No available client connector supports the required protocol: 'HTTP'

Greeting. I am playing with Restlet fr开发者_如何学编程amework, when I am running following code getting and exception Internal Connector Error (1002) - No available client connector supports the required protocol: 'HTTP'.

ClientResource cr = new ClientResource(
"http://127.0.0.1:8888/user/123");
UserResource resource = cr.wrap(UserResource.class);
User user = new User();
user.setName("xxx");
user.setPassword("xxx");
UserValidation userValidation = resource.retrieve(user);
if (userValidation != null) {
  System.out.println("Welcome, User");
} else {
  System.out.println("Not a vliad user");
}

Is there anybody here tried the Retlet before? Can guide me to proper direction? Or can redirect to helpfull tutorial?

---

Restlet depends on "connectors" to implement clients and servers. They're kind of like plugins, in that they're modular, and you can easily choose which to use. At runtime, Restlet checks the classpath to see which connectors are available, and loads them. Each connector is packaged in 1 JAR file for the connector itself plus N files for dependencies. So you can make a connector available to the framework by simply adding the relevant JARs to the classpath.

You must be using Restlet 1.0 or 1.1, because 2.0 includes simple built-in HTTP client and server connectors. I suggest you upgrade to 2.0; it's a lot easier to develop with because a single JAR contains the framework, engine, and the built-in connectors; with 1.1 you can sometimes need 6-7 JARs just to test a simple app.