Introduction

Perhaps one of the most compelling reasons to use Representational state transfer (REST) is its focus on developing a design based on the concept of a remote resource. You could imagine that an application based on group messaging would require services where users could exchange messages; client applications would communicate by making HTTP connections to remote resources—the remote resource for a group called My Best Friends might be /groups/MyBestFriends. You could query to see what messages were available request by accessing that URL. You could send new messages to that group by sending an HTTP POST to it—the HTTP POST request could contain a JSON object with the sender's name, the text of the message, and other details. You could just as easily remove this group when it's no longer required by sending HTTP DELETE request to the same endpoint. You could specify that you need only JSON data by sending an Accept header set to application/json or specify that you want a web page by asking for application/html. The RESTful approach of designing a remote resource and then interoperating with that resource through simple HTTP calls naturally extends the Web.

ServiceStack's message-based approach often leads to a simpler service interface. SOAP, Microsoft WCF, and even WebAPI encourage a remote procedure call (RPC) style of programming, which encourages the creation of more and more methods—while a message-based approach encourages you to think about your API. We are aware of one project that took an RPC-based approach over two or three years and ended up with over seventy distinct methods being published. A redesign and the careful application of the message pattern reduced this to just two different REST resources. The result was far more manageable—it was also easier to extend, maintain, test, secure, and document.

While a full treatment of developing REST services is outside the scope of this book, the authors will purposefully take a RESTful approach to building services throughout the example. This is not by accident—and is made much easier when working with ServiceStack.