I recently had the opportunity to work on a project in which we implemented REST as part of a solution. Since REST simply uses the HTTP protocol, how it is used is open to the desired architecture of the solution as long as it follows the HTTP protocol.

The REST vs SOAP debate is blogged about all over the place so I’m not going to go into that here. I believe, but have no proof, that anywhere SOAP is used, so too can REST with the added benefit that any stream can be returned with REST instead of just xml.

In this post, I am going to present the simplest code sample possible for implementing REST in .Net. In this example I will be returning a stream (formatted to xml, although JSON is certainly another option) and will be doing an HTTP GET to retrieve the information.

So here is the simplest example to get REST in .Net up and running.

This example assume the use of the .Net Framework 4.0.

First create a new WCF Service Application and ensure that you create a reference to the 4.0 .Net library System.ServiceModel.Activation.

The code base consists of three files.

It’s a fairly simple example. I’ve created a REST URI format of the type http://server/simplerest?getnumbers1to&lastnumber=12. If you compile the example and debug it and type that url into the web browser you will see something like this:

<?xml version=”1.0″ encoding=”utf-8″?><numbers><number>1</number><number>2</number>…<number>[lastnumber]</number></numbers>

What is happening in the code:

The web.config file is there for one reason only. The setting up of routes for REST requires the code base to require ASP.NET compatability.  That’s it.

The Global.asax.cs file sets up the REST route table. Essentially you specify as many routes as you want. In this example we picked simplerest which then is required to be part of a query. The route table can also be version friendly, so we could set up a route such as simplerest/v1.0 and so on. You’ll notice the type of the service class is passed to add the new route.

Finally the SimpleRestService is the WCF service. In this example I don’t have an interface because my goal is to make the code base as small as possible. This is the meat of processing the REST GET request. It gets the action for the incoming request, ex. ?action=getnumbersfrom1to. Then it uses the current UriTemplateMatch object to get the lastnumber value. It checks if it’s the one action we support and creates a MemoryStream which contains an xml-friendly format to be displayed in the browser by using an XmlTextWriter.

Why I wrote this example:

To figure out how to do this I did a number of things. First, I bought the following book, which I highly recommend.

I love tech books and I wanted to add this to my library. Then, because I didn’t have the luxury of studying the book, I googled many sites until I figured out how to implement REST for my solution. The problem was, even after googling many sites there was still not a short cohesive example that I could find for setting up REST in the easiest manner possible. For this post, I condensed my knowledge to under 50 lines of code.

What is wrong with this example:

Well, everything, really. The one thing the code does right is it works. Let’s say I was your manager and I asked you to create me a RESTful .Net service and I gave you the REST interface I wanted supported and you delivered me the above piece of code. You’d be fired immediately. The code does not follow an object-oriented design paradigm, there is no error handling, no loose coupling, non-extensible, not data driven, and I can go on. The purpose of this code is so you can take the simplest possible example of what it takes to get a REST service up and running and deploy it in a sound architecture of your choosing.

I hope you enjoyed this REST example as much as I did writing it.