'Initialize the service.'

def __init__(self, api_key, app_secret, event, tracker):

    self._api_key = api_key
    self._app_secret = app_secret
    self._event = event
    self._tracker = tracker
    self._headers = {HTTP_HEADER_APPID: self._api_key, HTTP_HEADER_APPSECRET: self._app_secret, HTTP_HEADER_CONTENT_TYPE: CONTENT_TYPE_JSON}
