interface MessageInterface

1. 8.x drupal/core/modules/contact/lib/Drupal/contact/MessageInterface.php \Drupal\contact\MessageInterface
2. 8.x drupal/core/vendor/guzzle/http/Guzzle/Http/Message/MessageInterface.php \Guzzle\Http\Message\MessageInterface

interface MessageInterface {

  /**
   * Get application and plugin specific parameters set on the message.
   *
   * @return Collection
   */
  public function getParams();

  /**
   * Add a header to an existing collection of headers.
   *
   * @param string $header Header name to add
   * @param string $value  Value of the header
   *
   * @return MessageInterface
   */
  public function addHeader($header, $value);

  /**
   * Add and merge in an array of HTTP headers.
   *
   * @param array $headers Associative array of header data.
   *
   * @return MessageInterface
   */
  public function addHeaders(array $headers);

  /**
   * Retrieve an HTTP header by name. Performs a case-insensitive search of all headers.
   *
   * @param string $header Header to retrieve.
   * @param bool   $string Set to true to get the header as a string
   *
   * @return string|Header|null Returns NULL if no matching header is found. Returns a string if $string is set to
   *                            TRUE. Returns a Header object if a matching header is found.
   */
  public function getHeader($header, $string = false);

  /**
   * Get a tokenized header as a Collection
   *
   * @param string $header Header to retrieve
   * @param string $token  Token separator
   *
   * @return Collection|null
   */
  public function getTokenizedHeader($header, $token = ';');

  /**
   * Set a tokenized header on the request that implodes a Collection of data into a string separated by a token.
   *
   * @param string           $header Header to set
   * @param array|Collection $data   Header data
   * @param string           $token  Token delimiter
   *
   * @return MessageInterface
   * @throws InvalidArgumentException if data is not an array or Collection
   */
  public function setTokenizedHeader($header, $data, $token = ';');

  /**
   * Get all headers as a collection
   *
   * @param bool $asObjects Set to true to retrieve a collection of Header objects
   *
   * @return Collection Returns a {@see Collection} of all headers
   */
  public function getHeaders($asObjects = false);

  /**
   * Get an array of message header lines
   *
   * @return array
   */
  public function getHeaderLines();

  /**
   * Check if the specified header is present.
   *
   * @param string $header The header to check.
   *
   * @return bool Returns TRUE or FALSE if the header is present
   */
  public function hasHeader($header);

  /**
   * Remove a specific HTTP header.
   *
   * @param string $header HTTP header to remove.
   *
   * @return MessageInterface
   */
  public function removeHeader($header);

  /**
   * Set an HTTP header
   *
   * @param string $header Name of the header to set.
   * @param mixed  $value  Value to set.
   *
   * @return MessageInterface
   */
  public function setHeader($header, $value);

  /**
   * Overwrite all HTTP headers with the supplied array of headers
   *
   * @param array $headers Associative array of header data.
   *
   * @return MessageInterface
   */
  public function setHeaders(array $headers);

  /**
   * Get the raw message headers as a string
   *
   * @return string
   */
  public function getRawHeaders();

  /**
   * Get a Cache-Control directive from the message
   *
   * @param string $directive Directive to retrieve
   *
   * @return null|string
   */
  public function getCacheControlDirective($directive);

  /**
   * Check if the message has a Cache-Control directive
   *
   * @param string $directive Directive to check
   *
   * @return bool
   */
  public function hasCacheControlDirective($directive);

  /**
   * Add a Cache-Control directive on the message
   *
   * @param string      $directive Directive to set
   * @param bool|string $value     Value to set
   *
   * @return MessageInterface
   */
  public function addCacheControlDirective($directive, $value = true);

  /**
   * Remove a Cache-Control directive from the message
   *
   * @param string $directive Directive to remove
   *
   * @return MessageInterface
   */
  public function removeCacheControlDirective($directive);

}