What is the difference between REST and HTTP protocols?

Question

What is the REST protocol and what does it differ from HTTP protocol ?

Answer 1

REST is an approach that leverages the HTTP protocol, and is not an alternative to it.

• http://en.wikipedia.org/wiki/Representational_State_Transfer

Data is uniquely referenced by URL and can be acted upon using HTTP operations (GET, PUT, POST, DELETE, etc). A wide variety of mime types are supported for the message/response but XML and JSON are the most common.

For example to read data about a customer you could use an HTTP get operation with the URL http://www.example.com/customers/1. If you want to delete that customer, simply use the HTTP delete operation with the same URL.

The Java code below demonstrates how to make a REST call over the HTTP protocol:

String uri =
    "http://www.example.com/customers/1";
URL url = new URL(uri);
HttpURLConnection connection =
    (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("Accept", "application/xml");

JAXBContext jc = JAXBContext.newInstance(Customer.class);
InputStream xml = connection.getInputStream();
Customer customer =
    (Customer) jc.createUnmarshaller().unmarshal(xml);

connection.disconnect();

For a Java (JAX-RS) example see:

• http://bdoughan.blogspot.com/2010/08/creating-restful-web-service-part-45.html