# File lib/casclient/client.rb, line 82
    def validate_service_ticket(st)
      uri = URI.parse(validate_url)
      h = uri.query ? query_to_hash(uri.query) : {}
      h['service'] = st.service
      h['ticket'] = st.ticket
      h['renew'] = 1 if st.renew
      h['pgtUrl'] = proxy_callback_url if proxy_callback_url
      uri.query = hash_to_query(h)
      
      st.response = request_cas_response(uri, ValidationResponse)
      
      return st
    end