The timeout can appear when the web service is failed respond to the client's request. In this case, the ESAPI service instance closes itself.
The timeout value is measured in milliseconds.
The following WebAPI method has response timeout:
DEFINE ses web.Session
DEFINE rq web.Request
DEFINE rs web.Response
....
....
CALL ses.perform(rq.param("timeout","1000")) RETURNING rs
DISPLAY rs.GetHTTPCode()
LET s = rs.getBody()