content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you 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 org.apache.calcite.avatica.remote;
  
  import org.apache.calcite.avatica.remote.Service.RpcMetadataResponse;
  
  import java.util.Objects;
  
  /**
   * API for text request-response calls to an Avatica server.
   *
   * @param <T> The type this handler accepts and returns
   */
  public interface Handler<T> {
    int HTTP_OK = 200;
    int HTTP_BAD_REQUEST = 400;
    int HTTP_UNAUTHENTICATED = 401;
    int HTTP_UNAUTHORIZED = 403;
    int HTTP_INTERNAL_SERVER_ERROR = 500;
    String HANDLER_SERIALIZATION_METRICS_NAME = "Handler.Serialization";
  
    /**
     * Struct that encapsulates the context of the result of a request to Avatica.
     * @param <T> the response type
     */
    class HandlerResponse<T> {
      private final T response;
      private final int statusCode;
  
      public HandlerResponse(T response, int statusCode) {
        this.response = Objects.requireNonNull(response);
        this.statusCode = statusCode;
      }
  
      public T getResponse() {
        return response;
      }
  
      public int getStatusCode() {
        return statusCode;
      }
  
      @Override public String toString() {
        return "Response: " + response + ", Status:" + statusCode;
      }
    }
  
    HandlerResponse<T> apply(T request);
  
    /**
     * Sets some general server information to return to the client in all responses.
     *
     * @param metadata Server-wide information
     */
    void setRpcMetadata(RpcMetadataResponse metadata);
  }
  
  // End Handler.java
  