AutoREST Nominatim Example

AutoREST generates utility code which should help you extract the request data on each endpoint call and use it to populate a request. So in simplified example you define…

@AutoRestGwt @Path("search") interface Nominatim {
  @GET Observable<SearchResult> search(@QueryParam("q") String query);
}

AutoREST generates a Nominatim_RestServiceModel, and you should implement a ResourceVisitor provided as factory to the model, this makes your services instantiations similar to…

Nominatim nominatim = new Nominatim_RestServiceModel(DummyResourceVisitor::new);
nominatim.search("málaga").subscribe(n -> out.println("received " + n));

…on each call to the model (like the previous .search("málaga")) a new visitor (like next one) is evaluated…

class DummyResourceVisitor {
  public ResourceVisitor path(Object... paths) { out.println("path " + Arrays.toString(paths)); return this; }
  public ResourceVisitor param(String key, @Nullable Object value) { out.println("param " + key + "=" + value); return this; }
  public ResourceVisitor method(String method) { out.println("method " + method); return this; }
  public <T> T as(Class<? super T> container, Class<?> type) { return null; }
}

…producing this output "method GET" ⏎ "path [search]" ⏎ "param q=málaga".

Ok, this dummy visitor makes nothing, just print Request configuration, do not even generate a request. Gathering the request data, creating a request and handling the response into the expected type is now your responsibility. BUT this project try to demonstrate how moving the responsibility out of the library and giving to you the full control of the request building, request encoding and response decoding is not only much easier, simpler and clear as you may expect, but also make it almost trivial to extend and customize your services.

AutoREST separates services handling in three responsibilities

• schema defines the REST service interface and models using JAX-RS standard
• request the goal of client side services is to create a request to transfer the payload
• codec the url, headers and request payload should be encoded/decoded

You should note that AutoREST should not build the request (althought include a basic implementation), do not implement codecs, and schema definition uses the standard JAX-RS, so not AutoREST involved neither. For all this, AutoREST should be considered a blueprint which help you organize this responsabilities giving a common template and best practices to keep service implementation clean and simple.

Modules

Client modules of this project shows how to implement the request and codec responsibilities for various environments, API module shows how to define the service schema in one place and share this schema not only between the different client but also with the server implementation.

• api module contains the Nominatim scheme definition (models as inner classes), and is shared between the other modules
• client implementations: uses the API to build a request
  • jre module
  • gwt module
• server implementations: uses the API to expose a service
  • server module implements the Nominatim service definition as ResourceNominatim, and exposes it using a jetty + jersey + jackson server. Configuration of this libraries are all here and you can run the server as an plain java using the Main.main.