Object http provides access to Http client and gives information about HTTP responses:

http.client Returns instance of org.apache.commons.httpclient.HttpClient class which is used as primary HTTP client during the configuration execution.
http.contentLength Lenght of the last HTTP response's content in bytes.
http.charset Encoding of the last HTTP response, if it contain textual content.
http.mimeType Mime type of the last HTTP response.
http.headers Map of last HTTP response's headers. To access individual header, use http.headers.get("headername").
http.statusCode Status code of the last HTTP response.
http.statusText Status message of the last HTTP response.
http.totalLength Total length in bytes of all responses returned to this HTTP client.
http.totalResponses Total number of responses returned to this HTTP client.