Always The Critic

Groovy and Grails

Overview

I've spent the past couple of weeks reading up on Grails, a web application framework inspired by Ruby on Rails. It takes advantage of Groovy, a dynamic programming language that runs on the JVM and is best described as a cross between Java and Ruby. Groovy has support for most existing Java syntax, but also a lot of Ruby-style syntax and dynamic features. To be honest I find that the Java aspects of Groovy (and Grails) drag the whole experience down a bit compared to writing Ruby, but it should be significantly nicer to work with than pure Java.

The big selling point of Groovy and Grails over Ruby on Rails comes from the compatibility with the whole Java ecosystem. You can have your clever dynamic language without giving up the Java libraries and deployment environments that your projects and customers may demand. This is clearly quite a compelling idea if like me you've got a long history of doing big Java web apps but have recently been converted to the dynamic cause.

One thing that is very important to realise is that Grails is not a port of Rails. It is in fact built on top of the Spring stack, including Spring MVC, REST support, dependency injection, transactionality and Hibernate amongst others. If you're already familiar with Spring this is probably a good thing, though I do worry that the framework on top of framework approach could lead to having more to learn (and mess up) overall.

Practical findings

My initial experiments showed an interesting result that rather worried me. I set up a domain class and a controller with def scaffold = true to provide built-in CRUD for my domain class. However the CRUD pages this presented were noticeably sluggish in the browser and benchmarking confirmed it could only manage about 2 requests per second. This is lamentably poor and even now I can't figure out how it's managing to spend so much time achieving not very much.

After a bit of experimentation I determined that if I use grails generate-all to put the scaffolding code in place in my classes (rather than using the dynamic scaffolding) then things speed up enormously. In fact I can now get about 200 requests per second. It's hard to see how there can be such a massive performance gulf between the two scenarios as I would have thought that the only extra overhead for dynamic scaffolding is the initial dynamic intercept of the missing action method and calling into the scaffolding code. Hopefully a Grails expert can explain this, or I will eventually figure it out myself. At least now I have determined that for real-world scenarios there isn't going to be a performance issue, though I am surprised that the Grails docs don't have a massive "Warning - dynamic scaffolding is really slow" box.

For now I haven't done much but read the docs and try a few things. I hope to get deeper into it soon.

RVM and NetBeans

I've been having a lot of trouble with my Ruby 1.9.1 install on Mac OS X. Mostly it works fine, but I struggle when installing gems that require native extensions. I think this is because the way my install was built causes linkage problems, perhaps due to 32 vs 64 bit issues, or due to linkage with other libraries. I'm not entirely sure what's causing the problems, but recently I decided enough was enough and tried out rvm since I've heard a lot of good things about it. I got the impression that by compiling from my own source I was stubbornly making a lot of my own trouble.

Rvm is trivial to install: it's a gem that installs some of its own executables. I did hack my PATH first, to remove /usr/local/bin (where my custom Ruby lived) so that I'd be using the stock Mac OS X Ruby for the rvm install.

> sudo gem install rvm
> rvm-install

Note that rvm-install added the following to the end of ~/.bash_profile automatically, so I could ignore the instruction it gave me about adding it myself:

if [ -s ~/.rvm/scripts/rvm ] ; then source ~/.rvm/scripts/rvm ; fi

I then used rvm to install a fresh version of Ruby 1.9.1: >> rvm install 1.9.1

Actually that failed with an error about libsqlite3.dylib being the wrong architecture - perhaps another hangover from my old manual installs, or a problem I'm going to have to solve sometime in the future! For now I moved the old version of that file and tried again:

> sudo mv /usr/local/lib/libsqlite3.dylib /usr/local/lib/libsqlite3.dylibOLD
> rvm install 1.9.1

And that left me with a decent ruby 1.9.1 install. Which brought me back to one of the things that I was originally frustrated by: getting NetBeans Ruby debugging working with the fast debugger. With my old install the ruby-debug-ide gem would not install, but I'm pleased to report that it does with this new setup.

However getting NetBeans to actually use my new rvm ruby required a bit of a trick. The Ruby Platform management GUI in NetBeans doesn't show you hidden folders in its file picker, so you can't navigate to the ~/.rvm/ruby-1.9.1-p243/bin/ruby file that it wants. The trick is to create a non-hidden symlink, so you can then find it from NetBeans (and it's also handy to get at your rvm files from Finder):

> ln -s ~/.rvm ~/rvm

One word of warning: once you're using an RVM Ruby install, do not use sudo for gem installs, as the gems (and every part of rvm) live in ~/.rvm so sudo is not required. In fact using sudo will knacker your gems quite badly as it gets its PATH wrong and its permissions and you end up deleting a bunch of stuff to get back to a known good state. I learnt this the hard way!

UKNatureBlog

I'm afraid that the nature posts are going to dry up here, but never fear for they're all now going to be on UKNatureBlog.com - a new blog specifically for the flora and fauna of the UK and all related things, setup by myself and Mrs C.

Go and have a look, bookmark it, and do please contribute. The cheeky chap below will be over there from now on.

MacRuby 0.5 beta 1 Released

I was very excited to see MacRuby 0.5 beta 1 had been announced, complete with ahead of time compilation via LLVM. It has been long while since the previous update on the MacRuby blog in March, but clearly a lot of work has been taking place. At the moment this beta shows the promise of things to come but isn't yet fit for much more than anticipatory experimentation. If you want to try the macrubyc compiler, Antonio Cangiano's blog post on the topic is a must-read.

The MacRuby notes suggest that compiled ahead of time or not, it uses LLVM for a big speed win, but my own quick experiment showed the macruby interpreter to be about 3 times slower than the standard MRI Ruby 1.9.1. This was with a single small benchmark app only though, just to prove things were working, so I can't draw conclusions. I can't pretend I wasn't a little disappointed not to see MRI blown out of the water though, even though I know it's unscientific and wrong of me!

I couldn't get a fully compiled version to produce any output, though it appeared to run without barfing, so I couldn't tell if it was really working or not. It was notable that the compiled binary was nearly 15MB so there must be a lot of statically linked code being included to swell my couple of KB of Ruby code so much. I'm hopeful that this can be improved in the future in order to support my dream of iPhone apps being written with Ruby hooking into Cocoa. In fact more than a dream - I'm hopeful and optimistic that in the long-run Apple will make Ruby a heavily promoted first class citizen for Mac and iPhone development, sitting on top of Objective-C but hiding it for the most part. The whole world has moved on from primitive C-based languages to higher levels of abstraction and I think Apple really needs a successor to Objective-C within the next 5 years. Is MacRuby it?

Blank Page When Printing PDFs from Google Chrome

When I print a PDF straight from Google's Chrome web browser I get a blank page with just the header and footer (URL etc.) and nothing else. This is what happens when using the "Print..." command in the 'page' menu - the menu to the right of the address bar with a page icon.

This can be worked around by instead right-clicking on the PDF body itself and selecting "Print..." which takes you through Adobe's own print dialogs and gives the correct result.

Fridge Temperature Control

The temperature controls in most fridges really get my design goat. Are they a thermostatic  'temperature' control or a 'power' control? They're not giving anything away! If I want my fridge to be colder should I turn up the control to 5 for maximum cooling power, or turn it down to 1 as in 1 degree centigrade? Labelling it 1 to 5 is just begging for confusion. If it's truly a thermostat (and well enough calibrated) then make it clear with 'c' markings. If it's a power control then make that clear with "cooler" / "warmer", red / blue gradients or something. Perhaps I need to buy more expensive fridges with digital thermostatic controls.

Snow Leopard Arrives

Precisely one week after it was launched, my copy of Mac OS X 10.6 "Snow Leopard" landed on my desk at work. Apple claim to have posted it last Friday, but the bank holiday weekend and postal strikes have conspired to keep me waiting this long.

On my recent Mac Pro it installed in 28 minutes and recovered a startling 31GB of disk space. I'm not quite sure how it managed that to be honest, as it's a lot more than most others are reporting. [Update: actually I suspect it's because Apple have changed the definition of a GB for Snow Leopard, so my comparisons of space used before and after are not comparing like for like. Now 1GB = 10^9 = 1,000,000,000 bytes, whereas previously it was 2^10 * 2^10 * 2^10 = 1024 * 1024 * 1024 = 1,073,741,824 bytes.]

That same Mac Pro is also capable of booting into the 64 bit kernel by holding down '6' and '4' during boot. You can check it's worked in System Profiler, where on the Software page it should say  "64-bit Kernel and Extensions: Yes". I've not noticed any abnormalities and supposedly it might run a bit faster this way, so if it stays good then I'll probably set it to 64 bit kernel permanently.

Note that only XServe machines boot with the 64 bit kernel by default, and many 64 bit Macs (like older Core 2 Duo MacBooks) can't do so because they lack 64 bit EFI (Extensible Firmware Interface).

In general I like Snow Leopard - it's the same as Leopard but all round snappier and a bit nicer. Some changes confuse me though. Take the new arbitrarily styled menus for dock items, as shown below. Nothing else in the system looks the same, and that's probably a good thing because it's hard to read, with the section heads and tick marks being far too low contrast. They're almost invisible! A real UI own goal if you ask me. Maybe they designed it before they set the gamma to 2.2...

Snow Leopard Up-To-Date Program: Not Working for UK

Update (26th Aug 2009): It does now seem to be working and I've successfully ordered my copy. In fact it tried to order me 4 copies, apparently having remembered my previous failed attempts.

I recently bought a new Mac so I qualify to get Mac OS X 10.6 (Snow Leopard) super-cheap as part of Apple's Up-To-Date program. Unfortunately, the online up-to-date system doesn't seem to be working, for the UK at least. Here's my transcript of live chat with the Apple rep, where they state that indeed it's not working and they know it.

• You are chatting with Danielle C, an Apple Expert

• Hi, my name is Danielle C. Welcome to Apple!

• Hello - I'm struggling to use the Snow Leopard Up to date program.

• Good evening

• You are trying to register for it online?

• I click through, fill in details, it says my computer is qualifying, but then it says "There are no items in your basket"

• yes - using website

• I apologize for the inconvenience.

• I'm clicking through from http://www.apple.com/uk/macosx/uptodate/index.html

• Unfortunately there is a glitch in the site, you can still order via post or fax in your order form.

• :-/

• I've been trying for days.

• Using different browsers, assuming the problem might be my fault.

• The site is not working for most people trying to order it unfortunately.

• You would have to fax or send in your order form.

• How about putting something up on the page to say so, to save all those people's time?

• I am very sorry about the inconvenience.

• How do I email in an order?

• You cannot email it in, it has to be Fax or Post.

• I bet a lot of people will stump up the full amount, to get past the inconvenience.

• Which might be why nobody's fixing it or even putting up a sign saying it's broken. But that's the cynic in me.

• Do you know when it might be fixed? I'll wait if it's fairly soon.

• Unfortunately I would not have that information.

• Do you mind if I post this transcript on my blog?

• Thanks for waiting. I'll be right with you.

• Sure.

BarclayCard Website Improvements

I was pleasantly surprised when I went to pay my most recent credit card bill. Not only was it relatively small for a change, but the BarclayCard website has been revamped, with that most unusual of results: a markedly better user experience!

They now show a coloured bar meter indicating your total credit limit (the whole length of the bar) with your last statement and current total outstanding clearly marked as coloured portions of it. It's a really great way to graphically show the balance. They've clearly paid attention to every aspect of user interaction, with the flow being very straightforward and very clearly guided at all times, but not onerous.

Perhaps the very best change is the return of the option to pay off your last statement in full. For the last year or so they had things set up so the options when paying were: minimum amount, whole balance (including new transactions since last statement) or custom amount. To pay off your last statement in full you had to manually read off the amount and type it into the custom field. This was very cheeky of them, clearly trying to steer the punters into taking less advantage of the free credit grace period (by paying more than their last statement amount) or paying less than their last statement amount and so accruing expensive interest. I'm glad to see this cynical move has been reversed.

Update iPhone Software Using Internet Tethering: Don't!

Because my broadband wasn't working I've been using internet tethering with my iPhone for my main internet connection for my computer. So when my iPhone demanded I update its software to cure its SMS vulnerability I thought hey why not go ahead! I figured it would download the update to the computer (via the iPhone's net connection) as per normal, then perform the update. No reason to suspect a problem. 

Unfortunately once it had got the whole 300MB package and tried to install it, it required access to some Apple server in order to finish the install, but the iPhone was half-updated and no longer providing internet connectivity. So I got stuck there, with an iPhone just showing a "connect to iTunes" graphic when switched on. I understand this is known as "recovery mode". And that's how it's been for a full day, but thankfully I now have broadband working and have managed to get it back up on its feet. That required a factory restore then update from backup then full sync though, and I'm yet to determine if all is truly well.

So the lesson here is - don't use your iPhone as the sole internet connection in order to update your iPhone!