vREST

Simple single class REST server using Java SE only.

Jave SE 1.6 or above
No HTTP server / servlet container required
Uses Java SE socket to listen and process client requests
Multi-threaded request processing (100 threads by default)
Uses jackson mapper (org.codehaus.jackson) for JSON processing
Automatic scanning of all REST resources in current classpath (no configurations required)

Limitations:

Not a production ready server (for quick REST services testing only)
supports JSON data communications only

Setup

Download or checkout and run following maven command:

$ mvn compile
$ mvn exec:exec -DRESTServer

This command should scan all the classes in current directory for REST resources and listens on 4001 port:

$ mvn exec:exec -DRESTServer
[INFO] Scanning for projects...
...
[INFO] --- exec-maven-plugin:1.3.2:exec (default-cli) @ vjrest ---
INFO: scanning resources...
INFO: Found api: CityResource.delete => /cities/:city
INFO: Found api: CityResource.all => /cities
INFO: Found api: CityResource.create => /cities/new
INFO: Found api: CityResource.update => /cities/:city
INFO: Found api: CityResource.getCity => /cities/:city
INFO: Found api: CityResource.echo => /echo/:str
INFO: Found api: CityResource.getRequestParams => /params
INFO: scanning completed.
INFO: starting server...
INFO: listening on http://localhost:4001

Usage

Import static properties from RESTServer class and add @Resource annotation with path to any POJO (or non-POJO) classes:

import static com.kumarvv.vrest.RESTServer.*;

@Resource("/cities")
public class CityResource {
...

Add @GET (or @POST, @PUT, @UPDATE) annotation to the class method. This annotation also supports resource path to append to class resource path.

@GET
public Map<String, City> all() {
...

@GET("favorties")  // resolves to "/cities/favorites"
public Map<String, City> favorites() {
	return cities;
}

Add @Param to inject request or url parameter value to method arguments:

@GET(":city")
public City getCity(@Param("city") String cityCode) {
	return cities.get(cityCode);
}

Request using /cities/NYC url will pass the NYC value to cityCode method argument. Add @Data to inject request payload (form-data) to method argument:

@PUT(":city")
public City update(@Param("city") String cityCode, @Data City upd) {
	City city = cities.get(cityCode);
...

Sample REST Resource class

import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import static com.kumarvv.vrest.RESTServer.*;

/**
 * Sample request with full CRUD
 */
@Resource("/cities")
public class CityResource {

	private static Map<String, City> cities;
	static {
		cities = new HashMap<String, City>();
		cities.put("NYC", new City("NYC", "New York"));
		cities.put("LAX", new City("LAX", "Los Angeles"));
		cities.put("SFO", new City("SFO", "San Francisco"));
		cities.put("BOS", new City("BOS", "Boston"));
	}

	@GET
	public Map<String, City> all() {
		return cities;
	}

	@GET(":city")
	public City getCity(@Param("city") String cityCode) {
		return cities.get(cityCode);
	}

	@POST("new")
	public City create(@Data City city) {
		city.setCreatedAt(new Date());
		cities.put(city.getCode(), city);
		return city;
	}

	@PUT(":city")
	public City update(@Param("city") String cityCode, @Data City upd) {
		City city = cities.get(cityCode);
		if (city != null) {
			city.setName(upd.getName());
			city.setUpdatedAt(new Date());
			cities.put(city.getCode(), city);
			return city;
		} else {
			return null;
		}
	}

	@DELETE(":city")
	public String delete(@Param("city") String cityCode) {
		cities.remove(cityCode);
		return "City [" + cityCode + "] deleted successfully";
	}

	@GET("/echo/:str")
	public String echo(@Param("str") String str) {
		return "echo: " + str;
	}

	@GET("/params")
	public Map<String, String> getRequestParams(@Params Map<String, String> params) {
		return params;
	}
}

This class generates REST resources in following context paths:

GET /cities          => maps to CityResource.all() 
GET /cities/:city    => maps to CityResource.getCity()
POST /cities/new     => maps to CityResource.create() 
PUT /cities/:city    => maps to CityResource.update() 
DELETE /cities/:city => maps to CityResource.delete() 
GET /echo/:str       => maps to CityResource.echo() 
GET /params          => maps to CityResource.getRequestParams()

Note on /echo/:str, starting with / in @GET("/echo/:str") makes the resource to be at root bypassing the @Resource annotation at class level. All other resources have /cities as prefix from @Resource annotation.

Sample Request/Response

GET request of http://localhost:4001/cities/NYC will return following json:

{
    "code": "NYC",
    "name": "New York",
    "created": "Sun Jul 18 13:24:12 EDT 2014",
    "updated": "Sun Jul 18 13:24:34 EDT 2014"
}