Is REST supported by default in JavaScript and Java or do I need to install new software?

Question

Do I require to install new software to use REST services with JavaScript and Java?

Answer 1

No, you do not. REST services that only use the GET and POST HTTP verbs can be accessed just like any URL in javascript. Most commonly, you'd use AJAX to access a REST service and do something with the response.

Answer 2

You don't need anything beyond a web server. The basic point of REST is this:

• every "resource" has a URI (read "URL") address
• every resource can deal with the four basic HTTP methods: GET, PUT, POST, DELETE

So, let's say you have a customer record, and the record is identified with an ID number. You might have the customer be identified with a URL like

http://example.com/customer/124c41

A GET on that URL would give you the information for display; a PUT would update it; a POST would create it (most people actually use POST where formally you'd want PUT) and a DELETE deletes it.

It's you're responsibility to handle the exact implementation, but that's the model.

Answer 3

Another thing to consider is the client side.

You can use the standard Java SE APIs:

private void updateCustomer(Customer customer) {
    try {
        URL url = new URL("http://www.example.com/customers");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setInstanceFollowRedirects(false);
        connection.setRequestMethod("PUT");
        connection.setRequestProperty("Content-Type", "application/xml");

        OutputStream os = connection.getOutputStream();
        jaxbContext.createMarshaller().marshal(customer, os);
        os.flush();

        connection.getResponseCode();
        connection.disconnect();
    } catch(Exception e) {
        throw new RuntimeException(e);
    }
}

Or you can use the REST client APIs provided by JAX-RS implementations such as Jersey. These APIs are easier to use, but require additional jars on your class path.

WebResource resource = client.resource("http://www.example.com/customers");
ClientResponse response = resource.type("application/xml");).put(ClientResponse.class, "<customer>...</customer.");
System.out.println(response);