For several years, much of the code for the systems at thetrainline.com has been versioned and deployed together as a single ‘platform’. Recently, we have begun to divide up the platform into smaller chunks, to enable us to deliver some parts more frequently and rapidly, leaving other parts to evolve more slowly (as needed). Moving from a single version number for all subsystems to multiple version numbers for independent subsystems has implications for how code is built and released; this blog post outlines some of the work we have done so far in this area.

My colleague Owain Perry and I recently presented on this topic at the London Continuous Delivery meetup group (http://londoncd.org.uk/) and the slides we showed relate to the details in this post: