I spent a lot of time in my childhood and early twenties traveling on the Irish Rail Network. Mostly this seemed to involve waiting for ages at Limerick Junction or barely finding a space to stand on a packed train from Dublin. Those experiences didn’t exactly leave me with a great impression of Iarnród Éireann.
Given this, I was amazed to find out recently, that Iarnród Éireann have an XML API for accessing realtime data about the trains running on their network. Credit where credit is due, this is an excellent idea and I wish more companies would implement something similar.
The API provides functionality for getting a list of the stations and what trains are due at those stations in the next ninety minutes. It also gives a list of all trains active on the network. It can filter by DART, Suburban or Mainline trains (that leaves some trains in an ‘other’ category - I’m not too sure what these actually are).
I used this API as part of a Backbone learning project. It was quite fun to do. The API returns latitude and longitude coordinates for each station and train, allowing them to be plotted on a Google Map widget. I never realised there were so many stations in Ireland until I saw them plotted on the map.
One issue I ran into was testing the application with live data. Given that I was programming this at night after work, you’d soon reach a time when there are very few trains left on the network!
One technical detail about the API is that it is in XML rather than JSON. This means that I can’t use Ajax or JSONP to get the data, due to the same origin policy. Instead I had to bounce the results through YQL. YQL exposes a SQL like interface to web data. I’m only using a basic ‘select all’ query here but looking at their site you can do lots of cool and complex stuff. I found a good tutorial from Cypress North on how to use YQL in your code to consume an XML API.