By David Ingham from Bury, Lancashire, England (P2204757 Uploaded by oxyman) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Changing the Primary Key Type in Ruby on Rails Models

Ruby on Rails (RoR) likes to emphasise the concept of convention over configuration. Therefore, it seeks to minimialise the amount of configuration by resorting to some defaults. These defaults are sometimes not desirable, and RoR does not always make it easy to deviate from these defaults.

My little Backpressure: Flow Control is magic

When we’re designing systems that are designed to be robust against failure, it’s important to know how behaviour at your Integration points (a term borrowed from Michael Nygard’s book Relase It!) impacts the rest of the system. For example, if your database or a remote API is running slowly, then in Synchronous systems, because you…

Testing the Reactor pattern

A good while ago I wrote a SIP stack. Like many network things, a SIP stack needs to keep track of multiple tasks – reading or writing from sockets, asking the user to respond to events, and so on. And so I naïvely added a bunch of threads. And then I spent a few weeks…

Precise scheduling with RabbitMQ

On a project recently, we needed to be able to process jobs asynchronously, but we also needed to be able to specify that they should be run at a certain point in the future. We also needed to be able to implement exponential backoff on failure. We initially tried to integrate Sidekiq, but unfortunately it…

Assuming there’s a user is sometimes a bad idea

Squeak has a very strong (historic) assumption that there’s a(n interactive) user interface. I stumbled across another occurrence of this assumption the other day. Let’s take a look at the problem, and how to fix it.

The great GC vs reference counting debate

I read a blog post post recently to the effect that GC is too expensive in mobile devices, Steve Jobs was right, reference counting is the way. It’s titled ‘why mobile web apps are slow’. I’m inclined to take issue with this: It’s a long since resolved dispute, and GC won. I don’t want Steve…

Delimited dynamic variables from call/cc

I’m prepared to own up to my biases. I like delimited continuations. I like zippers. I like getting halfway through my work, shelving my work for a time, and coming back to it later. We’ve seen the relationship between resumable exceptions and delimited dynamic variables before, but what about languages where you don’t have direct…

Controlling fast producers in a Rabbit-as-a-Service

Offering a RabbitMQ server on the public internet poses a few challenges. Today we’ll look at the problem of controlling fast producers.

POSIX Threads and fork(2): on not crossing the streams

You’ve maybe heard that with C and C++, it’s rarely a good idea to mix usage of the POSIX threading library, and fork(2) based concurrency. I’d heard this myself, but to be honest, I never quite understood why.

Hybrid apps

We recently developed an iPad app. It’s requirements were very simple: Essentially, the app was to be a brochure that a salesperson could use to demonstrate and talk about products with a customer. It needed to be able to display text and videos, and provide links to further online web resources and PDFs. iOS development…