To understand the details of how Ethereum works I’ve been working my way through the yellow paper. And since there’s no better way to really understand things than to explain them, I thought I’d write up my own explanation for some of the things that stood out to me.

Fair warning: I’m no expert, there’s guaranteed to be sloppy usage of terminology and a high likelihood of mistakes. If you’re just looking for an easier to read version of the yellow paper, try the beige paper, it’s had some actually knowledgable people look it over. Comments and corrections are most welcome either via email or @ajsutton on twitter.

After 7 years at LMAX, I’ll be winding up with them at the end of the month. It’s been a pretty remarkable journey and certainly not an easy decision to move on but ultimately another opportunity came up that I just couldn’t refuse.

I had intended to write up some reflections on the past 7 years at LMAX but I just can’t find the words. Suffice to say, it’s been an amazing journey full of wonderful people, big technical challenges and lots of innovative solutions. The early years in particular were just a fire hose of new knowledge to try and absorb. There have been many changes over the years, but it’s still an amazing place to work and leaving is sad.

Hapi 17 was released a while back with quite a few nice improvement – mostly centered around using promises instead of callbacks and thus fitting in with async/await well.  However, it’s a very significant change right across it’s APIs so it took quite a while for the various plugins that Moolah uses to be updated.

Eventually though they were all ready and then the actual upgrade of Moolah code was pretty straight forward.  Moolah had been using async handlers via a plugin all along so there were minor changes to how they were specified but very few changes to the control flow they then used.

I dropped out of the habit of writing about Moolah but it’s been ticking along doing what I need it to for a fair while with a few additions here and there. Recently I spent a chunk of time adding the ability to ‘earmark’ money for a particular use.

My main motivation is that we’re planning a family trip to Germany at the end of the year and I want to be able to set aside money through the year as we save for it. Various things will need to be paid upfront and those expense need to come out of the earmarked funds. I could track that with a new account for the savings, but since I’m not setting up a new bank account the balances wouldn’t match up and I’d spend a lot of time transferring money in and out of the holiday account.

I ran into an issue with Vuetify recently where the 1.0 betas were constantly utilising a CPU core when run in Safari. It turned out, I wasn’t alone and it had been reported as bug 2773.

There wasn’t a lot to go on – the problem only happened in Safari and the timeline showed it was constantly invalidating and recalculating the layout, apparently without any JavaScript executing.

First step was to create a simple reproduction case, which turned out to be a template with just:

At LMAX, we’ve been using Vue.js for all our new JavaScript work very successfully for a while now. Our existing products used Vue.js for the logic but continued to use bootstrap as the component library to ensure the UI remained consistent.  For anything new though, we started using Vuetify to give us better UIs much more easily.

Vuetify is close to reaching it’s 1.0 release now and we’ve been using it for a while so when we first started with it, the vast majority of development and support was being done by the project founder, John Leider in his spare time. Migrating UI libraries is painful so having an early stage project without a lot of community (at the time) was a pretty big risk for us, but the code was excellent and John was obviously very committed to the project, being very responsive to bug reports and questions.  So LMAX jumped on board as a platinum supporter of Vuetify, making regular monthly payments to support Vuetify development.

The internet is full of forum posts with various questions, tips and suggestions for IPv6 on EdgeRouters as people struggle to get it working. The challenge is that the fix you actually need depends on which version of EdgeOS you’re running (ubnt are continuing to flesh out the IPv6 configuration support) and the setup of your ISP.

So here’s the magic steps I needed for an ERX running EdgeOS 1.9.7+hotfix.3 with SkyMesh NBN over HFC (cable).

As Vue gradually spreads through our JavaScript, it’s reached the point where we need to support internationalisation. We already have a system for localising numbers and dates that we can reuse easily enough with Vue filters. We also have an existing system for translations, but it’s tied into the mustache templates we’ve used to date so we’ll need to adapt or change it somehow to work with Vue.

In mustache we simply wrap any strings to be translated with {{#i18n}}…{{/i18n}} markers and a webpack loader takes care of providing a translation function as the i18n property of the state for the compiled template.

Thanks to Oncle Tom’s “SSH deploys with Travis CI“, I’ve now fully automated Moolah deployment for both the client and server.

Previously the client was automated using a cronjob that pulled any changes from GitHub, built and ran the tests and if that all worked resync’d the built resources to apache’s docroot. That meant my not-particularly-powerful server was duplicating the build and test steps already happening in Travis CI and there was up to a 10 minute delay before changes went live.

moment is one of those javascript libraries that just breaks my heart. It does so much right – nearly every date function you’d want right at your finger tips, no major gotchas causing bugs, clean API and good docs. I’ve used moment in some pretty hard code, very date/time orientated apps and been very happy.

But it breaks my heart because when you pull it in via webpack, it winds up being a giant monolithic blob. I only need a couple of date functions but with moment I wind up getting every possible date function you can imagine plus translations into a huge range of languages I don’t need. If I use moment, about 80% of Moolah’s client javascript is moment.

Ultimately the point of Moolah isn’t just to record a bunch of transactions, it’s to provide some insight into how your finances are going. The key question being how much more or less are we spending than we earn? I use a few simple bits of analysis to answer that question in Moolah, the first of which is income vs expenses over the past x months.

The simple way to do that is to show totals based on calendar month (month to date for the current month), but since my salary is paid monthly that doesn’t provide a very useful view of the current month since no income has arrived yet.

Moolah just reached it’s first key milestone – it’s reached “data parity” with the old version. Basically it has enough functionality that it’s viable to import the data from the old version and get the same balances and totals. Using real data that’s been generated over the last 5 years has revealed a few important things.

The good:

• The balances add up so things really are working
• It really does load way faster
• The old version allowed some data inconsistencies that the new version will prevent

The bad: