AsyncHttpFetch.h

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/*
 * Copyright (c) 2013 LinkedIn Corp. 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.
 *
 */

/**
 * @file AsyncHttpFetch.h
 * @author Brian Geffon
 * @author Manjesh Nilange
 */

#pragma once
#ifndef ATSCPPAPI_ASYNCHTTPFETCH_H_
#define ATSCPPAPI_ASYNCHTTPFETCH_H_

#include <string>
#include <atscppapi/shared_ptr.h>
#include <atscppapi/Async.h>
#include <atscppapi/Request.h>
#include <atscppapi/Response.h>

namespace atscppapi {

// forward declarations
class AsyncHttpFetchState;
namespace utils { class internal; }

/**
 * @brief This class provides an implementation of AsyncProvider that
 * makes HTTP requests asynchronously. This provider automatically
 * self-destructs after the completion of the request.
 *
 * See example async_http_fetch for sample usage.
 */
class AsyncHttpFetch : public AsyncProvider {
public:
  AsyncHttpFetch(const std::string &url_str, HttpMethod http_method = HTTP_METHOD_GET);

  /**
   * Used to manipulate the headers of the request to be made.
   *
   * @return A reference to mutable headers.
   */
  Headers &getRequestHeaders();

  enum Result { RESULT_SUCCESS = 10000, RESULT_TIMEOUT, RESULT_FAILURE };

  /**
   * Used to extract the response after request completion. 
   *
   * @return Result of the operation
   */
  Result getResult() const;

  /**
   * @return Non-mutable reference to the request URL.
   */
  const Url &getRequestUrl() const;

  /**
   * Used to extract the response after request completion. 
   *
   * @return Non-mutable reference to the response.
   */
  const Response &getResponse() const;

  /**
   * Used to extract the body of the response after request completion. On
   * unsuccessful completion, values (NULL, 0) are set.
   *
   * @param body Output argument; will point to the body
   * @param body_size Output argument; will contain the size of the body 
   * 
   */
  void getResponseBody(const void *&body, size_t &body_size) const;

  virtual ~AsyncHttpFetch();

  /**
   * Starts a HTTP fetch of the Request contained.
   */  
  virtual void run(shared_ptr<AsyncDispatchControllerBase> dispatch_controller);

private:
  AsyncHttpFetchState *state_;
  friend class utils::internal;
};

} /* atscppapi */

#endif /* ATSCPPAPI_ASYNCHTTPFETCH_H_ */