There and back again: a {json:api} tale at Trainline

Our team was tasked with creating a new RESTful API to help reduce the amount of logic that is implemented in potentially different ways across our front-end channels. One item discussed early on was if we should try using JSON API to structure our responses.

Other teams within Trainline have had some success creating JSON-API-based services in Ruby, and we saw no reason why our C# implementation would be any less successful. This blog post is an attempt to tell the story of the journey we took and where we ended up. Continue reading

Trainline replatforming: our front-end journey

screen-shot-2016-12-16-at-12-47-28

We recently started working on rebuilding the desktop version of the Trainline website. It is a big deal for the front-end engineering team because we have to make sure every choice is justified so that the user experience is never compromised. I am writing this blog post to explain how we went about selecting our front-end tech stack and why we made these choices. Continue reading

Dockerize your WebdriverIO environment to run everywhere

With functional tests being an integral part of a webapp workflow, we should always try to find ways to make them run smoother and make our lives easier.

My dilemma

I’ve been working with Selenium Webdriver/WebdriverIO for years now, but I have always thought: “Wouldn’t it be great not to need a Selenium server running before starting my tests?”

This may seem like a minor problem, but it means having another tab open in my terminal, starting/stopping that process, and it all gets far more difficult when you try to automate it in a CI environment. In addition to that, you need Java installed to run the Selenium server (or you can use the selenium-standalone npm package, which removes the dependency from Java but still needs to be started/stopped). Continue reading

Microservices with API Gateway, AWS Lambda and JVM languages

At Trainline we use AWS Lambda [1] in conjunction with API Gateway [2] for some of our microservices. Different teams use different languages, but in the Data Engineering team we use Clojure [3] – which is a JVM based functional programming language. Here we share some of the experiences we’ve had developing and deploying REST based APIs using JVM based Lambdas.

Although we normally use Clojure, in this blog post we will present a Java based example (for the benefit of a wider audience). However, we expect that the same results would apply to all JVM based languages (Clojure, Scala, Groovy, etc.) Continue reading

Comment nous avons basculé vers la nouvelle API SNCF sans rien casser

(click here for the English version)

En janvier, nous avons appris que la SNCF souhaitait mettre à jour son système tarifaire, c’est-à-dire l’ensemble des règles qui déterminent le prix d’un billet. Elle laissait tomber les prix des périodes d’affluence des TGV, elle diminuait les changements de prix brusques, elle offrait tant de cadeaux aux porteurs de cartes de réduction que ça sentait bon Noël.

Mais ces nobles objectifs s’accompagnent de grands défis. Tout comme une princesse doit combattre un dragon pour délivrer son prince charmant, la SNCF devrait combattre son système tarifaire actuel pour en extraire une perle de ses cendres. Le sang de ce combat ne pouvait éviter de couler sur leurs partenaires : les guichetiers, les agences de voyage, les GDS, et nous.

Un chevalier sur un train

Les systèmes tarifaires n’ont qu’à bien se tenir !

Continue reading

How We Switched Without A Hitch To A New API

(cliquez ici pour la version française)

Back in January, here at Trainline Europe, we learnt that SNCF, the main French railway company, wanted to update their fare system — that is, the set of rules which determine their ticket prices. The plan was to scrap congestion pricing on TGVs (France’s high-speed trains), reduce sudden price increases, introduce so many offers to discount card owners that it would feel like Christmas!

However, those goals were not without challenges. Just as a princess must defeat a dragon to free her Prince Charming, SNCF had to fight the complexity of its current fare system to extract a pearl from its ashes. The blood from this fight had to drip onto their partners: counter agents, travel agencies, GDSes … and yours truly.

Un chevalier sur un train

Fighting fare systems requires extensive equipment.

Continue reading

An Introduction to XUnit, Moq and AutoFixture

When it comes to unit testing .NET applications, there are various frameworks, test runners and libraries available. Teams often undergo meticulous efforts to write the right testing strategy for their applications. We in the Odyssey Team, here at Trainline, have been experimenting with a combination of XUnit, Moq and AutoFixture. These technologies fulfil our needs for writing test suites that are much easier to understand, are robust and are quicker to write.

This short walkthrough will give you a brief introduction to each technology and show you how we’ve been working with them. Continue reading

How we implemented a single-page application using React

BuyNowWeb is our latest offering for Train Operating Companies in the UK to sell train tickets. The solution consists of white-labelled web and mobile applications. This post will look into how we implemented a React-based, white-labelled, single-page application.

Nowadays user devices are much more performant. This has made it possible to run application logic on the client side. JavaScript support in modern browsers has come a long way and websites are providing rich user experience comparable with native applications. Because single-page applications can provide a very engaged user experience, we have architected our application to utilise the capabilities of user devices. React became our technology choice because it is a simple and deterministic way of building a user interface composed of small reusable components. Continue reading

Handling API calls in Redux with Redux API middleware

The context

It is very likely that, at a given point during the development of a client-side web app, it will be necessary to communicate with the server side using a RESTful API. If your stack is based on React/Redux, you may have found yourself wondering about where the ideal spot is to call your API and how to handle your application state based on the outcome of the interaction. Continue reading