java/src/main/com/google/appengine/api/search/SearchApiHelper.java

   1 // Copyright 2010 Google Inc. All rights reserved.
   2 package com.google.appengine.api.search;
   3
   4 import com.google.appengine.api.utils.FutureWrapper;
   5 import com.google.apphosting.api.ApiProxy;
   6 import com.google.protobuf.GeneratedMessage;
   7 import com.google.protobuf.InvalidProtocolBufferException;
   8
   9 import java.util.concurrent.Future;
  10
  11 /**
  12  * Provides support for translation of calls between userland and appserver
  13  * land.
  14  *
  15  */
  16 class SearchApiHelper {
  17
  18   private static final String PACKAGE = "search";
  19
  20   /**
  21    * Makes an asynchronous call.
  22    *
  23    * @param method the method on the API to call
  24    * @param request the request to forward to the API
  25    * @param responseBuilder the response builder used to fill the response
  26    * from the call
  27    */
  28   <T extends GeneratedMessage.Builder<T>>
  29   Future<T> makeAsyncCall(String method, GeneratedMessage request, final T responseBuilder) {
  30     Future<byte[]> response =
  31         ApiProxy.makeAsyncCall(PACKAGE, method, request.toByteArray());
  32     return new FutureWrapper<byte[], T>(response) {
  33       @Override
  34       protected T wrap(byte[] responseBytes) {
  35         if (responseBytes != null) {
  36           try {
  37             responseBuilder.mergeFrom(responseBytes);
  38           } catch (InvalidProtocolBufferException e) {
  39             throw new SearchServiceException(e.toString());
  40           }
  41         }
  42         return responseBuilder;
  43       }
  44
  45       @Override
  46       protected Throwable convertException(Throwable cause) {
  47         return cause;
  48       }
  49     };
  50   }
  51 }