com.google.api.server.spi.discovery.ProxyingDiscoveryProvider Maven / Gradle / Ivy

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A framework for building RESTful web APIs.
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/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.api.server.spi.discovery;

import com.google.api.server.spi.Client;
import com.google.api.server.spi.config.ApiConfigException;
import com.google.api.server.spi.config.ApiConfigWriter;
import com.google.api.server.spi.config.model.ApiConfig;
import com.google.api.server.spi.config.model.ApiKey;
import com.google.api.server.spi.response.InternalServerErrorException;
import com.google.api.server.spi.response.NotFoundException;
import com.google.api.services.discovery.Discovery;
import com.google.api.services.discovery.model.ApiConfigs;
import com.google.api.services.discovery.model.DirectoryList;
import com.google.api.services.discovery.model.RestDescription;
import com.google.api.services.discovery.model.RpcDescription;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

import java.io.IOException;
import java.util.Map;
import java.util.logging.Level;

/**
 * Provides discovery information by proxying to the v1.0 discovery service.
 */
public class ProxyingDiscoveryProvider extends AbstractDiscoveryProvider {

  private final ApiConfigWriter configWriter;
  private final Discovery discovery;

  public ProxyingDiscoveryProvider(
      ImmutableList apiConfigs, ApiConfigWriter configWriter) {
    this(apiConfigs, configWriter, createDiscovery());
  }

  public ProxyingDiscoveryProvider(
      ImmutableList apiConfigs, ApiConfigWriter configWriter, Discovery discovery) {
    super(apiConfigs);
    this.configWriter = configWriter;
    this.discovery = discovery;
  }

  @Override
  public RestDescription getRestDocument(String root, String name, String version)
      throws NotFoundException, InternalServerErrorException {
    try {
      return discovery.apis()
          .generateRest(new com.google.api.services.discovery.model.ApiConfig().setConfig(
              getApiConfigStringWithRoot(getApiConfigs(name, version), root))).execute();
    } catch (IOException | ApiConfigException e) {
      logger.log(Level.SEVERE, "Could not generate or cache discovery doc", e);
      throw new InternalServerErrorException("Internal Server Error", e);
    }
  }

  @Override
  public RpcDescription getRpcDocument(String root, String name, String version)
      throws NotFoundException, InternalServerErrorException {
    try {
      return discovery.apis()
          .generateRpc(new com.google.api.services.discovery.model.ApiConfig().setConfig(
              getApiConfigStringWithRoot(getApiConfigs(name, version), root))).execute();
    } catch (IOException | ApiConfigException e) {
      logger.log(Level.SEVERE, "Could not generate or cache discovery doc", e);
      throw new InternalServerErrorException("Internal Server Error", e);
    }
  }

  @Override
  public DirectoryList getDirectory(String root) throws InternalServerErrorException {
    try {
      Map configStrings =
          configWriter.writeConfig(rewriteConfigsWithRoot(getAllApiConfigs(), root));
      ApiConfigs configs = new ApiConfigs();
      configs.setConfigs(Lists.newArrayList(configStrings.values()));
      return discovery.apis().generateDirectory(configs).execute();
    } catch (IOException | ApiConfigException e) {
      logger.log(Level.SEVERE, "Could not generate or cache directory", e);
      throw new InternalServerErrorException("Internal Server Error", e);
    }
  }

  private String getApiConfigStringWithRoot(ImmutableList configs, final String root)
      throws InternalServerErrorException, ApiConfigException {
    Map configMap = configWriter.writeConfig(rewriteConfigsWithRoot(configs, root));
    if (configMap.size() != 1) {
      logger.severe("config generation yielded more than one API");
      throw new InternalServerErrorException("Internal Server Error");
    }
    return Iterables.getFirst(configMap.values(), null);
  }

  private static Discovery createDiscovery() {
    Client client = Client.getInstance();
    return new Discovery.Builder(client.getHttpTransport(), client.getJsonFactory(),
        null /* httpRequestInitializer */) .build();
  }
}