the dongle.

In the absence of anything worthwhile of my own to write here at the moment, I thought I’d instead highlight a couple of interesting blog posts that I’ve discovered recently by id Software’s John Carmack.

I read Carmack’s thoughts on static analysis a few weeks ago and his reports on the effectiveness of tools for analysis of C++ code chimed with my own experiences with Java tools such as FindBugs and IntelliJ IDEA.

The first step is fully admitting that the code you write is riddled with errors. That is a bitter pill to swallow for a lot of people, but without it, most suggestions for change will be viewed with irritation or outright hostility. You have to want criticism of your code.

Automation is necessary. It is common to take a sort of smug satisfaction in reports of colossal failures of automatic systems, but for every failure of automation, the failures of humans are legion. Exhortations to “write better code” plans for more code reviews, pair programming, and so on just don’t cut it, especially in an environment with dozens of programmers under a lot of time pressure. The value in catching even the small subset of errors that are tractable to static analysis every single time is huge.

In the other article, which I only read today, Carmack espouses the virtues of pure (i.e. side-effect-free) functions. His is a pragmatic approach concerned with how to exploit purity in mainstream languages, where it is entirely optional, as opposed to advocating jumping ship to Haskell. Even when 100% purity is impractical there are still benefits in minimising impurity.

A large fraction of the flaws in software development are due to programmers not fully understanding all the possible states their code may execute in. In a multithreaded environment, the lack of understanding and the resulting problems are greatly amplified, almost to the point of panic if you are paying attention. Programming in a functional style makes the state presented to your code explicit, which makes it much easier to reason about, and, in a completely pure system, makes thread race conditions impossible.

My experiences with Haskell have informed how I approach coding in other languages. In certain cases I’ve ended up taking the functional approach to such extremes that I’ve been left questioning my original choice of implementation language.

No matter what language you work in, programming in a functional style provides benefits. You should do it whenever it is convenient, and you should think hard about the decision when it isn’t convenient.