I’ve been reading and thinking about RESTful web applications and services quite a bit recently. The last large web application I wrote evolved into a RESTful web application: readable, bookmarkable URLs; resources with unique addresses; and alternative renderings of a resource depending on the request.
It would have been a short step to complete this evolution and then expose the programmable interface as RESTful as well. This all happened without being aware of REST: it just seemed like the logical way to design a web application.
REST is starting to make a big splash now. Web services have been around for a few years, and many systems have been built upon them. Beyond the architectural considerations, it seems that the main differences between the two approaches is that it is easier to write clients for a RESTful service, and it is easier to write the service using SOAP.
Up until recently most of the development of web services has been for systems that do not cross organisation boundaries. Therefore, the consumer of the web service has usually been the programmer who wrote it. Or, if not actually the same programmer, then a programmer in the same organisation. SOAP works well in this environment as one development tool can be mandated and this tool can generate all the painful code required to consume a SOAP service, and when the SOAP service changes every single consumer can be informed.
However, now there are many services being exposed on the Internet that provide useful data. Services such as Google Maps. It is becoming more common to write applications that consume a handful of services from different organisations. Suddenly, it is more important for the client to be robust and easy to write.
Unfortunately though, it is still much easier to write the service using SOAP than REST. Most web servers don’t deal well with the concept of the URI not referring to an actual file on disk, and there aren’t many frameworks that put resources rather pages at the centre. There seems to a hole in the eco-system here.
I’m going to take a shot at filling it. For this project, as I’ll be doing this for interest and to learn, I’m going to talk about what I do as I do it. Ruby On Rails will ultimately provide the full RESTful service framework that the world needs; I’m not expecting to make money off this project. No need to hide anything.
I’ve started writing some code, and planning a simple design. I’m going to make some apparently unusual technology choices, but this is for my learning. I’ll talk about the technology and design in some upcoming posts.