Android архитектура клиент-серверного приложения

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compile 'com.squareup.retrofit:retrofit:2.0.0-beta1'
compile 'com.squareup.retrofit:converter-gson:2.0.0-beta1'
compile 'com.squareup.okhttp:okhttp:2.0.0'

public class Airport {

    @SerializedName("iata")
    private String mIata;

    @SerializedName("name")
    private String mName;

    @SerializedName("airport_name")
    private String mAirportName;

    public Airport() {
    }
}

public interface AirportsService {

    @GET("/places/coords_to_places_ru.json")
    Call<List<Airport>> airports(@Query("coords") String gps);

}

public class ApiFactory {

    private static final int CONNECT_TIMEOUT = 15;
    private static final int WRITE_TIMEOUT = 60;
    private static final int TIMEOUT = 60;

    private static final OkHttpClient CLIENT = new OkHttpClient();

    static {
        CLIENT.setConnectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS);
        CLIENT.setWriteTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS);
        CLIENT.setReadTimeout(TIMEOUT, TimeUnit.SECONDS);
    }

    @NonNull
    public static AirportsService getAirportsService() {
        return getRetrofit().create(AirportsService.class);
    }

    @NonNull
    private static Retrofit getRetrofit() {
        return new Retrofit.Builder()
                .baseUrl(BuildConfig.API_ENDPOINT)
                .addConverterFactory(GsonConverterFactory.create())
                .client(CLIENT)
                .build();
    }
}

public class MainActivity extends AppCompatActivity implements Callback<List<Airport>> {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        AirportsService service = ApiFactory.getAirportsService();
        Call<List<Airport>> call = service.airports("55.749792,37.6324949");
        call.enqueue(this);
    }

    @Override
    public void onResponse(Response<List<Airport>> response) {
        if (response.isSuccess()) {
            List<Airport> airports = response.body();
            //do something here
        }
    }

    @Override
    public void onFailure(Throwable t) {
    }
}