code: function encode(body) {
    // Handles 3 cases
    // - body is utf8 string
    // - body is instance of Buffer
    // - body is an object and its JSON representation is sent
    // Does not handle the case for streaming bodies.
    // Returns buffer.
    if (typeof(body) == 'string') {
      return [new Buffer(body, 'utf8')];
    } else if (body instanceof Buffer) {
      return [body];
    } else {
      var jsonBody = JSON.stringify(body);
      return [new Buffer(jsonBody, 'utf8'), 'application/json'];
    }
  }
docs: either encode msg as json, and return encoded msg and content-type value, or use string value and return null content-type @return [contentType, buffer] Note: implementation ripped out of node-amqp  XXX should this be merged to STOMP? if so, could be optional, triggered only if body is not a string/buffer, and if header has no content-type.